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PubMed1997

NTP Toxicology and Carcinogenesis Studies of Molybdenum Trioxide (CAS No. 1313-27-5) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Molybdenum is an essential element for the function of nitrogenase in plants and as a cofactor for enzymes including xanthine oxidoreductase, aldehyde oxidase, and sulfide oxidase in animals. Molybdenum trioxide is used primarily as an additive to steel and corrosion-resistant alloys. It is also used as a chemical intermediate for molybdenum products; an industrial catalyst; a pigment; a crop nutrient; components of glass, ceramics, and enamels; a flame retardant for polyester and polyvinyl chloride resins; and a reagent in chemical analyses. Molybdenum trioxide was nominated by the NCI for toxicity and carcinogenicity studies as a representative inorganic molybdenum compound. The production of molybdenum trioxide is the largest of all the molybdenum compounds examined. Male and female F344/N rats and B6C3F1 mice were exposed to molybdenum trioxide (approximately 99% pure) by inhalation for 14 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells. 14-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 3, 10, 30, 100, or 300 mg molybdenum trioxide/m(3). Rats were exposed for 6 hours per day, 5 days per week, for a total of 10 exposure days during a 14-day period. All rats survived to the end of the study. The final mean body weights of male rats exposed to 100 mg/m(3) and male and female rats exposed to 300 mg/m(3) were significantly lower than those of the control groups. Male rats exposed to 300 mg/m(3) lost weight during the study. There were no clinical findings related to exposure to molybdenum trioxide. No chemical-related lesions were observed. 14-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 3, 10, 30, 100, or 300 mg molybdenum trioxide/m(3). Mice were exposed 6 hours per day, 5 days per week, for a total of 10 exposure days during a 14-day period. All mice survived to the end of the study. Final mean body weights of male and female mice exposed to 300 mg/m(3) were significantly lower than those of the control groups. Male mice exposed to 300 mg/m(3) lost weight during the study. There were no clinical findings related to exposure to molybdenum trioxide. No chemical-related lesions were observed. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to molybdenum trioxide by inhalation at concentrations of 0, 1, 3, 10, 30, or 100 mg/m(3) for 6.5 hours per day, 5 days per week, for 13 weeks. All rats survived to the end of the study. The final mean body weights of exposed rats were similar to those of the control groups. No clinical findings related to molybdenum trioxide exposure were observed. There were no significant chemical-related differences in absolute or relative organ weights, hematology or clinical chemistry parameters, sperm counts or motility, or liver copper concentrations between control and exposed rats. No chemical-related lesions were observed. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to molybdenum trioxide by inhalation at concentrations of 0, 1, 3, 10, 30, or 100 mg/m(3) for 6.5 hours per day, 5 days per week, for 13 weeks. All mice survived to the end of the study. The final mean body weights of exposed mice were similar to those of the control groups. There were no chemical-related clinical findings. There were no significant differences in absolute or relative organ weights or sperm counts or motility between control and exposed mice. There were significant increases in liver copper concentrations in female mice exposed to 30 mg/m(3) and in male and female mice exposed to 100 mg/m(3) compared to those of the control groups. No chemical-related lesions were observed. 2-YEAR STUDIES IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to molybdenum trioxide by inhalation at concentrations of 0, 10, 30, or 100 mg/m(3). Rats were exposed for 6 hours per day, 5 days per week, for 106 weeks. Survival, Body Weights, and Special Studies: Survival rates of exposed maleed male and female rats were similar to those of the control groups. Mean body weights of exposed groups of male and female rats were similar to those of the control groups throughout the study. There was a significant exposure-dependent increase in blood molybdenum concentration in exposed rats. Blood concentrations of molybdenum in exposed male rats were greater than those in exposed female rats. There were no toxicologically significant differences in bone density or curvature between control and exposed rats. Pathology Findings: The incidences of alveolar/bronchiolar adenoma or carcinoma (combined) were increased in male rats with a marginally significant positive trend. No increase in the incidences of lung neoplasms occurred in female rats. Incidences of chronic alveolar inflammation in male and female rats exposed to 30 or 100 mg/m(3) were significantly greater than those in the control groups. No nasal or laryngeal neoplasms were attributed to exposure to molybdenum trioxide. Incidences of hyaline degeneration in the nasal respiratory epithelium in 30 and 100 mg/m(3) males and in all exposed groups of females were significantly greater than those in the control groups. The incidences of hyaline degeneration in the nasal olfactory epithelium of all exposed groups of females were significantly greater than that in the control group. In the larynx, incidences of squamous metaplasia of the epithelium lining the base of the epiglottis in all exposed groups of male and female rats were significantly greater than those in the control groups and increased with increasing exposure concentration. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were exposed to molybdenum trioxide by inhalation at concentrations of 0, 10, 30, or 100 mg/m(3). Mice were exposed for 6 hours per day, 5 days per week, for 105 weeks. Survival, Body Weights, and Special Studies: The survival rate of male mice exposed to 30 mg/m(3) was marginally lower than that of the control group; survival rates of 10 and 100 mg/m(3) males and of all exposed groups of females were similar to those of the control groups. Mean body weights of exposed male mice were generally similar to those of the control group throughout the study. Mean body weights of exposed female mice were generally greater than those of the control group from week 11 until the end of the study. There was a significant exposure-dependent increase in blood molybdenum concentration in exposed mice. There were no toxicologically significant differences in bone density or curvature between control and exposed mice. Pathology Findings: The incidences of alveolar/bronchiolar carcinoma in all exposed groups of males were significantly greater than that in the control group. Incidences of alveolar/bronchiolar adenoma in females in the 30 and 100 mg/m(3) groups were significantly greater than that in the control group. Incidences of alveolar/bronchiolar adenoma or carcinoma (combined) in 10 and 30 mg/m(3) males and in 100 mg/m(3) females were significantly greater than those in the control groups and exceeded the historical control ranges for 2-year NTP inhalation studies. Incidences of metaplasia of the alveolar epithelium of minimal severity in the centriacinar region of the lung were significantly increased in all exposed groups of mice. The incidences of histiocyte cellular infiltration in all exposed groups of males were significantly greater than that in the control group. Incidences of hyaline degeneration of the respiratory epithelium of the nasal cavity in 100 mg/m(3) males and females and hyaline degeneration of the olfactory epithelium of the nasal cavity in 100 mg/m(3) females were significantly greater than those in the control groups. The incidences of squamous metaplasia of the epithelium lining the base of the epiglottis were significantly increased in all exposed groups of males and females. In both male and female mice, the incidences of hyperplasia of the laryngeal epithelium in level II of the larynx increased with increasing exposure concentration. The increase was statistically significant only in mice exposed to 100 mg/m(3) with 82% of male and 70% of female mice affected. GENETIC TOXICOLOGY: Molybdenum trioxide was not mutagenic in any of five strains of Salmonella typhimurium, and it did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells in vitro. All tests were conducted with and without S9 metabolic activation enzymes. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was equivocal evidence of carcinogenic activity of molybdenum trioxide in male F344/N rats based on a marginally significant positive trend of alveolar/bronchiolar adenoma or carcinoma (combined). There was no evidence of carcinogenic activity of molybdenum trioxide in female F344/N rats exposed to 10, 30, or 100 mg/m(3). There was some evidence of carcinogenic activity of molybdenum trioxide in male B6C3F1 mice based on increased incidences of alveolar/bronchiolar carcinoma and adenoma or carcinoma (combined). There was some evidence of carcinogenic activity of molybdenum trioxide in female B6C3F1 mice based on increased incidences of alveolar/bronchiolar adenoma and adenoma or carcinoma (combined). Exposure of male and female rats to molybdenum trioxide by inhalation resulted in increased incidences of chronic alveolar inflammation, hyaline degeneration of the respiratory epithelium, hyaline degeneration of the olfactory epithelium (females), and squamous metaplasia of the epiglottis. Exposure of male and female mice to molybdenum trioxide by inhalation resulted in increased incidences of metaplasia of the alveolar epithelium, histiocyte cellular infiltration (males), hyaline degeneration of the respiratory epithelium, hyaline degeneration of the olfactory epithelium (females), squamous metaplasia of the epiglottis, and hyperplasia of the larynx. Synonyms: Molybdic oxide; molybdic trioxide; molybdic anhydride; molybdenum (VI) oxide; molybdenum peroxide; molybdic acid anhydride; molybdenum anhydride; natural molybdite; molybdena

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of Nitromethane (CAS No. 75-52-5) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Nitromethane is used as a rocket and engine fuel; as a synthesis intermediate for agricultural fumigants, biocides, and other products; as a solvent; and as an explosive in mining, oil-well drilling, and seismic exploration. It has been detected in air, in surface and drinking water, and in cigarette smoke. Nitromethane was studied because of the potential for widespread human exposure and because it is structurally related to the carcinogens 2-nitropropane and tetranitromethane. Male and female F344/N rats and B6C3F1 mice received nitromethane (purity 98% or greater) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and peripheral blood erythrocytes of mice. 16-DAY STUDY IN RATS: Groups of five male and five female rats were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 16 days. All rats survived until the end of the study. The mean body weight gain of male rats in the 1,500 ppm group was slightly but significantly less than that of the controls; the final mean body weights and mean body weight gains of exposed females were similar to those of the controls. Clinical findings in all male and female rats in the 1,500 ppm groups included increased preening, rapid breathing, hyperactivity early in the study, and hypoactivity and loss of coordination in the hindlimbs near the end of the study. The relative liver weights of all exposed groups of male rats and the absolute and relative liver weights of females exposed to 375 ppm or greater were significantly greater than those of the controls. Minimal to mild degeneration of the olfactory epithelium was observed in the nose of males and females exposed to 375 ppm or greater. Sciatic nerve degeneration was present in all male and female rats exposed to 375 ppm or greater; rats exposed to 750 or 1,500 ppm also had reduced myelin around sciatic axons. 16-DAY STUDY IN MICE: Groups of five male and five female mice were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 16 days. All mice survived to the end of the study. The final mean body weights and weight gains of exposed males and females were similar to those of the controls. Clinical findings included hypoactivity and tachypnea in male and female mice in the 1,500 ppm groups. Absolute and relative liver weights of male mice in the 750 and 1,500 ppm groups and female mice in all exposed groups and the relative liver weight of males in the 375 ppm group were significantly greater than those of the controls. Degeneration of the olfactory epithelium of the nose was observed microscopically in all males and females exposed to 375 ppm or greater; this lesion was of minimal severity in males and minimal to mild severity in females. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 13 weeks. All rats survived to the end of the study. The final mean body weight and weight gain of male rats in the 1,500 ppm group were significantly less than those of the controls. Clinical findings included hindlimb paralysis in rats in the 750 and 1,500 ppm groups. Inhalation exposure of rats to nitromethane resulted in an exposure concentration-dependent, microcytic, responsive anemia; anemia was most pronounced in males and females exposed to 375 ppm or greater. The presence of schistocytes, Heinz bodies, and spherocytes and increased mean cell hemoglobin concentration and methemoglobin concentration were evidence that a hemolytic process was occurring; this hemolytic process could have accounted, in part, for the anemia. Thrombocytosis accompanied the anemia and would be consistent with a reactive bone marrow or could have been due to the erroneous inclusion of small erythrocyte fragments as part of the platelet count. On day 23, transient decreases in serum triiodothyronine, thyroxine, and fr and free thyroxine were observed in male rats exposed to 375 ppm or greater and female rats exposed to 750 or 1,500 ppm. There was little or no pituitary response to the thyroid hormone decreases, as evidenced by the lack of significantly increased concentrations of thyroid-stimulating hormone in exposed rats. No biologically significant differences in organ weights were observed. The forelimb and hindlimb grip strengths of males in the 1,500 ppm group were significantly less than those of the controls. The hindlimb grip strengths of females in the 750 and 1,500 ppm groups were also significantly less than the control value. Minimal to mild hyperplasia of the bone marrow was observed microscopically in male rats in the 750 and 1,500 ppm groups and in females exposed to 188 ppm or greater. Nasal lesions in exposed males and females included olfactory epithelial degeneration in males and females exposed to 375 ppm or greater and in one female exposed to 188 ppm and respiratory epithelial hyaline droplets and goblet cell hyperplasia in males and females in the 750 and 1,500 ppm groups; the severity of nasal lesions in males and females was minimal to mild. Males and females exposed to 375 ppm or greater had minimal to mild degeneration of the sciatic nerve and the lumbar spinal cord. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 13 weeks. All mice survived to the end of the study. The final mean body weights and weight gains of exposed mice were generally similar to those of the controls. There were no treatment-related clinical findings. The absolute right kidney weights of all groups of exposed male mice except the 1,500 ppm group and of females exposed to 188 ppm or greater and the relative right kidney weights of all groups of exposed males and of females in the 750 and 1,500 ppm groups were significantly greater than those of the controls. The absolute liver weight of male mice in the 750 ppm group and the relative liver weights of males exposed to 375 ppm or greater were significantly greater than those of the controls. Olfactory epithelial degeneration and respiratory epithelial hyaline droplets were observed microscopically in all male and female mice exposed to 375 ppm or greater. Degeneration also occurred in females in the 188 ppm group, and hyaline droplets occurred in females in the 94 and 188 ppm groups. The average severity of the nasal lesions ranged from minimal to mild in males. In females, the average severity of olfactory epithelial degeneration ranged from minimal to mild and the severity of respiratory epithelial hyaline droplets ranged from minimal to moderate. All males and nine females in the 1,500 ppm groups also had minimal extramedullary hematopoiesis of the spleen. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to 0, 94, 188, or 375 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 103 weeks. Survival,Body Weights, and Clinical Findings: There were no significant differences in survival rates between exposed and control male or female rats. The mean body weight of females in the 375 ppm group was slightly greater than that of the control group; the mean body weights of exposed males were generally similar to the mean body weight of the controls throughout the study. Clinical findings were consistent with incidences of mammary gland neoplasms in females exposed to 188 or 375 ppm; no hindlimb paralysis, as occurred in rats in the 13-week study, was observed in male or female rats in the 2-year study. Pathology Findings: The incidences of mammary gland fibroadenoma and fibroadenoma, adenoma, or carcinoma (combined) in female rats in the 188 and 375 ppm groups were significantly greater than those in the controls. Additionally, the incidences of mammary gland carcinoma in the 375 ppm group were significantly greater than those in the controls. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to 0, 188, 375, or 750 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 103 weeks. Survival,Body Weights, and ClinicalFindings The survival rate of females in the 750 ppm group was marginally greater than that of the controls. The mean body weights of exposed females were generally slightly greater than the mean body weights of the controls during the study but were generally similar to the mean body weight of the controls at the end of the study. The mean body weights of exposed males were similar to those of the controls throughout the study. Clinical findings included swelling around the eyes and exophthalmos in exposed males and females; these findings were coincident with harderian gland neoplasms. Pathology Findings: The incidences of harderian gland adenoma and adenoma or carcinoma (combined) in exposed mice increased with increasing exposure concentration and were significantly greater in males and females in the 375 and 750 ppm groups than those in the controls. The incidences of harderian gland carcinoma in males and females in the 375 and 750 ppm groups were also slightly greater than those in the controls. Female mice in the 188 and 750 ppm groups had significantly greater incidences of hepatocellular adenoma and hepatocellular adenoma or carcinoma (combined) than the controls. The incidences of liver eosinophilic focus increased with increasing exposure concentration, and the incidences in the 375 and 750 ppm groups were significantly greater than the control incidence. The incidences of alveolar/bronchiolar carcinoma in male mice in the 750 ppm group and female mice in the 375 ppm group were significantly greater than those in the controls. Females in the 750 ppm group also had a significantly greater incidence of alveolar/bronchiolar adenoma or carcinoma (combined) and a slightly greater incidence of alveolar/bronchiolar adenoma than the controls. Females in the 375 ppm group had a significantly greater incidence of cellular infiltration of histiocytes in the lung than the controls. The incidences of degeneration and metaplasia of the olfactory epithelium and hyaline degeneration of the respiratory epithelium were significantly greater in exposed male and female mice than those in the controls. Additionally, males in the 375 and 750 ppm groups had significantly greater incidences of inflammation of the nasolacrimal duct than did the controls. GENETIC TOXICOLOGY: Nitromethane was not mutagenic in any tests performed by the NTP. It did not induce mutations in Salmonella typhimurium, with or without S9 metabolic activation, and no induction of sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells exposed to nitromethane was noted with or without S9. No increase in the frequency of micronucleated erythrocytes was observed in peripheral blood samples of male and female mice at the end of the 13-week inhalation study of nitromethane. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of nitromethane in male F344/N rats exposed to 94, 188, or 375 ppm. There was clear evidence of carcinogenic activity of nitromethane in female F344/N rats based on increased incidences of mammary gland fibroadenomas and carcinomas. There was clear evidence of carcinogenic activity of nitromethane in male B6C3F1 mice based on increased incidences of harderian gland adenomas and carcinomas. There was clear evidence of carcin ogenic activity in female B6C3F1 mice, based on increased incidences of liver neoplasms (primarily adenomas) and harderian gland adenomas and carcinomas. Increased incidences of alveolar/bronchiolar adenomas and carcinomas in male and female mice exposed to nitromethane were also considered to be related to chemical administration. Exposure to nitromethane by inhalation for 2 years resulted in increased incidences of nasal lesions including degeneration and metaplasia of the olfactory epithelium and degeneration of the respiratory epithelium in male and female mice. Synonym: Nitrocarbol

Journal Article↗
PubMed1997

Effect of Dietary Restriction on Toxicology and Carcinogenesis Studies in F344/N Rats and B6C3F1 Mice.

Studies were conducted to compare outcomes when four chemicals were evaluated under typical NTP bioassay conditions as well as under protocols employing dietary restriction. Specific experiments were designed to evaluate the effect of diet restriction on the sensitivity of the bioassay toward chemical-induced chronic toxicity and carcinogenicity and to evaluate the effect of weight-matched control groups on the sensitivity of the bioassays. Two chemicals, butyl benzyl phthalate and t-butylhydroquinone, were administered in feed; one chemical, salicylazosulfapyridine, was administered in corn oil by gavage; and one chemical, scopolamine hydrobromide trihydrate, was administered in distilled water by gavage. In each of four protocols, the effects of the chemical were assessed by a comparison between a group exposed to a single dose concentration of the study chemical and a nonexposed control group. F344/N rats and B6C3F1 mice were fed NIH-07 diet either ad libitum or in amounts that restricted mean body weights according to the following design requirements. For the core bioassay, groups of 50 to 60 ad libitum-fed animals were allotted to a control group and three dosed groups for approximately 104 weeks or up to 128 weeks (t-butylhydroquinone study). The comparison between the control group and the group receiving the highest dose was used to represent the outcome of the bioassay under ad libitum feeding protocols. In a second comparison, outcomes from the group receiving the highest dose were compared with a weight-matched group of 50 to 60 untreated controls; the weight-matched controls received feed in amounts restricted so that the mean body weight matched the mean body weight of the dosed group. Two additional groups of 48 to 60 animals (one control and one dosed group) were offered feed in amounts that limited the mean body weight of the control group to approximately 85% that of the controls fed ad libitum under the first protocol. Animals assigned to this dietary restriction paradigm were evaluated after 104 weeks or 130 weeks (t-butylhydroquinone). A fourth protocol was em- loyed to evaluate whether an additional period of exposure (up to 1 year) would influence the neoplasm profile of animals fed a restricted diet. Two groups of approximately 50 animals (one control and one dosed group) in the butyl benzyl phthalate, salicylazosulfapyridine, and scopolamine hydrobromide trihydrate studies received restricted diets, as under the third protocol, for 3 years or until survival in either group was reduced to 20%. Butyl benzyl phthalate caused an increased incidence of pancreatic acinar cell neoplasms in ad libitum-fed male rats relative to ad libitum-fed and weight-m atched controls. This change did not occur in rats in the restricted feed protocol after 2 years; however, acinar cell adenomas were observed in three exposed, feed-restricted males at 30 months. Feed restriction is known to influence the incidence of pancreatic acinar cell neoplasms and may have prevented the full expression of this chemical-induced effect. Butyl benzyl phthalate also caused an increased incidence of urinary bladder neoplasms in female rats in the 32-month restricted feed protocol. The incidences of urinary bladder neoplasms were not significantly increased in female rats in any of the 2-year protocols, suggesting that the length of study, and not body weight, was the primary factor in the detection of this carcinogenic response. Salicylazosulfapyridine caused an increased incidence of urinary bladder papillomas in male rats fed ad libitum relative to ad libitum-fed and weight- matched controls. This increase was associated with an increased incidence of urinary bladder calculi; the incidences of urinary bladder concretions, dilatation, and hyperplasia were also increased in dosed males. The incidences of urinary bladder papillomas and calculi were not increased in male rats receiving salicylazosulfapyridine that were fed restricted diets. In male mice, salicylazosulfapyridine caused an increased incidence of liver neoplasms relative tsms relative to the ad libitum-fed and weight-matched controls. This increase did not occur in the restricted feed protocols. Liver neoplasms in mice are greatly influenced by body weight, and the marked mean body weight reduction observed in dosed male mice in the restricted feed protocols may have overridden the carcinogenic response. Neither t-butylhydroquinone nor scopolamine hydro bromide trihydrate caused increased neoplasm incidences under any of the experimental protocols. Results consistently show that feed restriction caused decreased incidences of neoplasms and nonneoplastic lesions at a variety of anatomic sites in control and dosed animals. Furthermore, the sensitivity of the bioassay to detect a carcinogenic response was altered by dietary restriction: two of the four chemicals caused increased incidences of neoplasms at three sites when evaluated under a standard ad libitum feeding protocol for 104 weeks. When control and dosed groups were subjected to dietary restriction, none of these three sites was detected as a target of carcinogenesis after 2 to 3 years. Rather, one different site of carcinogenesis was detected after 32 months. When dosed animals in the ad libitum feeding protocol were compared to weight-matched control groups, three sites were identified as targets of carcinogenesis and corresponded to the three sites discovered under the ad libitum feeding protocol. The magnitude of the response was greater when the weight-matched controls protocol was used. Dietary restriction of dosed and control animals decreased the sensitivity of these carcinogenesis bioassays. Regarding the future use of dietary restriction regimens in long-term studies, only limited conclusions can be drawn because only four chemicals were evaluated and none of these proved to be a strong carcinogen. However, the results of these studies are consistent with previous findings that dietary restriction increases survival rates and decreases the incidences of neoplasms and nonneoplastic lesions at a variety of sites in rats and mice. This association between reduced body weights and decreased neoplasm incidences underlines the necessity that the doses selected for chronic studies not exceed "minimally toxic doses" so that no marked body weight reductions (or increases) will occur in the dosed groups. Such body weight changes complicate the detection of carcinogenic effects. The following tables summarize and compare the findings from ad libitum-fed, weight-matched, and feed-restricted groups for each chemical. Tabular Summary of Dietary Restriction Study of Butyl Benzyl Phthalate is available in web version of this document. TabularSummary of the Dietary Restriction Study of t-Butylhydroquinone is available in web version of this document. TabularSummary of the Dietary Restriction Studies of Salicylazosulfapyridine is available in web version of this document. TabularSummary of the Dietary Restriction Study of Scopolamine Hydrobromide Trihydrate is available in web version of this document.

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of t-Butylhydroquinone (CAS No. 1948-33-0) in F344/N Rats and B6C3F(1) Mice (Feed Studies).

t -Butylhydroquinone is used as an antioxidant in cosmetic products such as lipsticks, eye shadows, perfumes, blushers, and skin care preparations at concentrations ranging from 0.1% to 1.0%; the chemical is also used at concentrations up to 0.02% in oils, fats, and meat products to prevent rancidity, and as a polymerization inhibitor for various polyunsaturated polyesters (CIR, 1986). t-Butylhydroquinone was nominated for toxicity and carcinogenicity testing by the Food and Drug Administration. Toxicology and carcinogenicity studies were conducted in F344/N rats and B6C3F(1) mice. Mice were exposed to t-butyl hydroquinone (99% pure) in feed for 13 weeks or 2 years. For rats, exposure to t-butylhydroquinone began in utero and continued through lactation. After weaning, pups were fed diets containing the same levels of t-butylhydroquinone as those given to their respective dams for 13 weeks or for up to 30 months. The oral route of administration was selected for these studies because t-butylhydroquinone is used as a food additive and human exposure occurs predominantly through this route. In addition to the oral route of exposure, rats were exposed prenatally because perinatal exposure to butylated hydroxytoluene (a structurally related chemical) induced hepatocellular neoplasms in rats. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells in vitro and in mouse bone marrow cells in vivo. 13-WEEK STUDY IN RATS: In the perinatal exposure phase of the 13-week study, groups of 10 female rats (F(0)) were fed 0, 2,500, 5,000, 10,000, 20,000, or 40,000 ppm t-butylhydroquinone from 2 weeks prior to cohabitation until the F(1) pups were weaned. F(0) females exposed to 20,000 or 40,000 ppm did not litter. The number of pup deaths in the 5,000 and 10,000 ppm groups was greater than that in the control group, and the average number of surviving pups per litter in the 10,000 ppm group was less than that in the control group. Mean body weights of pups exposed perinatally to 5,000 or 10,000 ppm were lower than that of the controls at the time of weaning. Groups of 10 male and 10 female F(1) rats continued to receive diets containing 0, 2,500, 5,000, or 10,000 ppm t-butylhydroquinone for 13 weeks fol lowing weaning. These dietary levels corresponded to approximately 200, 400, or 800 mg t-butylhydro quinone/kg body weight (males) or 200, 400, or 750 mg/kg (females) per day. All rats survived to the end of the study. The final mean body weights of males and females in the 5,000 and 10,000 ppm groups were significantly lower than those of the controls, as was the mean body weight gain of males exposed to 10,000 ppm. However, interpretation of these findings was complicated by the significantly lower initial mean body weights of the 10,000 ppm groups. Differences in initial body weights were due to in utero exposure to t-butylhydroquinone. Feed consumption by exposed groups of rats was lower than that by controls at week 2, and feed consumption by 5,000 and 10,000 ppm males and 10,000 ppm females was slightly lower than that by controls at the end of the study. Hair discoloration in all exposed groups of rats, except females exposed to 2,500 ppm, was the only clinical observation considered related to chemical exposure. The mean spermatid count, spermatid heads per testis, and spermatid heads per gram of testis were significantly decreased in males exposed to 5,000 ppm. The estrous cycles of females exposed to 2,500 or 5,000 ppm were significantly longer than that of the controls. There were no biologically significant changes in clinical pathology parameters or in organ weights. Increased incidences of hyperplasia of the nasal respiratory epithelium were observed in males exposed to 5,000 ppm and males and females exposed to 10,000 ppm, and an increased incidence of nasal exudate was observed in males in the 10,000 ppm group. Increased incidences of pigmentation were observed in the spleen of male and female rats exposed to 5,000 or 10,000 ppm. Based on lower final mean body weights wer final mean body weights and decreased feed consumption in males and females exposed to 10,000 ppm t-butylhydroquinone, exposure concentrations selected for the long-term rat study were 1,250, 2,500, and 5,000 ppm. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were fed diets containing 0, 2,500, 5,000, 10,000, 20,000, or 40,000 ppm t-butylhydroquinone for 13 weeks. These dietary levels corresponded to approximately 440, 880, 1,950, 4,000, and 8,400 mg t-butylhydro quinone/kg body weight (males) or 500, 1,100, 2,200, 4,600, and 9,000 mg/kg body weight (females) per day. There were no exposure-related deaths. Final mean body weights and body weight gains of males and females exposed to 10,000, 20,000, or 40,000 ppm were significantly less than those of the controls. Feed consumption by exposed mice appeared to be similar to that by controls, but there was excessive scatter of feed by mice exposed to 10,000, 20,000, or 40,000 ppm. Therefore, feed consumption by male and female mice in these groups was likely less than that by controls. Significant increases in segmented neutrophil counts occurred at week 3 and at the end of the study in females exposed to 10,000 ppm and males and females exposed to 20,000 or 40,000 ppm. Left caudal, left epididymis, and left testis weights of males exposed to 10,000 or 40,000 ppm were generally significantly lower than those of the controls. The estrous cycle of females exposed to 40,000 ppm was significantly longer than that of the control group. There were no biologically significant differences in organ weights. Increased incidences and severities of mucosal hyperplasia were observed in the forestomach of males exposed to 20,000 or 40,000 ppm and in females exposed to 10,000, 20,000, or 40,000 ppm, and increased incidences of inflammation were observed in the nose and skin of males and females exposed to 10,000, 20,000, or 40,000 ppm. Increased incidences of hyperplasia also occurred in the skin of males and females exposed to 10,000, 20,000, or 40,000 ppm. Based on lower final mean body weights, increased incidences of inflammation of the nose and skin, increased incidences of forestomach mucosal hyperplasia, and increased severity of nonneoplastic lesions observed in mice exposed to 10,000, 20,000, or 40,000 ppm, exposure concentrations selected for the 2-year study were 1,250, 2,500, and 5,000 ppm. LONG-TERM STUDY IN RATS: In the perinatal exposure phase of the long-term study, groups of 60 female F(0) rats were fed diets containing 0, 1,250, 2,500, or 5,000 ppm t-butyl hydroquinone, beginning 2 weeks prior to cohabitation and continuing until F(1) pups were weaned. Following weaning, groups of 70 male and 70 female F(1) rats continued to receive diets containing 0, 1,250, or 5,000 ppm, and groups of 68 male and 68 female rats continued to receive diets containing 2,500 ppm. The duration of dosing in feed was 123 weeks post-weaning for males and 129 weeks for females. These exposure concentrations resulted in daily doses of approximately 50, 100, and 200 mg t-butylhydro quinone/kg body weight (males) or 60, 120, and 240 mg/kg (females). Ten male and ten female F(1) rats from each exposure group were evaluated at 3 months. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of females exposed to 5,000 ppm was significantly greater than that of the control group. The mean body weights of males and females exposed to 5,000 ppm were generally less than those of the controls throughout the study. Feed consumption by exposed groups was similar to that by controls. Clinical findings of hair discoloration in exposed groups of males and females were considered to be related to chemical exposure. Pathology Findings: No increased neoplasm incidences in male or female rats were attributed to t-butylhydroquinone exposure. The incidences of mammary gland fibroadenoma and fibroadenoma or adenoma (combined) were significantly decreased in males exposed to 1,250 ppm and in all exposed groups of females; and combined incidences of mammary gland fibroadenoma, adenoma, or carcinoma were significantly decreased in all groups of exposed females. The decreases occurred with significant negative trends. Incidences of renal cysts and inflammation were generally increased in exposed groups of male rats. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice received 0, 1,250, 2,500, or 5,000 ppm t-butylhydroquinone in feed for 104 to 105 weeks. These exposure concentrations resulted in daily doses of approximately 150, 300, or 600 mg t-butylhydroquinone/kg body weight (males) or 150, 300, or 700 mg/kg (females). As many as 10 males and 10 females from each exposure group were evaluated at 15 months. Survival, Body Weights and Feed Consumption: Survival of all exposed groups of males and females was similar to that of the control groups. Mean body weights of the 5,000 ppm groups were generally lower than those of the control groups from week 13 until the end of the study. Feed consumption by exposed groups of males and females was similar to that by the controls. There were no biologically significant differences in clinical pathology parameters between control and exposed groups of mice. Pathology Findings: No increased incidences of neoplasms or nonneoplastic lesions in male or female mice were considered to be related to t-butylhydroquinone exposure. GENETIC TOXICOLOGY: t-Butylhydroquinone was not mutagenic in any of four strains of Salmonella typhimurium, with or without liver S9 metabolic activation enzymes. It did, however, induce sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells in the presence, but not the absence, of S9. No increase in the frequency of micronucleated erythrocytes was observed in bone marrow of male mice treated with t-butylhydroquinone. CONCLUSIONS: Under the conditions of this long-term feed study, there was no evidence of carcinogenic activity of t-butylhydroquinone in male or female F344/N rats exposed to 1,250, 2,500, or 5,000 ppm. Under the conditions of this 2-year feed study, there was no evidence of carcinogenic activity of t-butylhydroquinone in male or female B6C3F(1) mice exposed to 1,250, 2,500, or 5,000 ppm. Exposure of rats to t-butylhydroquinone in feed resulted in decreased incidences of mammary gland neoplasms in males and females. Synonyms: Tert-butyl-hydroquinone; 2-(1,1-dimethylethyl)-1,4-benzenediol; 2-tert-butylhydroquinone; mono-tert-butylhydroquinone; tert-butyl-1,4-benzenediol: mono-tertiarybutylhydroquinone; 2-tert-butyl-1,4-benzenediol; 2-(1,1-dimethyl)hydroquinone; 2-(tert-butyl)-p-hydroquinone; TBHQ; MTBHQ Trade Names: Sustane; Tenox TBHQ; Banox 20BA

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of Butyl Benzyl Phthalate (CAS No. 85-68-7) in F344/N Rats (Feed Studies).

Butyl benzyl phthalate is a plasticizer added to polymers to give flexibility and softness. It is used extensively in polyvinyl chloride and in cellulose plastics, polyvinyl acetate, polysulfides, and polyurethane. Butyl benzyl phthalate was nominated as part of a class study of phthalates. Previous studies of butyl benzyl phthalate by the NTP (1982a) resulted in chemical-related mortality in male rats beginning at about 14 weeks of exposure and, thus, were inadequate for evaluating carcinogenicity in male rats. The companion studies revealed a marginal increase in leukemia in female rats and no evidence of carcinogenicity in B6C3F1 mice. Consequently, the present evaluations were conducted only in F344/N rats. Male and female F344/N rats were given butyl benzyl phthalate (at least 97% pure) in feed for 10 weeks, 26 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, L5178Y mouse lymphoma cells, cultured Chinese hamster ovary cells, mouse bone marrow cells, and Drosophila melanogaster. 10-WEEK MODIFIED MATING STUDY IN RATS: Groups of 15 male F344/N rats were given 0, 300, 2,800, or 25,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 20, 200, or 2,200 mg butyl benzyl phthalate/kg body weight) in feed for 10 weeks. All rats survived to the end of the study. The final mean body weight and body weight gain of the 25,000 ppm group were significantly less than those of the controls. Feed consumption by the 25,000 ppm group was less than that by the controls at the end of the study. A few minimal hematology changes occurred in the 25,000 ppm male rats. There was some evidence of a minimal anemia characterized by a decreased erythrocyte count and increases in mean cell hemoglobin and platelet count. The absolute and relative prostate gland weights of the 25,000 ppm males were significantly less than those of the controls. Degeneration of the seminiferous tubule germinal epithelium was observed in all males from the 25,000 ppm group. The absolute right cauda, right epididymis, and right testis weights of the 25,000 ppm males were significantly less than those of the controls. The epididymal spermatozoal concentrations in 2,800 and 25,000 ppm males were significantly less than that in the controls. Although 10 females mated to 25,000 ppm males were initially found to be sperm positive, none of these females were pregnant at necropsy. The fertility indices of males and females in the 25,000 ppm group were significantly lower than those of the controls. The maternal body weights of females mated to 300 and 2,800 ppm males were similar to those of females mated to control males. There were no significant differences in litter data between the controls and the 300 and 2,800 ppm groups. 26-WEEK STUDY IN RATS: Groups of 15 male F344/N rats were given 0, 300, 900, 2,800, 8,300, or 25,000 ppm butyl benzyl phthalate in feed for 26 weeks. Dietary levels of 300, 900, 2,800, and 8,300 ppm delivered average daily doses of approximately 30, 60, 180, and 550 mg butyl benzyl phthalate/kg body weight. The final mean body weight and body weight gain of the 25,000 ppm males were significantly less than those of the controls. Except for the 25,000 ppm males, feed consumption by all exposed groups was similar to that by the controls. An exposure-related macrocytic responsive anemia was present in the 25,000 ppm group at all time points. Additionally, minimal erythrocyte count decreases occurred sporadically in the 2,800 and 8,300 ppm groups at various time points. Reticulocyte counts were increased on days 60 and 90. Increases in mean cell hemoglobin and mean cell hemoglobin concentrations occurred in the 8,300 and 25,000 ppm rats. The absolute right cauda, right epididymis, and right testis weights and the sperm concentration of 25,000 ppm males were significantly less than those of the controls. The incidences of hypospermia and of atrophy of the seminiferous tubule in the testis and of hypospermia in the epididymis in 25,000 ppm males were significantly greater than those in the in the controls. Degenerative changes of the testis and epididymis in the 25,000 ppm males were qualitatively and quantitatively similar to those observed in males in the 10-week modified mating study. 2-YEAR STUDY IN RATS: Groups of 60 male F344/N rats were given 0, 3,000, 6,000, or 12,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 120, 240, or 500 mg butyl benzyl phthalate/kg body weight), and groups of 60 female F344/N rats were given 0, 6,000, 12,000, or 24,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 300, 600, or 1,200 mg/kg) in feed for 2 years. Survival, Body Weights, and Feed Consumption: Survival of all exposed groups of male and female rats was similar to that of the controls. Mean body weights of the 12,000 ppm males and 24,000 ppm females were less than those of the controls throughout most of the study. Feed consumption by the females exposed to 24,000 ppm was less than that by the controls at the beginning of the study, but was similar to that by the controls by week 6. Hematology and Hormone Assays: In general, hematology changes were sporadic and minor. At 6 months, a minimal decrease in erythrocyte count and an increase in mean cell hemoglobin, similar to that which occurred in the 26-week study, occurred in male rats in the 12,000 ppm group. In female rats, a decreased hematocrit value occurred at 15 months in the 24,000 ppm group. There was also a mild decrease in triiodothyronine concentrations in the 24,000 ppm females at 6 and 15 months and at the end of the study. Pathology Findings: of pancreatic acinar cell adenoma and adenoma or carcinoma (combined) in 12,000 ppm males were significantly greater than those in the controls. The incidences of adenoma and of adenoma or carcinoma (combined) in 12,000 ppm males exceeded the ranges of historical controls from NTP 2-year feed studies. One carcinoma was observed in one 12,000 ppm male, and two adenomas were observed in 24,000 ppm females. At 2 years, the incidence of focal hyperplasia of the pancreatic acinar cell in 12,000 ppm males was significantly greater than that in the controls. At 2 years, transitional epithelial papillomas in the urinary bladder were observed in one control female and in two 24,000 ppm females. The incidence of this neoplasm exceeded the range of historical controls from NTP 2-year feed studies. The incidence of transitional epithelial hyperplasia in 24,000 ppm females was significantly greater than that in the controls. The absolute right kidney weight of 12,000 ppm females and the relative right kidney weights of all exposed groups of males and of 24,000 ppm females were significantly greater than those of the controls at the 15-month interim evaluation. The severities of renal tubule pigmentation in 12,000 ppm males and in 24,000 ppm females were greater than those in the controls at 15 months and 2 years. At 2 years, the incidences of kidney mineralization in 6,000 and 24,000 ppm females were significantly less than that in the controls, and the severity was decreased in exposed females. The incidence of preputial gland adenoma or carcinoma (combined) in 12,000 ppm male rats was significantly less than in the controls, and the incidences occurred with a negative trend. GENETIC TOXICOLOGY: Results from in vitro mutagenicity tests with butyl benzyl phthalate were uniformly negative. No mutagenic response was obtained in any of several strains of Salmonella typhimurium treated with up to 11,550 mg/plate butyl benzyl phthalate, with or without S9 metabolic activation enzymes. Negative results were also obtained in in vitro studies of mammalian cell systems with and without S9. No induction of trifluorothymidine resistance in L5178Y mouse lymphoma cells or sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells were observed. These assays also were conducted with and without S9. No significant increase in sex-linked recessive lethal mutations was observed in germ cells of male Drosophila melanogaster after administration of butyl benzyl phthalate either in feed or by injection. In contrast to the negative results obtained in vitro and in Drosophila, butyl benzyl phthalate gave positive responses in two in vivo studies with mice. Results of a mouse bone marrow sister chromatid exchange test were positive at sample times of 23 and 42 hours, but no confirmatory test was conducted. Chromosomal aberrations were induced in bone marrow cells of male mice sampled 17 hours after intraperitoneal injection of 5,000 mg/kg butyl benzyl phthalate. CONCLUSIONS: Under the conditions of this 2-year feed study, there was some evidence of carcinogenic activity of butyl benzyl phthalate in male F344/N rats based on the increased incidences of pancreatic acinar cell adenoma and of acinar cell adenoma or carcinoma (combined). There was equivocal evidence of carcinogenic activity of butyl benzyl phthalate in female 344/N rats based on the marginally increased incidences of pancreatic acinar cell adenoma and of transitional epithelial papilloma of the urinary bladder. Exposure of rats to butyl benzyl phthalate in feed for 2 years resulted in focal hyperplasia in the pancreas in male rats and in transitional epithelial hyperplasia in the urinary bladder of female rats. Synonyms: A13-14777; BBP; 1,2-benzenedicarboxylic acid butyl phenylmethyl ester (9CI); benzyl n-butyl phthalate; n-butyl benzyl phthalate; butyl phenylmethyl 1,2-benzenedicarboxylate; NCI-C54375; phthalic acid benzyl butyl ester (8CI) Trade names: Palatinol BB; Santicizer 160; Sicol 160; Unimoll BB

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of Salicylazosulfapyridine (CAS No. 599-79-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Salicylazosulfapyridine is widely used for the treatment of ulcerative colitis and Crohn's disease. It has been beneficial in the treatment of psoriasis and rheumatoid arthritis, and it has been used in veterinary medicine for the treatment of granulomatous colitis. Salicylazosulfapyridine was nominated for toxicity and carcinogenicity testing by the National Cancer Institute on the basis of its widespread use in humans and because it is a representative chemical from a class of aryl sulfonamides. Salicylazosulfapyridine is a suspect carcinogen because reductive cleavage of the azo linkage yields a p-amino aryl sulfonamide (sulfapyridine), and a related p-amino aryl sulfonamide (sulfamethoxazole) has been shown to produce thyroid neoplasms in rats. Toxicology and carcinogenicity studies were conducted in F344/N rats and B6C3F1 mice. Rats and mice were administered salicylazosulfapyridine (96% to 98% pure) in corn oil by gavage for 16 days, 13 weeks, or 2 years. The gavage route of administration was selected for these studies because it approximates the typical route of human exposure to the chemical. Genetic toxicology studies were conducted in vitro in Salmonella typhimurium and cultured Chinese hamster ovary cells and in vivo in rat and mouse bone marrow and mouse peripheral blood cells. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. All rats survived to the end of the study. With the exception of the 675 mg/kg male group, the final mean body weights of all dosed groups of males and females were significantly lower than those of controls. Mean body weight gains of all dosed groups were less than those of controls. Clinical findings included ruffled fur and distended abdomens in male and female rats receiving 2,700 mg/kg. Hypothyroidism, evidenced by decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentrations, occurred in 2,700 mg/kg male and female rats. The absolute and relative thymus weights of male rats receiving,350 or 2,700 mg/kg and female rats receiving 2,700 mg/kg were significantly lower than those of controls. At necropsy, all dosed rats had enlarged cecae/large intestines. Male rats receiving 1,350 mg/kg and male and female rats receiving 2,700 mg/kg had red, enlarged thyroid glands. Chemical-related microscopic lesions were present in the forestomach, thymus, thyroid gland, and pituitary gland. Minimal to mild hyperplasia of the forestomach mucosa was present in the 1,350 and 2,700 mg/kg male and female groups. Lymphoid depletion was observed in the thymus of three male and three female rats in the 2,700 mg/kg groups. Male and female rats receiving 1,350 and 2,700 mg/kg had thyroid gland follicular cell hyperplasia and an increase in thyroid-stimulating hormone producing cells in the pars distalis of the pituitary gland. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. There were no chemical-related deaths, and final mean body weights of dosed mice were similar to those of controls. No chemical-related clinical findings were noted for male or female mice. There were no differences in triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice. There were no biologically significant differences in absolute or relative organ weights between dosed and control male and female mice. At necropsy, male mice receiving 2,700 mg/kg had enlarged cecae/large intestines. There were no biologically significant histopathologic lesions attributed to salicylazosulfapyridine administration. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 0, 84, 168.8, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All rats survived to the end of the study. The finaludy. The final mean body weights of dosed male rats were similar to those of controls; the final mean body weights and body weight gains of dosed females were significantly lower than those of controls. No chemical-related clinical findings were noted in dosed male or female rats during the 13-week study. No significant differences in hematology or urinalysis parameters between control and dosed rats were observed. The absolute and relative right kidney weights of 337.5 mg/kg females were significantly greater than those of controls. At necropsy, some 337.5 mg/kg male rats had red, enlarged thyroid glands. Histopathologic changes were noted primarily in the thyroid gland and pituitary gland of males and females in the 337.5 mg/kg groups. The thyroid gland lesions observed were similar to those present in the 16-day study. Nine male rats receiving 168.8 mg/kg and ten male and seven female rats receiving.5 mg/kg had minimal but consistent changes in thyroid gland follicular cells. In the pituitary gland of 337.5 mg/kg males and females, the thyroid-stimulating hormone producing cells were enlarged and contained pale-staining cytoplasm and prominent Golgi complexes. Decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentration, similar to differences observed in the 16-day study, occurred in 337.5 mg/kg male rats; thyroid hormone concentrations were not affected in female rats. Sperm motility of all dosed groups of males was significantly lower than that of controls. Vaginal cytology parameters of dosed groups of females were similar to those of controls. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All mice survived to the end of the study. The final mean body weights of dosed male and female mice were similar to those of controls. The mean body weight gains of 1,350 and 2,700 mg/kg male mice were less than that of controls. No chemical-related clinical findings were noted in dosed male or female mice during the 13-week study. There was minimal evidence of a responsive anemia in mice in the 13-week study. The anemia was probably related to a methemoglobinemia. There were minimal decreases in thyroxine concentration in all dosed groups of male and female mice in the -week study. There were, however, no differences in triiodothyronine and thyroid-stimulating hormone concentrations between dosed and control animals. Absolute and relative liver weights of all groups of dosed male and female mice were significantly greater than those of controls. There were no chemical-related gross lesions. Microscopic evaluation of the liver revealed centrilobular hypertrophy in five 1,350 mg/kg and all 2,700 mg/kg male mice. The right cauda weight of the 1,350 mg/kg group and the right epididymis weights of all dose groups were significantly lower than those of controls. There was no evidence of chemical-related alteration in the vaginal cytology parameters of female mice. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female rats were administered 84, 168, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 105 weeks. Groups of 70 male and 60 female rats were administered the corn oil vehicle by gavage for up to 105 weeks. A stop-exposure group of 70 male rats was administered 337.5 mg/kg salicylazosulfapyridine in corn oil by gavage for 6 months, after which animals received the corn oil vehicle by gavage for the remainder of the 2-year study. Ten animals from the vehicle control male group and 10 animals from the 337.5 mg/kg stop-exposure group were evaluated at 6 months; animals from each core-study group were evaluated at 15 months. Survival, Body Weights, and Clinical Chemistry: Survival of 337.5 mg/kg male core-study rats was significantly lower than that of controls; survival of 84 and 168 mg/kg core-study males, all groups of dosed females, and the stop-exposure male group was similar to controls. Mean body weights of core-study males and stop-exposure males were similar to controls throughout the study. From week 45 to the end of the study, females in the 337.5 mg/kg group had mean body weights that were lower than those of controls. The serum thyroxine concentration in 337.5 mg/kg core-study males at study termination was minimally lower than that of controls; the serum thyroid-stimulating hormone, triiodothyronine, and reverse triiodothyronine concentrations of dosed males and females were similar to those of controls. Pathology Findings: Administration of salicylazosulfapyridine for 2 years was associated with transitional epithelial papilloma in the urinary bladder of male rats and may have been associated with transitional epithelial papilloma of the kidney and of the urinary bladder of female rats. Nonneoplastic effects in the urinary bladder and kidney of male and female rats and in the spleen of male rats were also observed. Dosed male and female rats had increased incidences of grossly and microscopically observed urinary bladder concretions (diagnosed grossly as calculi at necropsy); male and female rats that developed transitional epithelial papillomas of the urinary bladder had grossly observed concretions (calculi) in the urinary bladder at necropsy. The microscopic neoplastic and nonneoplastic urinary bladder and kidney effects observed in dosed male rats during the 2-year continuous study did not occur in dosed rats during the 2-year stop-exposure study, nor were there gross observations of concretions (calculi) at necropsy. The incidences of mononuclear cell leukemia in male and female rats were decreased. The thyroid gland hyperplasia seen in the -week study was not observed in the 2-year study, and there was no evidence of chemical-related thyroid gland follicular cell adenomas or carcinomas. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 104 weeks. Ten animals from each group were evaluated at 15 months. Survival, Body Weights,and Clinical Chemistry: Survival of all the dosed groups of male and female mice was similar to that of controls. Mean body weights of 675 and 1,350 mg/kg male and female mice were similar to controls throughout the study. From week 12 to the end of the study, 2,700 mg/kg male mice had mean body weights that were lower than those of controls. From week 14 to the end of the study, the 2,700 mg/kg female mice had mean body weights that were lower than those of controls. There were no chemical-related differences in triiodothyronine, reverse triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice at the 15-month evaluation. Pathology Findings: Exposure of mice to salicylazosulfapyridine in corn oil by gavage for 2 years was associated with increased incidences of hepatocellular neoplasms in males and females. Nonneoplastic effects in the liver and spleen were also observed in male and female mice. The incidences of forestomach squamous cell papilloma in females and forestomach hyperplasia in males and females were decreased. GENETIC TOXICOLOGY: Salicylazosulfapyridine was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535, and it did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro assays were performed with and without S9 metabolic activation enzymes. Results from in vivo mouse bone marrow chromo somal aberration tests were uniformly negative, while results of micronucleus assays performed on male or female mice exposed to salicylazosulfapyridine for periods ranging from 3 days to weeks were positive. Micronucleus tests in male mice for shorter exposure times (1 to 2 days) yielded negative or very weakly positive results. A three-treatment (72-hour exposure time) micronucleus test performed in male rats yielded equivocal results. Overall, results of these in vivo assays indicate that salicylazosulfa pyridine is capable of inducing chromosomal damage, possibly in the form of aneuploidy, in mouse bone marrow cells after multiple administrations. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of salicylazosulfapyridine in male and female F344/N rats based on increased incidences of neoplasms in the urinary tract. There was an increased incidence of transitional epithelial papilloma of the urinary bladder in males and a low incidence of rare transitional epithelial papillomas of the kidney and of the urinary bladder in females. There was clear evidence of carcinogenic activity of salicylazosulfapyridine in male and female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. Increased incidences of nonneoplastic lesions of the urinary bladder and kidney in male and female rats and of the spleen in male rats were observed. Increased incidences of nonneoplastic lesions of the liver and spleen in male and female mice were observed. Decreased incidences of mononuclear cell leukemia in male and female rats were related to salicylazosulfapyridine administration. Decreased incidences of forestomach squamous cell papilloma in female mice and forestomach hyperplasia in male and female mice were related to salicylazosulfapyridine administration. Synonyms: 2-Hydroxy-5-[[4-[2-(pyridinylamino)sulfonyl]phenyl]azo]benzoic acid; 5-[p- (2-pyridylsulfamoyl)phenylazo]salicylic acid; sulfasalazine; salazosulfapyridine; 5-[4-(2-pyridylsulfamoyl)phenylazo]-2-hydroxybenzoic acid; 4-(pyridyl-2-amidosulfonyl)-3'-carboxy-4'-hydroxyazobenzene; sulphasalazine Trade names: Azopyrin, Azulfidine, Benzosulfa, Colo-Pleon, Reupirin, Salazopyrin

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of 1,2-Dihydro-2,2,4-Trimethylquinoline (CAS No. 147-47-7) in F344/N Rats and B6C3F1 Mice (Dermal Studies) and the Dermal Initiation/Promotion Study in Female Sencar Mice.

1,2-Dihydro-2,2,4-trimethylquinoline (monomer) is used as an antioxidant in styrene-butadiene and nitrile-butadiene rubbers and latexes. It was nominated by the National Cancer Institute as part of a review of chemicals used in the manufacture and processing of rubber, during which potential occupational and consumer exposure to this compound can occur. It was selected for evaluation because it is a derivative of quinoline, a known rodent carcinogen, and was regarded as having potential carcinogenic activity. Because of the pattern of use and exposure, dermal administration was considered most appropriate. Male and female F344/N rats and B6C3F1 mice received topical applications of 1,2-dihydro-2,2,4-trimethylquinoline in acetone (greater than 90% pure) for 13 weeks or 2 years. Groups of female SENCAR mice received 1,2-dihydro-2,2,4-trimethylquinoline (greater than 90% pure) during a 1-year dermal initiation/promotion study to determine the tumor initiation or promotion potential of the chemical. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood cells. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were topically administered 0, 5, 20, 50, 100, or 200 mg 1,2-dihydro-2,2,4-trimethylquinoline/kg body weight in acetone, 5 days per week for 13 weeks. In addition, there were 10 male and 10 female untreated controls. All rats survived to the end of the study. Final mean body weights and mean body weight gains of treated male and female rats were similar to those of the vehicle controls except those of 200 mg/kg males, which were significantly lower than those of the vehicle controls. The only notable clinical observation was skin discoloration of treated rats. In the 200 mg/kg groups, absolute and relative liver weights of males and absolute liver weights of females were significantly greater than those of the vehicle controls. There were no significant differences in hematology or clinical chemistry parameters, reproductive tissue parameters, or estrous cycle characterization between treated and control groups. Histopathologic lesions of the skin at the site of application included acanthosis and hyperkeratosis in 100 and 200 mg/kg males and 200 mg/kg females. Cytoplasmic vacuolization of hepatocytes of mild to moderate severity was observed in the livers of all 200 mg/kg males and was considered treatment related. Based on the incidence and severity of skin and liver lesions observed in 200 mg/kg rats in the 13-week study, 100 mg/kg was selected as the high dose for the 2-year rat study. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were topically administered 0, 2.5, 5, 10, 20, or 50 mg 1,2-dihydro-2,2,4-trimethylquinoline/kg body weight in acetone, 5 days per week for 13 weeks. In addition, there were 10 male and 10 female untreated controls. All mice except one 2.5 mg/kg female survived to the end of the study. Final mean body weights and mean body weight gains of male and female mice were similar to those of the vehicle controls. There were no treatment-related clinical observations. There were no significant differences between treated and control groups in organ weights, hematology and clinical chemistry parameters, reproductive tissue parameters, or estrous cycle characterization. Histopathologic lesions of the skin at the site of application included acanthosis (epidermal hyperplasia), hyperkeratosis, and parakeratosis, all ranging from minimal to mild in severity. Minimal to mild fibrosis and subchronic inflammation were observed in the dermis. Based on the incidences and severities of skin lesions observed in 20 and 50 mg/kg mice in the 13-week study, 10 mg/kg was selected as the high dose for the 2-year mouse study. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female F344/N rats were topically administered 0, 36, 60, or 100 mg 1,2-dihydro-2,2,4-trimethylquinoline/kg body weight in acetone, 5 days per week for 103 (males) or 104 (females) weeks. Ten rats per group were evaluated after 15 moed after 15 months of treatment. Survival and Body Weights Survival of treated rats was similar to that of controls. Mean body weights of 60 mg/kg males and 100 mg/kg males and females were slightly lower than those of the controls after week 21. Mean body weights of 36 mg/kg males and females and 60 mg/kg females were generally similar to those of the controls throughout the study. Pathology Findings: No skin neoplasms were attributed to treatment with 1,2-dihydro-2,2,4-trimethylquinoline. Several nonneoplastic skin lesions were determined to be treatment related. Incidences of acanthosis at the site of application in all treated groups of males and in 100 mg/kg females at the 15-month interim evaluation were significantly greater than those in the controls. At the end of the 2-year study, incidences of acanthosis at the site of application in 60 and 100 mg/kg males and females and hyperkeratosis at the site of application in 60 mg/kg females were significantly greater than those in the controls. Absolute and relative right kidney weights of 60 and 100 mg/kg male rats were significantly greater than those of the controls at the 15-month interim evaluation. Incidences of renal tubule adenoma and adenoma or carcinoma (combined) in all treated groups of males were significantly greater than those in the controls. These incidences exceeded the range from the historical controls in 2-year NTP feed studies. An extended (step section) evaluation of the kidneys of male rats did not reveal an additional increase in neoplastic response because additional adenomas and hyperplasias were observed in the controls as well as in treated groups. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female B6C3F1 mice were topically administered 0, 3.6, 6, or 10 mg 1,2-dihydro-2,2,4-trimethylquinoline/kg body weight in acetone, 5 days per week for 103 (males) or 104 (females) weeks. Nine or ten mice per group were evaluated after 15 months of treatment. Survival and Body Weights: Survival of treated mice was similar to that of controls. Mean body weights of treated male and female mice were similar to those of the controls throughout the study. Pathology Findings: No neoplasms or nonneoplastic lesions were attributed to treatment with 1,2-dihydro-2,2,4-trimethylquinoline. 1-YEAR INITIATION/PROMOTION STUDY IN FEMALE SENCAR MICE: Groups of 30 female SENCAR mice were topically administered varying initiation/promotion treatments as outlined in the table below. Survival, Body Weights, and Clinical Findings: Survival in all treated groups was similar to that of the respective controls, except in the 2.5 mg 7,12-dimethylbenz(a)anthracene (DMBA)/0.5 mg 12-O-tetradecanoylphorbol-13-acetate (TPA) group in which survival was significantly lower than that of the controls. Mean body weights of all treated groups were similar to those of the respective controls throughout the study. No clinical observations were associated with 1,2-dihydro-2,2,4-trimethylquinoline treatment; however, mice promoted with TPA showed signs of irritation and papilloma at the site of application. Pathology Findings: Initiation and promotion with acetone alone was not associated with any skin lesions at the site of application. The incidences of acanthosis and chronic inflammation were increased in all groups promoted with TPA regardless of the initiator treatment; however, the incidences of nonneoplastic lesions were low in all other groups. Incidences of squamous cell papillomas and squamous cell carcinomas were markedly increased in the DMBA/TPA positive control group; however, no response was observed in groups initiated with DMBA and promoted with 5, 10, or 25 mg/kg 1,2-dihydro-2,2,4-trimethylquinoline or in the group initiated with 1,2-dihydro-2,2,4-trimethylquinoline and promoted with TPA. GENETIC TOXICOLOGY: 1,2-Dihydro-2,2,4-trimethylquinoline was not mutagenic in any of several strains of Salmonella typhimurium, with or without S9 metabolic activation. 1,2-Dihydro-2,2,4-trimethylquinoline induced sister chromatid exchanges in cultured Chinese hamster ovary cells in the absence of S9, but not in the presence of S9. However, no increase in the frequency of chromosomal aberrations was observed in cultured Chinese hamster ovary cells treated with 1,2-dihydro-2,2,4-trimethylquinoline, with or without S9. No increase in the frequency of micronucleated erythrocytes was noted in peripheral blood of male or female mice exposed topically to 1,2-dihydro-2,2,4-trimethylquinoline for 13 weeks. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was some evidence of carcinogenic activity of 1,2-dihydro-2,2,4-trimethylquinoline in male F344/N rats, based on increased incidences of renal tubule adenoma and adenoma or carcinoma (combined). There was no evidence of carcinogenic activity of 1,2-dihydro-2,2,4-trimethylquinoline in female F344/N rats receiving 36, 60, or 100 mg/kg, or in male or female B6C3F1 mice receiving 3.6, 6, or 10 mg/kg. Exposure of rats to 1,2-dihydro-2,2,4-trimethylquinoline by dermal application in acetone for 2 years resulted in acanthosis in males and females and hyperkeratosis in females at the site of application. No nonneoplastic lesions in male or female mice were attributed to treatment with 1,2-dihydro-2,2,4-trimethylquinoline. Synonyms: 2,2,4-Trimethyl-1,2-dihydroquinoline; acetone anil; methylquinoline Trade names: Agerite Resin D; Flectol A; Flectol H; Flectol Pastilles; Vulkanox HS/LG; Vulkanox HS/Powder

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of Tetrafluoroethylene (CAS No. 116-14-3) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Tetrafluoroethylene is used in the production of polytetrafluoroethylene (Teflon(R)) and other polymers. Tetrafluoroethylene was nominated by the National Cancer Institute for toxicity and carcinogenicity studies based on the potential for human exposure to the chemical due to the large production volume and on the lack of adequate data for tetrafluoroethylene in the literature. Male and female F344/N rats and B6C3F1 mice were exposed to tetrafluoroethylene (98% to 99% pure) by whole body inhalation exposure for 16 days, 13 weeks, or 2 years. Genetic toxicity studies were conducted in mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. All rats survived to the end of the study. The final mean body weights and body weight gains of males and females exposed to 5,000 ppm were significantly less than those of the controls. The mean body weight gain of females exposed to 2,500 ppm was also significantly less than that of the controls. There were no exposure-related clinical findings in male or female rats. There were no significant differences in hematology parameters that were considered to be related to tetrafluoroethylene exposure. Absolute and relative kidney weights of all exposed groups of males were significantly greater than those of the controls, as were those of females in the 2,500 and 5,000 ppm groups. The absolute kidney weight of females exposed to 1,250 ppm was also significantly greater than that of the controls. The relative liver weights of all exposed groups of males and the absolute liver weights of males in the 625 and 2,500 ppm groups were significantly greater than those of the controls. Increased incidences of renal tubule degeneration occurred in males and females exposed to 625 ppm or greater; this lesion was located predominantly at the corticomedullary junction. The severity of degeneration increased with increasing exposure concentration and was slightly greater in males than females. 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. All mice survived to the end of the study. Final mean body weights and body weight gains of all exposed groups of mice were similar to those of the controls. There were no exposure-related clinical findings in male or female mice. There were no significant differences in hematology parameters that were considered to be related to tetrafluoroethylene exposure. The absolute and relative liver weights of females exposed to 5,000 ppm were significantly greater than those of the controls, as was the absolute kidney weight of females in that group and the absolute liver weight of females in the 2,500 ppm group. Renal tubule karyomegaly was observed in male and female mice in the 1,250, 2,500, and 5,000 ppm groups, and the severity of this lesion increased with increasing exposure concentration. Karyomegaly was located predominantly in the inner renal cortex. 13-WEEK STUDY IN RATS: Groups of 10 male and 9 or 10 female F344/N rats were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 13 weeks. All rats survived to the end of the study. The final mean body weight and body weight gain of males exposed to 5,000 ppm were significantly less than those of the controls, as was the mean body weight gain of females in this exposure group. There were no clinical findings attributed to exposure to tetrafluoroethylene. Exposure of rats to tetrafluoroethylene resulted in a concentration-dependent normocytic, normochromic, nonresponsive anemia consistent with a secondary hypoproliferative anemia. An exposure concentration-dependent proteinuria also occurred, consistent with renal tubule th renal tubule degeneration observed histopathologically. The absolute and relative liver weights of all exposed groups of males and of females in the 5,000 ppm group were significantly greater than those of the controls. The absolute and relative right kidney weights of males and females exposed to 1,250 ppm or greater and of females in the 625 ppm group were also significantly greater than those of the controls. There were no differences in sperm morphology or vaginal cytology parameters between control and exposed groups of rats. Incidences of renal tubule degeneration in males exposed to 625 ppm or greater and in females exposed to 2,500 or 5,000 ppm were significantly greater than those in the controls. Renal lesions were similar to those observed in the 16-day study and were located predominantly at the corticomedullary junction. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 13 weeks. All mice survived to the end of the study. Final mean body weights and body weight gains of all exposed groups of male and female mice were generally similar to those of the controls. There were no clinical findings that were considered to be related to tetrafluoroethylene exposure. Exposure of mice to tetrafluoroethylene resulted in a concentration-dependent normocytic, normochromic, nonresponsive anemia, consistent with a secondary hypoproliferative anemia, and in polyuria. Differences in sperm morphology parameters and estrous cycle lengths were not considered to be exposure related. Incidences of karyomegaly of the renal tubule epithelial cells in male and female mice exposed to 1,250 ppm or greater were significantly greater than those in the controls. Karyomegaly was similar to that observed in the 16-day study and was observed primarily in the inner renal cortex. 2-YEAR STUDY IN RATS: Groups of 60 male rats were exposed to 156, 312, or 625 ppm and groups of 60 female rats were exposed to 312, 625, or 1,250 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 104 weeks, with an observation period of 11 days following the final exposure. Ten male and ten female rats from each exposure group were evaluated at 15 months for organ weights and clinical pathology. Survival, Body Weights, and Clinical Findings: Survival rates of males in the 625 ppm group and of all exposed groups of females were significantly less than those of the controls. Mean body weights of males exposed to 625 ppm were lower than those of the controls from week 81 until the end of the study, and the mean body weight of 1,250 ppm females was slightly lower than that of the controls at the end of the study. The only clinical finding associated with exposure to tetrafluoroethylene was opacity of the eyes in exposed groups of female rats; this change was observed microscopically as cataracts. Hematology, Clinical Chemistry, and Urinalysis: At the 15-month interim evaluation, there were no differences in hematology, clinical chemistry, or urinalysis parameters that were considered to be related to tetrafluoroethylene exposure. Pathology Findings: The absolute and relative kidney weights of males exposed to 625 ppm and females exposed to 1,250 ppm and the absolute kidney weight of females exposed to 625 ppm were significantly greater than those of the controls at the 15-month interim evaluation. At 15 months, renal tubule hyperplasia was observed in one male exposed to 312 ppm and one male and one female exposed to 625 ppm; oncocytic hyperplasia was observed in one female exposed to 1,250 ppm. At the end of the study, incidences of renal tubule adenoma were greater in males and females exposed to 312 ppm or greater than those in the controls. This exposure-related increase was confirmed by examination of step sections (extended evaluations). At the end of the study, the incidences of renal tubule hyperplasia in males exposed to 625 ppm and females exposed to 1,250 ppm were significantly greater than those in the controls. The incidences of renal tubule adenoma and renal tubule adenoma or carcinoma (combined) in the extended evaluations and in the standard and extended evaluations (combined) in the 1,250 ppm female group and the 625 ppm male group were significantly greater than those in the controls, and the incidences occurred with significant positive trends. Oncocytic hyperplasia was observed at the end of the study in one male exposed to 312 ppm and in three females exposed to 1,250 ppm. At 15 months and at the end of the study, the incidences of renal tubule degeneration in all exposed groups of males and in females in the 625 and 1,250 ppm groups were greater than those in the controls. Renal tubule degeneration was similar to that observed in the 13-week study and was located predominantly at the corticomedullary junction. The severity of nephropathy generally increased with increasing exposure concentration in male rats at 15 months and 2 years. The absolute and relative liver weights of females in the 1,250 ppm group and the absolute liver weight of females exposed to 625 ppm were significantly greater than those of the controls at the 15-month interim evaluation. At 2 years, the incidences of hepatocellular carcinoma and hepatocellular adenoma or carcinoma (combined) in males exposed to 312 ppm, the incidences of hepatocellular adenoma and adenoma or carcinoma (combined) in females in all exposed groups, and the incidences of hepatocellular carcinoma in females exposed to 312 or 625 ppm were significantly greater than those in the controls. Also at 2 years, the incidence of hemangiosarcoma in females exposed to 625 ppm was significantly greater than that in the controls. In all exposed groups of males, the incidences of clear cell foci at 15 months were greater than those in the controls; at 2 years, the incidences of eosinophilic foci in all exposed groups of males and the incidences of basophilic and mixed cell foci in males in the 312 and 625 ppm groups were greater than those in the controls. The incidences of mixed cell foci at 15 months in females exposed to 625 or 1,250 ppm and at 2 years in females exposed to 1,250 ppm were also significantly greater than those in the controls. At the end of the 2-year study, increased incidences of cystic degeneration occurred in the liver of all exposed groups of males, and increased incidences of hepatic angiectasis were observed in exposed groups of females. Incidences of mononuclear cell leukemia in males exposed to 156 ppm and in all exposed groups of females were significantly greater than those in the controls. Incidences of cataracts in females exposed to 1,250 ppm were greater than those in the controls at the end of the 2-year study. At the end of the study, there were slight increases in the incidences of testicular interstitial cell adenoma in rats exposed to 312 or 625 ppm. 2-YEAR STUDY IN MICE: Groups of 58 male and 58 female B6C3F1 mice were exposed to 0, 312, 625, or 1,250 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 95 to 96 weeks. Ten male and ten female mice from each exposure group were evaluated at 15 months for organ weights. Survival, Body Weights, and Clinical Findings: The survival rates of all exposed groups of males and females were significantly less than those of the controls. Because of the reduced survival due to exposure-related liver neoplasms, the study was terminated during week 96. Mean body weights of exposed groups of males and females were generally similar to those of the controls, except at the end of the study, when they were somewhat less than those of the controls. There were no clinical findings related to tetrafluoroethylene exposure. Pathology Findings: At the 15-month interim evaluation, there were no differences in absolute or relative kidney, liver, or lung weights between exposed and control groups of mice. At the end of the study, the incidences of multifocal coagulative necrosis of the liver were increased in males in the 625 and 1,250 ppm groups. Also at the end of the study, females in all exposed groups had greater incidences of hematopoietic cell proliferation in the liver than the controls. Angiectasis occurred in all exposed groups of males and females at 15 months and at the end of the study. At the 15-month interim evaluation, hemangiosarcomas were observed in three males exposed to 1,250 ppm and in one female exposed to 312 ppm. The incidences of hemangiosarcoma in all exposed groups of males and females at the end of the study were significantly greater than those in the controls and exceeded the historical chamber control ranges. Also at the end of the study, the incidences of hemangioma in males and females exposed to 312 ppm and in males exposed to 625 ppm were also significantly greater than those in the controls and exceeded the range in historical chamber controls. At 15 months, hepatocellular adenomas and carcinomas occurred in control males and all exposed groups of males and females. Females exposed to 625 or 1,250 ppm had significantly greater incidences of eosinophilic foci than the controls at the 15-month interim evaluation. At the end of the study, the incidences of eosinophilic foci in males exposed to 625 or 1,250 ppm and in females exposed to 312 or 625 ppm were significantly greater than those in the controls. In male and female mice, increased incidences of a variety of hepatocellular neoplasms, including adenomas, multiple adenomas, carcinomas, and multiple carcinomas, were considered related to tetrafluoroethylene exposure. At the end of the study, the incidences of histiocytic sarcoma (all organs) in all exposed groups of males and females were significantly greater than those in the controls and exceeded the historical control ranges for all organs. The greatest incidences of histiocytic sarcomas were observed in the liver and lung, but these neoplasms were also observed in the spleen, lymph nodes, bone marrow, and kidney. Significantly increased incidences of renal tubule dilatation (males) and karyomegaly (males and females), located predominantly in the inner cortex, were observed in mice exposed to 625 or 1,250 ppm at 15 months. At the end of the study, the increased incidences of dilatation and karyomegaly in all exposed groups of males and of karyomegaly in 1,250 ppm females were generally significant. Incidences of hematopoietic cell proliferation in the spleen of all exposed groups of males and females were significantly greater than those in the controls at the end of the study. Additionally, the severity of this lesion increased with increasing exposure concentration. GENETIC TOXICOLOGY: No increases in the frequency of micronucleated erythrocytes were observed in peripheral blood samples obtained from male and female mice at the end of the 13-week inhalation study of tetrafluoroethylene. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of tetrafluoroethylene in male F344/N rats based on increased incidences of renal tubule neoplasms (mainly adenomas) and hepatocellular neoplasms. There was clear evidence of carcinogenic activity of tetrafluoroethylene in female F344/N rats based on increased incidences of renal tubule neoplasms, liver hemangiosarcomas, hepatocellular neoplasms, and mononuclear cell leukemia. There was clear evidence of carcinogenic activity of tetrafluoroethylene in male and female B6C3F1 mice based on increased incidences of liver hemangiomas and hemangiosarcomas, hepatocellular neoplasms, and histiocytic sarcomas. Slight increases in the incidences of mononuclear cell leukemia and testicular interstitial cell adenomas in male rats may have been related to exposure to tetrafluoroethylene. Exposure of rats to tetrafluoroethylene resulted in increased incidences of renal tubule hyperplasia and degeneration in males and females, increased severity of kidney nephropathy in males, and increased incidences of liver angiectasis and cataracts in females. Exposure of mice to tetrafluoroethylene resulted in increased incidences of hematopoietic cell proliferation of the liver in females, liver angiectasis in males and females, renal tubule dilatation in males, renal tubule karyomegaly in males and females, and splenic hematopoietic cell proliferation in males and females. Synonyms: Perfluoroethylene; tetrafluoroethene; 1,1,2,2-tetrafluoroethylene; TFE

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of Scopolamine Hydrobromide Trihydrate (CAS No. 6533-68-2) in F344 Rats and B6C3F1 Mice (Gavage Studies).

Scopolamine hydrobromide trihydrate is used in ophthalmic preparations and as a preanesthetic sedative. Its major use is in transdermal patches for the treatment of motion sickness. Scopolamine hydrobromide trihydrate was selected for study because of considerable human exposure resulting from its use in prescription and over-the-counter preparations. Scopolamine was a suspect carcinogen because it contains an aliphatic epoxide moiety which may act as a biological alkylating agent. Male and female F344/N rats and B6C3F1 mice received scopolamine hydrobromide trihydrate (89% pure) in distilled water by gavage for 16 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 75, 150, 300, 600, or 1,200 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 16 days. All rats survived to the end of the study. The final mean body weights and body weight gains of males receiving 600 and 1,200 mg/kg and the mean body weight gain of males receiving 300 mg/kg were significantly lower than those of the control group. Clinical findings included bilateral pupillary dilation in all dosed animals and red eyelids in males and females receiving 1,200 mg/kg. There were no significant treatment-related gross or microscopic lesions. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 0, 150, 250, 450, 900, or 1,800 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 16 days. One male and two females receiving 1,800 mg/kg and one female receiving 150 mg/kg died during the study. The final mean body weights and body weight gains of dosed mice were similar to those of the control groups. Clinical findings related to scopolamine hydrobromide trihydrate administration included bilateral pupillary dilation and squinting in all dosed males and females. The relative liver weights of males receiving 1,800 mg/kg and of females in all dosed groups were significantly greater than those of the control groups. There were no significant treatment-related gross or microscopic lesions. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 0, 15, 45, 135, 400, or 1,200 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 14 weeks. One female receiving 45 mg/kg, one male and one female receiving 135 mg/kg, six males and one female receiving 400 mg/kg, and eight males and seven females receiving 1,200 mg/kg died during the study. The final mean body weights and mean body weight gains of all dosed males and females were significantly lower than those of the control groups. Clinical findings included bilateral pupillary dilation in all dosed males and females and reddening of the eyes in 15 mg/kg males and 135, 400, and 1,200 mg/kg males and females. Hematocrit, hemoglobin concentration, and/or erythrocyte count in male and female rats receiving 45 mg/kg or greater were slightly higher than those of the control groups. In general, these changes were most prominent in rats in the 400 and 1,200 mg/kg groups. Higher hematocrit, hemoglobin concentration, and erythrocyte count were likely due to hemoconcentration from dehydration (relative erythrocytosis). A minimal to mild mature neutrophilia, evidenced by higher segmented neutrophil numbers than in the control group, occurred in all dosed male rats. Sperm morphology and vaginal cytology parameters in dosed rats were similar to those in the control groups. Nine male and five female dosed rats died from esophageal obstructions consisting of feed and bedding material in the posterior pharynx. Tracheal obstruction occurred concurrently with esophageal obstruction as a result of food build-up in the oropharyngeal region. This condition is considered to be secondary to the inhibitory effects of scopolamine hydrobromide trihydrate on salivary gland secretions and on esopon esophageal smooth muscle involved in swallowing. There were no other significant treatment-related gross or microscopic findings. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 0, 15, 45, 135, 400, or 1,200 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 14 weeks. One male receiving 135 mg/kg and two males and one female receiving 1,200 mg/kg died during the study. The final mean body weights and mean body weight gains of all dosed male groups and females receiving 45 mg/kg and above were significantly lower than those of the control groups. Clinical observations included bilateral pupillary dilation, hyperactivity, and hypoactivity. A minimal to mild mature neutrophilia, similar to that which occurred in the 14-week rat study, occurred in male mice receiving 45 mg/kg or greater. As in the rat study, there was no microscopic evidence of inflammation that could account for the neutrophilia. The estrous cycle length of 1,200 mg/kg females was significantly greater than that in the control group. There were no significant treatment-related gross or microscopic lesions. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female rats were administered 0, 1, 5, or 25 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 104 weeks. Ten males and ten females from each dose group, excluding the 1 mg/kg female group, were evaluated at 15 months. Survival, Body Weights, Clinical Findings, and Ophthalmic Examination Findings: The survival rates of female rats receiving 1 and 25 mg/kg were significantly lower than that of the control group. Mean body weights of 1 and 5 mg/kg males and females were similar to those of the controls throughout the study. However, mean body weights of 25 mg/kg males and females were generally lower than those of the control groups after about week 25. Clinical findings included bilateral pupillary dilation in all dosed males and females. Ophthalmic examination revealed no significant findings. Hematology: Compared to controls, hematocrit was slightly higher in the 25 mg/kg male rats, similar to the effects observed in the 14-week study; this is consistent with dehydration resulting in hemoconcentration. Reticulocyte numbers in the 25 mg/kg female rats were slightly lower than those in the controls. This result is consistent with the lower body weights, and thus a decreased nutritional status, exhibited by these animals. Plasma Scopolamine Determinations: The serum scopolamine concentrations were 6 ng scopolamine/mL serum for the 5 mg/kg female sample and 12 and 28 ng/mL for the 25 mg/kg male and female samples, respectively. The amounts of scopolamine in the other serum samples were below the minimum detection limit (4 ng/mL) of the analysis method. Neurobehavioral Findings: Horizontal motor activity of 25 mg/kg females was significantly greater than that of the control group on days 90, 180, and 360. Startle response of 5 and 25 mg/kg females was significantly lower than that of the control group on day 90. On day 180, passive avoidance of 25 mg/kg males was significantly lower than that of the control group. Pathology Findings: The incidences of adenoma of the pituitary gland pars distalis decreased with increasing dose in both male and female rats; however, this trend was only significant in males (males: vehicle control, 19/49; 1 mg/kg, 17/49; 5 mg/kg, 13/50; 25 mg/kg, 10/50; females: 20/50, 13/60, 14/50, 10/50). The incidences of adenoma of the pituitary gland pars distalis in 25 mg/kg males and all groups of dosed females were below the NTP historical control range. The incidences of hyperplasia were not significantly different from those in the control groups. The incidences of mononuclear cell leukemia in 25 mg/kg males and females were significantly lower than those of the control groups (males: 33/50, 21/50, 26/50, 24/50; females: 20/50, 6/60, 13/50, 4/50). The incidence of mononuclear cell leukemia in females receiving 25 mg/kg was well below the NTP historical range. 2-YEAR STUDY IN MICE: Groups of 70 male and 70 female mice were administered 0, 1, 5, or 25 mg scopolamine hydrobromide trihydrate/kg body weight in distilled water by gavage for 104 to 105 weeks. Ten control animals and ten animals from each dose level were evaluated at 15 months. Survival, Body Weights, Clinical Findings, and Ophthalmic Examination Findings Survival of dosed males and females was similar to that of the controls. The mean body weights of males and females receiving 1 mg/kg were similar to those of the control groups throughout the majority of the study. The mean body weights of 5 mg/kg males and females were slightly lower than those of the controls. The mean body weights of males and females receiving 25 mg/kg were lower than those of the control groups after week 13. Clinical findings included bilateral pupillary dilation in all dosed male and female groups. Ophthalmic examination revealed no significant findings. Hematology: Hematocrit, hemoglobin concentration, and erythrocyte count in 25 mg/kg female mice were slightly lower than those in the control group. These results are consistent with development of a minimal normocytic, normochromic nonresponsive anemia. The anemia may be related to the lower body weights exhibited by these animals and are presumed to be due to a decreased nutritional status. Pathology Findings: The combined incidences of hepatocellular neoplasms (adenoma or carcinoma) occurred with a significant negative trend in males and females (males: vehicle control, 30/50; 1 mg/kg, 33/50; 5 mg/kg, 14/50; 25 mg/kg, 15/50; females: 22/51, 21/50, 16/50, 9/51). The combined incidences of hepatocellular neoplasms in 5 and 25 mg/kg males were within the NTP historical control range. The incidences of clear cell foci and eosinophilic foci in dosed male groups, and eosinophilic foci in 25 mg/kg females, were significantly lower than those of the control groups. The incidences of many spontaneously occurring nonneoplastic lesions were significantly lower in dosed mice than in the control groups and usually decreased with increasing dose. These included kidney nephropathy, alveolar epithelial hyperplasia, hyperplasia of the pancreatic islets, bone marrow myelofibrosis, hyperplasia of the pituitary gland pars distalis, cystic hyperplasia of the uterus, and hematopoietic cell proliferation of the spleen. The decreased incidences of these spontaneous lesions were most likely a result of lower body weights in dosed animals. GENETIC TOXICOLOGY: Scopolamine hydrobromide trihydrate did not induce mutations in any of five strains of Salmonella typhi murium, with or without S9 metabolic activation enzymes, nor did it induce sister chromatid exchanges in cultured Chinese hamster ovary cells, with or without S9. A weakly positive response was obtained, however, in a chromosomal aberrations test conducted in cultured Chinese hamster ovary cells with very high doses of scopolamine hydrobromide trihydrate in the presence of S9; without S9, no increase in aberrations was noted. Despite the evidence for chromosomal damage observed in vitro, no increase in the frequencies of micronucleated normochromatic erythrocytes was observed in peripheral blood samples of male or female mice exposed to scopolamine hydrobromide trihydrate for 14 weeks by gavage. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of scopolamine hydrobromide trihydrate in male or female F344/N rats or B6C3F1 mice administered 1, 5, or 25 mg/kg. Synonyms: Scopolamine hydrobromide, 6,7-epoxytropan-3-yl, euscopol, hydroscine hydrobromide, hyoscine bromide, (-)-hyoscine hydrobromide, hysco, isoscopil, scopolammonium bromide, (s)-tropate hydrobromide trihydrate, lα-tropyl-a-scopine

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Phenolphthalein (CAS No. 77-09-8) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Phenolphthalein is used as a laboratory reagent and acid-base indicator and in over-the-counter laxative preparations. The National Cancer Institute nominated phenolphthalein for study because of its widespread use as a component in numerous laxative preparations and the lack of adequate testing for carcinogenicity in experimental animals. Male and female F344/N rats and B6C3F1 mice were exposed to phenolphthalein (98% to 99% pure) in feed for 14 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood. 14-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were given 0, 6,250, 12,500, 25,000, 50,000, or 100,000 ppm phenolphthalein in feed for 14 days. All rats survived to the end of the study. The final mean body weights of all exposed groups of rats were similar to those of the controls. No chemical-related gross or microscopic lesions were observed. 14-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were given 0, 6,250, 12,500, 25,000, 50,000, or 100,000 ppm phenolphthalein in feed for 14 days. All mice survived to the end of the study. The final mean body weights of all exposed groups of mice were similar to those of the controls. No chemical-related gross or microscopic lesions were observed. 13-WEEK STUDY IN RATS: Groups of 10 male and 9 or 10 female F344/N rats were given 0, 3,000, 6,000, 12,000, 25,000, or 50,000 ppm phenolphthalein (equivalent to average daily doses of approximately 200, 400, 800, 1,600, or 3,500 mg phenolphthalein/kg body weight to males and 200, 400, 800, 1,700, or 3,600 mg/kg to females) in feed for 13 weeks. Additional groups of 10 male and 10 female rats designated for clinical pathology evaluations were also given 0, 3,000, 6,000, 12,000, 25,000, or 50,000 ppm phenolphthalein in feed until day 21. All core study rats survived to the end of the study. The final mean body weight of the 50,000 ppm females and the body weight gains of the 25,000 and 50,000 ppm females were significantly lower than those of the controls. The final mean body weights and mean body weight gains of all other exposed groups were similar to those of the controls. There was no cathartic action or any other clinical finding attributed to exposure to phenolphthalein. The few differences in the hematology and clinical chemistry parameters were sporadic and were not considered to be chemical related. The percentage of motile sperm in the 12,000 ppm males was significantly greater than that in the controls, but no other significant differences in sperm morphology or vaginal cytology between exposed and control groups were observed. Absolute and relative liver weights of 25,000 and 50,000 ppm males were significantly greater than those of the controls. No chemical-related gross or microscopic lesions were observed. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were given 0, 3,000, 6,000, 12,000, 25,000, or 50,000 ppm phenolphthalein (equivalent to average daily doses of approximately 500, 1,000, 2,000, 4,100, or 9,000 mg phenolphthalein/kg body weight to males and 600, 1,200, 2,400, 5,000, or 10,500 mg/kg to females) in feed for 13 weeks. All mice survived until the end of the study. The final mean body weights and mean body weight gains of all exposed groups were similar to those of the controls. There was no cathartic action or any other clinical finding attributed to exposure to phenolphthalein. The absolute right cauda weight of the 12,000 ppm males and the absolute right epididymis weights of 12,000, 25,000, and 50,000 ppm males were significantly less than those of the controls. The percentages of abnormal sperm in 12,000, 25,000, and 50,000 ppm males were significantly greater than that in the control group, and the sperm concentrations in 12,000 and 50,000 ppm males were significantly less than that of the control group. The absolute and relative right testis weights of males exposed to 6,000 ppm or greater and the absolute right testis weight of 3,000 ppm mof 3,000 ppm males were significantly less than those of the controls. The incidences of hypoplasia of the bone marrow in males and females exposed to 12,000 ppm or greater were significantly greater than those in the controls. The incidences of hematopoiesis of the spleen in 25,000 and 50,000 ppm males were significantly greater than that in the controls. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were given 0, 12,000, 25,000, or 50,000 ppm phenolphthalein (equivalent to average daily doses of approximately 500, 1,000, or 2,000 mg phenolphthalein/kg body weight to males and 500, 1,000, or 2,500 mg/kg to females) in feed for 2 years. Survival, Body Weights, and Clinical Findings: Survival of exposed males and females was similar to that of the controls. The mean body weights of exposed males were less than those of the controls through most of the second year of the study, and the mean body weights of exposed females were less than those of the controls from about week 16 until the end of the study. Clinical findings attributed to phenolphthalein exposure included thin appearance and ruffled fur in all exposed groups of males. Determinations of Total Phenolphthalein in Plasma: The mean plasma concentrations of total phenolphthalein (free and conjugated) after 2 years of exposure varied little with time of day. Plasma concentrations of total phenolphthalein were approximately the same between exposure groups and between males and females. Pathology Findings: The incidences of benign pheochromocytoma of the adrenal medulla in all exposed groups of males were significantly greater than those in the controls and occurred with a significant positive trend. The incidences of benign pheochromocytoma in 12,000 ppm females and of benign or malignant pheochromocytoma (combined) in 12,000 and 25,000 ppm females were significantly greater than those in the controls. The numbers of exposed males with bilateral benign pheochromocytomas exceeded the number of controls with these neoplasms. The incidences of malignant pheochromocytomas in exposed rats were similar to those in the controls. The incidences of focal hyperplasia of the adrenal medulla in the 12,000 and 50,000 ppm males were significantly greater than in the controls. The incidences of renal tubule adenoma in 50,000 ppm male rats and of renal tubule adenoma or carcinoma (combined) in 12,000 and 50,000 ppm male rats were significantly greater than those in the controls. Although the increased incidences were predominantly of renal tubule adenoma, four carcinomas were observed in exposed males (0 ppm, 0/50; 12,000 ppm, 1/50; 25,000 ppm, 1/50; 50,000 ppm, 2/50). The incidences of renal tubule neoplasms in exposed groups of females were similar to those in the controls. The findings from an extended evaluation (step section) of the kidneys of female rats were similar to those from the standard evaluation. The incidences of nephropathy in all exposed groups of females were significantly greater than in the controls, and the severity of nephropathy in all exposed groups of males and in 25,000 and 50,000 ppm females was significantly greater than in the controls. The incidences of diffuse hyperplasia of the parathyroid gland (0/41, 16/48, 14/49, 14/46), fibrous osteodystrophy of the bone (0/50, 17/50, 14/50, 12/50), and mineralization (0/50, 11/50, 5/50, 5/49) and degeneration (0/50, 11/50, 5/50, 4/49) of the glandular stomach in exposed groups of males were generally significantly greater than those in the controls. The incidences of hyperplasia of the thyroid gland C-cells (13/50, 3/50, 9/49, 4/49) in 12,000 and 50,000 ppm males were significantly less than in the controls. These lesions are commonly observed in male rats with more advanced nephropathy and are considered to be associated with a calcium/phosphorus imbalance created by compromised functional capacity of the kidney. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were given 0, 3,000, 6,000, or 12,000 ppm phenolphthalein (equivalent to average daily doses of approximately 300, 600, or 1,200 mg phenolphthalein/kg body weight to males and 400, 800, or 1,500 mg/kg to females) in feed for 2 years. Survival, Body Weights, and Clinical Findings: Survival of the 12,000 ppm females was significantly lower than that of the controls; survival of all other exposed groups of mice was similar to that of the controls. The mean body weights of 12,000 ppm males were slightly less than those of the controls beginning at week 93 of the study, and the mean body weights of the 3,000, 6,000, and 12,000 ppm females were less than those of the controls during most of the second year of the study. In exposed mice, there were no clinical findings related to phenolphthalein exposure. Determinations of Total Phenolphthalein in Plasma: The mean plasma concentrations of total phenolphthalein (free and conjugated) after 2 years of exposure varied little with time of day. Plasma concentrations of total phenolphthalein were approximately the same between exposure groups and between males and females. Pathology Findings: The incidences of histiocytic sarcoma in 6,000 and 12,000 ppm males and females were significantly greater than those in the controls and occurred with a significant positive trend. In this study, histiocytic sarcoma was consistently observed in the liver with several other sites (e.g., spleen, lung, bone marrow, and various lymph nodes) involved less frequently. The incidences of all types of malignant lymphoma and of lymphoma of thymic origin in all exposed groups of females were significantly greater than those in the controls and occurred with significant positive trends, while the incidences of all types of malignant lymphoma in all exposed groups of males were similar to that in the controls. The incidences of lymphoma of thymic origin were increased in exposed groups of males, but were significantly increased only in the 6,000 ppm group. The incidences of atypical hyperplasia of the thymus in 6,000 and 12,000 ppm males and in all exposed groups of females were significantly greater than those in the controls. The incidences of benign sex-cord stromal tumors of the ovary in all exposed groups of females were significantly greater than in the controls. The incidences of hyperplasia of the ovary in 3,000 and 12,000 ppm females were significantly greater than in the controls. The incidences of germinal epithelial degeneration of the testis in all exposed groups of males were significantly greater than that in the controls. There were increased incidences of myelofibrosis of the bone marrow in 12,000 ppm males (0 ppm, 3/50; 3,000 ppm, 8/50; 6,000 ppm, 8/50; 12,000 ppm, 19/49) and an increased severity but not incidence of this lesion in exposed females. There were also increased incidences of pigmentation of minimal to mild severity in the bone marrow of 6,000 and 12,000 ppm males (0/50, 2/50, 5/50, 16/49) and females (2/50, 3/50, 11/50, 11/50). Also, the incidences of hematopoietic cell proliferation in the red pulp of the spleen (10/50, 22/50, 28/50, 21/49) in all exposed groups of males were significantly greater than that in the controls, and the severity of this lesion increased with increasing exposure concentration. The incidences of hepatocellular adenoma in all exposed groups of males and females and of hepatocellular adenoma or carcinoma (combined) in 6,000 and 12,000 ppm males and all exposed groups of females were significantly less than those in the controls, and these lesions occurred with significant negative trends. Multiple hepatocellular adenomas were observed more frequently in the control groups than in the exposed groups. The incidences of clear cell and eosinophilic foci in all exposed groups of males and of mixed cell foci in 12,000 ppm males were significantly less than those in the controls. The incidences of eosinophilic foci in exposed groups of females were significantly less than that in the controls. GENETIC TOXICOLOGY: Phenolphthalein, tested in two laboratories, was not mutagenic in any of four strains of Salmonella typhimurium with or without S9 metabolic activation enzymes, and no induction of sister chromatid exchanges was observed in cultured Chinese hamster ovary cells treated with phenolphthalein with or without S9. However, significant increases in chromosomal aberrations were observed after treatment of cultured Chinese hamster ovary cells with phenolphthalein in the presence of S9, and the frequencies of micronucleated erythrocytes were increased in peripheral blood samples from male and female mice administered phenolphthalein in feed for 13 weeks. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenic activity of phenolphthalein in male F344/N rats based on markedly increased incidences of benign pheochromocytomas of the adrenal medulla and of renal tubule adenomas and adenomas or carcinomas (combined). There was some evidence of carcinogenic activity of phenolphthalein in female F344/N rats based on the increased incidences of benign pheochromocytomas of the adrenal medulla in the 12,000 ppm group and of benign or malignant pheochromocytomas (combined) in the 12,000 and 25,000 ppm groups. There was clear evidence of carcinogenic activity of phenolphthalein in male B6C3F1 mice based on increased incidences of histiocytic sarcomas and of malignant lymphomas of thymic origin. There was clear evidence of carcinogenic activity of phenolphthalein in female B6C3F1 mice based on increased incidences of histiocytic sarcomas, malignant lymphomas of all types, lymphomas of thymic origin, and benign sex-cord stromal tumors of the ovary. Exposure of rats to phenolphthalein in feed for 2 years resulted in increased incidences of focal hyperplasia of the adrenal medulla in males and in increased incidences and/or severity of nephropathy of the kidney in males and females. Exposure of mice to phenolphthalein in feed for 2 years resulted in increased incidences of atypical hyperplasia of the thymus in males and females, degeneration of the germinal epithelium of the testis in males, and ovarian hyperplasia in females. Exposure of mice to phenolphthalein in feed for 2 years resulted in decreased incidences of hepatocellular neoplasms and nonneoplastic lesions in males and females. Synonyms: 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone; 3,3-bis( p-hydroxyphenyl)phthalide; a-p -hydroxyphenyl)-a- (4-oxo-2,5-cyclohexadien-1-ylidene)- o-toluic acid Trade names: Agoral®, Alophen®, Colax®, Correctol®, Dialose®, Doxidan®, Espotabs®, Evac-U-Gen®, Evac-U-Lax®, Ex-Lax®, Feen-A-Mint®, FemiLax®, Kondremul®, LaxCaps®, Lax-Pills®, Medilax®, Modane®, Phenolax®, Prulet®

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Nickel Sulfate Hexahydrate (CAS No. 10101-97-0) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Nickel sulfate hexahydrate is used in nickel plating, as a mordant in dyeing and printing textiles, as a blackening agent for zinc and brass, and in the manufacture of organic nickel salts. Nickel sulfate hexahydrate was nominated by the National Cancer Institute to the NTP as part of a class study of nickel compounds for which there was little information on the toxic and carcinogenic effects of inhalation exposure. Male and female F344/N rats and B6C3F1 mice were exposed to nickel sulfate hexahydrate (greater than 98% pure) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in L5178Y mouse lymphoma cells. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 3.5, 7, 15, 30, or 60 mg nickel sulfate hexahydrate/m(3) (equivalent to 0, 0.7, 1.4, 3.1, 6.1, or 12.2 mg nickel/m(3)). Rats were exposed on weekdays only, for a total of 12 exposure days during a 16-day period. Additional groups of four or five male and female F344/N rats were exposed to 0, 3.5, 15, or 30 mg nickel sulfate hexahydrate/m(3)for tissue burden studies. In the core study, two 60 mg/m(3) males, one 30 mg/m(3) female, and all 60 mg/m(3)females died before the end of the study. Final mean body weights of all exposed groups of males and females were significantly lower than those of the controls, as were mean body weight gains of male rats. Clinical findings included increased rates of respiration and reduced activity levels in rats in all exposure groups, except those exposed to 3.5 mg/m(3). Absolute lung weights of 60 mg/m(3) males and of all exposed groups of females were significantly greater than those of the controls, as were the relative lung weights of all exposed groups of males and females. Inflammation (including degeneration and necrosis of the bronchiolar epithelium) occurred in the lungs of all exposed groups of males and females. Atrophy of the olfactory epithelium occurred in the nasal passages of all exposed groups of males (except 60 mg/m(3)) and in 15, 30, and 60 mg/m(3) females. Lymphoid hyperplasia in the bronchial or mediastinal lymph nodes was observed in 30 mg/m(3) males and in 60 mg/m(3) males and females. The concentration of nickel in the lungs of all exposed groups of males and females was greater than in control animals. 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 3.5, 7, 15, 30, or 60 mg nickel sulfate hexahydrate/m(3). Mice were exposed on weekdays only, for a total of 12 exposure days during a 16-day period. Additional groups of five male and five female B6C3F1 mice were exposed to 0 or 3.5 mg nickel sulfate hexahydrate/m(3)for tissue burden studies. All core study mice exposed to 7 mg/m(3) or greater died before the end of the study; all control and 3.5 mg/m(3)mice survived to the end of the study. Final mean body weights and weight gains of 7, 15, 30, and 60 mg/m(3)males and females were significantly less than those of the controls, and clinical findings in these groups included emaciation, lethargy, and rapid respiration rates. Absolute and relative lung weights of male and female mice exposed to 7 mg/m(3) or greater were significantly greater than those of the controls. Only tissues from mice exposed to 0, 3.5, or 7 mg/m(3) were examined histopathologically. Inflammation occurred in the lungs of 3.5 and 7 mg/m(3) males and females; necrosis of the alveolar and bronchiolar epithelium was a component of the inflammation in 7 mg/m(3)males and females. In addition, atrophy of the olfactory epithelium of the nasal passages was observed in 3.5 mg/m(3) males and females. Nickel concentrations in the lungs of mice exposed to 3.5 mg/m(3) were greater than those in the controls. 13-WEEK STUDY IN RATS: Groups of ten male and ten female F344/N rats were exposed to 0, 0.12, 0.25, 0.5, 1, or 2 mg nickel sulfate hexahydrate (equivalent to 0, 0.03, 0.06, 0.11, 0.22, or 0.44 mg nickel/m(3)), 5 days per week for 13 weeks. Additional groups of six male and six female F344/N rats were exposed to 0, 0.12, 0.5, or 2 mg nic mg nickel sulfate hexahydrate/m(3)for tissue burden studies. In the core study, one 2 mg/m(3)male rat died before the end of the study; all other males and all females survived until the end of the study. Final mean body weights and body weight gains of all exposed groups were similar to those of the controls. There were no significant clinical findings noted during the study. Exposure-related increases in neutrophil and lymphocyte numbers occurred and were most pronounced in female rats. With the exception of 0.12 mg/m(3)rats, absolute and relative lung weights of all exposed groups were generally significantly greater than those of the controls. Exposure-related increases in the incidence and severity of inflammatory lesions (alveolar macrophages, chronic inflammation, and interstitial infiltration) occurred in the lungs of all exposed groups of males and females. Lymphoid hyperplasia of the bronchial and/or mediastinal lymph nodes occurred in males exposed to 0.5 mg/m(3)or greater. Atrophy of the olfactory epithelium occurred in males and females exposed to 0.5, 1, and 2 mg/m(3)and in 0.25 mg/m(3)females. The concentration of nickel in the lungs of 0.5 and 2 mg/m(3) rats was greater than that in the lungs of control animals at 4, 9, and 13 weeks for males and at 13 weeks for females. 13-WEEK STUDY IN MICE: Groups of ten male and ten female B6C3F1 mice were exposed to 0, 0.12, 0.25, 0.5, 1, or 2 mg nickel sulfate hexahydrate, 5 days per week for 13 weeks. Additional groups of up to five or six male and female B6C3F1 mice were exposed to 0, 0.12, 0.5, or 2 mg nickel sulfate hexahydrate/m(3)for tissue burden studies. In the core study, four control males, three control females, and one 0.12 mg/m(3)male died before the end of the study; the deaths were not considered to be chemical related, and all other mice survived to the end of the study. The final mean body weights and body weight gains of all exposed groups were similar to those of the controls. There were no chemical-related clinical findings. Hematology changes similar to those reported in female rats occurred in female mice, but the mice were minimally affected. The absolute and relative lung weights of 1 mg/m(3)males and 2 mg/m(3)males and females were significantly greater than those of the controls. Increased numbers of alveolar macrophages occurred in all males and females exposed to 0.5 mg/m(3)or greater. Chronic active inflammation and fibrosis occurred in 1 and 2 mg/m(3)males and females. Lymphoid hyperplasia of the bronchial lymph node and atrophy of the olfactory epithelium in the nasal passages were observed in 2 mg/m(3)males and females. Nickel concentration in the lung of 2 mg/m(3)females was significantly greater than in control animals. 2-YEAR STUDY IN RATS: Groups of 63 to 65 male and 63 to 64 female rats were exposed to nickel sulfate hexahydrate by inhalation at concentrations of 0, 0.12, 0.25, or 0.5 mg/m(3) (equivalent to 0, 0.03, 0.06, or 0.11 mg nickel/m(3)). Animals were exposed for 6 hours plus T90 (8 minutes) 5 days per week for 104 weeks. Five male and five female rats from each group were evaluated at 7 months for histopathology; an additional seven males and seven females from each group were evaluated at 7 months for nickel tissue burden in the lung and kidney; and five males and five females from each group were evaluated at 15 months for alterations in hematology, nickel tissue burden in the lung and kidney, and histopathology. Survival, Body Weights, Clinical Findings, and Hematology The survival rates of all exposed groups of males and females were similar to those of the controls. Mean body weights of 0.5 mg/m(3)female rats were slightly lower (6% to 9%) than those of the controls throughout the second year of the study; final mean body weights of all exposed groups of males and 0.12 and 0.25 mg/m(3)females were similar to those of the controls. There were no clinical findings or hematology differences that were considered to be related to nickel sulfate hexahydrate administration. Pathology Findings No exposure-related neoplasms occurred in male or female rats exposed by inhalation to nickel sulfate hexahydrate for 2 years. Increased incidences of inflammatory lung lesions were generally observed in all exposed groups of male and female rats at the end of the study. The incidences of chronic active inflammation, macrophage hyperplasia, alveolar proteinosis, and fibrosis were markedly increased in male and female rats exposed to 0.25 or 0.5 mg/m(3). Increased incidences of lymphoid hyperplasia in the bronchial lymph nodes occurred in 0.5 mg/m(3)male and female rats at the end of the 2-year study. The incidences of atrophy of the olfactory epithelium in 0.5 mg/m(3)males and females were significantly greater than those in controls at the end of the study. Tissue Burden Analyses Lung nickel burdens in exposed male and female rats were greater than those in the controls at the 7- and 15-month interim evaluations, and lung nickel burdens values increased with increasing exposure concentration. 2-YEAR STUDY IN MICE: Groups of 80 male and 80 female mice were exposed to nickel sulfate hexahydrate by inhalation at concentrations of 0, 0.25, 0.5, or 1 mg/m(3) (equivalent to 0, 0.06, 0.11, or 0.22 mg nickel/m(3)). Animals were exposed for 6 hours plus T90 (8 minutes) 5 days per week for 104 weeks. Five male and five female mice from each group were evaluated at 7 months for histopathology; five males and five females from each group were evaluated at 7 months for nickel tissue burden in the lung and kidney; five males and five females from each group were evaluated at 15 months for alterations in hematology and histopathology; and five males and five females from each group were evaluated at 15 months for nickel tissue burden in the lung and kidney. Survival, Body Weights, Clinical Findings, and Hematology The survival rates of all exposed groups of males and females were similar to those of the controls. The mean body weights of 1 mg/m(3)males and of all exposed groups of females were lower than those of the controls during the second year of the study. There were no clinical findings or hematology differences considered to be related to chemical exposure. Pathology Findings Inflammatory lesions of the lung generally occurred in all exposed groups of male and female mice at the end of the 2-year study. These lesions included macrophage hyperplasia, chronic active inflammation, bronchialization (alveolar epithelial hyperplasia), alveolar proteinosis, and infiltrating cells in the interstitium. Incidences of macrophage hyperplasia and/or lymphoid hyperplasia occurred in the bronchial lymph nodes of most of the 1 mg/m(3)males and females and in some 0.5 mg/m(3)females at the end of the 2-year study. Atrophy of the olfactory epithelium was observed in 0.5 and 1 mg/m(3)males and in all exposed groups of females at the end of the 2-year study. Tissue Burden Analyses At the 7- and 15-month interim evaluations, lung nickel burden parameters measured in control and exposed groups were below the limit of detection. Absolute lung weights of 0.5 and 1 mg/m(3)lung burden study females were significantly greater than those of the controls at 15 months. GENETIC TOXICOLOGY: Nickel sulfate hexahydrate (500 to 800 g/mL) was tested for induction of trifluorothymidine resistance in L5178Y mouse lymphoma cells. A positive response was observed in the absence of S9. The test was not performed with S9. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of nickel sulfate hexahydrate in male or female F344/N rats exposed to 0.12, 0.25, or 0.5 mg/m(3) (0.03, 0.06, or 0.11 mg nickel/m(3)). There was no evidence of carcinogenic activity of nickel sulfate hexahydrate in male or female B6C3F1 mice exposed to 0.25, 0.5, or 1 mg/ m3 (0.06, 0.11, or 0.22 mg nickel/m(3)). Exposure of rats to nickel sulfate hexahydrate by inhalation for 2 years resulted in increased incidences of chronic active inflammation, macrophage hyperplasia, alveolar proteinosis, and fibrosis of the lung; lymphoid hyperplasia of the bronchial lymph node; and atrophy of the olfactory epithelium. Exposure of mice to nickel sulfate hexahydrate by inhalation for 2 years resulted in increased incidences of chronic active inflammation, bronchialization (alveolar epithelial hyperplasia), macrophage hyperplasia, interstitial infiltration, and alveolar proteinosis of the lung; lymphoid and macrophage hyperplasia of the bronchial lymph node; and atrophy of the olfactory epithelium. Synonyms: Blue salt; hexahydrate, nickel (2+) salt; nickel monosulfate hexahydrate; nickel (2+) sulfate hexahydrate; nickel (II) sulfate hexahydrate; nickel sulphate hexahydrate; nickelous sulfate hexahydrate; nickelous sulphate hexahydrate; single nickel salt, sulfuric acid

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Codeine (CAS No. 76-57-3) in F344 Rats and B6C3F1 Mice (Feed Studies).

Codeine is used in a variety of pharmaceuticals including analgesics, sedatives, hypnotics, antiperistaltics, and antitussive agents. The National Cancer Institute and the Food and Drug Administration nominated codeine for study because it is a widely used drug and it is representative of the morphine class of compounds, for which chronic carcinogenicity studies had not been conducted. The oral route of administration was selected because it is the primary route of human exposure. Male and female F344/N rats and B6C3F1 mice were given codeine (99% pure) in feed for 14 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells. 14-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were given 0, 1,562, 3,125, 6,250, 12,500, or 25,000 ppm codeine in feed for 14 days, which resulted in daily doses of approximately 125, 250, 450, 650, or 750 mg codeine/kg body weight to males and 125, 250, 500, 700, or 300 mg/kg to females. One female exposed to 6,250 ppm, one male and three females exposed to 12,500 ppm, and all males and females exposed to 25,000 ppm died during the study. Final mean body weights and mean body weight gains of all exposed groups except 1,562 ppm females were significantly lower than those of the controls. No chemical-related gross lesions were observed in rats at necropsy. Thickening of the forestomach mucosa (hyperplasia and hyperkeratosis) and lymphoid depletion of the thymus in exposed males and females and testicular degeneration in exposed males, observed primarily in the 12,500 and 25,000 ppm groups, were associated with decreased survival and increased morbidity in these groups. 14-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were given 0, 781, 1,562, 3,125, 6,250, or 12,500 ppm codeine in feed for 14 days, which resulted in daily doses of approximately 150, 300, 600, 1,300, or 3,000 mg codeine/kg body weight to males and 200, 400, 750, 1,500, or 3,000 mg/kg to females. All mice survived to the end of the study. The final mean body weight of 3,125 ppm females was significantly greater than that of the controls; the final mean body weight of 12,500 ppm females and the mean body weight gains of 12,500 ppm males and females were significantly lower than those of the controls. Absolute and relative liver weights of 3,125, 6,250, and 12,500 ppm males and of 12,500 ppm females and the absolute and relative right kidney weights of 12,500 ppm males were significantly lower than those of the controls. No gross or histopathologic lesions were attributed to codeine exposure. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were given 0, 390, 781, 1,562, 3,125, or 6,250 ppm codeine in feed for 13 weeks, which resulted in daily doses of approximately 25, 50, 100, 200, or 450 mg codeine/kg body weight to males and 25, 50, 100, 250, or 500 mg/kg to females. There were no chemical-related deaths during the study. Final mean body weights and mean body weight gains of all groups of exposed males and of females exposed to 1,562, 3,125, and 6,250 ppm were significantly lower than those of the controls. Feed consumption decreased with increasing exposure concentration during the first week of the study; however, by the end of the study, feed consumption by most exposed groups was similar to that by the controls. There were alterations of various hematology and clinical chemistry parameters at the end of the study. There was a mild dose-dependent lymphopenia in females receiving 1,562 ppm and above and in 6,250 ppm males. There also was a minimal to mild macrocytosis that occurred in all exposed groups of males and in females exposed to 781, 3,125, or 6,250 ppm. No significant differences between control and exposed rats were observed in sperm morphology or vaginal cytology parameters. Absolute and relative adrenal gland weights of exposed males and of 3,125 and 6,250 ppm females were significantly greater than those of the controls. Absolute and relative liver weights of exposed males werees were significantly lower than those of the controls. Relative thymus weights of 3,125 and 6,250 ppm males were significantly lower than that of the controls. No chemical-related gross or histopathologic lesions were observed in male or female rats. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were given 0, 390, 781, 1,562, 3,125, or 6,250 ppm codeine in feed for 13 weeks, which resulted in daily doses of approximately 60, 120, 260, 460, or 1,000 mg codeine/kg body weight to males and 60, 130, 280, 530, or 1,200 mg/kg to females. Two male mice in the 3,125 ppm group died during week 7. All other mice survived to the end of the study. Final mean body weights of exposed males and females were similar to those of the controls. Feed consumption by exposed males and females was similar to that by the controls. Abnormal posture was observed in all exposed groups of males. There were no significant differences in hematology or urinalysis parameters in male or female mice. Minor, sporadic changes occurred in a few of the clinical chemistry parameters; they were not considered biologically significant. No significant differences in sperm morphology or vaginal cytology were attributed to codeine exposure. Absolute and relative kidney weights of 3,125 and 6,250 ppm males were lower than those of the controls. No chemical-related differences in organ weights were observed in females. No chemical-related gross or histopathologic lesions were observed in male or female mice. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female F344/N rats were fed diets containing 0, 400, 800, or 1,600 ppm codeine for up to 106 weeks, with 9 or 10 rats per group evaluated at 15 months. These exposure concentrations resulted in average daily doses of approximately 15, 30, and 70 mg codeine/kg body weight to males and 15, 40, and 80 mg/kg to females. Survival, Body Weights, Feed Consumption, and Clinical Findings Survival of 400 ppm females was significantly greater than that of the controls; survival of all groups of exposed males and of 800 and 1,600 ppm females was similar to that of the controls. There was an exposure-related decrease in mean body weights of males and females. The final mean body weight of 1,600 ppm males was 88% that of the controls, and the final mean body weight of 1,600 ppm females was 89% that of the controls. Feed consumption by exposed groups was similar to that by the controls. Chemical-related clinical findings were limited to ocular discharge in exposed males and females. Pathology Findings: Absolute and relative adrenal gland weights of 800 and 1,600 ppm males were significantly greater than those of the controls at 15 months. There were no increased incidences of neoplasms attributable to codeine exposure at any site. At 2 years, there were exposure-related decreases in the incidences of adrenal medulla hyperplasia in males and females. There was an exposure-related decrease in the incidence of benign pheochromocytomas in males, and the incidences in exposed males were significantly lower than that in the controls. In 1,600 ppm females the incidences of mammary gland fibroadenomas and of fibroadenomas or adenocarcinomas (combined) were significantly lower than those in the controls. The decreased incidences of benign pheochromocytomas in males and mammary gland neoplasms in females were considered to be related to codeine exposure. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female B6C3F1 mice were fed diets containing 0, 750, 1,500, or 3,000 ppm codeine for up to 106 weeks, with 9 or 10 mice per group evaluated at 15 months. These exposure concentrations resulted in average daily doses of approximately 100, 200, or 400 mg codeine/kg body weight to males and females. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of exposed males and females was similar to that of the controls. Mean body weights of 750 and 1,500 ppm males and females were similar to those of the controls throughout most of the study. Mean body weights of 3,000 ppm males and females were less than those of the controls from about week 13, and the final mean body weights of these groups were 86% and 82% those of the respective controls. Feed consumption by exposed groups was similar to that by the controls. Pathology Findings: There were no increased incidences of neoplasms attributable to codeine exposure at any site. At 15 months, the incidence of thyroid gland follicular cell hyperplasia in 3,000 ppm males was significantly greater than that of the controls, and this lesion was observed in 1,500 and 3,000 ppm females. At 2 years, the incidences of follicular cell hyperplasia in all exposed groups of mice were significantly greater than those in the controls, but there were no increases in thyroid gland follicular cell neoplasms. The incidence of centrilobular fatty change in the liver of 3,000 ppm males was significantly lower than that in the controls at 15 months, and the decreased incidence appeared to be related to exposure level. At 2 years, the incidences of eosinophilic foci, foci of fatty change, centrilobular cytomegaly, and centrilobular fatty change in 3,000 ppm males were lower than those in the controls. The incidence of hepatocellular adenomas and the incidence of hepatocellular adenomas or carcinomas (combined) in 3,000 ppm males and females were significantly lower than those in the controls; this was considered to be related to lower body weights in these groups. GENETIC TOXICOLOGY: Codeine phosphate was not mutagenic in any of four strains of Salmonella typhimurium, with or without S9 metabolic activation enzymes. In cytogenetic tests with cultured Chinese hamster ovary cells, codeine phosphate induced dose-related increases in sister chromatid exchanges, with and without S9, only at concentration levels that caused cell cycle delay. No induction of chromosomal aberrations was noted in cultured Chinese hamster ovary cells treated with codeine phosphate, with or without S9. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity of codeine in male or female F344/N rats exposed to 400, 800, or 1,600 ppm. There was no evidence of carcinogenic activity of codeine in male or female B6C3F1 mice exposed to 750, 1,500, or 3,000 ppm. Thyroid gland follicular cell hyperplasia was increased in exposed male and female mice. Decreased incidences of benign pheochromocytomas of the adrenal medulla in male rats and mammary gland fibroadenomas and fibroadenomas or adenocarcinomas (combined) in female rats were related to codeine exposure. Synonyms: 7,8-didehydro-4,5-epoxy-3-methoxy-17-methylmorphinan-6-ol; methylmorphine; 3-0-methylmorphine monohydrate; N-methylnorcodeine; morphine-3-methyl ether; morphine monomethyl ether Trade names: Codeinum, Codicept, Coducept, Metilmorfina

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Nickel Subsulfide (CAS No. 12035-72-2) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Nickel subsulfide is used in the manufacture of lithium batteries and is a major component in the refining of certain nickel ores. Nickel subsulfide was nominated as part of a class study of nickel compounds, for which there was little information on the toxic and carcinogenic effects of inhalation exposure. Male and female F334/N rats and B6C3F1 mice were exposed to nickel subsulfide (at least 97% pure; the mean value for the mass median aerodynamic diameter at each exposure concentration ranged from 2.0 to 2.2 mm by inhalation 6 hours per day, 5 days per week, for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, and mouse peripheral blood samples were analyzed for frequency of micronucleated normochromatic erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to atmospheres containing 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel subsulfide/m(3) (equivalent to 0, 0.44, 0.88, 1.83, 3.65, and 7.33 mg nickel/m(3)) 6 hours per day, 5 days per week for a total of 12 exposure days during a 16-day period. Additionalmgroups of three male and three female rats were exposed to 0, 0.6, 2.5, or 10 mg/m(3) for tissue burden studies. One male exposed to 10 mg nickel subsulfide/m(3) in the core study died on day 14; all other rats survived until the end of the study. Final mean body weights and mean body weight gains of males exposed to 5 or 10 mg nickel subsulfide/m(3) and females exposed to 2.5, 5, or 10 mg/m(3) were significantly lower than those of the controls. Clinical findings of toxicity on day 5 of the study included labored respiration in 10 mg/m(3) males and 5 and 10 mg/m(3) females and dehydration in 5 and 10 mg/m(3) females. Absolute and relative lung weights of 2.5, 5, and 10 mg/m(3) males and all exposed groups of females were significantlymgreater than those of the controls, as was the absolute lung weight of 1.2 mg/m(3) males. Inflammation of the lung and atrophy of the nasal olfactory epithelium occurred in all exposed mgroups. The concentrations of nickel in the lungs of exposedmgroups of rats increased with exposure concentration (males, 7 to 67 mg nickel/g lung; females, 9 to 77 mg/g lung). 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to atmospheres containing 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel subsulfide/m(3) for 6 hours per day, 5 days per week for a total of 12 exposure days during a 16-day period. Additional groups of three male and three female mice were exposed to 0, 0.6, 2.5, or 10 mg/m(3) for tissue burden studies. All male and female mice exposed to 10 mg nickel subsulfide/m(3) in the core study died before the end of the study; the death of one female was accidental. One control male, one control female, and one 1.2 mg/m(3) male also died before the end of the study. Final mean body weights and mean body weight gains of 5 mg/m(3) males were significantly lower than those of the controls. Clinical findings at day 5 included labored respiration in 10 mg/m(3) males and females. The absolute lung weight of 5 mg/m(3) males, the absolute and relative lung weights of 10 mg/m(3) males and 5 mg/m(3) females, and the relative lung weight of 10 mg/m(3) females were significantly greater than those of the controls. Inflammation of the lung occurred in 2.5, 5, and 10 mg/m(3) male and female mice, fibrosis of the lung occurred in 5 mg/m(3) males and females, and lymphoid hyperplasia of the bronchial lymph nodes and atrophy of the nasal olfactory epithelium occurred in 1.2, 2.5, 5, and 10 mg/m(3) males and females. Nickel concentrations in the lung of exposed male and female mice were greater than those of the controls (males, 10 to 20 mg nickel/g lung; females, 8 to 20 mg/g lung) 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to atmospheres containing 0, 0.15, 0.3, 0.6, 1.2, or 2.5 mg nickel subsulfide/m(3) (equivalent to 0, 0.11, 0.22, 0.44, 0.88, and 1.83 mg nickel/m(3)) 6 hours per day, 5 days per week for 13 weeks. Additional groups of 18 male and 18 female female rats were exposed to 0, 0.15, 0.6, or 2.5 mg/m(3) for tissue burden studies. All core study rats survived until the end of the study. Final mean body weights and mean body weight gains of 2.5 mg/m(3) males were significantly lower than those of the controls; final mean body weights of all other exposure groups were similar to those of the controls. Chemical-related clinical findings included labored respiration in 2.5 mg/m(3) males and females during weeks 2 through 7. In general, neutrophil and erythrocyte counts, hematocrit values, and hemoglobin concentrations were minimally increased in exposed rats. Absolute and relative lung weights of all exposed groups were significantly greater than those of the controls. Increases in the number of alveolar macrophages, interstitial infiltrates, or incidences of chronic inflammation of the lung occurred in all groups exposed to nickel subsulfide concentrations of 0.3 mg/m(3) or greater; the severity of these lesions generally increased with increasing exposure concentration. Increases in the number of alveolar macrophages were observed in 0.15 mg/m(3) males and females. Lymphoid hyperplasia of the bronchial and mediastinal lymph nodes was observed in rats exposed to 0.3 mg/m(3) or greater. Most 0.6, 1.2, and 2.5 mg/m(3) males and females had atrophy of the nasal olfactory epithelium, and the severity generally increased with increasing exposure concentration. Nickel concentrations in the lung increased with exposure concentration and were greater than those in the controls in rats exposed for 13 weeks (males, 5 to 18 mg nickel/g lung; females, 5 to 17 mg/g lung). 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to atmospheres containing 0, 0.15, 0.3, 0.6, 1.2, or 2.5 mg nickel subsulfide/m(3) for 6 hours per day, 5 days per week for 13 weeks. Additional groups of six male and six female mice were exposed to 0, 0.15, 0.6, or 2.5 mg/m(3) for tissue burden studies. Final mean body weights of all exposure groups were similar to those of the controls. No chemical-related clinical findings were observed. Lymphocyte counts in 1.2 and 2.5 mg/m(3) males were minimally greater than that of the controls. Hemoglobin concentrations and erythrocyte counts in 0.3, 0.6, 1.2, and 2.5 mg/m(3) females were minimally greater than those of the controls. Absolute and relative lung weights of 1.2 and 2.5 mg/m(3) males and females were significantly greater than those of the controls. An increase in alveolar macrophages was present in mice from the 0.3 mg/m(3) and higher exposure groups. Chronic inflammation and fibrosis were observed in the lung of 1.2 and 2.5 mg/m(3) males and females. Interstitial infiltrates of lymphocytes were observed in mice exposed to 0.6, 1.2, or 2.5 mg/m(3). Lymphoid hyperplasia of the bronchial lymph nodes was observed in groups exposed to 1.2 or 2.5 mg/m(3). Atrophy of the nasal olfactory epithelium occurred in 0.6, 1.2, and 2.5 mg/m(3) males and females, and incidences and severity generally increased with increasing exposure concentration. At 13 weeks, nickel concentrations in the lungs of exposed mice were greater than those of the controls (males, 3 to 17 g nickel/g lung; females, 6 to 23 mg/g lung), and these concentrations increased with increasing exposure concentration. 2-YEAR STUDY IN RATS: Survival, Body Weights, Clinical Findings, and Hematology: Groups of 63 male and 63 female F344/N rats were exposed to 0, 0.15, or 1 mg nickel subsulfide/m(3) (equivalent to 0, 0.11, or 0.73 mg nickel/m(3)) by inhalation for 6 hours per day, 5 days per week for 104 weeks. Survival of exposed males and female rats was similar to that of the controls. Mean body weights of males and females exposed to 0.15 mg/m(3) were similar to those of the controls. Mean body weights of rats exposed to 1 mg/m(3) were lower than those of the controls throughout the second year of the study. Chemical-related clinical findings included rapid and shallow breathing following exposure periods. Hematocrit values and hemoglobin concentrations in 1 mg/m(3) males and females and the erythrocyte count in 1 mg/m(3) males were mildly greater than those in the controls. Pathology Findings: In general, the absolute and relative lung weights of exposed males and females were significantly greater than those of the controls at 7 and 15 months. There were exposure-related increases in the incidences of alveolar/bronchiolar adenoma in males, alveolar/bronchiolar carcinoma in males and females, and alveolar/bronchiolar adenoma or carcinoma (combined) in males and females at 2 years. Nonneoplastic lung lesions generally observed in exposed males and females included fibrosis; chronic active inflammation; focal alveolar epithelial hyperplasia, macrophage hyperplasia, and proteinosis; bronchial lymphoid hyperplasia; and interstitial inflammation. At 2 years, there were significant exposure-related increases in the incidences of benign pheochromocytoma, malignant pheochromocytoma, and benign or malignant pheochromocytoma (combined) in males and of benign pheochromocytoma in females. The incidence of adrenal medulla hyperplasia in 1 mg/m(3) females was significantly greater than that of the controls At 2 years, the incidences of chronic active inflammation of the nose in 1 mg/m(3) females and of olfactory epithelial atrophy in 1 mg/m(3) males and females were significantly greater than those of the controls. The incidences of lymphoid hyperplasia of the bronchial lymph node in exposed males at 7 and 15 months and in exposed males and females at 2 years were significantly greater than those of the controls. Incidences of macrophage hyperplasia in the bronchial lymph node of exposed males at 15 months and exposed males and females at 2 years were greater than those of the controls. Tissue Burden Analyses: Nickel concentrations in the lungs of exposed rats were greater than those of the controls at 7 months (males, 6 to 9 mg nickel/g lung; females, 6 to 9 mg/g lung) and 15 months (males, 4 to 3 mg nickel/g lung; females, 4 to 7 mg/g lung). 2-YEAR STUDY IN MICE: Survival, Body Weights, Clinical Findings, and Hematology: Groups of 80 male and 80 female B6C3F1 mice were exposed to 0, 0.6, or 1.2 mg nickel subsulfide/m(3) (equivalent to 0, 0.44, or 0.88 mg nickel/m(3)) by inhalation for 6 hours per day, 5 days per week for 105 weeks. Survival of exposed male and female mice was similar to that of the controls. Mean body weights of 0.6 and 1.2 mg/m(3) males and females were less than those of the controls throughout the second year of the study. Chemical-related clinical findings in male and female mice included labored respiration following exposure periods. The hematocrit value and the segmented neutrophil, monocyte, lymphocyte, and total leukocyte counts in 1.2 mg/m(3) females were greater than those in the controls. Pathology Findings: Absolute and relative lung weights of exposed males and females were generally significantly greater than those of the controls at 7 and 15 months. The incidence of alveolar/bronchiolar carcinoma in 0.6 mg/m(3) females and the incidences of alveolar/bronchiolar adenoma or carcinoma (combined) in 0.6 mg/m(3) males and 0.6 and 1.2 mg/m(3) females were significantly less than those of the controls. In general, the incidences of chronic active inflammation; bronchialization (alveolar epithelial hyperplasia), macrophage hyperplasia and proteinosis; interstitial infiltration; and fibrosis in exposed groups of males and females were greater than those of the controls at 7 and 15 months and at 2 years. The incidences of atrophy of the nasal olfactory epithelium and inflammation of the nose in exposed mice were also generally greater than those of the controls. At 2 years, the incidences of degeneration of olfactory epithelium in exposed females were significantly less than that of the controls. The incidences of lymphoid hyperplasia of the bronchial lymph node in 1.2 mg/m(3) males at 15 months, in 0.6 and 1.2 mg/m(3) females at 15 months, and in 0.6 and 1.2 mg/m(3) males and females at 2 years were significantly greater than those of the controls. The incidences of macrophage hyperplasia in 1.2 mg/m(3) males at 7 and 15 months, in 0.6 and 1.2 mg/m(3) females at 15 months, and in 0.6 and 1.2 mg/m(3) males and females at 2 years were significantly greater than those of the controls. Tissue Burden Analyses: Nickel concentrations in the lungs of exposed mice were greater than those of the controls at 7 months (males, 10 to 11 mg nickel/g lung; females, 10 to 14 mg/g lung) and 15 months (males, 12 to 20 mg nickel/g lung; females, 15 to 26 mg/g lung). GENETIC TOXICOLOGY: Nickel subsulfide was considered to be equivocal in the Salmonella gene mutation assay overall. Sporadic weakly positive and equivocal responses were obtained in strain TA100 with and without S9 metabolic activation enzymes; all other strain/activation combinations gave negative results. No increase in the frequency of micronucleated erythrocytes was observed in peripheral blood samples from male or female mice exposed to nickel subsulfide by inhalation for 13 weeks. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of nickel subsulfide in male F344/N rats based on increased incidences of alveolar/bronchiolar adenoma, carcinoma, and adenoma or carcinoma (combined) and on increased incidences of benign, malignant, and benign or malignant (combined) pheochromocytoma of the adrenal medulla. There was clear evidence of carcinogenic activity of nickel subsulfide in female F344/N rats based on increased incidences of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) and an increased incidence of benign pheochromocytoma of the adrenal medulla. There was no evidence of carcinogenic activity of nickel subsulfide in male or female B6C3F1 mice exposed to 0.6 or 1.2 mg/m(3). Exposure of male and female rats to nickel subsulfide by inhalation for 2 years resulted in inflammation, hyperplasia, and fibrosis in the lung; inflammation and atrophy of the olfactory epithelium in the nose; and hyperplasia in the adrenal medulla (females). Exposure of male and female mice to nickel subsulfide by inhalation for 2 years resulted in inflammation, bronchialization, hyperplasia, and fibrosis in the lung and inflammation and atrophy of the olfactory epithelium in the nose. Synonyms: Heazlewoodite, nickel subsulphide, nickel sulfide (3:2), a-nickel sulfide (3:2) crystalline, nickel sulphide, nickel tritadisulphide, trinickel disulfide

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of 2,2-Bis(Bromomethyl)-1,3-Propanediol (FR-1138(R)) (CAS No. 3296-90-0) in F344 Rats and B6C3F1 Mice (Feed Studies).

2,2-Bis(bromomethyl)-1,3-propanediol is used as a fire retardant in unsaturated polyester resins, in molded products, and in rigid polyurethane foam. 2,2-Bis(bromomethyl)-1,3-propanediol was chosen for study because it is a widely used flame retardant and little toxicity and carcinogenicity data were available. Groups of male and female F344/N rats and B6C3F1 mice were exposed to technical grade 2,2-bis(bromomethyl)-1,3-propanediol (78.6% pure) in feed for 13 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, mouse bone marrow, and mouse peripheral blood. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were fed diets containing 0, 1,250, 2,500, 5,000, 10,000, or 20,000 ppm 2,2-bis(bromomethyl)- 1,3-propanediol for 13 weeks. These levels corresponded to approximately 100, 200, 400, 800, or 1,700 mg 2,2-bis(bromomethyl)-1,3-propanediol/kg body weight (males) and 100, 200, 400, 800, or 1,600 mg/kg (females). No rats died during the studies. The final mean body weights and weight gains of 5,000, 10,000, and 20,000 ppm males and females were significantly lower than those of the controls. Feed consumption by exposed animals was lower than that by controls at week 1, but was generally similar to or slightly higher than that by controls at week 13. No chemical-related clinical findings were observed. Chemical-related differences in clinical pathology parameters included increased urine volumes accompanied by decreased urine specific gravity and minimally increased protein excretion in 10,000 and 20,000 ppm males. In females, urine parameters were less affected than males. Water deprivation tests demonstrated that male and female rats were able to adequately concentrate their urine in response to decreased water intake. Serum protein and albumin concentrations in female rats exposed to 2,500 ppm and higher were slightly lower than those of the controls. Renal papillary degeneration was present in 5,000 and 10,000 ppm males, and in 20,000 ppm males and females. Hyperplasia of the urinary bladder was present in 20,000 ppm males. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were fed diets containing 0, 625, 1,250, 2,500, 5,000, or 10,000 ppm 2,2-bis(bromomethyl)-1,3-propanediol for 13 weeks. These levels corresponded to approximately 100, 200, 500, 1,300, or 3,000 mg 2,2-bis(bromomethyl)-1,3-propanediol/kg body weight (males) and 140, 300, 600, 1,200, or 2,900 mg/kg (females). One control female, two males and one female receiving 625 ppm, one female receiving 1,250 ppm, one female receiving 2,500 ppm, one female receiving 5,000 ppm, and three males receiving 10,000 ppm died during the study. The final mean body weights and body weight gains of males and females receiving 1,250, 2,500, 5,000, or 10,000 ppm and of females receiving 625 ppm were significantly lower than those of the controls. Feed consumption by exposed mice was generally higher than that by controls throughout the study. Clinical findings included abnormal posture and hypoactivity in 10,000 ppm male and female mice. Blood urea nitrogen concentrations of 5,000 ppm females and 10,000 ppm males and females were greater than those of controls. Also, urine specific gravity was lower in 10,000 ppm females. Differences in organ weights generally followed those in body weights. Papillary necrosis, renal tubule regeneration, and fibrosis were observed in the kidneys of 2,500 and 5,000 ppm males and 10,000 ppm males and females. Urinary bladder hyperplasia was observed in 5,000 and 10,000 ppm males and females. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female rats received 2,500, 5,000, or 10,000 ppm 2,2-bis(bromomethyl)- 1,3-propanediol in feed for 104 to 105 weeks. Groups of 70 males and 60 females received 0 ppm 2,2-bis(bromomethyl)-1,3-propanediol in feed for 104 to 105 weeks. A stop-exposure group of 70 male rats received 20,000 ppm 2,2-bis(bromomethyl)-1,3-propanediol in feed for 3 months, after which animals received undosed feed for the remainder of the 2-year styear study. Average daily doses of 2,2-bis(bromomethyl)-1,3-propanediol were 100, 200, or 430 mg/kg body weight for males and 115, 230, or 460 mg/kg for females. Stop-exposure males received an average daily dose of 800 mg/kg. Ten animals from the 0 ppm male group and the 20,000 ppm stop-exposure group were evaluated at 3 months; nine or 10 control animals and five to nine animals from each of the continuous-exposure groups were evaluated at 15 months. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of 5,000 and 10,000 ppm continuous-exposure study males and females and 20,000 ppm stop-exposure males was significantly lower than that of the controls. Mean body weights of exposed male and female rats receiving 10,000 ppm and stop-exposure males receiving 20,000 ppm were lower than those of the controls throughout most of the study. In the continuous-exposure study, feed consumption by exposed rats was generally similar to that by controls throughout the study. In 20,000 ppm stop-exposure males, the feed consumption was lower than that by controls. Clinical findings included skin and/or subcutaneous masses on the face, tail, and the ventral and dorsal surfaces of exposed rats. Pathology Findings: In the 2-year continuous and stop-exposure studies in male rats, exposure to 2,2-bis(bromomethyl)-1,3-propanediol was associated with neoplastic effects in the skin, mammary gland, Zymbal's gland, oral cavity, esophagus, forestomach, small and large intestines, mesothelium, urinary bladder, lung, thyroid gland, hematopoietic system, and seminal vesicle. Nonneoplastic effects in the kidney, lung, thyroid gland, seminal vesicle, pancreas, urinary bladder, and forestomach were also observed. In females, 2-year exposure to 2,2-bis(bromomethyl)-1,3-propanediol was associated with neoplastic effects in the oral cavity, esophagus, mammary gland, and thyroid gland. Nonneoplastic effects in the kidney were also observed. These findings are outlined in the two summary tables. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice received 0, 312, 625, or 1,250 ppm 2,2-bis(bromomethyl)-1,3-propanediol in feed for 104 to 105 weeks. Average daily doses of 2,2-bis(bromomethyl)-1,3-propanediol were 35, 70, or 140 mg/kg (males) and 40, 80, or 170 mg/kg (females). Eight to 10 animals from each group were evaluated at 15 months. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of 1,250 ppm males and females was significantly lower than that of the controls. Mean body weights of exposed male and female mice were similar to controls throughout the study. Final mean body weights were also generally similar to those of controls. Feed consumption by exposed male and female mice was similar to that by controls. Clinical findings included tissue masses involving the eye in exposed mice. Pathology Findings: Exposure of male mice to 2,2-bis(bromomethyl)-1,3-propanediol for 2 years was associated with neoplastic effects in the harderian gland, lung, and kidney. Exposure of female mice to 2,2-bis(bromomethyl)-1,3-propanediol was associated with increased incidences of neoplasms of the harderian gland, lung, and skin. Nonneoplastic effects in the lung were also observed in exposed females. These findings are outlined in the two summary tables. GENETIC TOXICOLOGY: 2,2-Bis(bromomethyl)-1,3-propanediol was mutagenic in Salmonella typhimurium strain TA100 when tested in the presence of induced 30% hamster liver S9; all other strain/activation combinations gave negative results. In cultured Chinese hamster ovary cells, 2,2-bis(bromomethyl)-1,3-propanediol induced chromosomal aberrations only in the presence of S9; no induction of sister chromatid exchanges was observed in cultured Chinese hamster ovary cells after treatment with 2,2-bis(bromomethyl)-1,3-propanediol, with or without S9. In vivo, 2,2-bis(bromomethyl)-1,3-propanediol induced significant increases in the frequencies of micronucleated erythrocytes in male and female mice. Significant increases in micronuclei were observed in peripheral blood samples from male and female mice exposed to 2,2-bis(bromomethyl)-1,3-propanediol for 13 weeks via dosed feed. Results of a bone marrow micronucleus test in male mice, where 2,2-bis(bromomethyl)-1,3-propanediol was administered by gavage, were considered to be equivocal due to inconsistent results obtained in two trials. An additional bone marrow micronucleus test was performed with male and female mice and 2,2-bis(bromomethyl)-1,3-propanediol was administered as a single intraperitoneal injection; results of this test were positive in females and negative in males. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenic activity of 2,2-bis-(bromomethyl)-1,3-propanediol (FR-1138) in male F344/N rats based on increased incidences of neoplasms of the skin, subcutaneous tissue, mammary gland, Zymbal's gland, oral cavity, esophagus, forestomach, small and large intestines, mesothelium, urinary bladder, lung, thyroid gland, and seminal vesicle, and the increased incidence of mononuclear cell leukemia. There was clear evidence of carcinogenic activity of 2,2-bis(bromomethyl)-1,3-propanediol in female F344/N rats based on increased incidences of neoplasms of the oral cavity, esophagus, mammary gland, and thyroid gland. There was clear evidence of carcinogenic activity of 2,2-bis(bromomethyl)-1,3-propanediol in male B6C3F1 mice based on increased incidences of neoplasms of the harderian gland, lung, and kidney. There was clear evidence of carcinogenic activity of 2,2-bis(bromomethyl)-1,3-propanediol in female B6C3F1 mice based on increased incidences of neoplasms of the harderian gland, lung, and subcutaneous tissue. Slight increases in the incidences of neoplasms of the pancreas and kidney in male rats; forestomach in male mice; and forestomach, mammary gland, and circulatory system in female mice may have also been related to treatment. Exposure of male and female rats to 2,2-bis(bromomethyl)-1,3-propanediol was associated with alveolar/bronchiolar hyperplasia in the lung (males only); focal atrophy, papillary degeneration, transitional epithelial hyperplasia (pelvis), and papillary epithelial hyperplasia in the kidney; follicular cell hyperplasia in the thyroid gland (males only); hyperplasia in the seminal vesicle and pancreas (males only); mucosal hyperplasia in the forestomach (males only); and urinary bladder hyperplasia (males only). Exposure of mice to 2,2-bis(bromomethyl)-1,3-propanediol was associated with hyperplasia of the alveolar epithelium in females. Synonyms: 2,2-Bis(2-bromomethyl)-1,3-propanediol; 1,3-dibromo-2,2-dihydroxymethylpropane; 1,3-dibromo-2,2-dimethylolpropane; 2,2-dibromomethyl-1,3-propanediol; dibromopentaerythritol; dibromoneopentyl glycol; pentaerythritol dibromide; pentaerythritol dibromohydrin

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Nickel Oxide (CAS No. 1313-99-1) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Nickel oxide (NiO) "sinters" are used in stainless steel and alloy steel production. Nickel oxide was nominated by the National Cancer Institute to the NTP for testing because exposure to this form of nickel is prevalent in the nickel industry. Increased incidences of lung and nasal sinus cancers have occurred among workers in certain nickel refining facilities, and nickel oxide was studied as part of a class study of nickel compounds. Male and female F344/N rats and B6C3F1 mice were exposed to nickel oxide (high temperature, green nickel oxide; mass median diameter 2.2 +/- 2.6 &mgr;m; at least 99% pure) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in peripheral blood of B6C3F1 mice exposed to nickel oxide for 13 weeks. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 1.2, 2.5, 5, 10, or 30 mg nickel oxide/m(3)(equivalent to 0, 0.9, 2.0, 3.9, 7.9, or 23.6 mg nickel/m(3)) by inhalation for 6 hours per day, 5 days per week for a total of 12 exposure days during a 16-day period. Additional groups of five male and five female rats were exposed to 0, 1.2, 5, or 10 mg/m(3) for tissue burden studies. All core study rats survived until the end of the study, final mean body weights of exposed male and female rats were similar to those of the controls, and there were no clinical findings related to nickel oxide exposure. Absolute and relative lung weights of male and female rats exposed to 10 or 30 mg/m(3) were significantly greater than those of the controls. Pigment particles in alveolar macrophages or within the alveolar spaces were observed in the lungs of exposed groups of males and females. Chronic-active inflammation and accumulation of macrophages in alveolar spaces of the lungs and hyperplasia in the respiratory tract lymph nodes were most severe in 10 and 30 mg/m(3) males and females. Hyperplasia of bronchial lymph nodes occurred in 30 mg/m(3) rats. Atrophy of the olfactory epithelium was observed in one male and one female exposed to 30 mg/m(3). The concentrations of nickel oxide in the lungs of exposed groups of rats were greater than those in the lungs of control groups (males, 42 to 267 mg nickel/g lung; females, 54 to 340 mg/g lung). 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 1.2, 2.5, 5, 10, or 30 mg nickel oxide/m(3) by inhalation for 6 hours per day, 5 days per week for a total of 12 exposure days during a 16-day period. Additional groups of five male and five female mice were exposed to 0, 1.2, 2.5, or 5 mg/m(3) for tissue burden studies. No exposure-related deaths occurred among core study mice, and final mean body weights of exposed male and female mice were similar to those of the controls. There were no chemical-related clinical findings. Pigment particles were present in the lungs of mice exposed to 2.5 mg/m(3) or greater. Accumulation of macrophages in alveolar spaces was observed in the lungs of 10 and 30 mg/m(3)males and females. The concentrations of nickel oxide in the lungs of exposed groups of mice were significantly greater than those in the lungs of control animals (males, 32 to 84 mg nickel/g lung; females, 31 to 71 mg/g lung). 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel oxide/m(3) (equivalent to 0, 0.4, 0.9, 2.0, 3.9, or 7.9 mg nickel/m(3)) by inhalation for 6 hours per day, 5 days per week for 13 weeks. Additional groups of 18 male and 18 female rats were exposed to 0, 0.6, 2.5, or 10 mg/m(3) for tissue burden studies. No exposure-related deaths occurred among core study rats, final mean body weights of exposed male and female rats were similar to those of the controls, and no clinical findings in any group were related to nickel oxide exposure. Lymphocyte, neutrophil, monocyte, and erythrocyte counts; hematocrit values; and hemoglobin and mean cell hemoglobin concentrations in exposed rats were minimally to mildly greater than those of the controls; these differences were most pronounced ironounced in females. Mean cell volumes in exposed rats were generally less than those in the controls. Absolute and relative lung weights of exposed groups of males and females were generally significantly greater than those of controls. Chemical-related nonneoplastic lesions were observed in the lungs of male and female rats exposed to concentrations of 2.5 mg/m(3) or higher, and the severity of these lesions generally increased with exposure concentration. Accumulation of alveolar macrophages, many of which contained black, granular pigment, was generally observed in all exposed groups of males and females, and increased incidences of inflammation occurred in males and females exposed to 2.5 mg/m(3) or higher. In addition, lymphoid hyperplasia and pigment occurred in the bronchial and mediastinal lymph nodes of 2.5, 5, and 10 mg/m(3) males and females. The concentration of nickel oxide in the lungs of 0.6, 2.5, and 10 mg/m(3)males was greater than in the lungs of controls at 4, 9, and 13 weeks, and nickel continued to accumulate in the lung at the end of the 13-week exposures (4 weeks, 33 to 263 mg nickel/g lung; 9 weeks, 53 to 400 mg/g lung; 13 weeks, 80 to 524 mg/g lung). 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 0.6, 1.2, 2.5, 5, or 10 mg nickel oxide/m(3) by inhalation for 6 hours per day, 5 days per week for 13 weeks. Additional groups of six male and six female mice were exposed to 0, 0.6, 2.5, or 10 mg/m(3) for tissue burden studies. No exposure-related deaths occurred among core study animals, final mean body weights of exposed male and female mice were similar to those of the controls, and no clinical findings in any group were related to nickel oxide exposure. Hematocrit values and erythrocyte counts in 5 and 10 mg/m(3) females were minimally greater than those of the controls, as was the hemoglobin concentration in 5 mg/m(3) females. Absolute and relative lung weights of 10 mg/m(3) males and females were significantly greater than those of controls, and absolute and relative liver weights of 10 mg/m(3) males were significantly less than those of controls. Accumulation of alveolar macrophages, many of which contained pigment particles, occurred in all groups of mice exposed to nickel oxide. Inflammation (chronic active perivascular infiltrates or granulomatous) occurred in 2.5, 5, and 10 mg/m(3) males and females. In addition, lymphoid hyperplasia and pigment occurred in the bronchial lymph nodes of males and females exposed to 2.5 mg/m(3) or higher. The concentration of nickel in the lung was greater than that of controls in 0.6, 2.5, and 10 mg/m(3) males at 13 weeks (42 to 736 mg nickel/g lung). 2-YEAR STUDY IN RATS: Survival, Body Weights, Clinical Findings, and Hematology Groups of 65 male and 65 female F344/N rats were exposed to 0, 0.62, 1.25, or 2.5 mg nickel oxide/m(3) (equivalent to 0, 0.5, 1.0, or 2.0 mg nickel/m(3)) by inhalation for 6 hours per day, 5 days per week for 104 weeks. Survival of exposed male and female rats was similar to that of the controls. Mean body weights of 1.25 mg/m(3) females and 2.5 mg/m(3) males and females were slightly lower than those of the controls during the second year of the study. No chemical-related clinical findings were observed in male or female rats during the 2-year study. No chemical-related differences in hematology parameters were observed in male or female rats at the 15-month interim evaluation. Pathology Findings: Absolute and relative lung weights of 1.25 and 2.5 mg/m(3) males and females were significantly greater than those of the controls at 7 and 15 months. At 2 years, there were exposure-related increased incidences of alveolar/bronchiolar adenomas alveolar/bronchiolar adenoma or carcinoma (combined) in males and females. Incidences of atypical alveolar epithelial hyperplasia in the lungs generally increased with increasing exposure concentration in male and female rats. Chronic inflammation of the lung was observed in most exposed rats at 7 and 15 months and at 2 years; the incidences in exposed males and females at 2 years were significantly greater than those in the controls, and the severity of the inflammation increased in exposed groups. The incidences of pigmentation in the alveolus of exposed groups of males and females were significantly greater than those of the controls at 7 and 15 months and at 2 years. Pigmentation in the bronchial lymph nodes similar to that in the lungs was observed in all exposure groups with the exception of 0.62 mg/m(3)males and females at 7 months. Lymphoid hyperplasia was observed in the bronchial lymph nodes of 1.25 and 2.5 mg/m(3) males and females at 7 and 15 months, and the incidence at 2 years generally increased with exposure concentration. At 2 years, there was an exposure-related increase in the incidence of benign pheochromocytoma in males and females. The incidences of benign pheochromocytoma and adrenal medulla hyperplasia in 2.5 mg/m(3) females and the incidence of benign or malignant pheochromocytoma (combined) in 2.5 mg/m(3) males were significantly greater than those in the controls. Tissue Burden Analyses: Nickel concentrations in the lungs of exposed rats were greater than those in the controls at 7 and 15 months (7 months, 173 to 713 mg nickel/g lung; 15 months, 262 to 1,116 mg/g lung), and nickel concentrations increased with increasing exposure concentration and with time. 2-YEAR STUDY IN MICE: Survival, Body Weights, Clinical Findings, and Hematology Groups of 74 to 79 B6C3F1 mice were exposed to 0, 1.25, 2.5, or 5 mg nickel oxide/m(3) by inhalation for 6 hours per day, 5 days per week for 104 weeks. Survival of exposed male and female mice was similar to that of the controls. Mean body weights of 5 mg/m(3) females were slightly lower than those of the controls during the second year of the study. No chemical-related clinical findings were observed in male or female mice during the 2-year study. No chemical-related differences in hematology parameters were observed in male or female mice at the 15-month interim evaluation. Pathology Findings: At 2 years, the incidence of alveolar/bronchiolar adenoma in 2.5 mg/m(3) females was significantly greater than that of the controls, as was the incidence of alveolar/bronchiolar adenoma or carcinoma (combined) in 1.25 mg/m(3) females. Generally, incidences of chronic inflammation increased with exposure concentration in males and females at 7 and 15 months. Bronchialization of minimal severity in exposed animals and proteinosis were first observed at 15 months. At 2 years, the incidences of chronic inflammation, alveolar epithelial hyperplasia, and proteinosis in exposed groups of males and females were significantly greater than those of the controls. The severity of chronic inflammation increased with exposure concentration in females, and proteinosis was most severe in 5 mg/m(3) males and females. Pigment occurred in the lungs of nearly all exposed mice at 7 and 15 months and at 2 years, and the severity increased with exposure concentration. Lymphoid hyperplasia occurred in two animals after 7 months; at 15 months, lymphoid hyperplasia occurred in males exposed to 2.5 and 5 mg/m(3) and in all exposed groups of females. At 2 years, lymphoid hyperplasia occurred in some control animals, but this lesion was still observed more often in exposed males and females and the incidence increased with exposure concentration. Pigmentation was observed in the bronchial lymph nodes of exposed males and females at 7 and 15 months and in nearly all exposed animals at 2 years. Tissue Burden Analyses: Nickel concentrations in the lungs of exposed mice were significantly greater than those in the controls at 7 and 15 months (7 months, 162 to 1,034 mg nickel/g lung; 15 months, 331 to 2,258 mg/g lung), and nickel concentrations increased with increasing exposure concentration and with time. GENETIC TOXICOLOGY: No increase in the frequency of micronucleated normochromatic erythrocytes was observed in peripheral blood samples from male or female mice exposed to nickel oxide. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of nickel oxide in male F344/N rats based on increased incidences of alveolar/bronchiolar adenoma or carcinoma (combined) and increased incidences of benign or malignant pheochromocytoma (combined) of the adrenal medulla. There was some evidence of carcinogenic activity of nickel oxide in female F344/N rats based on increased incidences of alveolar/bronchiolar adenoma or carcinoma (combined) and increased incidences of benign pheochromocytoma of the adrenal medulla. There was no evidence of carcinogenic activity of nickel oxide in male B6C3F1 mice exposed to 1.25, 2.5, or 5 mg/m(3). There was equivocal evidence of carcinogenic activity of nickel oxide in female B6C3F1 mice based on marginally increased incidences of alveolar/bronchiolar adenoma in 2.5 mg/m(3) females and of alveolar/bronchiolar adenoma or carcinoma (combined) in 1.25 mg/m(3) females. Exposure of rats to nickel oxide by inhalation for 2 years resulted in inflammation and pigmentation in the lung, lymphoid hyperplasia and pigmentation in the bronchial lymph nodes, and hyperplasia of the adrenal medulla (females). Exposure of mice to nickel oxide by inhalation for 2 years resulted in bronchialization, proteinosis, inflammation, and pigmentation in the lung and lymphoid hyperplasia and pigmentation in the bronchial lymph nodes. Synonyms: Bunsenite; C.I. 77777; green nickel oxide; mononickel oxide; nickel monoxide; nickel oxide sinter 75; nickel protoxide; nickel (II) oxide; nickel (T+) oxide; nickelous oxide

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Isobutyl Nitrite (CAS No. 542-56-3) in F344 Rats and B6C3F1 Mice (Inhalation Studies).

Isobutyl nitrite is used to a limited extent as an intermediate in the syntheses of aliphatic nitrites. It is also an ingredient of various incenses or room odorizers and is used as a euphoric. The chemical has also been used as a jet propellant and in the preparation of fuels. Isobutyl nitrite was nominated by the Consumer Product Safety Commission to the NTP for toxicology and carcinogenicity studies because of its possible contribution to the high incidence of Kaposi's sarcoma among male homosexual acquired immune deficiency syndrome patients and because of the lack of available data on the potential carcinogenicity of isobutyl nitrite. Male and female F344/N rats and B6C3F1 mice were exposed to isobutyl nitrite (purity of 93% or greater) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melanogaster, and mouse peripheral blood. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 100, 200, 400, 600, or 800 ppm (approximately 420, 840, 1,700, 2,500, or 3,300 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. All males and females exposed to 600 or 800 ppm and one 400 ppm female died on the first day of the study. Final mean body weights and mean body weight gains of 400 ppm males and females were significantly lower than those of the controls. Clinical findings observed in 400 ppm males and females included ocular discharge, lethargy, hunched posture, and rough coats. Absolute and relative lung weights of all exposed groups of males and of 200 and 400 ppm females were less than those of the controls. Chemical-related hyperplasia of the bronchial epithelium was observed in 200 and 400 ppm males and females and hyperplasia of the nasal turbinate epithelium was observed in rats exposed to 400 ppm or less. Hemosiderin pigmentation was observed in the spleen of 200 and 400 ppm males and females and bone marrow hematopoietic hyperplasia was observed in rats exposed to 400 ppm or less. 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 100, 200, 400, 600, or 800 ppm (approximately 420, 840, 1,700, 2,500, or 3,300 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. Three males and four females exposed to 800 ppm died before the end of the study. Final mean body weights and mean body weight gains of 600 and 800 ppm males and females were significantly lower than those of the controls. Mice exposed to 400 ppm or greater were lethargic and exhibited hunched posture and rough coats. Absolute and relative lung weights of 600 and 800 ppm males and the relative lung weight of 600 ppm females were significantly greater than those of the controls. Chemical-related hyperplasia of the bronchiolar epithelium was observed in all exposed groups of males and females. Lymphocytic atrophy of the spleen and thymus was observed in males and females exposed to 400 ppm or greater. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to 0, 10, 25, 75, 150, or 300 ppm (approximately 42, 105, 315, 630, or 1,260 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week for 13 weeks. All rats survived to the end of the study. Final mean body weights and mean body weight gains of 300 ppm males and females were significantly lower than those of the controls, as was the mean body weight gain of 150 ppm females. Clinical findings observed during the study included ruffled fur in 300 ppm males and females, hypoactivity in 300 ppm males, and hyperactivity in 150 and 300 ppm females. A very mild chemical-related methemoglobinemia and anemia occurred in male and female rats in the 75, 150, and 300 ppm groups. Hematopoietic hyperplasia occurred in the bone marrow of all exposed groups of males and females and was considered to be a secondary response to the anemia and methed methemoglobinemia. There was minimal hemosiderin pigment accumulation in the spleens of males and females exposed to 75 ppm or greater, mild to moderate epithelial cell hyperplasia of the nasal mucosa was observed in 300 ppm males and females, and minimal hyperplasia occurred in 150 ppm males and females. Hyperplasia of the bronchial epithelium was observed in 300 ppm males and females. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 10, 25, 75, 150, or 300 ppm (approximately 42, 105, 315, 630, or 1,260 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week for 13 weeks. There were no chemical-related deaths. Final mean body weights and mean body weight gains of 150 and 300 ppm females were significantly less than those of the controls. Final mean body weights and mean body weight gains of exposed groups of males were similar to those of the controls. There were no chemical-related clinical findings. A very mild chemical-related methemoglobinemia occurred in male and female mice in the 150 and 300 ppm groups. A very mild anemia occurred in the 300 ppm groups. In the lung, increased incidences of mild to moderate hyperplasia of the bronchiolar epithelium occurred in males and females exposed to 300 ppm. Minimal hyperplasia occurred in males exposed to 75 ppm or greater and in females exposed to 150 ppm. Minimal epithelial cell hyperplasia of the nasal mucosa was observed in 300 ppm males. Increased hematopoiesis of the spleen, secondary to the hematotoxicity, occurred in males exposed to 75 ppm or greater and in females exposed to 150 or 300 ppm. Increased hemosiderosis of the spleen occurred in males exposed to 300 ppm and in females exposed to 75 ppm or greater. 2-YEAR STUDY IN RATS: Based on the low final mean body weights, anemia, and the mild to moderate nasal mucosal lesions and the hyperplastic bronchial lesions observed in 300 ppm males and females, isobutyl nitrite exposure concentrations selected for the 2-year inhalation study in rats were 37.5, 75, and 150 ppm. Groups of 56 male and 56 female rats were exposed to 0, 37.5, 75, or 150 ppm (equivalent to 0, 158, 315, or 630 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week, for 103 weeks. Ten male and 10 female rats from each group were evaluated at 15 months for clinical pathology and histopathology. Survival, Body Weights, Clinical Findings, Hematology, and Clinical Chemistry: Survival rates of exposed groups of rats were greater than those of the controls, and the survival rates of 75 and 150 ppm males were significantly greater than that of the control. Mean body weights of 150 ppm males and females were 3% to 11% lower than those of the controls throughout the course of the study. There were no clinical findings considered to be related to isobutyl nitrite exposure. A very mild methemoglobinemia and anemia occurred in male and female rats exposed to 75 or 150 ppm. Pathology Findings: Incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) occurred with significant positive trends in exposed males and females, and the incidences of these neoplasms in 75 ppm males and in 150 ppm males and females were significantly greater than those in the controls. The incidence of alveolar/bronchiolar carcinoma was significantly greater in 150 ppm male rats than that in the controls. The incidences of alveolar epithelial hyperplasia were also increased in 75 and 150 ppm males and in all exposed groups of females. The incidences of mononuclear cell leukemia in exposed groups of males and females were significantly less than those in the controls. 2-YEAR STUDY IN MICE: Based on the low final mean body weight of 300 ppm females and the mild to moderate bronchiolar hyperplasia observed in 300 ppm males and females, isobutyl nitrite exposure concentrations selected for the 2-year inhalation study in mice were 37.5, 75, and 150 ppm. Groups of 60 male and 60 female mice were exposed to 0, 37.5, 75, or 150 ppm (equivalent to 0, 158, 315, or 630 mg/m(3)) isobutyl nitrite by inhalation for 6 hours per day, 5 days per week, for 103 weeks. As many as 10 male and 10 female mice from each group were evaluated at 15 months for clinical pathology and histopathology. Survival, Body Weights, Clinical Findings, and Hematology and Clinical Chemistry: Survival rates of exposed groups of males were similar to those of the controls. Survival rates of exposed groups of females were greater than those of the controls, and the survival rate in 37.5 ppm females was significantly greater than that of the controls. Mean body weights of exposed groups of males and of 37.5 and 75 ppm females were similar to those of the controls throughout the study. Mean body weights of 150 ppm females were lower than those of the controls from week 20 until the end of the study. There were no biologically significant clinical findings noted in the 2-year study in mice. A very mild methemoglobinemia and anemia occurred in male and female mice exposed to 75 or 150 ppm. Pathology Findings: Incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) occurred with significant positive trends in exposed males and females, and the incidences of these neoplasms were significantly greater than those in the controls in 75 ppm males and in 150 ppm males and females. Incidences of alveolar epithelial hyperplasia were significantly increased in 75 and 150 ppm male and female mice. Thyroid gland follicular cell adenoma occurred with a significant positive trend in male mice; the incidences of thyroid gland follicular cell hyperplasia were increased in all exposed groups of males, and the incidences in males exposed to 37.5 or 150 ppm were significantly greater than those in the controls. Incidences of serous exudate and olfactory epithelium atrophy in the nose of 150 ppm females were significantly greater than those in the controls. Incidences of minimal to mild hemosiderin pigment in the spleen of 75 and 150 ppm male mice were significantly greater than those in the controls. GENETIC TOXICOLOGY: Isobutyl nitrite was found to be mutagenic in vitro and in vivo. It induced base-pair substitution mutations in Salmonella typhimurim strains TA100 and TA1535 and sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells. Positive responses in the S. typhimurium tests required S9 activation, but isobutyl nitrite induced chromosomal effects in cultured Chinese hamster ovary cells with and without S9. In vivo, no induction of sex-linked recessive lethal mutations was noted in the germ cells of male Drosophila melanogaster exposed to isobutyl nitrite via feeding or injection. However, significant increases in micronucleated normochromatic erythrocytes were observed in the peripheral blood of male and female mice treated with isobutyl nitrite for 90 days by inhalation. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of isobutyl nitrite in male and female F344/N rats based on the increased incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined). There was some evidence of carcinogenic activity of isobutyl nitrite in male and female B6C3F1 mice based on the increased incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) in males and females. The increased incidence of thyroid gland follicular cell adenoma in male mice may have been related to isobutyl nitrite exposure. Exposure of rats and mice to isobutyl nitrite by inhalation for 2 years resulted in increased incidences of alveolar epithelial hyperplasia (male and female rats and mice), thyroid gland follicular cell hyperplasia and splenic hemosiderin pigmentation (male mice), and serous exudate and atrophy of the olfactory epithelium of the nose (female mice). Exposure of rats to isobutyl nitrite by inhalation for 2 years resulted in decreased incidences of mononuclear cell leukemia in males and females.

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of Acetonitrile (CAS No. 75-05-8) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Acetonitrile is used primarily as a solvent in extractive distillation and crystallization of pharmaceutical and agricultural products and as a catalyst in chemical reactions. It was nominated for testing by the National Cancer Institute due to its presence in drinking water supplies and the environment, due to lack of information on the carcinogenicity of alkyl cyanides, and because of widespread worker exposure. Male and female F344/N rats and B6C3F1 mice were exposed to acetonitrile (at least 99% pure) by inhalation for 13 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and peripheral blood of B6C3F1 mice exposed to acetonitrile for 13 weeks. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to 0, 100, 200, 400, 800, or 1,600 ppm (equivalent to 0, 168, 335, 670, 1,340, or 2,681 mg/m(3)) acetonitrile by inhalation for 6 hours per day, 5 days per week for 13 weeks. Six male and three female rats that received 1,600 ppm and one male that received 800 ppm died during the study. At exposure concentrations up to and including 800 ppm, the final mean body weights and body weight gains were generally similar to those of the controls. At 1,600 ppm, body weight gain was lower and the final mean body weights of both males and females were significantly lower than those of the controls. Hypoactivity and ruffled fur were observed during the first week of the study in males receiving 800 ppm and males and females receiving 1,600 ppm. Additional clinical findings in 1,600 ppm males that died during week 1 were ataxia, abnormal posture, and clonic convulsions. Clinical pathology findings included nonresponsive, normocytic, normochromic anemia in 1,600 ppm males and females and in 800 ppm females, and decreased triiodothyronine (T3) concentrations in 1,600 ppm females. Absolute and relative thymus weights were significantly lower than those of the controls in the 800 and 1,600 ppm males and females. Females exposed to 1,600 ppm had significantly greater absolute and relative heart, kidney, and liver weights than those of the controls. There were no clear exposure-related histopathologic effects, although pulmonary congestion and edema and hemorrhage in the lung and brain were seen in some rats that died early. These lesions are consistent with cyanide-induced anoxia. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 100, 200, 400, 800, or 1,600 ppm (equivalent to 0, 168, 335, 670, 1,340, or 2,681 mg/m(3)) acetonitrile by inhalation for 6 hours per day, 5 days per week for 13 weeks. All mice exposed to 1,600 ppm died during the first 3 weeks of the study. In addition, one 400 ppm female and one male and four females from the 800 ppm groups also died before the end of the study. Body weight gains were similar to those of controls for all surviving groups of mice except the 800 ppm males, for which the final mean body weight was slightly lower than that of the controls. Clinical findings observed during the first week in 800 and 1,600 ppm mice were hypoactivity and a hunched, rigid posture. In males that received 200 ppm and above, absolute liver weights were greater than that of the controls and relative liver weights were greater in all exposed groups. In 800 ppm females, the absolute liver weight was greater than that of the controls and relative liver weights of females that received 400 ppm and above were greater than that of the controls. Lesions clearly associated with acetonitrile exposure were observed in the stomach, predominantly the forestomach, of males that received 400 ppm and above and of females that received 200 ppm and above. Histologically, these focal or multifocal pale to dark raised lesions consisted of areas of focal epithelial hyperplasia and ulceration, sometimes associated with hemosiderin deposition. An increased incidence of cytoplasmic vacuolation occurred in the liver of males and females exposed to 400 or 800 ppm. A lack of fatty degenerative change was observed inrved in the X-zone of the adrenal cortex of 800 and 1,600 ppm female mice. 2-YEAR STUDY IN RATS: The doses selected for the 2-year study of acetonitrile were based on reduced survival of 800 ppm males and 1,600 ppm males and females in the 13-week study. Groups of up to 56 male and 56 female rats were exposed to 0, 100, 200, or 400 ppm (equivalent to 0, 168, 335, or 670 mg/m(3)) acetonitrile by inhalation for 6 hours per day, 5 days per week for 2 years. Eight male and eight female rats from each exposure group were evaluated at 15 months for histopathology and hematology parameters. Survival, Body Weights, Clinical Findings, and Hematology: Two-year survival, mean body weights, organ weights, behavior, general health, and appearance of exposed male and female rats were similar to those of the controls. The hematologic effects observed were minor and of no biological significance. Pathology Findings: The incidences of hepatocellular adenoma (3/48), hepatocellular carcinoma (3/48), and hepatocellular adenoma or carcinoma (combined; 5/48) were greater in male rats exposed to 400 ppm than in the controls (one carcinoma). The incidences of hepatocellular adenoma and hepatocellular carcinoma were within the range of historical controls. However, the incidence of hepatocellular adenoma or carcinoma (combined) slightly exceeded the range of historical controls (2%-8%). In addition, the incidences of basophilic, eosinophilic, and mixed cell foci in 400 ppm males were marginally greater than in controls, suggesting hepatotoxicity of acetonitrile. There were no exposure-related liver lesions in female rats. 2-YEAR STUDY IN MICE: The exposure concentrations selected for the 2-year study were based on reduced survival and gross and histopathologic lesions in 400, 800, and 1,600 ppm groups of male and female mice in the 13-week study. Groups of 60 male and 60 female mice were exposed to 0, 50, 100, or 200 ppm (equivalent to 0, 84, 168, or 335 mg/m(3)) acetonitrile by inhalation for 6 hours per day, 5 days per week for 2 years. Ten male and 10 female mice from each exposure group were evaluated at 15 months for histopathology. Survival, Body Weights, and Clinical Findings: Two-year survival of exposed male and female mice was similar to that of the controls, except that the survival of male mice in the 200 ppm group was significantly greater than that of the controls. Mean body weights and organ weights of exposed groups of male and female mice were similar to those of the controls, and no clinical observations in any group were clearly related to acetonitrile exposure. Pathology Findings: There were no increases in the incidences of neoplasms that were considered related to acetonitrile exposure in mice. The incidence of squamous hyperplasia of the epithelium of the forestomach was significantly increased at 15 months in 200 ppm females. At 2 years, the increased incidence of this lesion was dose related in all exposed groups of males and females. GENETIC TOXICOLOGY: Acetonitrile was not mutagenic in Salmonella typhimurium strain TA97, TA98, TA100, TA1535, or TA1537, with or without S9 metabolic activation. In cultured Chinese hamster ovary cells, acetonitrile produced a weakly positive response in the sister chromatid exchange test without, but not with, S9. A small increase in chromosomal aberrations was observed in cultured Chinese hamster ovary cells treated with acetonitrile in the presence, but not in the absence, of S9. A significant increase in micronucleated normochromatic erythrocytes was observed in peripheral blood samples from male mice treated with acetonitrile for 13 weeks; the frequency of micronucleated erythrocytes in female mice was not affected by exposure to acetonitrile. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was equivocal evidence of carcinogenic activity of acetonitrile in male F344/N rats based on marginally increased incidences of hepatocellular adenoma and carcinoma. There was no evidence of carcinogenic activity of acetonitrile in female F344/N rats exposed to 100, 200, or 400 ppm. There was no evidence of carcinogenic activity of acetonitrile in male or female B6C3F1 mice exposed to 50, 100, or 200 ppm. Exposure to acetonitrile by inhalation resulted in increased incidences of hepatic basophilic foci in male rats and of squamous hyperplasia of the forestomach in male and female mice. Synonyms: Cyanomethane, ethanenitrile, ethyl nitrile, methanecarbonitrile, methyl cyanide, nitrile of acetic acid

Journal Article↗
PubMed1996

NTP Toxicology and Carcinogenesis Studies of 1-Trans-Delta(9)-Tetrahydrocannabinol (CAS No. 1972-08-3) in F344 Rats and B6C3F1 Mice (Gavage Studies).

1-Trans-delta(9)-tetrahydrocannabinol (THC) was nominated by the National Cancer Institute to the NTP for study because it is the major psychoactive component of marijuana and a widely used Schedule I substance. Male and female F344/N rats and B6C3F1 mice received THC (97% pure) in corn oil by gavage for 13 weeks, 13 weeks with a 9-week recovery period, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood cells. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats received 0, 5, 15, 50, 150, or 500 mg THC/kg body weight in corn oil by gavage, 5 days per week for 13 weeks. Six male and six female rats receiving 500 mg/kg died before the end of the study. The final mean body weights and weight gains of all dosed groups of males and females, except 5 mg/kg females, were significantly lower than those of the controls. Feed consumption by dosed groups was similar to that by controls. Clinical findings observed during the study included lethargy, sensitivity to touch, convulsions, tremors, and aggressiveness. There were no clinical pathology differences considered to be directly related to the administration of THC. The absolute and relative uterus weights of 50, 150, and 500 mg/kg females were significantly lower than those of the controls. Treatment-related multifocal atrophy was observed in the testes of 150 and 500 mg/kg males; uterine and ovarian hypoplasia observed in 150 and 500 mg/kg females was also considered to be related to THC administration. Based on final mean body weights and mortality observed in the 13-week study, doses selected for the 2-year rat study were 12.5, 25, and 50 mg/kg. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice received 0, 5, 15, 50, 150, or 500 mg THC/kg body weight in corn oil by gavage, 5 days per week for 13 weeks. There were no treatment-related deaths. The final mean body weight and weight gain of 500 mg/kg males were significantly lower than those of the controls. Clinical findings included lethargy and aggressiveness, and both male and female mice in all dosed groups were easily startled. There were no absolute or relative organ weight differences, clinical pathology differences, or microscopic changes observed that were considered to be related to the administration of THC. Due to the minimal THC-related effects observed in the 13-week study, doses selected for the 2-year mouse study were 125, 250, and 500 mg/kg. 13-WEEK WITH 9-WEEK RECOVERY STUDY IN RATS: Groups of 10 male and 10 female rats received 0, 5, 15, 50, 150, or 500 mg THC/kg body weight in corn oil by gavage, 5 days per week for 13 weeks, and then were allowed to recover during a 9-week treatment-free period. Five male and eight female 500 mg/kg rats, five male and two female 150 mg/kg rats, and three male and two female 50 mg/kg rats died before the end of the study. During the 13-week dosing period, mean body weight gains of all dosed groups of rats were lower than those of the controls but returned to normal during the recovery period. Final mean body weights of all dosed groups were similar to those of the controls. Clinical findings observed during the recovery period included sensitivity to touch, convulsions, and aggressiveness. The absolute right testis weight of 500 mg/kg males was significantly lower than that of the controls. Treatment-related multifocal atrophy of the testis was observed in 150 and 500 mg/kg males. There were no treatment-related lesions observed in females administered THC. 13-WEEK WITH 9-WEEK RECOVERY STUDY IN MICE: Groups of 10 male and 10 female mice received 0, 5, 15, 50, 150, or 500 mg THC/kg body weight in corn oil by gavage, 5 days per week for 13 weeks, and then were allowed to recover during a 9-week treatment-free period. The final mean body weights of all dosed groups were similar to those of the controls. Clinical findings observed during the study included lethargy and aggressiveness, and both male and female mice in all dosed groups were easily startled. The absolutebsolute and relative uterus weights of 150 and 500 mg/kg female mice were significantly lower than those of the controls, as was the absolute uterus weight of 50 mg/kg females. 2-YEAR STUDY IN RATS: Groups of 62 vehicle control male rats, 60 low-dose male rats, 70 mid- and high-dose male rats, and 60 female rats were administered 0, 12.5, 25, or 50 mg THC/kg body weight in corn oil by gavage for 104 to 105 weeks. Nine or ten animals from each group were evaluated at 15 months. Survival, Body Weights, and Clinical Findings: Survival of all dosed groups was generally significantly greater than that of the controls. Mean body weights of dosed groups of males and females were lower than those of the controls throughout the study. Convulsions and seizures were observed in all dosed groups of male and female rats, usually following dosing or handling. Hematology and Clinical Chemistry: At the 15-month interim evaluation, total leukocyte and lymphocyte counts in all dosed groups of females were greater than those of the controls, and platelet counts in these groups were lower than that of the controls. Levels of follicle stimulating and luteinizing hormones in all dosed groups of males were significantly greater than those of the controls, as was the serum corticosterone level of 25 mg/kg females. Pathology Findings: No increased incidences of neoplasms were considered related to administration of THC. The incidences of mammary gland fibroadenoma and uterine stromal polyps were decreased in dosed groups of females, as were the incidences of pituitary gland adenomas, interstitial cell adenomas of the testis, and pancreatic adenomas in dosed males. 2-YEAR STUDY IN MICE: Groups of 62 vehicle control male mice, 60 low-dose male mice, 61 mid-dose male mice, and 60 high-dose male mice and 60 female mice were administered 0, 125, 250, or 500 mg THC/kg body weight in corn oil by gavage for 104 to 105 weeks (males) or 105 to 106 weeks (females). Survival, Body Weights, and Clinical Findings: Survival of 500 mg/kg males was significantly less than that of the controls; survival of all other groups of males and of all dosed groups of females was similar to that of the controls. Mean body weights of all dosed groups were markedly lower than those of the controls throughout the study. Clinical findings in dosed groups included hyperactivity, convulsions, and seizures which occurred following dosing or handling. Hematology: At the 15-month interim evaluation, total leukocyte and lymphocyte counts in all dosed groups of males were significantly lower than those of the controls. Pathology Findings: Increased incidences of thyroid gland follicular cell adenoma occurred in 125 mg/kg males and females, but the increase was not dose-related. Increased incidences of thyroid gland follicular cell hyperplasia occurred in all dosed groups of males and females. Increased incidences of forestomach hyperplasia and ulcers occurred in all groups of males administered THC. Incidences of hepatocellular adenoma and of hepatocellular adenoma or carcinoma (combined) occurred with a significant negative trend in male and female mice, as did incidences of eosinophilic foci and fatty change in the liver. GENETIC TOXICOLOGY: THC was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535 with or without rat and hamster liver S9 fractions. In cultured Chinese hamster ovary cells, THC induced sister chromatid exchanges at the highest dose tested in the presence of S9; at this dose level, cell cycle delay indicative of toxicity was observed. THC did not induce chromosomal aberrations in cultured Chinese hamster ovary cells with or without S9 metabolic activation enzymes. In vivo, no increase in the frequency of micronucleated erythrocytes was observed in the peripheral blood of male or female mice administered THC by gavage for 13 weeks. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of 1-trans-delta(9)-tetrahydrocannabinol in male or female F344/N rats administered 12.5, 25, or 50 mg/kg. There was equivocal evidence of carcinogenic activity of THC in male and female B6C3F1 mice based on the increased incidences of thyroid gland follicular cell adenomas in 125 mg/kg groups. Increased incidences of thyroid gland follicular cell hyperplasia occurred in male and female mice, and increased incidences of hyperplasia and ulcers of the forestomach were observed in male mice. The incidences of mammary gland fibroadenomas and uterine stromal polyps were decreased in dosed groups of female rats, as were the incidences of pancreatic adenomas, pituitary gland adenomas, and interstitial cell adenomas of the testis in dosed male rats and liver neoplasms in dosed mice. These decreases were likely related to lower body weights in dosed animals. Synonyms: 3-Pentyl-6,6,9-trimethyl-6a,7,8,10a-tetrahydro-6h-dibenzo(b,d)pyran-1-ol; delta1-tetrahydrocannabinol; (-)-delta1-3,4-trans- tetrahydrocannabinol; delta(9)-tetrahydrocannabinon; THC; delta1-THC; delta(9)-THC

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