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National Toxicology Program

Publications and source records attributed to National Toxicology Program.

At least 451 records · Page 25Linked to original sources
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Diglycidyl Resorcinol Ether (Technical Grade) (CAS No. 101-90-6) In F344/N Rats and B6C3F1 Mice (Gavage Studies).

Diglycidyl resorcinol ether (DGRE), a pale, yellow, translucent, amorphous solid at room temperature, is used as a liquid spray epoxy resin, as a diluent in the production of other epoxy resins used in electrical, tooling, adhesive, and laminating applications, and as a curing agent for polysulfide rubber. Approximately 3,000 workers are exposed to DGRE. The quantity of DGRE produced in the United States is not known. Toxicology and carcinogenesis studies of technical grade diglycidyl resorcinol ether (81% pure) were conducted by administering the chemical in corn oil by gavage to groups of 50 male and 50 female F344/N rats at doses of 25 or 50 mg/kg and to groups of 50 male and female B6C3F1 mice at doses of 50 or 100 mg/kg. A supplemental study of similar design in male and female rats (0 or 12 mg/kg) was started approximately 12 months later because of high mortality in the 50 mg/kg dose groups. Doses were administered five times per week for 103 weeks. Groups of 50 rats and 50 mice of each sex received corn oil by gavage on the same dosing schedule and served as vehicle controls. Throughout most of the primary study, mean body weights of high dose male and female rats and female mice were lower than those of the corresponding vehicle controls. In the supplemental study, body weights of both sexes of the dosed rats were unaffected by administration of DGRE. Survival of dosed rats of each sex in the primary study was dose related and was shorter (P<0.001) than that of the vehicle controls. No high dose male rats and only 1/50 high dose female rats lived to the end of the study. Bronchopneumonia was the most frequent cause of early death among the rats and may have resulted from the animals' aspiration of corn oil containing diglycidyl resorcinol ether. Survival of the dosed male rats in the supplemental study was reduced (P<0.005) when compared to controls. There was no significant difference in survival between dosed and control female rats in the supplemental study. Survival of dosed and control mice was comparable but poorer in females, with 20/50 (40%) of the controls, 13/50 (26%) of the low dose, and 10/50 (20%) of the high dose groups alive at the end of 2 years. These early deaths were due to suppurative and necrotizing inflammation of the reproductive tract, possibly caused by a Klebsiella sp. infection. The incidences of rats and mice with hyperkeratosis and hyperplasia of the forestomach were compound related. For rats and mice of each sex, incidences of animals with squamous cell papillomas, squamous cell carcinomas, or both occurred with statistically significant positive trends and the incidences observed in other organs in dosed groups relative to the controls. An audit of the experimental data was conducted for the 2-year studies of diglycidyl resorcinol ether. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, technical grade diglycidyl resorcinol ether caused hyperkeratosis and hyperplasia of the forestomach in rats and mice. DGRE was carcinogenic for male and female F344/N rats and for male and female B6C3F1 mice, causing both benign and malignant neoplasms of the forestomach. Levels of Evidence of Carcinogenicity: Male Rats: Positive Female Rats: Positive Male Mice: Positive Female Mice: Positive Synonym: DGRE

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Commercial Grade 2,4 (80%)- and 2,6 (20%)- Toluene Diisocyanate (CAS No. 26471-62-5) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toluene diisocyanate (TDI) is commercially produced as an approximate 80:20 mixture of the 2,4- and 2,6-isomers. In 1980, 580,000 pounds of this chemical were produced in the United States, primarily for use in the manufacture of flexible polyurethane foams. These foam elastomers are found in furniture and automobile cushions, carpet underlays, pillow filling, mattresses, insulation, shoes, purses, and toys. TDI is also used to produce polyurethane coatings for lacquers and wood finishes. Groups of 50 female F344/N rats and 50 B6C3F1 mice were administered commercial grade toluene diisocyanate (80% 2,4- and 20% 2,6-) in corn oil by gavage at doses of 60 or 120 mg/kg body weight, 5 days per week for 105 or 106 weeks. Groups of 50 male F344/N rats received 30 or 60 mg/kg and groups of 50 male B6C3F1 mice received 120 or 240 mg/kg on the same schedule. Dosage analyses of toluene diisocyanate indicated that the chemical had reacted in the corn oil vehicle, resulting in actual gavage concentrations 77% to 90% of theoretical values. Groups of 50 rats and 50 mice of each sex received corn oil only and served as vehicle controls. Survival in all groups of dosed rats in the 2-year studies were shorter (P</=0.005) than that of the controls; depressions of the mean body weight gain relative to controls were greater than 10% in all dosed rat groups throughout most of the study. A dose-dependent pattern of cumulative toxicity began at 70 weeks and culminated in excessive mortality, indicating the estimated tolerated dose had been exceeded for rats. Acute bronchopneumonia occurred at increased incidences in groups of dosed male and female rats (males: control, 2/50; low dose, 6/50; high dose, 14/50; females: 1/50, 10/50, 25/49). Subcutaneous tissue fibromas or fibrosarcomas (combined) in male rats occurred with a positive trend (P<0.01; 3/50, 6/50, 12/50). The incidence in the high dose group was higher than that in the controls (P</=0.01). The same tumor comparisons were significant (P<0.001) in female rats by the life table analysis. Mammary gland fibroadenomas in female rats occurred with a positive trend (P<0.001), and the incidences in low and high dose groups were significantly higher than that in controls (P</=0.01). Pancreatic acinar cell adenomas in male rats occurred with a positive trend (P<0.05; 1/47, 3/47, 7/49). The incidence in the high dose group was higher than that in the controls (P<0.05). The incidences of pancreatic islet cell adenomas in female rats were higher by the incidental tumor test (P</=0.01) in low dose (6/49) and high dose (2/47) groups than in controls (0/50). An islet cell carcinoma was also observed in a low dose female rat. The incidences of female rats with neoplastic nodules in the liver occurred with a positive trend (P<0.05; 3/50, 8/50, 8/48), and the incidence in the high dose group was higher (P<0.05) than that in the controls. Survival of high dose male mice in the 2-year study was significantly shorter than that of the controls (P<0.001). During the second year of the study, mean body weight gains of high dose male mice were less than those of the controls. Cytomegaly of kidney tubular epithelium was found in 45/48 (94%) low dose male mice and 41/50 (82%) high dose male mice but not in any of the controls. Hemangiomas or hemangiosarcomas (combined) of the circulatory system in female mice occurred with a positive trend (P</=0.01; control, 0/50; low dose, 1/50; high dose, 5/50). The incidence in the high dose group was significantly higher than that in the controls (P<0.05). Hepatocellular adenomas in female mice occurred with a positive trend (P</=0.001; 2/50, 3/50, 12/50), and the incidence in the high dose group was higher than that in the controls (P<0.01). Toluene diisocyanate was mutagenic in Salmonella typhimurium strains TA98 and TA100 in the presence (but not the absence) of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9; it was not mutagenic in strains TA 1535 or 1537. An audit of the experimental data for these 2-year toxicological and carcinogenicity An audit of the experimental data for these 2-year toxicological and carcinogenicity studies on commercial grade 2,4- and 2,6-toluene diisocyanate was conducted. There were no data discrepancies that influenced the final interpretations. Under the conditions of these gavage studies, commercial grade toluene diisocyanate in corn oil was carcinogenic for F344/N rats, causing subcutaneous fibromas and fibrosarcomas (combined) in males and females, pancreatic acinar cell adenomas in males, and pancreatic islet cell adenomas, neoplastic nodules of the liver, and mammary gland fibroadenomas in females. Toluene diisocyanate was not carcinogenic for male B6C3F1 mice. TDI was carcinogenic for female B6C3F1 mice, causing hemangiomas or hemangiosarcomas (combined), as well as hepatocellular adenomas. Levels of Evidence of Carcinogenicity: Male Rats: Positive Female Rats: Positive Male Mice: Negative Female Mice: Positive Synonym: TDI

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of C.I. Basic Red 9 Monohydrochloride (Pararosaniline) (CAS No. 569-61-9) In F344/N Rats and B6C3F1 Mice (Feed Studies).

C.I. Basic Red 9 monohydrochloride is a triphenylmethane dye used for coloring textiles, leather, and paper and as a biological stain. Toxicology and carcinogenesis studies were conducted by administering the test chemical in feed to groups of 50 male and 50 female F344/N rats and B6C3F1 mice for 103 weeks at concentrations of 0, 1,000, or 2,000 ppm for male rats and 0, 500, or 1,000 ppm for female rats and mice of each sex. The average daily doses of C.I. Basic Red 9 monohydrochloride were estimated to be 49 and 103 mg/kg for male rats, 28 and 59 for female rats, 196 and 379 mg/kg for male mice, and 149 and 407 mg/kg for female mice. Two lots of the test chemical were used in the 2-year studies with purities of 93% (water content approximately 9%) and 99%. In rats, the thyroid gland and pituitary gland were identified as target sites in the 13-week studies. Therefore, 10 additional rats of each sex were added to the control and high dose groups in the 2-year studies to examine the effects on these organs after 1 year of exposure. In the 1-year studies in rats, final mean body weights were slightly decreased in both sexes. The thyroid gland weight to body ratio of dosed males was 1.7 times that of the controls, and the concentration of serum thyroxin in male and female rats was significantly lower than that of the controls at week 52. Compound-related histopathologic effects included thyroid gland cysts in both sexes (1/10; 1/10) and thyroid gland follicular cell hyperplasia (1/10), adenomas (1/10), and carcinomas (1/10) and fatty metamorphosis of the liver (4/10, two of these with focal necrosis) in males; no effect was seen in the controls. The doses selected for the 2-year studies were based on the results of the 13-week studies. The absence of toxicologic signs, histopathologic changes, significant body weight depressions, or mortality after 13 weeks of exposure to C.I. Basic Red 9 monohydrochloride suggested that these concentrations would not shorten survival. However, throughout the 2-year studies, mean body weights of high dose rats and dosed mice were lower than those of the controls, and significantly reduced survival relative to controls was observed for high dose rats of each sex (P<0.001), low dose male mice (P<0.03), and low dose and high dose female mice (P<0.001). In the 2-year studies, several types of neoplastic lesions occurred with significantly increased incidences in dosed animals (see table page 12 of the Technical Report). High dose male rats had increased incidences of squamous cell carcinomas, trichoepitheliomas, and sebaceous adenomas of the skin. Greater incidences of follicular cell carcinomas and of follicular cell adenomas were found in the thyroid glands of high dose male rats than in controls, whereas in high dose female rats, the combined incidence of follicular cell adenomas or carcinomas was greater than that in controls. Dosed rats of each sex had increased incidences of subcutaneous fibromas, and high dose rats had increased incidences of Zymbal gland carcinomas. Hepatocellular carcinomas were the compound-related neoplasms common to both species; the incidences were increased in both high dose male rats and in dosed mice of each sex. Dosed female mice had an increased incidence of pheochromocytomas or malignant pheochromocytomas. In addition, marginally increased incidences of mammary gland tumors (23/50; 32/50; 32/50) in female rats, and malignant lymphomas (17/50; 24/50; 25/50) in female mice were observed. C.I. Basic Red 9 monohydrochloride was mutagenic in strains TA98 and TA100 of Salmonella typhimurium by the preincubational protocol with or without metabolic activation. It was not mutagenic in strains TA1535 and TA1537 in this system with or without metabolic activation. It was mutagenic in the L5178Y/TK+/- mouse lymphoma assay with or without metabolic activation. C.I. Basic Red 9 monohydrochloride did not induce chromosomal aberrations in Chinese hamster ovary cells; it did induce sister-chromatid exchanges in the presence of Aroclor 1254-induced male Sprague-Dawley rat li-induced male Sprague-Dawley rat liver S9. C.I. Basic Red 9 monohydrochloride also induced unscheduled DNA synthesis in F344 male rat hepatocytes in vitro. An audit of the experimental data was conducted for these 2-year studies of C.I. Basic Red 9 monohydrochloride. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenicity of C.I. Basic Red 9 monohydrochloride for male and female F344/N rats and for male and female B6C3F1 mice. In male rats, C.I. Basic Red 9 monohydrochloride caused squamous cell carcinomas, trichoepitheliomas and sebaceous adenomas of the skin, subcutaneous fibromas, thyroid gland follicular cell adenomas and follicular cell carcinomas, Zymbal gland carcinomas, and hepatocellular carcinomas. In female rats, C.I. Basic Red 9 monohydrochloride caused subcutaneous fibromas, thyroid gland follicular cell adenomas or carcinomas (combined), and Zymbal gland carcinomas. In male mice, C.I. Basic Red 9 monohydrochloride caused hepatocellular carcinomas. In female mice, C.I. Basic Red 9 monohydrochloride caused hepatocellular carcinomas and adrenal gland pheochromocytomas or malignant pheochromocytomas (combined). Exposure to C.I. Basic Red 9 monohydrochloride also may have been related to increased incidences of mammary gland tumors in female rats and hematopoietic system tumors in female mice. Synonyms: pararosaniline; benzeneamine 4-((4-aminophenyl)(4-imino-2,5-cyclohexadian-1-ylidene)methyl)-monohydrochloride paramagenta

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of HC Red No. 3 [2,((Amino-2-nitrophenyl)amino)ethanol] (CAS No. 2871-01-4) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

oxicology and carcinogenesis studies of HC Red No. 3 (97% pure), a semipermanent hair dye, were conducted by administering the chemical in corn oil by gavage for 105 weeks to groups of 50 male and 50 female F344/N rats and for 104 weeks to groups of 50 male and 50 female B6C3F1 mice. The dosage regimen used for rats was 0, 250, or 500 mg/kg per day and for mice, 0, 125. or 250 mg/kg per day. Doses were administered 5 days per week. In prior 13-week studies, these doses produced no signs of toxicity when administered 5 days per week. In the 2-year studies, the administration of HC Red No. 3 did not affect body weight gains of male or female rats or mice. Body weight gains by all groups of female mice were reduced because of a reproductive tract infection. Survival of male and female rats and mice was not reduced by administration of HC Red No. 3. The survival of female mice, including vehicle controls, was reduced relative to historical survival rates due to a reproductive tract infection. The infection, accompanied by weight loss, high mortality, and suppurative inflammation of multiple organs, was found in 36/50 vehicle control, 32/50 low dose, and 29/50 high dose female mice. Klebsiella pneumoniae was isolated from infected tissues. Pigmentation of various tissues in both rats and mice was a common observation in both the 13-week and the 2-year studies. The pigment was not identified but was presumed to be a derivative of HC Red No. 3. Very minimal nephropathy was found in dosed female rats, but its relationship to HC Red No. 3 is equivocal. Mild nephrosis was found in dosed female mice, but this effect may have been secondary to the infection of the genital tract. There was an increase in the incidence of mammary gland fibroadenomas or cystadenomas in low dose female rats. The incidence of this lesion in high dose female rats was not increased (vehicle control, 14/50, 28%; low dose, 25/50, 50%; high dose, 11/50, 22%). Largely because of the lack of a dose response, the increased incidence in the low dose females was not considered to be due to HC Red No. 3. No increased incidences of neoplasms were seen in male rats. Transitional cell papillomas of the urinary bladder were detected in one high dose male rat, two low dose female rats, and one high dose female rat; none was observed in the vehicle controls. These uncommon neoplasms were found in animals that survived to the termination of the study and were not accompanied by other proliferative lesions. The incidence of hepatocellular adenomas or carcinomas (combined) was increased in high dose male mice, whereas the incidence of these neoplasms in low dose male mice was significantly lower than that in the vehicle controls (25/50; 15/50; 35/50). Hepatocellular carcinomas in three vehicle control, one low dose, and five high dose male mice metastasized to the lung. The incidences of liver neoplasms in dosed female mice were not significantly different from those in the vehicle control group. HC Red No. 3 was mutagenic in Salmonella typhimurium strains TA97, TA98, and TA100, but not in TA1535, in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9 when tested by the preincubational protocol. An audit of the experimental data was conducted for these 2-year toxicology and carcinogenesis studies on HC Red No. 3. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies of HC Red No. 3, there was no evidence of carcinogenicity for male or female F344/N rats given 250 or 500 mg/kg per day. There was equivocal evidence of carcinogenicity for male B6C3F1 mice as indicated by an increased incidence of hepatocellular adenomas or carcinomas (combined) in the 250 mg/kg dose group. Poor survival coupled with lack of significant findings rendered the study in female B6C3F1 mice an inadequate study of carcinogenicity. Both sexes of both species may have been able to tolerate higher doses of HC Red No. 3. Therefore, the sensitivity of these studies for detecting chese studies for detecting carcinogenesis may have been limited. Synonym: 2,((amino-2-nitrophenyl)amino)ethanol

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of o-Phenylphenol (CAS No. 90-43-7) Alone and with 7,12-Dimethylbenz(a)anthracene (CAS No. 57-97-6) in Swiss CD-1 Mice (Dermal Studies).

o-Phenylphenol is used primarily as a germicide and fungicide for citrus fruits and vegetables and was selected for carcinogenesis studies because of the potential for human exposure. Four-week studies were conducted in which groups of 10 male and 10 female Swiss Webster mice were given dermal applications to the dorsal interscapular region of 0, 6, 11, 21, 36, or 56 mg of o-phenylphenol in 0.1 ml of acetone. Doses were administered 3 days per week for 4 weeks, and animals were monitored for clinical changes. Reductions in body weights of acetone vehicle control were observed, but no compound-related changes in weight or survival occurred in male or female mice administered o-phenylphenol. o-Phenylphenol caused dose-related ulcerative lesions at the site of application. The severity of these lesions was judged not to be life threatening. Carcinogenesis studies were conducted to determine whether o-phenylphenol was a complete carcinogen for skin or a promoter in a two-stage initiation/promotion skin paint model. Groups of 50 Swiss CD-1 mice of each sex were used for up to 102 weeks. Five dose groups were used: an acetone vehicle control group; a positive control group initiated with 7,12-dimethylbenz(a)- anthracene (DMBA) and promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA); an initiator control group that received DMBA plus acetone; a group that received repeated applications of o-phenylphenol. The following doses were applied dermally to a clipped area on the dorsal interscapular region 3 days per week: o-phenylphenol - 55.5 mg/0.1 ml acetone; or TPA - 0.005 mg/0.1 ml acetone. DMBA was administered as a single dose at a concentration of 0.05 mg/0.1 ml acetone to the dorsal interscapular region. In the 2-year studies, mean body weights of the o-phenylphenol, DMBA/o-phenylphenol, and DMBA/TPA groups were not markedly different from those of mice that received DMBA/acetone. Similarly, there were no significant group differences in survival except for a decrease in survival in the positive control group (DMBA/TPA). Skin neoplasms classified as squamous cell papillomas, squamous cell carcinomas, basal cell tumors, basal cell carcinomas, keratoacanthomas, or sebaceous adenomas occurred in mice dosed with DMBA/acetone, DMBA/o-phenylphenol, or DMBA/TPA alone. However, the incidence of skin neoplasms in mice dosed with DMBA/acetone (15/100) was similar to that in mice dosed with DMBA/o-phenylphenol (17/100). The incidence of skin neoplasms in male and female mice dosed with DMBA/TPA (52/100) was substantially greater than those in mice dosed with either DMBA/acetone or DMBA/o-phenylphenol. Similarly, the mean time of appearance of skin papillomas occurred much earlier in the DMBA/TPA groups than in the DMBA/acetone or DMBA/o-phenylphenol groups. All groups had nonneoplastic lesions consisting of inflammation, ulceration, hyperkeratosis, and acanthosis at the site of application. These lesions were present in the acetone vehicle control group and, to a larger extent, in the o-phenylphenol, DMBA/o-phenylphenol, and DMBA/TPA groups. No skin neoplasms were observed in male or female mice receiving o-phenylphenol or in the acetone vehicle control groups. Moreover, a complete histopathologic review revealed no other neoplasms at any other site at significantly increased incidences in the groups receiving o-phenylphenol compared with the acetone vehicle controls. There were also no tumor-enhancing (or tumor-inhibiting) effects of o-phenylphenol and DMBA given in combination. o-Phenylphenol was weakly mutagenic in strains TA1535 of Salmonella typhimurium only in the absence of rat liver S9; it was not mutagenic in strains TA1537, TA98, or TA100. It was mutagenic in the mouse lymphoma L5178/TK+/- assay in the presence or absence of Aroclor 1254-induced male F344 rat liver S9. o-Phenylphenol did not induce sex-linked recessive lethal mutations in Drosophila melanogaster. o-Phenylphenol induced sister-chromatid exchanges in Chinese hamster ovary (CHO) cells only in the absence of rat liver S9. It did not induce chromosomal aberraterrations in CHO cells in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat liver S9. An audit of the experimental data was conducted for these 2-year studies of o-phenylphenol. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year dermal application studies, there was no evidence of carcinogenicity in male or female Swiss CD-1 mice administered o-phenylphenol alone or as a promoter following initiation with DMBA. o-Phenylphenol, however, caused nonneoplastic lesions, which included ulceration, inflammation, and hyperkeratosis, at the site of application.

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of 3-Chloro-2-methylpropene (Technical grade containing 5% dimethylvinyl chloride) (CAS No. 563-47-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis studies of technical-grade 3-chloro-2-methylpropene (containing 5% dimethylvinyl chloride), a widely used insecticide and a chemical intermediate, were performed on F344/N rats and B6C3F1 mice. In the 13-week studies, 50%-100% mortality occurred in groups of male and female rats receiving 400 mg/kg, male rats receiving 300 mg/kg, and male and female mice receiving 500-1,250 mg/kg. Inflammation and necrosis of the liver were seen in rats and mice, and necrosis of cortical tubules of the kidney was seen in mice. Based on these observations, groups of 50 male and 50 female rats were administered 3-chloro-2-methylpropene in corn oil by gavage at doses of 0, 75, or 150 mg/kg body weight, 5 days per week for 103 weeks, and groups of 50 male and 50 female mice received 3-chloro-2-methylpropene at 0, 100, or 200 mg/kg on the same schedule. In the 2-year studies, the mean body weight of high dose male rats was consistently 10%-15% lower than that of the vehicle control group, and late in the study there was a marginal reduction in survival of high dose male rats. Mean body weights and survival in low dose male rats and in both dosed groups of female rats were comparable to those of their vehicle control groups. Mean body weights of high dose male mice and of both dosed groups of female mice were slightly (5%-9%) lower than those of the vehicle controls, whereas survival in both male and female mice was not affected by 3-chloro-2-methylpropene administration. Dose-related increases in the incidence of forestomach inflammation were observed in male and female mice (male: vehicle control, 0/49; low dose, 9/49; high dose, 7/49; female: vehicle control, 2/50; low dose, 3/48; high dose, 9/44). Increased incidences of forestomach basal cell hyperplasia were observed in rats and mice of each sex. 3-Chloro-2-methylpropene induced forestomach squamous cell papillomas and squamous cell carcinomas in rats and mice as shown in the table. Invasion or metastasis of the squamous cell carcinomas to other organs was observed in two low dose male, three high dose male, and one high dose female mice. Renal tubular cell adenocarcinomas (1/49), renal transitional cell carcinomas (1/49), and transitional cell papillomas (1/49) of the urinary bladder were observed in high dose male rats, and renal tubular cell adenomas (1/50) and renal tubular cell adenocarcinomas (1/50) were seen in low dose male rats. These urinary tract neoplasms were not observed in vehicle controls. The incidences of inflammation of the nasal cavity and of nephropathy/nephrosis were greater in the two dosed groups than in the vehicle control groups of rats and mice of each sex. Negative trends or lower incidences of pheochromocytomas of the adrenal gland and C-cell adenomas or carcinomas (combined) of the thyroid gland were observed in dosed male rats. Negative trends were observed in the incidences of hepatocellular adenomas or carcinomas (combined) in dosed male mice and of hemangiomas or hemangiosarcomas (combined) in dosed female mice. 3-Chloro-2-methylpropene was weakly mutagenic in Salmonella typhimurium strain TA1537 with 10% rat liver S9; results in strain TA100 with 10% Syrian hamster liver S9 or with 10% or 30% rat liver S9 were judged equivocal. Mutagenicity tests with S. typhimurium strains TA1535 and TA98 were negative with or without metabolic activation. 3-Chloro-2-methylpropene was mutagenic in the mouse lymphoma L5178/TK+/- forward mutation assay without exogenous metabolic activation. Cytogenetics tests with cultured Chinese hamster ovary cells were positive for induction of chromosomal aberrations and sister-chromatid exchanges (SCE's) in the absence of rat liver S9. With metabolic activation, SCE levels remained significantly elevated, but the number of chromosomal aberrations was reduced. An audit of the experimental data was conducted for these 2-year carcinogenesis studies on 3-chloro-2-methylpropene. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, d the final interpretations. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity for 3-chloro-2-methylpropene as shown by the increased incidences of squamous cell neoplasms in the forestomach of male and female F344/N rats and of male and female B6C3F1 mice. Synonyms: 2-methallyl chloride; methyl allyl chloride; b-methallyl chloride; pi-chloroisobutylene; isobutenyl chloride; 3-chloro-2-methyl-1-propene; 2-methyl-2-propenyl chloride

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of C.I. Disperse Blue 1 (A commercial dye containing approximately 50% 1,4,5,8-tetraaminoanthraquinone, and 20% water) (CAS No. 2475-45-8) in F344/N Rats and B6C3F1 Mice (Feed Studies).

C.I. Disperse Blue 1, a component of several semipermanent hair dyes, was studied as a commercial-grade product (minus lignosulfonate dispersants) containing approximately 50% 1,4,5,8-tetraaminoanthraquinone, 30% other compounds structurally related to 1,4,5,8-tetraaminoanthraquinone, and 20% water. C.I. Disperse Blue 1 was studied for toxicity and carcinogenicity in single-administration gavage, 14-day feed, 13-week feed, and 104-week feed studies. All studies used F344/N rats and B6C3F1 mice. In the single-administration gavage studies, no deaths occurred within 14 days at doses up to 3,000 mg/kg C.I. Disperse Blue 1 in rats or up to 2,000 mg/kg in mice. In the 14-day studies, rats and mice received dietary concentrations of up to 50,000 ppm. All male rats survived, and 2/5 female rats in the 50,000-ppm group died. All mice receiving 25,000 ppm or more died. Three of five males and 2/5 female mice in the 12,500-ppm groups died. In the 13-week studies, diets containing concentrations up to 20,000 ppm C.I. Disperse Blue 1 were fed to rats, and diets containing concentrations up to 10,000 ppm were fed to mice. No compound-related deaths of rats occurred; however, pathologic changes occurred at 2,500 ppm and higher and included urinary tract calculi, urinary bladder inflammation, hyperplasia of the urinary bladder transitional epithelium, and nephrosis, Compound-related deaths occurred at 10,000 ppm in mice of each sex. Pathologic changes included chronic inflammation and hyperplasia of the urinary bladder transitional epithelium and urinary tract calculi at dietary concentrations of 2,500 ppm and higher and nephrosis, myocardial necrosis, and testicular degeneration at 10,000 ppm. The renal lesions at 5,000 ppm were considered to be potentially life threatening. These composite findings from the short-term studies were used to identify target organs and to help select dietary concentrations for the longer term studies. In the 2-year studies in rats, groups of 50 animals of each sex were administered C.I. Disperse Blue 1 at dietary concentrations of 0, 1,250, 2,500, or 5,000 ppm. These dietary concentrations corresponded to 0, 45, 95, and 217 mg/kg per day for males and 0, 56, 111, and 240 mg/kg per day for females. Survival of males and females in the 5,000 ppm groups and males in the 2,500-ppm group was significantly reduced. Final body weights, as percent of controls, were: male-- low dose 100%; mid dose, 94%; high dose, 85%; female-- low dose, 99%; mid dose, 94%; high dose, 87%. Compound-related effects of feeding diets containing C.I. Disperse Blue 1 for 104 weeks to F344/N rats included urinary bladder neoplasms and calculi at the incidences noted in the table. Positive statistical associations existed between the presence of calculi and transitional cell neoplasms of the urinary bladder in male and female rats, leiomyomas or leiomyosarcomas (combined) in female rats, and squamous cell neoplasms in male rats. The increased incidence of pancreatic islet cell adenomas or carcinomas (combined) in high dose male rats was significant by survival-adjusted analyses (overall incidences: control, 1/49; low dose, 2/50; mid dose, 5/50; high dose, 3/50). In the 2-year studies in mice, 50 animals of each sex were administered diets containing C.I. Disperse Blue 1 at 0, 600, 1,200, or 2,500 ppm. These dietary concentrations corresponded to doses of 0, 112, 239, and 540 mg/kg per day for males and 0, 108, 235, and 520 mg/kg per day for females. Survival was comparable among control and dosed male or female mice. Final body weights, as percent of controls, were as follows: male-- low dose, 97%; mid dose, 98%; high dose, 101%; female-- low dose, 110%; mid dose, 104%; high dose, 91%. The incidences of hepatocellular adenomas or carcinomas (combined) were increased for dosed male mice (9/50; 21/50; 16/50) and for low dose female mice (3/50; 13/49; 3/50; 4/50). Alveolar/bronchiolar adenomas or carcinomas (combined) occurred with an increased incidence in high dose male mice (4/50; 9/49; 5/50; 11/50). Several nonneoplastic effects were increased incidence in high dose male mice (4/50; 9/49; 5/50; 11/50). Several nonneoplastic effects were detected in the kidneys of mid dose and high dose male and high dose female rats and of all dosed groups of male and female mice. These effects on the kidney included calculi, hydronephrosis, and epithelial hyperplasia in rats and casts and renal tubular degeneration in mice. C.I. Disperse Blue 1 was studied for mutagenicity in Salmonella typhimurium in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9. C.I. Disperse Blue 1 was mutagenic in strain TA1535 in the presence of S9 and in strains TA97 and TA98 in the presence or absence of S9; it was not mutagenic in strain TA100. An audit of the experimental data was conducted for the 2-year toxicology and carcinogenesis studies of C.I. Disperse Blue 1. No data discrepancies were found that influenced the final interpretations. Under the conditions of these feed studies of C.I. Disperse Blue 1, there was clear evidence of carcinogenicity for male and female F344/N rats as shown by the increased occurrence of transitional cell papillomas and carcinomas, of leiomyomas and leiomyosarcomas, and of squamous cell papillomas and carcinomas of the urinary bladder. Urinary bladder calculi were observed in the groups of rats in which urinary bladder neoplasms were increased. Positive associations existed between the presence of calculi and transitional cell neoplasms in male and female rats, leiomyomas or leiomyosarcomas (combined) in female rats, and squamous cell neoplasms in male rats. A marginally increased occurrence of pancreatic islet cell adenomas or carcinomas (combined) was observed in male rats exposed to C.I. Disperse Blue 1. There was equivocal evidence of carcinogenicity of C.I. Disperse Blue 1 in male B6C3F1 mice as shown by marginally increased incidences of hepatocellular adenomas or carcinomas (combined) in dosed male mice and a marginally increased occurrence of alveolar/bronchiolar adenomas or carcinomas (combined) in high dose male mice. There was no evidence of carcinogenicity of C.I. Disperse Blue 1 in female B6C3F1 mice. Synonyms: C.I. 64500; 1,4,5,8-tetraamino-9,10-anthracenedione; 1,4,5,8-tetraaminoanthraquinone

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Dimethyl Morpholinophosphoramidate (CAS No. 597-25-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Dimethyl morpholinophosphoramidate (DMMPA, greater than 99% pure) was developed for use as a simulant for the physical (but not biologic) properties of anticholinesterase agents in chemical defense training. Because of the potential for human exposure, the toxicity and carcinogenicity of DMMPA were investigated. Fourteen-day and 13-week studies were conducted to determine short-term toxicity, to identify target organs, and to establish doses for the 2-year toxicology and carcinogenesis studies. In the 14-day studies, groups of five male and five female F344/N rats were administered DMMPA in corn oil by gavage daily at 0, 313, 1,250, 2,500, or 5,000 mg/kg body weight for 14 consecutive days. All the rats receiving DMMPA at 2,500 or 5,000 mg/kg, except one male receiving 5,000 mg/kg, died before the end of the studies. Rats receiving DMMPA at doses of 1,250 mg/kg or less survived. The final mean body weights of the surviving dosed rats were within +/- 8% of those of the vehicle controls. Compound-related gross lesions were not found at necropsy. Groups of five B6C3F1 mice of each sex were given DMMPA by the same route on the same schedule at 0, 250, 500, 1,000, 2,000, or 4,000 mg/kg. All the mice given DMMPA at 2,000 or 4,000 mg/kg died before the end of the studies. Mice administered DMMPA at doses of 1,000 mg/kg or less survived. The final mean body weight of the male mice given DMMPA at 1,000 mg/kg was 14% greater than that of the vehicle controls, whereas that of the other dosed survivors was within 10% of that of the vehicle controls. Compound-related gross lesions were not found at necropsy. In the 13-week studies, groups of 10 male and 10 female F344/N rats and B6C3F1 mice were given DMMPA by gavage in corn oil at 0, 200, 400, 1,200, or 1,600 mg/kg body weight, 5 days per week for 13 weeks. All rats given DMMPA at 400 mg/kg or less survived, and no more than 3/10 died in any of the higher dose groups. The final mean body weights of the dosed male rats were 6% to 11% greater than that of the vehicle controls; weights of the dosed female rats were similar to that of the vehicle controls (-6% to 1%). There was a dose-related increase in liver weight/body weight ratio. All the mice given DMMPA at 1,600 mg/kg, except one female, died before the end of the 13-week studies; mice receiving DMMPA at 1,200 mg/kg or less survived. The final mean body weights of the dosed male mice were 3.4% to 6.9% greater than that of the vehicle controls. The final mean body weights of dosed female mice and vehicle controls were similar. Compound-related gross or histopathologic changes were not observed in rats or mice. In the 2-year toxicology and carcinogenesis studies, groups of 50 male and 50 female F344/N rats were given DMMPA in corn oil by gavage at doses of 0, 150, 300, or 600 mg/kg body weight, 5 days per week for 103 weeks. Groups of 50 male B6C3F1 mice were given DMMPA at 0, 150, 300 mg/kg body weight, and groups of 50 female B6C3F1 mice were given DMMPA at 0, 300, 600 mg/kg body weight on the same schedule. Doses of 300 or 600 mg/kg were originally selected for male mice for the 2-year study; because 19/50 high dose male mice died by week 19, all male mice were killed and doses of 0, 150, and 300 mg/kg were selected for the restart of the 2-year study in male mice. The survival of high dose male (22/50) and female (24/50) rats was reduced (P<0.025) relative to that of the male (37/50) and female (36/50) vehicle controls. Mean body weights were less than 10% lower in the mid dose and high dose male rats and in the high dose female rats than in the vehicle controls. DMMPA administration did not significantly affect body weight gain or survival of male and female mice. At the 600 mg/kg dose, increased (P<0.05) incidences of mononuclear cell leukemia occurred in both male rats (vehicle control, 14/50; 150 mg/kg, 21/50; 300 mg/kg, 19/50; 600 mg/kg, 25/50) and female rats (9/50; 13/50; 12/49; 18/50). DMMPA-related neoplastic or nonneoplastic lesions were not observed in the dosed mice. DMMPA was not mutagenic in strains TA100, TA1535ns were not observed in the dosed mice. DMMPA was not mutagenic in strains TA100, TA1535, TA1537, or TA98 of Salmonella typhimurium in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9. DMMPA was mutagenic in the L5178Y/TK&plusmn; mouse lymphoma assay in the absence of S9; it was not tested in the presence of S9. DMMPA induced chromosomal aberrations and sister-chromatid exchanges in Chinese hamster ovary cells in the absence of S9, but cytogenetic effects were not observed in the presence of Aroclor 1254-induced rat liver S9. An audit of the experimental data for these 2-year carcinogenesis studies on DMMPA was conducted. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenicity for male and female F344/N rats given dimethyl morpholinophosphoramidate, as indicated by increased incidences of mononuclear cell leukemia. There was no evidence of carcinogenicity for male and female B6C3F1 mice given dimethyl morpholinophosphoramidate at doses of 150 (male), 300, or 600 (female) mg/kg for 2 years. Synonyms: dimethyl morpholinophosphonate; phosphonic acid, morpholino, dimethyl ester; DMMPA; phosphonic acid, 4-morpholinyl-, dimethyl ester

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Chlorinated Trisodium Phosphate (CAS No. 56802-99-4)* in B6C3F1 Mice (Gavage Studies).

Two-year toxicology and carcinogenesis studies of chlorinated trisodium phosphate, an inclusion complex of trisodium phosphate and sodium hypochlorite used in various cleaning compounds, were conducted by administering 0, 500, or 1,000 mg/kg (dose volume: 10 ml/kg) of the chemical in water by gavage, 5 days per week for 103 weeks, to groups of 50 male and 50 female B6C3F1 mice. Groups of mice receiving 250 mg/kg were included in these studies but were removed after 6 months because of a lack of toxicity in the 500 and 1,000 mg/kg groups. Two-year studies were begun in male and female F344/N rats at doses of 0, 500, 1,000, or 2,000 mg/kg of chlorinated trisodium phosphate in water by gavage (10 ml/kg). The 2,000 mg/kg groups were killed at 15 weeks because of poor survival, and the other groups were killed at 35 weeks because of toxicity in the 1,000 mg/kg group. The doses selected for the 2-year studies were based on the general lack of adverse effects seen in the 14-day and 13-week studies in which rats received 0-1,000 mg/kg and mice received 0-2,000 mg/kg by gavage in water. No compound-related histopathologic effects were observed in the 14-day or the 13-week studies in mice. In the 2-year studies, survival and mean body weights of dosed and vehicle control male mice groups were comparable (survival-- vehicle control, 39/50; low dose, 35/50; high dose, 32/50). Survival of the dosed female mice was lower than that of the vehicle controls (30/50; 16/50; 21/50), although at week 80 survival of female mice was 42/50, 39/50, and 36/50. The mean body weights of the high dose female mice were lower than those of the vehicle control mice, primarily after week 32; final body weights were 11% lower in the high dose group compared with that in the vehicle controls. The lower survival and mean body weights of the dosed female mice may have been due to a greater incidence of uterine/ovarian infections in these mice rather than to a direct toxic effect of chlorinated trisodium phosphate. Nine of 20 vehicle control, 20/34 low dose, and 21/29 high dose female mice that died before the end of the studies had such infections. This reduced survival decreased the sensitivity of the study of female mice for detecting the presence or absence of carcinogenic effects. At no site was the incidence of neoplasms considered to be related to the administration of chlorinated trisodium phosphate. Minimal necrosis and fatty changes were observed in the livers of male mice. Kidneys in male mice were characterized by small, multifocal areas of mineralization, primarily in the cortex but not at the corticomedullary junction or in the tubes of the medulla. Neither effect was considered compound related. Five different types of ovarian neoplasms were found in six dosed female mice; because these lesions were from tissues of different embryonic origin, they were considered unrelated to administration of chlorinated trisodium phosphate. Chlorinated trisodium phosphate was weakly mutagenic in strain TA1535 of Salmonella typhimurium in the presence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9. This compound was not mutagenic in strains TA97, TA98, or TA100. An audit of the experimental data was conducted for these 2-year studies of chlorinated trisodium phosphate. No data discrepancies were found that influenced the final interpretation of these experiments. Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenicity for either male or female B6C3F1 mice given chlorinated trisodium phosphate by gavage in water for 103 weeks at doses of 500 or 1,000 mg. Survival of dosed female mice was 78% and 72% after 80 weeks and 32% and 42% at the termination of the study. The studies in male and female F344/N rats were considered to be inadequate studies of carcinogenicity because the experiments were terminated at 35 weeks due to poor survival. Synonym: sodium hypochlorite phosphate

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Isophorone (CAS No. 78-59-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis studies of isophorone (greater than 94% pure), a widely used solvent and chemical intermediate, were conducted by administering 0, 250, or 500 mg isophorone/kg body weight per day by gavage in corn oil to groups of 50 F344/N rats and 50 B6C3F1 mice of each sex, 5 days per week for 103 weeks. Doses selected for the 2-year studies were based on the 16-day studies in which rats and mice of each sex received doses of 0-2,000 mg/kg per day and on 13-week studies in which rats and mice of each sex received doses ranging from 0 to 1,000 mg/kg per day by gavage in corn oil. No chemically related gross or histopathologic effects were observed in the 16-day or 13-week studies, but 1/5 high dose male rats, 4/5 high dose female rats, and all high dose male and female mice died during the 16-day studies. During the 13-week studies, 1/10 high dose female rats and 3/10 high dose female mice died. The high dose for the 2-year studies was set at 500 mg/kg per day for each sex of rats and mice, based mainly on the deaths in the 13-week studies. Throughout the 2-year study, the mean body weights of the high dose male rats averaged 5% lower than those of the vehicle controls. During the second year, the mean body weights of the female high dose rats averaged 8% lower than those of the vehicle controls, and the high dose female mice averaged 5% lower. The survival of high dose male rats was significantly lower than that of the vehicle controls after week 96 (final survival: vehicle control, 33/50; low dose, 33/50; high dose, 14/50). The survival of dosed female rats was poor (30/50; 23/50; 20/50), due in part to 20 gavage-related accidental deaths of dosed animals. The survival of male mice was also low (16/50; 16/50; 19/50), but there was a significant trend toward increased survival of dosed female mice relative to that of the vehicle controls (26/50; 35/50; 34/50). Dosed male rats showed a variety of proliferative lesions of the kidney (tubular cell hyperplasia: 0/50; 1/50; 4/50; tubular cell adenoma: 0/50; 0/50; 2/50; tubular cell adenocarcinoma: 0/50; 3/50; 1/50; epithelial hyperplasia of the renal pelvis: 0/50; 5/50; 5/50). Dosed male rats also exhibited increased mineralization of the medullary collecting ducts (1/50; 31/50; 20/50), and low dose male rats showed a more severe nephropathy than is commonly seen in aging F344/N rats. Carcinomas of the preputial gland were increased in high dose male rats (0/50; 5/50; 5/50). With the exception of a moderate increase in nephropathy (21/50; 39/50; 32/50), female rats did not show chemically related increased incidences of neoplastic or nonneoplastic lesions. In high dose male mice, isophorone exposure was associated with increased incidences of hepatocellular adenomas and carcinomas (18/48; 18/50; 29/50) and of mesenchymal tumors of the integumentary system (fibroma, fibrosarcoma, neurofibrosarcoma, or sarcoma: 6/48; 8/50; 14/50). An increased incidence of lymphomas or leukemias was noted in low dose male mice (8/48; 18/50; 5/50). Coagulative necrosis (3/48; 10/50; 11/50) and hepatocytomegaly (23/48; 39/50; 37/50) were observed more frequently in the livers of dosed male mice than in vehicle controls. No compound-related neoplastic or nonneoplastic lesions associated with isophorone exposure were seen in female mice. Isophorone was not mutagenic in strains TA100, TA1535, TA1537, or TA98 of Salmonella typhimurium in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster liver S9. Isophorone was weakly mutagenic in the mouse L5178Y/TK+/- assay in the absence of S9; it was not tested in the presence of S9. Isophorone induced sister-chromatid exchanges in the absence of S9 in Chinese hamster ovary cells; it did not induce sister-chromatid exchanges in the presence of Aroclor 1254-induced male rat liver S9, and it did not induce chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of S9. An audit of the experimental data was conducted for the 2-year toxicology and carcinogenesis studies of isophorcarcinogenesis studies of isophorone. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenicity of isophorone in male F344/N rats as shown by the occurrence of renal tubular cell adenomas and adenocarcinomas in animals given 250 or 500 mg/kg per day; carcinomas of the preputial gland were also observed at increased incidence in male rats given 500 mg/kg. There was no evidence of carcinogenicity in female F344/N rats given 250 or 500 mg/kg per day. For male B6C3F1 mice, there was equivocal evidence of carcinogenicity of isophorone as shown by an increased incidence of hepatocellular adenomas or carcinomas (combined) and of mesenchymal tumors in the integumentary system in animals given 500 mg/kg per day and by an increase in malignant lymphomas in animals given 250 mg/kg per day. There was no evidence of carcinogenicity of isophorone in female B6C3F1 mice given 250 or 500 mg/kg per day. Synonym: 3,5,5-trimethyl-2-cyclohexen-1-one

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Benzene (CAS No. 71-43-2) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Benzene ranks 16th in production volume for chemicals produced in the United States, with approximately 9.9 billion pounds being produced in 1984, 9.1 billion pounds in 1983, and 7.8 billion pounds in 1982. This simplest aromatic chemical in used in the synthesis of styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes (detergents), chlorobenzenes, and other products used in the production of drugs, dyes, insecticides, and plastics. Benzene, along with other light, high-octane aromatic hydrocarbons, such as toluene and xylenes, is a component of motor gasoline. Benzene is also used as a solvent, but for most applications, it has been replaced by less hazardous solvents. During the 17-week studies, groups of 10 or 15 male and female F344/N rats and B6C3F1 mice were gavaged 5 days per week with benzene in corn oil (5 ml/kg) at doses of 0 to 600 mg/kg. No benzene-related deaths occurred; in rats that received benzene, final mean body weights were 14%-22% lower compared with vehicle controls and in mice, slight dose-related reductions were observed (less than 10% differences). Doses for the 2-year studies were selected based on clinical observations (tremors in higher dosed mice), on clinical pathologic findings (lymphoid depletion in rats and leukopenia in mice), and on body weight effects. Two-year toxicology and carcinogenesis studies of benzene (greater than 99.7% pure) were conducted in groups of 50 F344/N rats and 50 B6C3F1 mice of each sex and for each dose. Doses of 0, 50, 100, or 200 mg/kg body weight benzene in corn oil (5 ml/kg) were administered by gavage to male rats, 5 days per week, for 103 weeks. Doses of 0, 25, 50, or 100 mg/kg benzene in corn oil were administered by gavage to female rats and to male and female mice for 103 weeks. Ten additional animals in each of the 16 groups were killed at 12 months and necropsies were performed. Hematologic profiles were performed at 3-month intervals. These studies were designed and conducted because of large production volume and potential human exposure, because of the epidemiologic association with leukemia, and because previous experiments were considered inadequate or inconclusive for determining potential carcinogenicity in laboratory animals. In the 2-year studies, mean body weights of the 200 mg/kg male rats (-23%) and the 100 mg/kg mice (-14% to -19%) were lower than those of the vehicle controls, and survival of dosed groups decreased with increasing dose (rats--male: vehicle control, 32/50; low dose, 29/50; mid dose, 25/50; high dose, 16/50; female: 46/50; 38/50; 34/50; 25/50; mice--male: 28/50; 23/50; 18/50; 7/50; female: 30/50; 26/50; 24/50; 18/50). At week 92 for rats and week 91 for mice, survival was greater than 60% in all groups; most of the dosed animals that died before week 103 had neoplasia. Compound-related nonneoplastic or neoplastic effects on the hematopoietic system, Zymbal gland, forestomach, and adrenal gland were found both for rats and mice. Further, the oral cavity was affected in rats, and the lung, liver, harderian gland, preputial gland, ovary, and mammary gland were affected in mice. Significantly increased (P<0.05) incidences of neoplasms were observed at multiple sites for male and female rats and for male and female mice. Primary neoplasms observed in rats and mice are summarized in Table 1 (see page 12 of the Technical Report). Hematologic data from vehicle control and dosed rats and mice were obtained at 3-month intervals from 0 to 24 months. Reliably identifiable hematologic effects were limited to lymphocytopenia and associated leukocytopenia in benzene-dosed rats and mice. These effects were seen from 3 to 18 months in dosed male rats and in dosed male mice; a similar but less pronounced response was observed in dosed female rats during this same time period. The effect in female mice was limited to 12-18 months. The technical quality of certain of these data was questionable; thus, more detailed analyses (e.g., investig questionable; thus, more detailed analyses (e.g., investigation of the association between hematologic and pathologic changes) are deemed inappropriate for these data. Benzene increased the frequency of micronucleated normchromatic peripheral erythrocytes in male and female mice (rats were not examined); males were more sensitive than females. The hematopoietic system of rats and mice of each sex was affected by benzene in the 2-year studies. The incidences of malignant lymphomas in all dosed groups of mice were greater than those in the vehicle controls (male: 4/49; 9/48; 9/50; 15/49; female: 15/49; 24/45; 24/50; 20/49). Lymphoid depletion of the splenic follicles (rats) and thymus (male rats) was observed at increased incidences. Bone marrow hematopoietic hyperplasia was observed at increased incidences in dosed mice of each sex (male: 0/49; 11/48; 10/50; 25/49; female: 3/49; 14/45; 8/50; 13/49). The incidences of Zymbal gland carcinomas in mid and high dose male rats and in dosed female rats were greater than those in the vehicle controls (male: 2/32; 6/46; 10/42; 17/42; female: 0/45; 5/40; 5/44; 14/46). The incidences of Zymbal gland carcinomas in mid and high dose male mice and in high dose female mice were greater than those in the vehicle controls (male: 0/43; 1/34; 4/40; 21/39; female: 0/43; 0/32; 1/37; 3/31). In mid and high dose male mice and in high dose female mice, the incidences of epithelial hyperplasia of the Zymbal gland were also increased (male: 0/43; 3/34; 12/40; 10/39; female: 1/43; 1/32; 2/37; 6/31). Hyperplasia of the adrenal capsule was observed at increased incidences in dosed mice of each sex (male: 2/47; 32/48; 14/49; 4/46; female: 5/49; 19/44; 34/50; 30/48). The incidence of pheochromocytomas in mid dose male mice was greater than that in the vehicle controls (male: 1/47; 1/48; 7/49; 1/46), whereas the incidences in dosed female mice were lower than that in the vehicle controls (female: 6/49; 1/44; 1/50; 1/48). Hyperplasia of the zona fasciculata of the adrenal cortex was observed at increased incidences in low dose rats of each sex (male: 0/50; 13/49; 0/48; 2/49; female: 0/50; 17/50; 0/47; 0/49). Benzene was associated with increased incidences of neoplasms of the skin and oral cavity of rats. The incidences of squamous cell papillomas and squamous cell carcinomas of the skin in high dose male rats were greater than those in the vehicle controls (squamous cell papilloma: 0/50; 2/50; 1/50; 5/50; squamous cell carcinoma: 0/50; 5/50; 3/50; 8/50). Increased incidences of uncommon squamous cell papillomas or squamous cell carcinomas (combined) of the oral cavity were observed in dosed male and female rats (male: 1/50; 9/50; 16/50; 19/50; female: 1/50; 5/50; 12/50; 9/50). Incidences of squamous cell papillomas or carcinomas (combined) (male: 2/45; 2/42; 3/44; 5/38; female: 1/42; 3/40; 6/45; 5/42), hyperkeratosis, and epithelial hyperplasia of the forestomach were increased in some dosed groups of male and female mice; incidences of hyperkeratosis and acanthosis were increased in high dose male rats. Compound-related effects in the lung, harderian gland, preputial gland, ovary, mammary gland, and liver were seen in mice but not in rats. Administration of benzene was associated with increased incidences of alveolar epithelial hyperplasia in mid and high dose mice (male: 2/49; 3/48; 7/50; 10/49; female: 1/49; 1/42; 9/50; 6/49). Increased incidences of alveolar/bronchiolar carcinomas and alveolar/bronchiolar adenomas or carcinomas (combined) were observed in high dose male mice (carcinomas: 5/49; 11/48; 12/50; 14/49; adenomas or carcinomas: 10/49; 16/48; 19/50; 21/49). Alveolar/bronchiolar adenomas were seen at increased incidences in high dose female mice (4/49; 2/42; 5/50; 9/49), as were alveolar/bronchiolar carcinomas (0/49; 3/42; 6/50; 6/49) and alveolar/bronchiolar adenomas or carcinomas combined (4/49; 5/42; 10/50; 13/49) in mid and high dose female mice. The incidences of focal or diffuse hyperplasia of the harderian gland were increased in dosed mice of each sex (male: 0/49; 5/46; 11/49; 7/48; female: 6/48; 10/44; 11/50; 10/47). The incidences of harderian gland adenomas (0/49; 9/46; 13/49; 11/48) in dosed male mice were greater than that in the vehicle controls. A marginal increase in the incidence of adenomas or carcinomas (combined) of the harderian gland was seen in high dose female mice (5/48; 6/44; 10/50; 10/47). The administration of benzene to male mice was associated with increased incidences of hyperplasia (1/21; 18/28; 9/29; 1/35) and squamous cell carcinomas (0/21; 3/28; 18/29; 28/35) of the preputial gland. Increased incidences of mammary gland carcinomas were found in mid dose and high dose female mice (0/49; 2/45; 5/50; 10/49) and carcinosarcomas in high dose female mice (0/49; 0/45; 1/50; 4/49). Increased incidences of various uncommon neoplastic and nonneoplastic lesions of the ovary (papillary cystadenoma, luteoma, granulosa cell tumor, tubular adenoma, benign mixed tumor, epithelial hyperplasia, and senile atrophy) were associated with the administration of benzene to female mice. In mid and high dose female mice, the incidences of granulosa cell tumors (1/47; 1/44; 6/49; 7/48) and benign mixed tumors (0/47; 1/44; 12/49; 7/48) were greater than those in the vehicle controls. Increased incidences of hepatocellular adenomas were observed in low dose female mice (1/49; 8/44; 5/50; 4/49) and hepatocellular adenomas or carcinomas (combined) in low dose and mid dose female mice (4/49; 12/44; 13/50; 7/49). An audit of the experimental data was conducted for these 2-year carcinogenesis studies on benzene. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of benzene for male F344/N rats, for female F344/N rats, for male B6C3F1 mice, and for female B6C3F1 mice. For male rats, benzene caused increased incidences of Zymbal gland carcinomas, squamous cell papillomas and squamous cell carcinomas of the oral cavity, and squamous cell papillomas and squamous cell carcinomas of the skin. For female rats, benzene caused increased incidences of Zymbal gland carcinomas and squamous cell papillomas and squamous cell carcinomas of the oral cavity. For male mice, benzene caused increased incidences of Zymbal gland squamous cell carcinomas, malignant lymphomas, alveolar/bronchiolar carcinomas and alveolar/bronchiolar adenomas or carcinomas (combined), harderian gland adenomas, and squamous cell carcinomas of the preputial gland. For female mice, benzene caused increased incidences of malignant lymphomas, ovarian granulosa cell tumors, ovarian benign mixed tumors, carcinomas and carcinosarcomas of the mammary gland, alveolar/bronchiolar adenomas, alveolar/bronchiolar carcinomas, and Zymbal gland squamous cell carcinomas. Dose-related lymphocytopenia was observed for male and female F344/N rats and male and female B6C3F1 mice. Synonyms: benzol, cyclohexatriene, pyrobenzol

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of n-Butyl Chloride (CAS No. 109-69-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis studies of n-butyl chloride (greater than 99.5% pure), a solvent as well as an alkylating agent, were conducted by exposing groups of F344/N rats and B6C3F1 mice to n-butyl chloride in corn oil by gavage for 14 days, 13 weeks, and 2 years. In the 14-day studies, no compound-related gross pathologic effects were observed in groups of five male or female rats or mice administered doses of up to 3,000 mg/kg body weight. However, deaths occurred in the groups administered 750, 1,500, or 3,000 mg/kg. Tremors and convulsions following gavage administration were observed. In the 13-week studies, groups of 10 male and 10 female rats were administered up to 500 mg/kg n-butyl chloride, and similar groups of mice received up to 1,000 mg/kg, Three of 10 male rats in the 500 mg/kg dose group and one female mouse in the 120 mg/kg dose group died before the end of the studies. Mild to moderate extramedullary hematopoiesis was observed in 3/10 male rats receiving 500 mg/kg. Mean body weights of male and female rats receiving 250 or 500 mg/kg were lower than those of the vehicle controls. Convulsions were observed in male and female rats receiving 250 mg/kg or higher and in 2/10 female mice receiving 1,000 mg/kg. Based on these results, 2-year toxicology and carcinogenesis studies of n-butyl chloride were conducted by administering doses of 0, 60, or 120 mg/kg in corn oil by gavage to groups of 50 male and 50 female rats and doses of 0, 500, or 1,000 mg/kg to groups of 50 male and 50 female mice. In the 2-year studies, survival relative to that of vehicle controls was significantly lower in high dose male rats (40/50 vs 17/50) and high dose female rats (35/50 vs 11/50) and in male mice receiving 1,000 mg/kg (33/50 vs 10/50). Due to excessive mortality in the 1,000 mg/kg female mice, the group was terminated in the 45th week and a second series of 2-year studies in mice of each sex was started at concentrations of 0 and 250 mg/kg. Male mice in the 1,000 mg/kg group had 10% lower mean body weights than the vehicle control group. No adverse effects on survival or body weights in other dosed groups of rats and mice were observed. Convulsions were observed before or after gavage administration on several occasions during the rat studies. These observations were noted primarily in the high dose groups (male: vehicle control, 1/50; low dose, 3/50; high dose, 27/50; female: vehicle control, 0/50; low dose, 7/50; high dose, 45/50). Hemorrhage of the brain and alveoli were observed primarily in high dose male and female rats dying from convulsions. Lymphoid depletion of the spleen and splenic hemosiderosis were also observed inthese animals. In mice, convulsions were observed only in the first studies (in the high dose female mice that were terminated early and in 6/50 high dose male mice). Pheochromocytomas of the adrenal gland occurred at marginally increased incidence in low dose female rats (1/50; 6/50; 1/49). Hyperplasia was observed in 3/50 vehicle controls, 7/50 low dose females, and 4/49 high dose females. The incidence of pheochromocytomas was low, not dose related, and not seen in males, and thus it was not considered to be compound related. Cytoplasmic vacuolization of the adrenal cortex occurred at increased incidences in males (5/50; 10/50; 20/50) but not in female rats. Nephropathy of the kidney occurred at increased incidences in female rats (13/50; 25/50; 20/50) but not in male rats. Additional nonneoplastic lesions such as congestion, inflammation, or nephrosis were not present to any degree in either vehicle control or dosed female rats. An increased incidence of alveolar/bronchiolar adenomas or carcinomas (combined) was observed in the 500 mg/kg group of female mice (3/50 vs 9/50), but little effect was seen in the 250 mg/kg group (6/50 vs 8/50). The incidences of adenomas or carcinomas (combined) in dosed female mice were not significantly different from that in the pooled vehicle control group from the first and second studies (pooled controls, 9/100; 250 mg/kg, 8/50; 500 mg/kg, 9/50). The lack o0). The lack of hyperplasia in female mice and the negative trend in male mice suggest that these marginal effects were probably not related to the administration of n-butyl chloride. An increased incidence of hepatocellular adenomas or carcinomas (combined) was observed in the 500 mg/kg dose group of female mice (3/50 vs 8/50) but not in the 250 mg/kg dose group (9/50 vs 7/50). An increased incidence of hemangiosarcomas was observed in male mice in the first study (1/50; 3/50; 4/50) but not in the second study (4/50 vs 2/50). Neither of these marginal effects was regarded as compound related. n-Butyl chloride was not mutagenic in Salmonella typhimurium strains TA98, TA1535, or TA1537 in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat liver S9 or in the presence of male Syrian hamster liver S9. n-Butyl chloride was mutagenic in the mouse lymphoma L5178Y/TK&plusmn; assay in the absence of Aroclor-induced male rat liver S9 and was not tested in the presence of S9. n-Butyl chloride did not induce sister-chromatid exchanges or chromosomal aberrations in Chinesehamster ovary cells in the presence or absence of Aroclor-induced male rat liver S9. An audit of the experimental data was conducted for the 2-year studies of n-butyl chloride. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenicity of n-butyl chloride for male and female F344/N rats at daily doses of 60 or 120mg/kg, for male B6C3F1 mice at doses of 250, 500, or 1,000 mg/kg, or for female B6C3F1 mice at doses of 250 or 500 mg/kg. Chemical-induced toxicity in high dose rats (primarily females) reduced the sensitivity of the study for determining carcinogenicity. Synonyms: 1-chlorobutane; butyl chloride; n-propylcarbinyl chloride

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Tetrachloroethylene (Perchloroethylene) (CAS No. 127-18-4) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Tetrachloroethylene is used primarily as a dry cleaning agent, an industrial solvent for fats, oils, tars, rubber, and gums, and a metal degreasing agent. Tetrachloroethylene had antihelminthic uses, particularly for hookworms (1.6-8 g/60 kg), and was formerly used in combination with some grain protectants and fumigants. Toxicology and carcinogenesis studies of tetrachloroethylene (99.9% pure) were conducted by inhalation exposure of groups of 50 male and 50 female F344/N rats and B6C3F1 mice 6 hours per day, 5 days per week, for 103 weeks. The exposure concentrations used (0, 200, or 400 ppm for rats and 0, 100, or 200 ppm for mice) were selected on the basis of results from 13-week inhalation studies in which groups of 10 rats and 10 mice of each sex were exposed to tetrachloroethylene at 100-1,600 ppm for 6 hours per day, 5 days per week. During the 13-week studies, 1,600 ppm tetrachloroethylene was lethal to 20%-70% of the rats and mice and reduced the final body weights of survivors. In rats, tetrachloroethylene at 200-800 ppm caused minimal to mild hepatic congestion. In dosed male and female mice, minimal to mild hepatic leukocytic infiltration, centrilobular necrosis, bile stasis (400-1,600 ppm), and mitotic alteration (200-1,600 ppm) were produced. Tetrachloroethylene exposure also caused minimal renal tubular cell karyomegaly in mice at concentrations as low as 200 ppm. During the 2-year studies, exposure to tetrachloroethylene did not consistently affect body weight gains in either rats or mice. Exposure at 400 ppm tetrachloroethylene reduced the survival of male rats (control, 23/50; low dose, 20/50; high dose, 12/50). This reduced survival may have been related to an increased incidence of mononuclear cell leukemia. Tetrachloroethylene at both exposure concentrations reduced the survival of male mice (46/50; 25/50; 32/50), whereas exposure at 200 ppm reduced female mouse survival (36/50; 31/50; 19/50). Early deaths in mice may have been related to the development of hepatocellular carcinomas. Both concentrations of tetrachloroethylene were associated with increased incidences of mononuclear cell leukemia in male rats (28/50; 37/50; 37/50). In female rats, tetrachloroethylene increased the incidence of leukemia (18/50; 30/50; 29/50) and decreased the time to occurrence of the disease. Tetrachloroethylene produced renal tubular cell karyomegaly in male and female rats, renal tubular cell hyperplasia in male rats, and renal tubular cell adenomas or adenocarcinomas (combined) in male rats (1/49; 3/49; 4/50). The incidence of the renal tubular cell tumors was not statistically significant; these uncommon tumors have been consistently found at low incidences in male rats in other 2-year studies of chlorinated ethanes and ethylenes. One low dose male rat had a kidney lipoma, and another had a nephroblastoma. Four high dose male and two high dose female rats had gliomas of the brain, whereas one control male and one control female had this tumor. In male and female mice, tetrachloroethylene caused dose-related increases in the incidences of hepatocellular neoplasms. In males, tetrachloroethylene at 200 ppm increased the incidence of hepatocellular adenomas (11/49; 8/49; 18/50) and at both concentrations increased the incidence of hepatocellular carcinomas (7/49; 25/49; 26/50). In female mice, tetrachloroethylene at both concentrations increased the incidences of hepatocellular carcinomas (1/48; 13/50; 36/50). Tetrachloroethylene also produced renal tubular cell karyomegaly in both sexes of mice, and one low dose male mouse had a tubular cell adenocarcinoma. In these inhalation studies, there were no neoplastic changes in the respiratory tracts of either species, but there was an increase in the incidence of squamous metaplasia in the nasal cavities in dosed male rats (0/50; 5/50; 5/50). Tetrachloroethylene was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 in the presence or absence of male Syrian hamster or male Sprague-Dawley rat liver S9. Tetrachloroethylene was not mutagenic in was not mutagenic in L5178Y/TK&plusmn; mouse lymphoma cells with or without metabolic activation and did not induce sex-linked recessive lethal mutations in Drosophila melanogaster. Tetrachloroethylene did not induce sister-chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of metabolic activation. An audit of the experimental data was conducted for these 2-year studies on tetrachloroethylene. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenicity of tetrachloroethylene for male F344/N rats as shown by an increased incidence of mononuclear cell leukemia and uncommon renal tubular cell neoplasms. There was some evidence of carcinogenicity of tetrachloroethylene for female F344/N rats as shown by increased incidences of mononuclear cell leukemia. There was clear evidence of carcinogenicity for B6C3F1 mice as shown by increased incidences of both hepatocellular adenomas and carcinomas in males and of hepatocellular carcinomas in females. Synonyms: carbon bichloride; carbon dichloride; ethylene tetrachloride; per; perc; perchlor; perchlorethylene; perchloroethylene; perk; tetrachlorethylene; 1,1,2,2-tetrachloroethylene Trade names: Ankilostin; Antisal 1; Dee-Solv; Didakene; Dow-Per; ENT 1860; Fedel-Un; Nema; Perclene; Percosolv; Perklone; PerSec; Tetlen; Tetracap; Tetraleno; Tetravec; Tetroguer; Tetropil

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Marine Diesel Fuel (NO CAS) and JP-5 Navy Fuel (CAS No. 8008-20-6) in B6C3F1 Mice (Dermal Studies).

Toxicology and carcinogenesis studies were conducted by applying marine diesel fuel or JP-5 navy fuel to clipped dorsal interscapular skin of male and female B6C3F1 mice to determine both systemic and dermal effects. Doses for the 2-year studies were set by conducting 14-day and 13-week studies. Doses of 2,000-40,000 mg/kg marine diesel fuel were applied neat in the 14-day studies; in the 13-week studies, doses of 250-4,000 mg/kg marine diesel fuel in acetone were applied with a dose volume of 0.1 ml. Doses of 5,000-40,000 mg/kg JP-5 navy fuel in ethanol were applied in the 14-day studies with a dose volume of 0.5 ml; in the 13-week studies, doses of 500-8,000 mg/kg JP-5 navy fuel in acetone were applied with a dose volume of 0.2 ml. For the 2-year studies, doses were selected which did not cause deaths, decrease body weight gain, or produce excessive dermatitis in the 14-day or 13-week studies. Two-year studies were conducted by administering marine diesel fuel or JP-5 navy fuel by dermal application to groups of 49 or 50 male and 50 female B6C3F1 mice at doses of 0, 250, or 500 mg/kg in an acetone vehicle with a dose volume of 0.1 ml. Both sexes of mice dosed with 500 mg/kg marine diesel fuel (84-week exposure) and female mice dosed with 500 mg/kg JP-5 navy fuel (90-week exposure) were killed early because of excessive irritation and ulceration at the site of application and to prevent the spread of infection. Survival rates at those times were 26/50 males and 29/50 females dosed with marine diesel fuel and 17/50 females dosed with JP-5 navy fuel. Survival rates at the end of the studies (104 weeks) were reduced (P<0.01) in low dose female mice receiving marine diesel fuel (40/50 in vehicle controls compared with 12/50 in the low dose group) or with JP-5 navy fuel (44/50 in vehicle controls compared with 33/50 in the low dose group). Body weight gain was decreased below that of the vehicle controls after week 30 in all groups of mice receiving marine diesel fuel and in both sexes of mice receiving the high dose of JP-5 navy fuel. There was a marked increase in the incidence of chronic dermatitis in mice receiving marine diesel fuel or JP-5 navy fuel. Chronic dermatitis was defined as a composite lesion of epidermal histopathologic changes generally consisting of acanthosis, hyperkeratosis, and in some instances necrosis and ulceration of the overlying epidermis. Dermal changes frequently included fibrosis, increased amounts of melanin, and the presence of acute and chronic inflammatory cell infiltrates. A dose-related, proportional increase in the severity of the lesions was twofold to threefold greater in the dosed groups than in the vehicle controls. The averagedegree of severity of the lesions was judged to be minimal in the vehicle controls, mild in the low dose groups, and moderate in the high dose groups of mice dosed with marine diesel fuel or JP-5 navy fuel. There were similar responses at the site of inguinal skin to which the chemicals had migrated after application, but the degree of severity of the lesions was judged to be minimal to mild in the vehicle control and dosed groups of mice. Squamous cell papillomas or carcinomas (combined) occurred with a positive trend (P<0.05) at the site of application in male mice administered marine diesel fuel (vehicle control, 0/49; low dose, 0/49; high dose, 3/49). The total numbers of mice with squamous cell papillomas or carcinomas (combined) both for the site of application and the adjacent inguinal skin were 1/50, 2/49, and 3/50 for the vehicle control, low dose, and high dose groups of male mice and 0/50, 1/45, and 2/48 for female mice. There are no NTP historical data for B6C3F1 mice that received acetone by dermal application. The NTP historical incidence of squamous cell papillomas or carcinomas (combined) in untreated male and female B6C3F1 mice is 0.3%-0.4% in over 3,500 observations. Marine diesel fuel was not mutagenic in Salmonella typhimurium TA98, TA100, TA1535, or TA1537, and JP-5 navy fuel was not mutagenic in strains TA97, TA98, TA100, or TA1535 in th100, or TA1535 in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat or male Syrian hamster S9 when tested according to the preincubation protocol. Audits of the experimental data were conducted for these 2-year studies on marine diesel fuel and JP-5 navy fuel. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year dermal studies, marine diesel fuel at doses of 250 and 500 mg/kg resulted in dose-related increased incidences of squamous cell neoplasms of the skin (primarily carcinomas), providing equivocal evidence of carcinogenicity for male and female B6C3F1 mice. The sensitivity for detecting systemic carcinogenicity in female mice dosed with marine diesel fuel was reduced by poor survival. Under the conditions of these 2-year dermal studies, JP-5 navy fuel at doses of 250 and 500 mg/kg provided no evidence of carcinogenicity for male and female B6C3F1 mice.

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Decabromodiphenyl Oxide (CAS No. 1163-19-5) In F344/N Rats and B6C3F1 Mice (Feed Studies).

Toxicology and carcinogenesis studies of decabromodiphenyl oxide, a flame retardant for plastics and other materials, were conducted by exposing groups of 50 male and 50 female F344/N rats and B6C3F1 mice at 0, 25,000, and 50,000 ppm in the diet for 103 weeks. These concentrations were selected because no toxicity was observed at any dose in the 14-day or 13-week studies and 50,000 ppm chemical in the diet is considered to be the highest dose to which rats and mice can be exposed for extended periods of time without reducing the nutritional value of the diet. No compound-related gross or microscopic pathologic effects were observed in the 14-day or 13-week studies. Body weights of dosed male and female rats and mice in the 2-year studies were comparable to those of the controls. Decreased survival of low dose male rats was not believed to be compound related. No other effects on survival were observed in the 2-year studies. Loss of control male mice (presumably due to fighting) was significant during the first part of the study. In the 2-year studies, nonneoplastic lesions were observed at increased incidences in rats and mice of each sex. Thrombosis and degeneration of the liver, fibrosis of the spleen, and lymphoid hyperplasia were observed in high dose male rats. Degeneration of the eye was observed in low dose female rats. Nonneoplastic lesions observed in dosed mice were granulomas in the liver of low dose males and hypertrophy in the liver of low dose and high dose males. Follicular cell hyperplasia was observed in thyroid glands of dosed male mice (control, 2/50; low dose, 10/50; high dose, 19/50). The incidences of neoplastic nodules in the liver of low and high dose male rats (1/50; 7/50; 15/49) and high dose female rats (1/50; 3/49; 9/50) were significantly greater than those in the controls. Mononuclear cell leukemia occurred in dosed male rats with a positive trend (30/50; 33/50; 35/50); this marginal increase was not considered biologically significant. Acinar cell adenomas were observed in the pancreas of four high dose male rats, and a sarcoma was observed in the spleen of one low dose and one high dose male rat. Hepatocellular adenomas or carcinomas (combined) occurred at marginally increased incidences in dosed male mice (8/50; 22/50; 18/50). The incidences of thyroid gland follicular cell adenomas or carcinomas (combined) were increased in dose male mice (0/50; 4/50; 3/50). A study of decabromodiphenyl oxide absorption from the gastrointestinal tract indicated that absorption was minimal, possibly less than 1%, at the doses administered in the 2-year studies. Additional chemical analysis indicated than the decabromodiphenyl oxide used in these studies contained several less brominated diphenyl oxides. Therefore, since absorption and toxicity of minor impurities are unknown, effects observed in these studies must be attributed to the approximately 95% pure preparation used rather than to pure decabromodiphenyl oxide. Decabromodiphenyl oxide was not mutagenic in strains TA1535, TA1537, TA98, or TA100 of Salmonella typhimurium in the presence or absence of Aroclor 1254-induced Sprague-Dawley male rat or Syrian hamster liver S9 when tested according to the preincubational protocol. Decabromodiphenyl oxide was not mutagenic in the mouse lymphoma L5178Y/TK+/- assay in the presence or absence of Aroclor 1254-induced F344/N male rat liver S9. Decabromodiphenyl oxide did not induce sister-chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in vitro in the presence or absence of S9 prepared from livers of Aroclor 1254-induced male Sprague-Dawley rats. An audit of experimental data was conducted for these 2-year studies on decabromodiphenyl oxide. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year feed studies of decabromodiphenyl oxide, there was some evidence of carcinogenicity for male and female F344/N rats as shown by increased incidences of neoplastic nodules of the liver in low dose (25,000 ppm) males and high dose (50, and high dose (50,000 ppm) groups of each sex. There was equivocal evidence of carcinogenicity for male B6C3F1 mice as shown by increased incidences of hepatocellular adenomas or carcinomas (combined) in the low dose group and of thyroid gland follicular cell adenomas or carcinomas (combined) in both dosed groups. There was no evidence of carcinogenicity for female B6C3F1 mice receiving 25,000 or 50,000 ppm in the diet. Several nonneoplastic lesions were observed at increased incidences, the most notable being thyroid gland follicular cell hyperplasia in male mice. Synonyms: decabromodiphenyl ether; bis(pentabromophenyl)ether; DBDPO

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Chlorinated Paraffins (C12, 60% Chlorine) (CAS No. 108171-26-2*) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis assessments of chlorinated paraffins (C12, 60% chlorine), a material widely used as a flame retardant and extreme-pressure lubricant, were conducted in male and female F344/N rats and male and female B6C3F1 mice in single-administration, 16-day, 13-week, and 2-year studies. Doses used in the 2-year studies were 0, 312, or 625 mg/kg body weight per day administered by gavage in corn oil five times per week to groups of 70 male and female rats and 0, 125, or 250 mg/kg administered to groups of 50 male and female mice. Ten male and 10 female rats were killed after 6 and 12 months of dosing and examined for toxicity. No chemically related toxicity was observed in single-administration studies in which male and female rats received doses of chlorinated paraffins (C12, 60% chlorine) up to 13,600 mg/kg body weight and male and female up to 27,200 mg/kg. In 16-day studies, deaths did occur in groups of male and female rats given 7,500 mg/kg and in groups of male and female mice given doses of 1,875 mg/kg or higher. In 13-week studies, no chemically related deaths occurred among male and female rats given up to 5,000 mg/kg or mice given up to 2,000 mg/kg. Increased liver weights were noted in dosed rats and mice of each sex in the short-term studies, and dosed male rats showed more severe nephropathy than did vehicle controls. Doses selected for the 2-year studies were those that caused a minimal increase in liver weight in the short-term studies. Liver and kidney weights were increased in dosed rats killed at 6 and 12 months. Morphometric measurements demonstrated hepatocyte hypertrophy in the livers of dosed rats. Lesions of the kidney tubules and interstitial inflammation increased with dose in male and female rats. During the 2-year studies, body weights of high dose male rats were 8%-12% lower than those of vehicle controls after week 20, and body weights of dosed female mice were about 10% lower than those of vehicle controls during the second year. Survival of dosed male rats was lower than that of vehicle controls after about week 85, perhaps due to toxicity to the kidney (final survival: vehicle control, 27/50; low dose, 6/50; high dose, 3/50). Survival of low dose female rats was lower than that of vehicle controls (34/50; 24/50; 29/50). Survival of dosed male mice was not significantly different from that of vehicle controls (34/50; 31/50; 31/50). Survival of high dose female mice was lower than that of vehicle controls after about week 75 (final survival: 36/50; 31/50; 25/50). Chemically related nonneoplastic lesions consisted of hypertrophy and minimal focal necrosis of the liver in rats; erosion, inflammation, and ulceration of the glandular stomach and forestomach a in male rats; and formation ofmultiple cysts in the kidney tubules of male rats. The incidence of nephropathy was also increased in dosed female rats and mice. The maximum tolerated dose may have been exceeded in male and female rats. Neoplastic lesions associated with chlorinated paraffins (C12, 60% chlorine) administration were found in the liver of rats and mice of each sex (see table p. 12 of Technical Report) Dosed male rats showed increased incidences of kidney tubular cell hyperplasia (1/50; 9/50; 12/49) and of tubular cell adenomas (0/50; 7/50; 3/49); two low dose males had tubular cell adenocarcinomas. The incidences of mononuclear cell leukemia were increased in dosed male rats (7/50; 12/50; 14/50) and in low dose female rats (11/50; 22/50; 16/50). Pancreatic acinar cell tumors occurred at increased incidences in low dose male rats (11/50; 22/50; 17/50). Follicular cell adenomas or carcinomas (combined) of the thyroid gland were found at increased incidences in both female rats (0/50; 6/50; 6/50) and female mice (8/50; 12/49; 15/49). Chlorinated paraffins (C12, 60% chlorine) was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535 in the presence or absence of Aroclor 1254-induced male Sprague-Dawley or male Syrian hamster liver S9 when tested according to the preincubational protocol. An ed according to the preincubational protocol. An audit of the experimental data was conducted for these 2-year studies on chlorinated paraffins (C12, 60&percnt; chlorine). No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of chlorinated paraffins (C12, 60&percnt; chlorine) for F344/N rats based on increased incidences of hepatocellular neoplasms (primarily neoplastic nodules) in male and female rats, of adenomas or adenocarcinomas (combined) of the kidney tubular cells in male rats, and of follicular cell adenomas or carcinomas (combined) of the thyroid gland in female rats. Mononuclear cell leukemia in dosed male rats may have been related to administration of chlorinated paraffins (C12, 60&percnt; chlorine). There was clear evidence of carcinogenicity of chlorinated paraffins (C12, 60&percnt; chlorine) for B6C3F1 mice as shown by increased incidences of hepatocellular adenomas and of adenomas or carcinomas (combined) in dosed male and female mice and increased incidences of adenomas and of adenomas or carcinomas (combined) of thyroid gland follicular cells in dosed female mice.

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Ephedrine Sulfate (CAS No. 134-72-5) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Ephedrine sulfate is a sympathomimetic amine that affects both the central and peripheral nervous systems. An effective bronchiodilator and weak vasoconstrictor, ephedrine sulfate is used extensively in nonprescription pharmaceutical preparations such as nose drops, cold tablets, cough syrups, and, in particular, asthma relief medicines. Ephedrine sulfate was nominated for carcinogenesis studies by the National Cancer Institute because of its widespread and long-term use for the relief of symptoms associated with asthma. In 14-day repeated-exposure studies, F344/N rats of each sex received diets containing 0-1,500 ppm ephedrine sulfate or drinking water containing 0-1,200 ephedrine sulfate; B6C3F1 mice received diets or drinking water containing 0-5,000 ppm ephedrine sulfate. In the feed studies, the average feed consumption by dosed rats and mice was comparable to that of their respective controls. The average water consumption by rats and mice decreased with increasing concentration of ephedrine sulfate in the drinking water. Thus, subsequent studies used the feed route of administration. Doses for the 2-year studies were selected on the basis of results from 13-week studies in which F344/N rats of each sex were given diets containing 0, 125, 250, 500, 1,000, or 2,000 ppm ephedrine sulfate and B6C3F1 mice of each sex were given diets containing 0, 310, 630, 1,250, 2,500, or 5,000 ppm ephedrine sulfate. The major response that occurred during the 13-week studies was compound-associated reduction in weight gain. Toxicology and carcinogenesis studies of ephedrine sulfate were conducted by administering diets containing 0, 125, or 250 ppm ephedrine sulfate to groups of 50 F344/N rats and 50 B6C3F1 mice of each sex for 103 weeks. The estimated average amount of ephedrine sulfate consumed per day during the 2-year study was 4 mg/kg and 9 mg/kg for low dose and high dose male rats, 5 mg/kg and 11 mg/kg for female rats, 14 mg/kg and 29 mg/kg for male mice, and 12 mg/kg and 25 mg/kg for female mice. Survival of chemically exposed female rats during the 2-year study was greater than that of the controls (control, 27/50; low dose, 39/50; high dose, 39/50); survival of exposed male rats and male and female mice was comparable to that of controls. Throughout most of the 2-year studies, mean body weights of rats and mice of each sex receiving diets containing ephedrine sulfate were lower than those of controls. Neoplasms that occurred in these studies were not considered to be related to administration of ephedrine sulfate. Two high dose female mice had ovarian granulosa cell tumors, and luteomas were found in one low dose and one high dose female mouse. Because of the low incidence, these uncommon, benign tumors could not be clearly related to ephedrine sulfate administration. Ephedrine sulfate was not mutagenic in four strains of Salmonella typhimurium (TA100, TA1535, TA97, or TA98) with or without Aroclor 1254-induced male Sprague-Dawley rat or Syrian hamster liver S9 activation. Ephedrine sulfate did not induce sister-chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. An audit of the experimental data was conducted for these 2-year studies of ephedrine sulfate. No data discrepancies were found that influenced the final interpretations. Under the conditions of these studies, there was no evidence of carcinogenicity for F344/N rats or B6C3F1 mice of either sex receiving 125 or 250 ppm ephedrine sulfate in the diet for 2 years.

Journal Article↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Dichloromethane (Methylene Chloride) (CAS No. 75-09-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Dichloromethane is widely used in industrial processes, food preparation, and agriculture. In industry, dichloromethane is used as a solvent in paint removers, degreasing agents, aerosol propellants, and triacetate solutions; as a blowing agent in flexible urethane foams; and as a process solvent in the manufacture of steroids, antibiotics, vitamins, and tablet coatings. The use of dichloromethane as an extraction solvent for spice oleoresins, hops, and caffeine from coffee has been approved by the U.S. Food and Drug Administration. Dichloromethane has been used as an inhalation anesthetic and as a fumigant for grain and strawberries. Toxicology and carcinogenesis studies of dichloromethane (99% pure) were conducted by inhalation exposure of groups of 50 male and 50 female F344/N rats and B6C3F1 mice 6 hours per day, 5 days per week, for 102 weeks. The exposure concentrations used (0, 1,000, 2,000, or 4,000 ppm for rats and 0, 2,000, or 4,000 ppm for mice) were selected on the basis of results from 13-week inhalation studies in which groups of 10 rats and 10 mice of each sex were exposed to dichloromethane at concentrations of 525-8,400 ppm 6 hours per day, 5 days per week. During the 2-year studies in rats, body weight gains for exposed males and females were comparable to those of the chamber controls. The survival of exposed male rats was comparable to that of the chamber controls; however, the survival of all groups of males at the termination of the study was low (control, 16/50; low dose, 16/50; mid dose, 17/50; high dose, 9/50). Most of the early deaths among male rats occurred during the final weeks of the study; the survival of male rats through week 86 of the study was 36/50, 39/50, 37/50, and 33/50. This decreased survival is believed to be related to the high incidence of leukemia (34/50; 26/50; 32/50; 35/50). Survival of female rats exposed at 4,000 ppm was reduced relative to that of the chamber controls (30/50; 22/50; 22/50; 15/50); leukemia occurred frequently in all female rat groups. Final mean body weights of high dose male mice and low and high dose female mice were 10%-17% lower than those of the chamber controls; these reductions occurred during the last 16 weeks of the study. The survival of dosed male mice and high dose female mice was reduced relative to that of the chamber controls (male: control, 39/50; low dose, 24/50; high dose, 11/50; female: 25/50; 25/50; 8/50). This reduced survival may have been due to the chemically induced development of liver and lung neoplasia in male and female mice. Increased incidences of benign mammary gland lesions (adenomas and fibroadenomas) occurred in male and female rats exposed to dichloromethane (male: 0/50; 0/50; 2/50; 5/50; female: 5/50; 11/50; 13/50; 23/50). The incidence of malignant mammary gland neoplasms was not increased in female rats (2/50; 2/50; 2/50; 0/50); none was observed in male rats. In addition, integumentary system tumors in the area of the mammary chain occurred with a positive trend in male rats (subcutaneous tissue fibroma or sarcoma: 1/50; 1/50; 2/50; 5/50); the combined incidence of all tumors in the mammary area in male rats was 1/50, 1/50, 4/50, and 9/50. Exposure to dichloromethane was associated with increased incidences of hepatic hemosiderosis, cytomegaly, cytoplasmic vacuolization, necrosis, granulomatous inflammation, and bile duct fibrosis in both male and female rats. There was a positive but marginal trend in the incidence of hepatocellular neoplastic nodules or hepatocellular carcinomas (combined) in female rats (2/50; 1/50; 4/50; 5/50). The incidence of squamous metaplasia of the nasal cavity was increased in female rats exposed at 4,000 ppm (1/50; 2/50; 3/50; 9/50) but not in males (4/50; 5/50; 3/50; 3/50). No nasal cavity tumors were observed in rats. The increased incidences of mononuclear cell leukemia in mid dose and high dose female rats (17/50; 17/50; 23/50; 23/50) were statistically significant by age-adjusted analyses. In male rats, mesotheliomas (arising primarily from the tunica vaginalis) occurred at increas) occurred at increased incidences (0/50; 2/50; 5/50; 4/50). Lung tumors occurred at increased incidences in male and female mice exposed to dichloromethane (alveolar/bronchiolar adenomas: male - 3/50; 19/50; 24/50; female - 2/50; 23/48; 28/48; alveolar/bronchiolar carcinomas: male - 2/50; 10/50; 28/50; female - 1/50; 13/48; 29/48). Cytologic degeneration of the liver was observed at increased incidences in high dose male and dosed female mice (male: 0/50; 0/49; 22/49; female: 0/50; 23/48; 21/48). Incidences of hepatocellular adenomas or hepatocellular carcinomas (combined) were increased in high dose male and dosed female mice (male: 22/50; 24/49; 33/49; female: 3/50; 16/48; 40/48). There were also dose-related increases in the numbers of mice bearing multiple lung or liver neoplasms. Dose-related increases were observed in the incidences of testicular atrophy in male mice and uterine and ovarian atrophy in female mice; these effects are considered to be secondary responses to neoplasia. An audit of the experimental data was conducted for the 2-year studies of dichloromethane. No data discrepancies were found that influenced the final interpretations. Under the conditions of these inhalation studies, there was some evidence of carcinogenicity of dichloromethane for male F344/N rats as shown by an increased incidence of benign neoplasms of the mammary gland. There was clear evidence of carcinogenicity of dichloromethane for female F344/N rats as shown by increased incidences of benign neoplasms of the mammary gland. There was clear evidence of carcinogenicity of dichloromethane for male and female B6C3F1 mice, as shown by increased incidences of alveolar/bronchiolar neoplasms and of hepatocellular neoplasms. Synonyms: DCM; methylene chloride

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