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National Toxicology Program

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PubMed1999

NTP Toxicology and Carcinogenesis Studies of Oleic Acid Diethanolamine Condensate (CAS No. 93-83-4) in F344/N Rats and B6C3F1 Mice (Dermal Studies).

Oleic acid diethanolamine condensate is widely used as an emollient, thickener, and foam stabilizer present in cosmetic formulations of bath additives, shampoos, conditioners, lipsticks, and hair dyes. Male and female F344/N rats and B6C3F1 mice received dermal applications of diethanolamine in 95% ethanol for 13 weeks or 2 years. Genetic toxicology studies were performed in Salmonella typhimurium and L5178Y mouse lymphoma cells. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were admin istered 0, 25, 50, 100, 200, or 400 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 13 weeks. All male and female rats survived until the end of the study. The final mean body weights and body weight gains of 200 and 400 mg/kg males and the mean body weight gain of 400 mg/kg females were significantly less than those of the vehicle controls. The only chemical-related clinical finding was irritation of the skin at the site of application in most males administered 100 mg/kg or greater and in all females administered 50 mg/kg or greater. Segmented neutrophil counts were increased relative to the vehicle controls in the 400 mg/kg male group on days 5 and 19, in the 200 mg/kg female group on day 19 and at week 13, and in the 400 mg/kg female group on days 5 and 19 and at week 13. Alkaline phosphatase concentrations were significantly increased in the 200 mg/kg male group on day 19, the 200 mg/kg female group at week 13, and in the 400 mg/kg groups of males and females at week 13. Kidney weights of 200 and 400 mg/kg females were significantly greater than those of the vehicle controls. Lesions of the skin at the site of application included epidermal hyperplasia, parakeratosis, chronic active dermal inflammation, suppurative epidermal inflammation, and sebaceous gland hypertrophy in dosed rats. The severities of these lesions generally increased with increasing dose. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were admin istered 0, 50, 100, 200, 400, or 800 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 13 weeks. All male and female mice except one 800 mg/kg male survived until the end of the study. Final mean body weights and body weight gains of 800 mg/kg males and females and 400 mg/kg females were significantly less than those of the vehicle controls. Clinical findings in dosed mice included irritation of the skin at the site of application. Irritation occurred in all surviving dosed males and in most females administered 100 mg/kg or greater and progressed to ulcer in one 800 mg/kg male. The heart weights of 400 and 800 mg/kg males and females and 200 mg/kg females and the kidney weights of 50, 100, and 400 mg/kg males were significantly greater than those of the vehicle controls. Relative to the vehicle controls, the liver weights were increased in all dosed groups. Lesions of the skin at the site of application in dosed mice included epidermal hyperplasia, parakeratosis, suppurative epidermal inflammation, chronic active dermal inflammation, sebaceous gland hypertrophy, and ulcer. The severities of these lesions generally increased with increasing dose. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were administered 0, 50, or 100 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 2 years. Survival, Body Weights, and Clinical Findings: Survival of dosed male and female rats was similar to that of the vehicle control groups. Mean body weights of 100 mg/kg males were slightly less than those of the vehicle controls throughout most of the study. Mean body weights of 100 mg/kg females were less than those of the vehicle controls beginning at week 24. The only significant treatment-related clinical finding was mild to moderate irritation of the skin at the site of application in dosed males and females. Pathology Findings: The predominant effects of oleic acid diethanolamine condensate administration were minimal to moderate nonneoplastic lesions of the skin at the site of application in dosed rats. These lesioe lesions included epidermal hyperplasia, sebaceous gland hyperplasia, hyperkeratosis, parakeratosis, chronic active dermal inflammation, and ulcer. 2-YEAR STUDY IN MICE: Groups of 55 male and 55 female mice were administered 0, 15, or 30 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 2 years. Five animals from each group were evaluated at 3 months for gross lesions and skin histopathology. Survival, Body Weights, and Clinical Findings: Survival of dosed male and female mice was similar to that of the vehicle control groups. Mean body weights of dosed males and of 15 mg/kg females were similar to those of the vehicle controls throughout the study. Mean body weights of 30 mg/kg females were less than those of the vehicle controls from week 76 until the end of the study. The only significant treatment-related clinical finding was irritation of the skin at the site of application in 30 mg/kg males. Pathology Findings: The incidences of epidermal hyperplasia, sebaceous gland hyperplasia, and chronic active inflammation of the dermis in all dosed groups were significantly increased relative to the vehicle controls at 3 months and at 2 years. The increased incidences of hyperkeratosis in dosed males at 3 months and in dosed males and females at 2 years, of parakeratosis in 30 mg/kg males at 3 months and 2 years, and of ulcer in 30 mg/kg males and exudate in 30 mg/kg males and females at 2 years were also attributed to chem ical administration. GENETIC TOXICOLOGY: Oleic acid diethanolamine condensate was not mutagenic in S. typhimurium strain TA97, TA98, TA100, or TA1535, with or without S9 metabolic activation enzymes. In addition, it did not induce mutations in mouse L5178Y lymphoma cells treated with or without S9. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of oleic acid diethanolamine condensate in male or female F344/N rats administered 50 or 100 mg/kg or in male or female B6C3F1 mice administered 15 or 30 mg/kg. Dermal administration of oleic acid diethanolamine condensate to male and female rats was associated with epidermal hyperplasia, sebaceous gland hyper plasia, hyperkeratosis, parakeratosis, chronic active inflammation of the dermis, and ulceration of the skin at the site of application. Dermal administration of oleic acid diethanolamine condensate to mice was associated with epidermal hyperplasia, sebaceous gland hyperplasia, hyperkeratosis, chronic active inflammation of the dermis, and exudate of the skin at the site of application in males and females and parakeratosis and ulcer of the skin at the site of application in males. Synonyms: Diethanolamine oleate; diethanolammonium oleate; (Z)-9-octadecenoic acid, compound with 2,2.-imnobis(ethanol) (1:1); oleamide diethanolamine

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Lauric Acid Diethanolamine Condensate (CAS NO. 120-40-1) in F344/N Rats and B6C3F1 Mice (Dermal Studies).

Lauric acid diethanolamine condensate is widely used in cosmetics, shampoos, soaps, and related consumer products, to which there is extensive human exposure. Because of the lack of information about potential risks associated with long-term exposure, lauric acid diethanolamine condensate, coconut oil acid diethanolamine condensate, and oleic acid diethanolamine condensate were selected as representative of the class of diethanolamides for evaluation of prechronic toxicity and carcinogenic potential. Male and female F344/N rats and B6C3F1 mice were exposed to lauric acid diethanolamine condensate dermally for 14 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, L5178Y mouse lymphoma cells, cultured Chinese hamster ovary cells, and mouse peripheral blood erythrocytes. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were admin istered 0, 25, 50, 100, 200, or 400 mg lauric acid diethanolamine condensate/kg body weight in ethanol by dermal application for 14 weeks. All animals survived until study termination. Final mean body weights and body weight gains of males receiving 200 or 400 mg/kg were significantly less than those of the vehicle control group. Irritation of the skin at the site of application was observed in males receiving 100 mg/kg or greater and in females receiving 200 or 400 mg/kg. Kidney weights of females administered 200 or 400 mg/kg were significantly greater than those of the vehicle control group. There were dose-dependent increases in the incidences of nonneoplastic lesions of the skin at the site of application, including epidermal and sebaceous gland hyperplasia, chronic inflammation, parakeratosis, and ulcer. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were admin istered 0, 50, 100, 200, 400, or 800 mg lauric acid diethanolamine condensate/kg body weight in ethanol by dermal application for 14 weeks. All animals survived until the end of the study, and final mean body weights and body weight gains of dosed mice were generally similar to those of the vehicle control groups. Irritation of the skin at the site of application was observed in all males and females administered 400 or 800 mg/kg. The kidney weights of males receiving 100, 400, or 800 mg/kg and females receiving 800 mg/kg were significantly greater than those of the vehicle controls. Liver weights of females administered 200 mg/kg or greater were significantly greater than those of vehicle controls. Increased incidences of nonneoplastic lesions of the skin at the site of application, including epidermal and sebaceous gland hyperplasia, chronic inflammation, parakeratosis, and ulcer, were observed in males and females receiving 200 mg/kg or greater. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were admin istered 0, 50, or 100 mg lauric acid diethanolamine condensate/kg body weight in ethanol by dermal application for 104 or 105 weeks. Survival and Body Weights There were no significant differences between vehicle control and dosed males or females in survival or mean body weights. Pathology Findings There were no chemical-related differences in neoplasm incidences. Dose-related increases occurred in the incidences of nonneoplastic lesions of the skin at the site of application, including epidermal and sebaceous gland hyperplasia, hyperkeratosis, chronic inflammation, parakeratosis, and ulcer. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were admin istered 0, 100, or 200 mg lauric acid diethanolamine condensate/kg body weight in ethanol by dermal application for 105 or 106 weeks. Survival and Body Weights There were no significant differences in survival between vehicle control and dosed males or females. Mean body weights of females that received 200 mg/kg were less than those of the vehicle controls beginning at week 33. Pathology Findings The incidences of hepatocellular adenoma or carcinoma (combined) were significantly increased in dosed females compared to the vehicle controls, as was the incidence of hepatocellular adenoma in the 100 mg/kg female group. There were dose-related increases in the incidences of nonneoplastic lesions of the skin at the site of application, including epidermal and sebaceous gland hyperplasia, hyperkeratosis, chronic inflammation, and parakeratosis. Dosed males had greater incidences of thyroid gland follicular cell focal hyperplasia than did the vehicle controls. GENETIC TOXICOLOGY: Lauric acid diethanolamine condensate was not mutagenic in Salmonella typhimurium strain TA97, TA98, TA100, or TA1535, with or without S9 metabolic activation enzymes. No increase in the frequency of mutant colonies of L5178Y mouse lymphoma cells was noted after exposure to lauric acid diethanolamine condensate, with or without S9. In cytogenetic tests with cultured Chinese hamster ovary cells, lauric acid diethanolamine condensate was shown to induce sister chromatid exchanges, but not chromosomal aberrations, with and without S9. In vivo, no increase in the frequency of micro nucleated normochromatic erythrocytes was observed in peripheral blood samples from male and female mice treated dermally with lauric acid diethanolamine condensate for 14 weeks. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of lauric acid diethanolamine condensate in male or female F344/N rats administered 50 or 100 mg/kg or in male B6C3F1 mice administered 100 or 200 mg/kg. There was some evidence of carcinogenic activity in female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. These increases were associated with free diethanolamine, which was present as a contaminant of lauric acid diethanolamine condensate. Dermal administration of lauric acid diethanolamine condensate to rats and mice for 2 years resulted in increased incidences of epidermal and sebaceous gland hyperplasia, hyperkeratosis, chronic inflammation, and parakeratosis at the site of application. Lauric acid diethanolamine condensate administration also resulted in increased incidences of thyroid gland follicular cell hyperplasia in dosed male mice. Synonyms: N,N-bis(2-hydroxyethyl) dodecanamide; N,N-bis(hydroxyethyl) lauramide; N,N-bis(b-hydroxyethyl) lauramide; bis(2-hydroxyethyl) lauramide; coco diethanolamide; coconut oil amide of diethanolamine; diethanollauramide; N,N-diethanollauramide; N,N-diethanollauric acid amide; lauramide DEA; lauric diethanolamide; lauroyl diethanolamide; lauryl diethanolamide; LDA; LDE Trade names: Clindrol 200 L; Ninol AA62; Onyxol 345; Rewomid DLMS; Rewomid DL 203/S; Richamide 6310; Rolamid CD; Standamidd LD; Steinamid DL 203 S; Super amide L-9A; Super amide L-9C; Synotol L-60; Unamide J-56; Varamid ML 1.

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Diethanolamine (CAS No. 111-42-2) in F344/N Rats and B6C3F1 Mice (Dermal Studies).

Diethanolamine is widely used in the preparation of diethanolamides and diethanolamine salts of long-chain fatty acids that are formulated into soaps and surfactants used in liquid laundry and dishwashing detergents, cosmetics, shampoos, and hair conditioners. Diethanolamine is also used in textile processing, in industrial gas purification to remove acid gases, as an anticorrosion agent in metalworking fluids, and in preparations of agricultural chemicals. Aqueous diethanolamine solutions are used as solvents for numerous drugs that are administered intravenously. Diethanolamine was selected for evaluation because its large-scale production and pattern of use indicate the potential for widespread human exposure. Male and female F344/N rats and B6C3F1 mice received dermal applications of diethanolamine in 95% ethanol for 2 years. Genetic toxicology studies were performed in Salmonella typhimurium, L5178Y mouse lymphoma cells, cultured Chinese hamster ovary cells, and B6C3F1 mouse peripheral blood erythrocytes. RATS: Groups of 50 male rats were administered 0, 16, 32, or 64 mg diethanolamine/kg body weight in ethanol dermally for 2 years. Groups of 50 female rats were administered 0, 8, 16, or 32 mg/kg in ethanol dermally for 2 years. Survival, Body Weights, and Clinical Findings Survival of vehicle control and dosed male and female rats was similar. Mean body weights of 64 mg/kg males were less than those of the vehicle controls beginning week 8, and mean body weights of females were generally similar to those of the vehicle control group. The only clinical finding attributed to diethanolamine administration was irritation of the skin at the site of application. Pathology Findings: Minimal to mild nonneoplastic lesions occurred at the site of application in the epidermis of dosed male and female rats. The incidence of acanthosis in 64 mg/kg males, the incidences of hyperkeratosis in 32 and 64 mg/kg males and in all dosed female groups, and the incidences of exudate in 64 mg/kg males and in all dosed female groups were greater than those in the controls. The incidences and severities of nephropathy were significantly increased in dosed female rats compared to the vehicle controls. MICE: Groups of 50 male and 50 female mice were administered 0, 40, 80, or 160 mg diethanolamine/kg body weight in ethanol dermally for 2 years. Survival, Body Weights, and Clinical Findings Survival of dosed male groups was similar to that of the vehicle control group; survival of dosed female groups was significantly less than that of the vehicle control group. Mean body weights of 80 and 160 mg/kg males were less than those of the vehicle controls after weeks 88 and 77, respectively. Mean body weights of dosed groups of females were generally less than those of the vehicle controls during the second year of the study. Pathology Findings: In male mice, the incidences of hepatocellular adenoma and of hepatocellular adenoma or carcinoma (combined) in all dosed groups and of hepatocellular carcinoma and hepatoblastoma in 80 and 160 mg/kg males were significantly increased compared to the vehicle controls. The incidences of hepatocellular neoplasms were significantly greater in dosed groups of female mice than in the vehicle control group. The incidences of hepatocellular neoplasms in all dosed groups of males and females exceeded the historical control ranges. Nonneoplastic hepatocyte changes were seen only in dosed male and female mice. Changes consisted of cytoplasmic alteration and syncytial alteration. The incidences of renal tubule adenoma in males occurred with a positive trend; however, the incidences of carcinoma and hyperplasia did not follow this pattern. An extended evaluation of kidney step sections revealed additional adenomas and hyperplasias in all dosed groups. The combined analysis of single and step sections indicated a dose-related increase in the incidences of renal tubule hyperplasia and renal tubule adenoma or carcinoma (combined), and an increase in the incidences of renal tubule adenoma in male mice. Incidences of thyroidthyroid gland follicular cell hyperplasia were increased in dosed male and female mice compared to vehicle controls. Hyperkeratosis, acanthosis, and exudate were treatment-related changes in the skin at the site of application. The incidences of hyperkeratosis were significantly greater than those in the vehicle control groups in all dosed groups except 40 mg/kg females. GENETIC TOXICOLOGY: Diethanolamine was not mutagenic in any of four strains of Salmonella typhimurium, in the presence or absence of S9 metabolic activation enzymes. No induction of trifluorothymidine resistance was observed in L5178Y mouse lymphoma cells treated with diethanolamine with or without S9. Diethanolamine did not induce significant sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells, with or without S9. Peripheral blood samples collected from male and female mice exposed to 80 to 1,250 mg/kg diethanolamine dermally for 13 weeks showed no increase in micronucleated normochromatic erythrocytes. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of diethanolamine in male F344/N rats administered 16, 32, or 64 mg/kg diethanolamine or in female F344/N rats administered 8, 16, or 32 mg/kg. There was clear evidence of carcinogenic activity of diethanolamine in male and female B6C3F1 mice based on increased incidences of liver neoplasms in males and females and increased incidences of renal tubule neoplasms in males. Dermal administration of diethanolamine to rats was associated with increased incidences of acanthosis (males only), hyperkeratosis, and exudate of the skin and increased incidences and severities of nephropathy in females. Dermal administration of diethanolamine to mice was associated with increased incidences of cytoplasmic alteration (males only) and syncytial alteration of the liver, renal tubule hyperplasia (males only), thyroid gland follicular cell hyperplasia, and hyperkeratosis of the skin. Synonyms: Bis-2-hydroxyethylamine; DEA, diethylolamine; 2,2'-dihydroxydiethylamine; diolamine; 2,2'-iminobisethanol; 2,2'-iminodiethanol; iminodiethanol

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Isoprene (CAS No. 78-79-5) in F344/N Rats (Inhalation Studies).

Isoprene, the monomeric unit of natural rubber and naturally occurring terpenes and steroids, is primarily obtained as a by-product of naphtha cracking for ethylene production. It is emitted from plants and trees, has been detected in tobacco smoke and automobile exhaust, and was identified as a major endogenous hydrocarbon in human breath. Isoprene was selected for toxicologic evaluation because of its structural similarity to 1,3-butadiene, a potent, multi-organ, rodent carcinogen, and the potential for human exposure due to its large annual production volume. A previous 26-week inhalation study followed by a 26-week recovery period provided clear evidence of carcinogenic activity of isoprene in male B6C3F1 mice. A similar study in male F344/N rats was inconclusive. Male and female F344/N rats were exposed to isoprene (99% pure) by whole body inhalation for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, mouse bone marrow and peripheral blood cells, and rat lung fibroblasts. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 220, 700, or 7,000 ppm isoprene by inhalation, 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights: Survival rates and mean body weights of exposed male and female rats were similar to those of the chamber controls throughout the study. Urinary Vinyl Lactic Acid - Biomarker of Exposure: At 3, 6, 12, and 18 months, the concentrations of vinyl lactic acid normalized to creatinine in the urine increased with increasing exposure concentration in all exposed groups of male and female rats; however, these increases were not proportional to isoprene exposure concentrations, indicating nonlinear metabolism over this range of exposure concentrations. Pathology Findings: Exposure-related increases in the incidences of mam mary gland fibroadenoma were observed in male rats in all groups. The incidences of fibroadenoma in 7,000 ppm males and in all groups of exposed females were significantly greater than those in the chamber control groups. The incidences of fibroadenoma in all exposed groups of males and females and of multiple fibroadenoma in 7,000 ppm males and in all groups of exposed females exceeded the historical control ranges. In addition, the finding of mammary gland carcinoma in exposed male rats was noteworthy because this neoplasm rarely occurs in control male rats. The incidences of renal tubule adenoma in 700 and 7,000 ppm males and of renal tubule hyperplasia in 7,000 ppm males were significantly greater than those in the chamber controls. The severity of kidney nephropathy was slightly increased in 7,000 ppm males when compared to chamber controls. An exposure-related increase in the incidences of interstitial cell adenoma of the testis was observed in male rats. The incidences of bilateral interstitial cell adenoma and of unilateral and bilateral interstitial cell adenoma (combined) of the testis in 700 and 7,000 ppm males were significantly greater than those in the chamber controls. The incidences of interstitial cell adenoma in 700 and 7,000 ppm males exceeded the historical control range. Several rare neoplasms including benign astrocytoma, malignant glioma, malignant medulloblastoma be nign meningeal granular cell tumor, and meningeal sarcoma were observed in the brain of exposed female rats. These neoplasms have seldom or never occurred in historical chamber controls. The incidences of splenic fibrosis in 700 and 7,000 ppm males were significantly greater than that in the chamber control group. GENETIC TOXICOLOGY: Isoprene was not mutagenic in S. typhimurium and did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells with or without exogenous metabolic activation; however, in mice, isoprene induced increases in the frequency of sister chromatid exchanges in bone marrow cells and in the frequency of micronucleated erythrocytes in peripheral blood. The cell cycle duration of proliferating bone marrow cells of mice f mice exposed to 7,000 ppm isoprene was significantly lengthened. No increases in the frequency of chromosomal aberrations were observed in bone marrow cells of male mice after 12 days of exposure to isoprene, and lung fibroblasts of male and female rats exposed to isoprene for 4 weeks showed no increase in the frequency of micronuclei. CONCLUSIONS: Under the conditions of this 2-year inhalation study, there was clear evidence of carcinogenic activity of isoprene in male F344/N rats based on increased incidences of mammary gland fibroadenoma and carcinoma, renal tubule adenoma, and testicular interstitial cell adenoma. There was some evidence of carcinogenic activity of isoprene in female F344/N rats based on increased incidences and multiplicity of mammary gland fibroadenoma. A low incidence of rare brain neoplasms in exposed female rats may have been due to exposure to isoprene. Exposure to isoprene by inhalation for 2 years resulted in increased incidences of renal tubule hyperplasia and splenic fibrosis in male rats. Synonyms: Isopentadiene; b-methylbivinyl; 2-methyl-1,3-butadiene

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Isobutyraldehyde (CAS No. 78-84-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Isobutyraldehyde, a branched alkyl aldehyde, is used as a chemical intermediate and flavoring agent. It was nominated by the National Cancer Institute for toxicity and carcinogenicity studies by the NTP. Reasons for nomination and selection of isobutyraldehyde for study included its high potential for human exposure as suggested by its high production volume, its use as a chemical intermediate and food flavoring agent, suspicion of carcinogenicity due to an increased incidence of cancer at an aldehyde manufacturing plant where workers were exposed to a variety of aldehydes, its structural relationship to formaldehyde (a nasal carcinogen in rats), and the lack of toxicity and carcinogenicity studies on isobutyraldehyde in animals. Although human exposure occurs orally, dermally, or via inhalation, the inhalation route of exposure was selected for these animal studies because of the instability of isobutyraldehyde in water and feed. Male and female F344/N rats and B6C3F1 mice were exposed to isobutyraldehyde (approximately 99% pure) by inhalation for 13 weeks or 2 years. Genetic toxicology studies were conducted in vitro in Salmonella typhimurium, L5178Y mouse lymphoma cells, and cultured Chinese hamster ovary cells; in vivo tests were conducted in Drosophila melanogaster germ cells and bone marrow cells of rats and mice. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days a week, for 13 weeks. All rats exposed to 8,000 ppm died before the end of the study. Three male rats and six female rats in the 4,000 ppm groups and one female in the 500 ppm group died before the end of the study. The final mean body weight of male rats in the 4,000 ppm group and the body weight gains of 4,000 ppm males and females were significantly less than those of the chamber controls. Clinical findings in rats exposed to 4,000 or 8,000 ppm included abnormal respiratory sounds, decreased activity, nasal discharge, prostration, and slowed respiration. A minimal mature neutrophilia, evidenced by increased segmented neutrophil numbers, occurred in exposed groups of male and female rats. Exposure to isobutyraldehyde resulted in minimal increases in alanine aminotransferase activity in all groups of male and female rats. Spermatozoal motility in 500 and 1,000 ppm males was significantly reduced and females exposed to 4,000 ppm differed significantly from the chamber control females in the relative time spent in the estrous stages. No gross lesions were observed at necropsy that could be associated with isobutyraldehyde exposure. In the 8,000 ppm groups, severe necrosis of the epithelium, and occasionally of the entire mucosa, of the nasal turbinates accompanied by an acute inflammatory reaction was observed. Increased incidences of squamous metaplasia and mild acute inflammation occurred in male and female rats exposed to 4,000 ppm. Minimal to mild degeneration of the olfactory epithelium was observed in all male rats in the 2,000 and 4,000 ppm groups. Male rats exposed to 4,000 or 8,000 ppm and females exposed to 4,000 ppm had mild osteodystrophy of the turbinate bone. The incidences of necrosis/degeneration of the larynx and trachea were increased in male rats in the 8,000 ppm group. The incidences of mild to moderate lymphoid depletion of the spleen and thymus and lymphoid necrosis of the thymus were significantly increased in male and female rats exposed to 8,000 ppm. 13-WEEK STUDY IN MICE: Ten male and 10 female B6C3F1 mice were exposed to 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 13 weeks. One male in the chamber control group, one male in the 1,000 ppm group, nine males and all females in the 4,000 ppm groups, and all males and females in the 8,000 ppm groups died before the end of the study. The final mean body weight and body weight gain of female mice in the 1,000 ppm group were significantly less than those of the chamber controls. Clinical findal findings included decreased activity, tremors, prostration, and slower and labored respiration. The absolute and relative kidney weights of males in the 1,000 and 2,000 ppm groups were significantly increased. There were no gross lesions observed at necropsy that could be associated with isobutyraldehyde exposure. Histopathologically, the nasal cavity and lymphopoietic tissues were considered target organs, with changes similar, but not identical, to those observed in rats. Increased incidences of nonneoplastic lesions of the nasal cavity were observed in male and female mice exposed to 1,000 ppm or greater. These lesions included necrosis, inflammation, hyperplasia, and squamous metaplasia of the epithelium; serous and suppurative exudate within the nasal passages; olfactory epithelial degeneration; and osteodystrophy of the turbinate bone. Mild to moderate lymphoid depletion and/or lymphoid necrosis were observed in the thymus of male and female mice exposed to 8,000 ppm. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 500, 1,000, or 2,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 105 weeks Survival, Body Weights, and Clinical Findings No differences in survival rates between exposed and chamber control rats were found. The mean body weights of male and female rats were generally similar to those of the chamber controls throughout the study. Pathology Findings No increase in neoplasm incidences that could be attributed to exposure to isobutyraldehyde was observed in male or female rats. Nonneoplastic lesions related to isobutyraldehyde exposure were limited to the nose and consisted of squamous metaplasia of the respiratory epithelium, degeneration of the olfactory epithelium, and suppurative inflammation. Incidences of minimal to mild squamous metaplasia in 1,000 and 2,000 ppm males and females and in 500 ppm females were significantly greater than those in the chamber controls. Another lesion associated with isobutyraldehyde exposure was minimal to mild degeneration of the olfactory epithelium in 2,000 ppm males and females. The incidences of suppurative inflammation (rhinitis) in male and female rats exposed to 2,000 ppm were increased compared to the chamber controls. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were exposed to 0, 500, 1,000, or 2,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 105 weeks. Survival, Body Weights, and Clinical Findings There was an exposure-related decrease in survival of male mice, and the survival of males exposed to 2,000 ppm was marginally lower than that of the chamber controls. The mean body weights of female mice exposed to 1,000 or 2,000 ppm were lower than those of the chamber controls during the second year of the study. Pathology Findings No neoplasms that could be attributed to iso butyraldehyde exposure were observed in mice. Non neoplastic lesions related to isobutyraldehyde exposure were limited to the nose. The incidences of olfactory epithelial degeneration in 1,000 and 2,000 ppm males and females were significantly greater than in the chamber controls. GENETIC TOXICOLOGY: Isobutyraldehyde is mutagenic in vitro and in vivo, with the strongest responses observed in mammalian cell assays that measured chromosomal damage. Results of an initial mutagenicity test in S. typhimurium were negative; a second test, con ducted with different strains and varying concentrations of induced S9 activation enzymes, gave equivocal results. Strongly positive responses were obtained in the mouse lymphoma assay for mutation induction in L5178Y cells without S9 and in cytogenetic tests for induction of sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells. Sister chromatid exchanges were significantly increased with and without S9, but induction of chromosomal aberrations was noted unequivocally only in the absence of S9. No induction of sex-linked recessive lethal mutations was observed in germ cells of male D. melanogaster administered isobutyraldehyde by feeding or by injection. In vivo, isobutyraldehyde was demonstrated to induce chromosomal aberrations in bone marrow cells of male mice, but no increases in micronuclei were observed in bone marrow cells of mice or rats after administration of isobutyraldehyde. All these in vivo cytogenetic studies used doses that reached lethality CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of isobutyraldehyde in male or female F344/N rats or male or female B6C3F1 mice exposed to 500, 1,000, or 2,000 ppm isobutyraldehyde. In male and female rats, exposure to isobutyraldehyde induced squamous metaplasia and suppurative inflammation of the nasal respiratory epithelium and degeneration of the nasal olfactory epithelium. In male and female mice, exposure to isobutyraldehyde caused degeneration of the nasal olfactory epithelium. Synonyms: Dimethylacetaldehyde; 2-formylpropane; isobutanal; isobutylcarboxaldehyde; isobutyral; isobutyric aldehyde; isobutyrylaldehyde; isopropylformaldehyde; 2-methylpropanal; 2-methyl-1-propanal; a-methylpropionaldehyde; 2-methylpropionaldehyde; valine aldehyde

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of AZT (CAS No. 30516-87-1) and AZT/alpha-Interferon A/D B6C3F1 Mice (Gavage Studies).

3'-Azido-3'-deoxythymidine (AZT) is the most widely used and evaluated chemotherapeutic agent for the treatment of persons with acquired immune deficiency syndrome (AIDS) and persons seropositive for human immunodeficiency virus (HIV). The National Cancer Institute nominated AZT for toxicity and carcinogenicity studies because of the impending large-scale use of AZT in the treatment of adult patients with AIDS or AIDS-related complex. alpha-Interferon A/D, which displays antiviral activity in mice, is a hybrid molecule composed of the N-terminal portion of human alpha-interferon A and the C-terminal portion of human alpha-interferon D. AZT and alpha-interferon A/D combination studies were conducted because in vitro studies of AZT and alpha-interferon have demonstrated that the combination is more effective in blocking HIV infection than either agent alone. Male and female B6C3F1 mice received AZT (approximately 98% pure) in 0.5% aqueous methylcellulose by gavage for 14 weeks or 2 years. In addition, male and female B6C3F1 mice received alpha-interferon A or alpha-interferon A/D by subcutaneous injection for 2 years, and male and female B6C3F1 mice received AZT in 0.5%% aqueous methylcellulose by gavage in combination with alpha-interferon A/D by subcutaneous injection for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, mouse bone marrow erythrocytes, and mouse peripheral blood erythrocytes. 14-WEEK AZT STUDY: Groups of 10 male and 10 female mice received AZT in 0.5% methylcellulose by gavage at doses of 0, 50, 100, 200, 800, or 2,000 mg/kg daily for 14 weeks. Additional groups of 10 male and 10 female mice received AZT in 0.5% methylcellulose by gavage at doses of 0, 100, 800, or 2,000 mg/kg daily for 14 weeks and then were held without treatment for an additional 4 weeks before necropsy. One female receiving 100 mg/kg and two females receiving 200 mg/kg died during week 1 as a result of gavage trauma; one female receiving 2,000 mg/kg also died prior to the end of the 14-week dosing period. One female receiving 2,000 mg/kg in the recovery study also died from gavage trauma during week 1. The final mean body weights of dosed mice were similar to those of the vehicle control groups at the end of the dosing period and at the end of the recovery period. Female mice receiving 200, 800, or 2,000 mg/kg gained less weight than the vehicle controls during the 14-week dosing period. Exposure to AZT was toxic to the bone marrow, resulting in significant changes in the peripheral blood (decreased hematocrit values, erythrocyte counts, and hemoglobin concentrations, and increased mean cell volume and mean cell hemoglobin) and bone marrow (erythroid hypoplasia) characteristic of a dose- and time-dependent, minimal to moderate, poorly regenerative macrocytic anemia. At the end of the 4-week recovery period, the hematology parameters had returned to normal, indicating that the hematotoxicity was reversible. 2-YEAR STUDIES: AZT Groups of 95 male and 95 female mice received AZT in 0.5% methylcellulose by gavage at daily doses of 0, 30, 60, or 120 mg/kg body weight, administered as two equal doses at least 6 hours apart, 5 days per week for 105 weeks. Each group of 95 animals was composed of a core group of 50 animals for evaluation of carcinogenic response, a group of 30 animals for evaluation of hematology and bone marrow cellularity, and a group of 15 animals from which blood was drawn for determination of plasma AZT concentrations at week 54. alpha-Interferon A/D and AZT/alpha-Interferon A/D Studies Groups of 80 male and 80 female mice received AZT in 0.5% aqueous methylcellulose by gavage at daily doses of 0, 30, 60, or 120 mg/kg body weight, given in two equal doses, 5 days per week for 105 weeks. Those groups receiving AZT also received sub-cutaneous injections of 500 or 5,000 U alpha-interferon A/D three times per week for 105 weeks. Additional groups of 80 male and 80 female mice received subcutaneous injections of the vehicle, 500 U alpha-interferon A/D, 5,000 Uutaneous injections of the vehicle, 500 U α-interferon A/D, 5,000 U α-interferon A/D, or 5,000 U α-interferon A, three times per week for 105 weeks. Each group of 80 animals was composed of a core group of 50 animals for evaluation of carcinogenic response and a group of 30 animals for evaluation of hematology and bone marrow cellularity. Because of the large number of animals involved, the 2-year studies were started in four phases and, for clarity, are presented as follows: the AZT study, the α-interferon A/D study, the AZT/500 U α-interferon A/D study, and the AZT/5,000 U α-interferon A/D study. Design of the 2-year AZT, AZT/α-Interferon A/D, and α-Interferon A/D Studies AZT Dose AZT Study AZT/500 U α-Interferon A/D Study AZT/5,000 U α-Interferon A/D Study 500 or 5,000 U α-Interferon A/D or 5,000 U α-Interferon A Study Vehicle Control 95 male and 95 female micea 80 male and 80 female miceb 80 male and 80 female miceb 80 male and 80 female miceb 30 mg/kg AZT 95 male and 95 female mice 80 male and 80 female mice 80 male and 80 female mice none 60 mg/kg AZT 95 male and 95 female mice 80 male and 80 female mice 80 male and 80 female mice none 120 mg/kg AZT 95 male and 95 female mice 80 male and 80 female mice 80 male and 80 female mice none aFor the AZT study, there were 95 male and 95 female mice; these were divided into 50 males and 50 females in the core groups, 30 males and 30 females in the clinical pathology groups (hematology and bone marrow analyses only), and 15 males and 15 females for plasma AZT concentration determinations. bFor the α-interferon A/D study and the AZT/α-interferon A/D studies, there were 80 male and 80 female mice for each study; these were divided into 50 males and 50 females in the core groups and 30 males and 30 females in the clinical pathology groups (hematology and bone marrow analyses only). Survival and Body Weights Survival and mean body weights of mice exposed to AZT, α-interferon A, α-interferon A/D, or AZT plus α-interferon A/D were generally similar to those of the vehicle control groups. Hematology and Bone Marrow Analyses All groups of male and female mice receiving AZT exhibited changes in peripheral blood and bone marrow characteristic of a dose- and time-dependent, minimal to mild, macrocytic, nonresponsive anemia. In females, these changes were evident throughout the study. In males, the macrocytic anemia had resolved by week 80 in the 30 mg/kg group; at study termination erythrocyte macrocytosis was present only in males receiving 60 or 120 mg/kg AZT or AZT plus α-interferon A/D. There were no treatment-related alterations in hematology or bone marrow parameters in groups that received only α-interferon A or A/D. Pathology Findings Incidences of squamous cell carcinoma and squamous cell papilloma or carcinoma (combined) of the vagina occurred with a positive trend and were significantly increased in groups of female mice receiving 60 or 120 mg/kg AZT alone or in combination with α-interferon A/D. Epithelial hyperplasia was observed in all dosed groups of females, and the incidence was significantly increased in the 120 mg/kg AZT group. Three renal tubule adenomas and one renal tubule carcinoma were observed in male mice receiving 120 mg/kg AZT; the combined incidence in this group exceeded the range in historical controls. A renal tubule adenoma was observed in one male receiving 60 mg AZT/kg and 500 U α-interferon A/D; how ever, none were observed in other groups. Evaluation of step sections revealed a few more renal tubule hyperplasias but no additional neoplasms. The incidence of harderian gland adenoma was increased in male mice receiving 120 mg/kg AZT and exceeded the range in historical controls. Harderian gland neoplasms were observed in other groups but did not follow a treatment-related pattern. Overall Incidences of Vaginal Neoplasms and Hyperplasia of the Vaginal Epithelium in Female Mice in the 2-Year Gavage Studies of AZT and AZT/α-Interferon A/Da Vehicle Control 30 mg AZT/kg 60 mg AZT/kg 120 mg AZT/kg AZT alone 2/197 (1%)b 1/197 0/49 (0%) 3/49 5/45 (11%%) 4/45 11/49 (22%%) 11/49 500 U α-Interferon A/D 0/49 (0%%) 0/49 0/44 (0%) 4/44 5/48 (10%) 8/48 6/48 (13%) 12/48 5,000 U α-Interferon A/D 1/50 (2%) 1/50 1/48 (2%) 4/48 5/48 (10%) 8/48 4/50 (8%) 15/50 aData are presented as number of vaginal neoplasms/number of animals microscopically examined (first line) and number of vaginal hyperplasias/number of animals microscopically examined (second line) bCombined incidences of controls from the AZT alone study and the AZT/α-interferon A/D studies; incidences in the vehicle control group from the AZT alone study are 0/50 (0%%) (neoplasms) and 0/50 (hyperplasia) Overall Incidence of Harderian Gland Neoplasms in Male Mice in the 2-Year Gavage Studies of AZT and AZT/α-Interferon A/Da Vehicle Control 30 mg AZT/kg 60 mg AZT/kg 120 mg AZT/kg AZT alone 13/200 (6%%)b 5/50 (10%%) 2/50 (4%) 10/50 (20%%) 500 U α-Interferon A/D 3/50 (6%) 3/50 (6%) 1/50 (2%%) 4/50 (8%%) 5,000 U α-Interferon A/D 3/50 (6%) 9/50 (18%%) 4/50 (8%%) 4/50 (8%) aData are presented as number of harderian gland neoplasms/number of animals necropsied bCombined incidences of controls from the AZT alone study and the AZT/α-interferon A/D studies; incidence in the vehicle control group from the AZT alone study is 3/50 (6%) Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms within the liver consistent with an infection with Helicobacter hepaticus. An organism compatible with H. hepaticus was confirmed by polymerase chain reaction-restriction fragment length polymorphism-based assays. Detection of dose-related differences in neoplasm incidences in these studies was not considered to have been significantly impacted by the infection with H. hepaticus or its associated hepatitis. GENETIC TOXICOLOGY: AZT is mutagenic in vitro and in vivo. It induced gene mutations in Salmonella typhimurium strain TA102, with and without S9; no increases in mutations were noted in the other tested strains of S. typhimurium. AZT induced sister chromatid exchanges, but not chromosomal aberrations, in cultured Chinese hamster ovary cells, with and without S9. In vivo studies with male mice administered AZT by gavage showed highly significant increases in micronucleated erythrocytes in bone marrow and peripheral blood after exposure periods that ranged from 72 hours to 14 weeks. CONCLUSIONS: Under the conditions of these 2-year gavage studies there was equivocal evidence of carcinogenic activity of AZT in male mice based on increased incidences of renal tubule and harderian gland neoplasms in groups receiving AZT alone. There was clear evidence of carcinogenic activity of AZT in female mice based on increased incidences of squamous cell neoplasms of the vagina in groups that received AZT alone or in combination with α-interferon A/D. Hematotoxicity occurred in all groups that received AZT. Treatment with AZT alone and AZT in combination with α-interferon A/D resulted in increased incidences of epithelial hyperplasia of the vagina in all dosed groups of females. Synonyms: AZT; 3'-azido-2',3'-dideoxythymidine; azidodeoxythymidine; azidothymidine; 3'-azidothymidine; 3'-deoxy-3'-azidothymidine; 3'-deoxy-(8CI) (9CI); BW A509U; Compound S; ZDV; zidovudine Trade name: Retrovir®

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Ethylbenzene (CAS No. 100-41-4) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Ethylbenzene is mainly used in the manufacture of styrene. Ethylbenzene is also a major component of mixed xylenes used as solvents in agricultural and home insecticide sprays, rubber and chemical manufacturing, and household degreasers, paints, adhesives, and rust preventives. Ethylbenzene is also used as an antiknock agent in aviation and motor fuels. Ethylbenzene was nominated for study by the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) because of its potential for widespread human exposure and because of its structural similarity to benzene and toluene. Male and female F344/N rats and B6C3F1 mice were exposed to ethylbenzene (greater than 99% pure) by inhalation for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, mouse lymphoma cells, cultured Chinese hamster ovary cells, and mouse peripheral blood erythrocytes. In previously reported 13-week toxicity studies in which F344/N rats and B6C3F1 mice were exposed to ethylbenzene by whole body inhalation exposure, no histopathologic changes were observed (NTP, 1992). 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 75, 250, or 750 ppm ethylbenzene by inhalation, 6 hours per day, 5 days per week, for 104 weeks. Survival, Body Weights, and Clinical Findings Survival of male rats in the 750 ppm group was significantly less than that of the chamber controls. Mean body weights of 250 and 750 ppm males were generally less than those of the chamber controls beginning at week 20. Mean body weights of exposed groups of females were generally less than those of chamber controls during the second year of the study. Pathology Findings In male rats exposed to 750 ppm, the incidences of renal tubule adenoma and adenoma or carcinoma (combined) were significantly greater than the chamber control incidences. In addition, the incidence of renal tubule hyperplasia in 750 ppm males was significantly greater than that in the chamber controls. The findings from an extended evaluation (step section) of the kidneys showed a significant increase in the incidences of renal tubule adenoma and hyperplasia in 750 ppm males and females; the incidence of renal tubule adenoma or carcinoma (combined) was significantly increased in 750 ppm males. The severities of nephropathy in 750 ppm male and all exposed female rats were significantly increased relative to the chamber controls. The incidence of interstitial cell adenoma in the testis of 750 ppm males was significantly greater than that in the chamber control group and slightly exceeded the historical control range for inhalation studies. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were exposed to 0, 75, 250, or 750 ppm ethylbenzene by inhalation, 6 hours per day, 5 days per week, for 103 weeks. Survival, Body Weights, and Clinical Findings Survival of exposed groups of male and female mice was similar to that of the chamber controls. Mean body weights of female mice exposed to 75 ppm were greater than those of the chamber controls from week 72 until the end of the study. Pathology Findings In 750 ppm males, the incidences of alveolar/ bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) were significantly greater than those in the chamber control group but were within the NTP historical control ranges. The incidence of alveolar epithelial metaplasia in 750 ppm males was significantly greater than that in the chamber controls. In 750 ppm females, the incidences of hepatocellular adenoma and hepatocellular adenoma or carcinoma (combined) were significantly greater than those in the chamber control group but were within the historical control ranges. The incidence of eosinophilic foci in 750 ppm females was significantly increased compared to that in the chamber controls. There was a spectrum of nonneoplastic liver changes related to ethylbenzene exposure in male mice, including syncytial alteration of hepatocytes, hepatocellular hypertrophy, and hepatocyte necrosis. rosis. The incidences of hyperplasia of the pituitary gland pars distalis in 250 and 750 ppm females and the incidences of thyroid gland follicular cell hyperplasia in 750 ppm males and females were significantly increased compared to those in the chamber control groups. GENETIC TOXICOLOGY: Ethylbenzene gave little indication of mutagenicity, in vitro or in vivo. No induction of mutations was noted in Salmonella typhimurium strain TA97, TA98, TA100, or TA1535 with or without S9 metabolic activation, and no increases in sister chromatid exchanges or chromosomal aberrations were observed in cultured Chinese hamster ovary cells treated with ethylbenzene, with or without S9. In the mouse lymphoma assay, a significant mutagenic response was noted in the absence of S9, but only at the highest nonlethal dose tested and with accompanying cytotoxicity; the test was not performed with S9. No increases in the frequency of micronucleated erythrocytes were observed in vivo in peripheral blood samples from male and female mice exposed to ethylbenzene for 13 weeks. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of ethylbenzene in male F344/N rats based on increased incidences of renal tubule neoplasms. The incidences of testicular adenoma were also increased. There was some evidence of carcinogenic activity of ethylbenzene in female F344/N rats based on increased incidences of renal tubule adenomas. There was some evidence of carcinogenic activity of ethylbenzene in male B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms. There was some evidence of carcinogenic activity of ethylbenzene in female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. Exposure of male and female rats to ethylbenzene resulted in increased incidences of renal tubule hyperplasia and increased severities of nephropathy. Exposure of male mice to ethylbenzene resulted in increased incidences of alveolar epithelial metaplasia, syncytial alteration of hepatocytes, hepatocellular hypertrophy, hepatocyte necrosis, and thyroid gland follicular cell hyperplasia. In female mice, ethylbenzene exposure resulted in increased incidences of eosinophilic foci of the liver, pituitary gland pars distalis hyperplasia, and thyroid gland follicular cell hyperplasia. Synonyms: EB; ethylbenzol; phenylethane

Journal Article↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Triethanolamine (CAS No. 102-71-6) in F344 Rats and B6C3F1 Mice (Dermal Studies).

Triethanolamine is widely used as an ingredient in emulsifiers, thickeners, wetting agents, detergents, and alkalinizing agents in cosmetic products; as a chemical intermediate for anionic and nonionic surfactants and surface active agents in household cleaning agents, textiles, herbicides, pharmaceutical ointments, and other products; as a vulcanization accelerator in the manufacture of rubber; and in many other industrial applications. The National Cancer Institute nominated triethanolamine for study because of its widespread use in cosmetics and other consumer products, its high potential for worker exposure due to its many industrial uses, and its potential for conversion to the carcinogen N -nitrosodiethanolamine. Dermal application was chosen as the route of exposure to mimic the principal means of human exposure to triethanolamine and because considerable systemic exposure is achieved with this route. Male and female F344/N rats and B6C3F1 mice received triethanol amine (purity 98% or greater) by dermal application for 13 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melano gaster, and mouse peripheral blood erythrocytes. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were topically administered 0, 125, 250, 500, or 1,000 mg triethanolamine per kilogram body weight in acetone or 2,000 mg/kg neat triethanolamine, 5 days per week, for 13 weeks. All rats survived to the end of the study. Final mean body weights and weight gains of males and females administered 2,000 mg/kg and the mean body weight gain of females administered 1,000 mg/kg were significantly less than those of the vehicle controls. Clinical observations included irritation, scaliness, and crustiness of the skin at the site of application for males and females. Males also had discoloration, and two males administered 2,000 mg/kg had ulceration at the site of application. Changes in clinical pathology parameters were minor and consistent with inflammation at the site of application. Kidney weights were generally greater in males and females administered 500, 1,000, or 2,000 mg/kg than in the vehicle controls. Microscopic lesions attributed to triethanolamine administration included acanthosis and inflammation at the site of application, nephropathy in females, and hypertrophy of the pituitary gland pars intermedia in males and females. These lesions generally occurred with dose-related increases in incidence and severity in males and females. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were topically administered 0, 250, 500, 1,000, or 2,000 mg triethanolamine per kilogram body weight in acetone or 4,000 mg/kg neat triethanolamine, 5 days per week, for 13 weeks. All mice survived to the end of the study. The final mean body weight and weight gain of males in the 250 mg/kg group were less than those of the vehicle controls. Clinical findings were observed only in mice in the 4,000 mg/kg groups and included scaliness, irritation, and discoloration at the site of triethanolamine application for males and females and skin erosion at this site in one male. The absolute kidney and liver weights of males and females administered 4,000 mg/kg were greater than those of the vehicle controls; relative kidney weights of males administered 1,000 mg/kg or greater and females in all dosed groups were also greater than those of the vehicle controls. Microscopic examination of the skin of dosed mice indicated acanthosis and inflammation at the site of application. Acanthosis occurred in all dosed groups and in one vehicle control female; the severity increased with increasing dose in males and females. Inflammation was observed in males and females in the 4,000 mg/kg groups and in one female in the 2,000 mg/kg group. 2-YEAR STUDY IN RATS: Based on the presence of acanthosis and inflammation at the site of application at the higher doses in the 13-week study, triethanolamine doses selected for the 2-year study in rats were 32, 63, and 125 mg/kg for malesr males and 63, 125, and 250 mg/kg for females. Groups of 60 male and 60 female rats were topically administered triethanolamine in acetone 5 days per week for 103 weeks. Ten male and ten female rats from each group were evaluated at 15 months for organ weights and histopathology. Survival, Body Weights, Clinical Findings, and Organ Weights: The survival rate of females in the 250 mg/kg group was slightly less than that of the vehicle controls. The mean body weight of females administered 250 mg/kg ranged from 9% to 12% less than that of the vehicle controls between weeks 73 and 93. Male and female rats receiving triethanolamine had irritated skin at the site of application; in dosed females, the site of application also had a crusty appearance. The number of animals in which these findings were observed increased with increasing dose. At the 15-month interim evaluation, the absolute left and right kidney weights and relative right kidney weight of females administered 250 mg/kg were significantly greater than those of the vehicle controls. Pathology Findings: The incidence of acanthosis at the site of application in males administered 125 mg/kg and the incidences of acanthosis, inflammation, and ulceration in dosed females were greater than in the vehicle controls at the 15-month interim evaluation and at the end of the 2-year study. Males in the 125 mg/kg group also had greater incidences of inflammation and ulceration than the vehicle controls, and females receiving 125 or 250 mg/kg had greater incidences of epidermal erosion than the vehicle controls at 2 years. There were no skin neoplasms at or away from the site of application that were considered related to treatment with triethanolamine. At the end of the study, renal tubule adenomas were observed in seven dosed males and in one vehicle control female and one female in the 63 mg/kg group. One male in the 125 mg/kg group and one female in the 250 mg/kg group had renal tubule hyperplasia. Extended (step-section) evaluation of the kidneys of all male rats revealed additional renal tubule adenomas in one vehicle control male, one male in the 32 mg/kg group, two males in the 63 mg/kg group, and three males in the 125 mg/kg group (including one male from the 15-month interim evaluation). An oncocytoma was also identified in one male in the 32 mg/kg group. Hyperplasia was identified in eight additional vehicle control males and in 19 additional dosed males. The total incidences (combined standard and extended evaluations) of renal tubule adenoma in dosed male rats were slightly greater than the vehicle control incidence (vehicle control, 1/50; 32 mg/kg, 2/50; 63 mg/kg, 6/49; 125 mg/kg, 4/50). The total incidence of hyperplasia in dosed and vehicle control males was similar (9/50, 8/50, 7/49, 6/50). The severity of hyperplasia in males in the 32 and 125 mg/kg groups was greater than that in the vehicle controls. 2-YEAR STUDY IN MICE: Based on dose-related inflammation at the site of application in the 13-week study, triethanolamine doses selected for the 2-year study in mice were 200, 630, and 2,000 mg/kg for males and 100, 300, and 1,000 mg/kg for females. Groups of 60 male and 60 female mice were topically administered triethanolamine in acetone 5 days per week for 103 weeks. Ten male and ten female mice from each group were evaluated at 15 months for organ weights and histopathology. Survival, Body Weights, Clinical Findings, and Organ Weights: Survival rates of all dosed groups of males and females were similar to those of the vehicle controls. The mean body weight of males administered 2,000 mg/kg ranged from 8% to 10% less than that of the vehicle controls from week 69 through the end of the study. Clinical findings included irritation and discoloration of the skin at the site of application for most males in the 2,000 mg/kg group and a few females in the 1,000 mg/kg group; males administered 200 or 630 mg/kg also had skin irritation. At the 15-month interim evaluation, the right kidney weights of male mice that received 630 or 2,000 mg/kg and the left kidney weights of males that received 2,000 mg/kg were significantly greater than those of the vehicle controls. Pathology Findings: Acanthosis and inflammation of the skin were observed at the site of application in male and female mice at the 15-month interim evaluation and at the end of the 2-year study. In males in the 2,000 mg/kg group, the incidences of both lesions were significantly greater than those in the vehicle controls at both time points; however, the severities of acanthosis and inflammation did not increase with dose. At the end of the study, the incidence of inflammation in females in the 1,000 mg/kg group was significantly greater than that in the vehicle controls. One vehicle control male and two males in each of the 630 and 2,000 mg/kg groups had ulcers at the site of application. At the 15-month interim evaluation, hepatocellular carcinomas were observed in dosed and vehicle control males and hepatocellular adenomas in dosed and vehicle control males and females; however, the incidences were not dose related. Nonneoplastic lesions observed at 15 months included foci of cellular alteration in a few dosed males and females; eosinophilic foci were also observed in two vehicle control females. At the end of the 2-year study, females in the 1,000 mg/kg group had significantly greater incidences of hepatocellular adenoma and multiple adenomas and a greater combined incidence of hepatocellular adenoma and carcinoma than the vehicle controls (adenoma: vehicle control, 22/50; 100 mg/kg, 22/50; 300 mg/kg, 24/50; 1,000 mg/kg, 40/50; multiple adenomas: 11/50, 9/50, 13/50, 29/50; combined adenoma and carcinoma: 23/50, 26/50, 28/50, 41/50). Females in the 300 mg/kg group had significantly greater incidences of hepatocellular carcinoma (1/50, 4/50, 7/50, 5/50) and eosinophilic foci (9/50, 10/50, 18/50, 16/50) than the vehicle controls. Incidences of hepatocellular adenoma and multiple adenomas in males in the 2,000 mg/kg group were significantly greater than those in the vehicle controls (adenoma: vehicle control, 27/50; 200 mg/kg, 27/50; 630 mg/kg, 29/50; 2,000 mg/kg, 37/50; multiple adenomas: 17/50, 18/50, 17/50, 29/50). Three males in the 2,000 mg/kg group had hepatoblastomas, and males in this group also had significantly greater incidences of hepatocellular neoplasms (combined) (adenoma, carcinoma, and hepatoblastoma: 31/50, 34/50, 33/50, 42/50) and eosinophilic foci (10/50, 17/50, 11/50, 23/50) than the vehicle controls. Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms within the liver which suggested an infection with Helicobacter hepaticus. With polymerase chain reaction-based assays and culture, the presence of an organism compatible with H. hepaticus was confirmed. An increased incidence of hepatocellular neoplasms in male mice has been shown to be associated with H. hepaticus infection when hepatitis is also present. Therefore, interpretation of the increased incidence of hepatocellular neoplasms in mice was confounded. GENETIC TOXICOLOGY: Triethanolamine was not mutagenic in any of the in vitro or in vivo short-term tests performed by the NTP. It did not induce mutations in Salmonella typhimurium, and no induction of sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells exposed to triethanolamine was noted. These in vitro tests were conducted with and without S9 metabolic activation. Triethanolamine did not induce sex-linked recessive lethal mutations in germ cells of adult male Drosophila melanogaster exposed by feeding or injection. No increase in the frequency of micronucleated erythrocytes was observed in peripheral blood samples of male and female mice that received dermal applications of triethanolamine for 13 weeks. CONCLUSIONS: Under the conditions of these dermal studies, there was equivocal evidence of carcinogenic activity of triethanolamine in male F344/N rats based on a marginal increase in the incidence of renal tubule cell adenoma. There was no evidence of carcinogenic activity in female F344/N rats receiving 63, 125, or 250 mg triethanolamine per kilogram body weight. The study in male and female B6C3F1 mice was considered inadequate, because the presence of a Helicobacter hepaticus infection complicated inter pretation of the relationship between triethanolamine administration and liver neoplasms in these animals. Dosed rats and mice had varying degrees of acanthosis and inflammation, dosed rats had ulceration, and dosed female rats had epidermal erosion at the site of skin application. Synonyms: Nitrilo-2,2',2"-triethanol; 2,2',2"-nitrilotriethanol; 2,2',2"-nitrilotrisethanol; TEA; triaethanolamin-NG; triethanolamin; triethylolamine; tri(hydroxyethyl)amine; 2,2',2"-trihydroxytriethylamine; trihydroxytriethylamine; tris(hydroxyethyl)amine; tris(2-hydroxyethyl)amine; triethylolamine; trolamine Trade Names: Daltogen; Sterolamide; Thiofaco T-35

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Isobutene (CAS No. 115-11-7) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Isobutene is produced during the fractionation of refinery gases or through the catalytic cracking of methyl-t-butyl ether. Isobutene is primarily used to produce diisobutylene, trimers, butyl rubber, and other polymers. In addition, it is used in the production of isooctane, high-octane aviation gasoline, methyl-t-butyl ether, and copolymer resins with butadiene and acrylonitrile. Isobutene was selected for evaluation because of the potential for human exposure due to its large production volume and the lack of adequate data on its carcinogenic potential. The toxicity and carcinogenicity of isobutene were determined in male and female F344/N rats and B6C3F1 mice exposed to isobutene (greater than 98% pure) by inhalation for 14 weeks or 2 years. The mutagenicity of isobutene was assessed in Salmonella typhimurium, and the frequency of micronuclei was determined in the peripheral blood of mice exposed by inhalation for 14 weeks. 14-WEEK STUDIES: Groups of 10 male and 10 female F344/N rats and B6C3F1 mice were exposed to isobutene at concentrations of 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm 6 hours per day, 5 days per week, for 14 weeks. Concentrations greater than 8,000 ppm isobutene were not used because of the danger of explosion. All rats and mice survived to the end of the study. The final mean body weights and body weight gains of all exposed groups were similar to those of the chamber controls. No exposure-related gross lesions were observed in male or female rats or mice at necropsy. Microscopically, minimal hypertrophy of goblet cells lining the nasopharyngeal duct in the most caudal nose section was observed in some rats in each exposed group of males and females. 2-YEAR STUDIES: Based on the lack of significant exposure-related toxicologic effects in the 14-week rat and mouse studies, 8,000 ppm was selected as the highest exposure concentration in the 2-year studies. Concentrations of 0, 500, 2,000, and 8,000 ppm were selected for rats and mice with the 500 and 2,000 ppm selection based on published metabolic elimination rates for Sprague-Dawley rats and B6C3F1 mice. Rats: Groups of 50 male and 50 female F344/N rats were exposed to isobutene at concentrations of 0, 500, 2,000, or 8,000 ppm 6 hours per day, 5 days per week, for 105 weeks. Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of exposed groups were generally similar to those of the chamber controls throughout the study. 2-Hydroxyisobutyric Acid - Biomarker of Exposure 2-Hydroxyisobutyric acid (HIBA), the major urinary metabolite of isobutene, was measured in the urine of male and female rats as an indicator of isobutene exposure at 6, 12, and 18 months. The amount of HIBA excreted increased with increasing exposure concentration. However, when HIBA concentration was normalized to isobutene exposure concentration, the relative amount of HIBA excreted decreased with increasing exposure concentration, implying nonlinear kinetics. Pathology Findings: The incidence of thyroid gland follicular cell carcinoma in male rats exposed to 8,000 ppm was increased compared to the chamber control group and exceeded the historical control range. The incidences of hyaline degeneration of the olfactory epithelium were marginally increased in exposed rats; however, the severities of hyaline degeneration increased with increasing exposure concentration in males and females. Mice: Groups of 50 male and 50 female B6C3F1 mice were exposed to isobutene at concentrations of 0, 500, 2,000, or 8,000 ppm 6 hours per day, 5 days per week, for 105 weeks. Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of exposed mice were generally similar to those of the chamber controls throughout the study except for female mice exposed to 2,000 or 8,000 ppm, which weighed slightly less than chamber controls from about week 52 until week 92. 2-Hydroxyisobutyric Acid - Biomarker of Exposure: HIBA was measured in the urine of male and female mice as an indicator of isobutene exposure at 6, 12t 6, 12,and 18 months. The amount of HIBA excreted increased with increasing exposure concentration. However, when HIBA concentration was normalized to isobutene exposure concentration, the relative amount of HIBA excreted decreased with increasing exposure concentration, implying nonlinear kinetics. Pathology Findings: The incidences of hyaline degeneration of the respiratory epithelium in all groups of exposed males and females were significantly greater than those in the chamber control groups. The incidences of hyaline degeneration of the olfactory epithelium in 2,000 and 8,000 ppm mice were greater than those in the chamber controls. GENETIC TOXICOLOGY: Isobutene was not mutagenic in any of four strains of S. typhimurium, with or without S9 metabolic activation, and no increase in the frequency of micronucleated erythrocytes was seen in peripheral blood of male or female mice treated with isobutene by inhalation for 14 weeks. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of isobutene in male F344/N rats based on an increased incidence of follicular cell carcinoma of the thyroid gland. There was no evidence of carcinogenic activity of isobutene in female F344/N rats or male or female B6C3F1 mice exposed to 500, 2,000, or 8,000 ppm. Exposure to isobutene by inhalation for 2 years resulted in increased incidences and/or severities of nasal lesions including hyaline degeneration of the olfactory epithelium in male and female rats and mice and hyaline degeneration of the respiratory epithelium in male and female mice. Synonyms: Isobutylene, 2-methylpropene, liquified petroleum gas, g-butylene.

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Polyvinyl Alcohol (CAS No.9002-89-5) in Female B6C3F1 Mice (Intravaginal Studies).

Polyvinyl alcohol is produced primarily for use in textile sizing, adhesives, polymerization aids, and paper coatings. It is also used in surgical drapes, towels, and gauze sponges; protective gloves; cosmetic formulations; topical ophthalmic preparations; plastic sponge implants for reconstructive surgery; and intravaginal contraceptive foam and film. In addition, polyvinyl alcohol is used with magnesium sulfate to dilate the cervix of women prior to induction of labor. It is estimated that hundreds of thousands of women in the United States use an intravaginal product containing polyvinyl alcohol each year. The Food and Drug Administration nominated low-viscosity polyvinyl alcohol for a 2-year study because of concern about the lack of information about the long-term toxic and carcinogenic effects by the intravaginal route. Female B6C3F1 mice received polyvinyl alcohol (approximately 99% pure) in deionized water by intravaginal administration for 30 days or 2 years. 30-DAY STUDY IN MICE: Three groups of 50 female B6C3F1 mice were used in this intravaginal study. The vehicle control group received only 20 &mgr;L of a deionized water vehicle. The other two groups each received 20 &mgr;L of 25% polyvinyl alcohol in deionized water. Animals in one dose group were returned to their cages after dosing; animals in the other dose group were restrained in a vertical nose-down position in restraint bags for several minutes after dosing. Animals were dosed daily for 30 consecutive days. All mice survived to the end of the study. The final mean body weights and body weight gains of dosed mice were similar to those of the vehicle control group. Abnormalities noted in the vaginal area after dosing included vaginal plugs, secretions, and swelling. These vaginal changes were minimal to mild and occurred in vehicle controls as well as in dosed mice. Restraint of mice after dosing appeared to eliminate vaginal secretions but increased both the incidence of vaginal irritation and the severity of vaginal opening swelling. At necropsy, mildly enlarged uterine horns were observed in 10 vehicle control mice, three 25% mice, and seven 25% (restrained) mice. No chemical-related lesions were observed. 2-YEAR STUDY IN MICE: Three groups of 100 female B6C3F1 mice were used in this intravaginal study: an untreated control group, a vehicle control group receiving 20 &mgr;L deionized water vehicle only, and a dosed group receiving 20 &mgr;L 25%% polyvinyl alcohol in deionized water. Animals were dosed 5 days per week, excluding holidays, for 104 to 105 weeks. Survival, Body Weights, and Clinical Findings: Survival of dosed mice was similar to that of the two control groups. The final mean body weight of vehicle control mice was less than that of the untreated control group. The mean body weights of the dosed mice were less than those of the untreated controls from week 17 until the end of the study. The only clinical finding was vaginal irritation, observed in six mice in the vehicle control group and 11 mice in the dosed group. Pathology Findings: No neoplasms or nonneoplastic lesions related to chemical treatment were observed. The incidences of reproductive tract nonneoplastic lesions in the dosed group did not differ significantly from those in the vehicle control group; similarly, the incidences of reproductive tract nonneoplastic lesions in the vehicle control group did not differ significantly from those in the untreated control group. CONCLUSIONS: Under the conditions of this 2-year study, there was no evidence of carcinogenic activity of polyvinyl alcohol (molecular weight approximately 24,000) in female B6C3F1 mice administered 20 &mgr;L of a 25%% solution intravaginally. There were no neoplasms or nonneoplastic lesions considered related to treatment with polyvinyl alcohol. Synonyms: Ethenol homopolymer, PVA Trade names: Akwa Tears, Alcotex, Alvyl, Aracet, Cipoviol, Covol, Elvanol, Ethenol, Gelvatol, Gohsenol, Ivalon, Kuralon, Kurare, Lemol, Liquifilm, Mowiol, Polydesis, Polysizer, Polyvinol, Polyviol, Poval, Resistoflex, Rhodoviol, Sno, Poval, Resistoflex, Rhodoviol, Sno Tears, Solvar, Sumitex, Vibatex, Vinacol, Vinalak, Vinarol, Vinarole, Vinavilol, Vinol, Vinylon

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Theophylline (CAS No. 58-55-9) in F344/N Rats and B6C3F1 Mice (Feed and Gavage Studies).

Theophylline is an alkaloid found in tea (Thea sinensis) and chocolate and is structurally related to caffeine and theobromine. Theophylline is used as a pharmaceutical agent. It stimulates the heart and central nervous system, relaxes the smooth muscles of the bronchi and blood vessels, and causes diuresis. The drug is used mainly as a bronchodilator in obstructive airway diseases, such as bronchial asthma, and for myocardial stimulation. Theophylline was nominated for toxicologic and carcinogenicity testing as a representative of the purine structural subclass, particularly because of its relationship to purines such as caffeine, 1-methyl-3-hydroxyguanine, and 3-hydroxy-1-methylxanthine, the latter two compounds having been shown to induce sarcomas in rats. Additional reasons for testing theophylline included its widespread use in humans as a pharmaceutical agent, its possible genotoxicity in vitro, and the lack of information on its potential toxicity and/or carcinogenicity under conditions of chronic oral usage. Based on reported teratogenicity and testicular toxicity, it was also recommended that reproductive studies be included in the evaluation of theophylline. The oral route of administration was selected because it is the primary route of human exposure, and the gavage route was selected because it mimics the pharmaceutical use of theophylline in humans. Male and female F344/N rats and B6C3F1 mice were given theophylline (greater than 99% pure) in feed or in corn oil by gavage for 16 days or 14 weeks or in corn oil by gavage for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, mouse bone marrow, and mouse peripheral blood. 16-DAY FEED STUDY IN RATS: Groups of five male and five female F344/N rats were given 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm theophylline in feed for 16 days, which resulted in approximate daily doses of 50, 100, 250, 450, or 1,000 mg theophylline/kg body weight to males and 75, 150, 250, 450, or 1,100 mg/kg to females. All rats survived until the end of the study. The final mean body weights and body weight gains of 8,000 ppm males and females were significantly less than those of the controls. The absolute and relative testis weights of 4,000 ppm males were significantly greater than those of the controls. Increased incidences of uterine hypoplasia were observed microscopically in exposed groups of females. 16-DAY GAVAGE STUDY IN RATS: Groups of five male and five female F344/N rats were given 0, 12.5 (twice daily), 25 (once daily), 50 (once daily), 50 (twice daily), 100 (once daily), 200 (once daily), 200 (twice daily), or 400 (once daily) mg theophylline/kg body weight in corn oil by gavage. All rats receiving 400 mg/kg once daily and all but one female receiving 200 mg/kg twice daily died during the study. In groups dosed once daily, final mean body weights and body weight gains of males receiving 100 or 200 mg/kg and mean body weight gains of females receiving 50, 100, or 200 mg/kg were less than those of controls. The final mean body weights and body weight gains of groups receiving theophylline twice daily were generally similar to those of groups receiving the same daily dosages once daily. Clinical findings included rapid or labored respiration, hunched posture, and squinting. In groups dosed once daily, absolute and relative uterus weights of females receiving 100 or 200 mg/kg once daily were significantly less than those of the controls, and the absolute and relative uterus weights of females receiving 100 mg/kg once daily were significantly less than those of females receiving 50 mg/kg twice daily. Uterine atrophy was observed in three females receiving 200 mg/kg twice daily. Periarteritis of the mesenteric arteries was observed in two males and two females receiving 400 mg/kg once daily. 16-DAY FEED STUDY IN MICE: Groups of five male and five female B6C3F1 mice were given 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm theophylline in feed for 16 days, resulting in approximate daily doses of 250, 475, 950, 1,800, or800, or 2,000 mg theophylline/kg body weight to males and 300, 450, 1,225, 2,000, or 4,375 mg/kg to females. All mice survived until the end of the study. Final mean body weights of 4,000 and 8,000 ppm females and mean body weight gains of 2,000, 4,000, and 8,000 ppm females were significantly greater than those of the controls. Feed consumption by exposed groups was similar to that by the controls, except that by the 8,000 ppm males, which was approximately 40% the amount of feed consumed by the control group. Histopathologic examinations were not performed due to the absence of mortality and significant exposure-related lesions. 16-DAY GAVAGE STUDY IN MICE: Groups of five male and five female B6C3F1 mice were given 0, 12.5 (twice daily), 25 (once daily), 50 (once daily), 50 (twice daily), 100 (once daily), 200 (once daily), 200 (twice daily), or 400 (once daily) mg theophylline/kg body weight in corn oil by gavage. Three males and all females receiving 400 mg/kg once daily died on day 1. There were no significant differences in final mean body weights or body weight gains. There were no histopathologic findings attributed directly to theophylline. 14-WEEK FEED STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were given 0, 1,000, 2,000, or 4,000 ppm theophylline in feed for 14 weeks, which resulted in approximate daily doses of 75, 125, or 250 mg theophylline/kg body weight to males and 75, 125, or 275 mg/kg to females. The final mean body weight of 1,000 ppm females was significantly greater than that of the control group. Feed consumption by exposed groups was similar to that by the controls. Mean cell volume and mean cell hemoglobin were significantly greater in males exposed to 2,000 or 4,000 ppm than those in the control group. Segmented neutrophil counts of all groups of exposed females were significantly greater than that of the control group. The absolute and relative kidney weights of 4,000 ppm males were significantly greater than those of the controls, and there was an exposure-related increase in the severity of nephropathy in males. Exposure-related increases in the incidences of mesenteric and/or pancreatic periarteritis were observed in males and females. 14-WEEK GAVAGE STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were given 0, 37.5, 75, or 150 mg theophylline/kg body weight in corn oil by gavage for 14 weeks. One male and one female receiving 150 mg/kg died before the end of the study. The mean body weight gain of 150 mg/kg females was significantly greater than that of the controls. Mean cell volume of 150 mg/kg males and mean cell hemoglobin of all groups of dosed males were significantly greater than those of the control group. There were slight dose-dependent increases in the incidences of mesenteric periarteritis in dosed males and females. 14-WEEK FEED STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were given 0, 1,000, 2,000, or 4,000 ppm theophylline in feed for 14 weeks, resulting in approximate daily doses of 175, 400, or 800 mg theophylline/kg body weight to males and 225, 425, or 850 mg/kg to females. All mice survived until the end of the study. The final mean body weights and body weight gains of all exposed groups of males and females were significantly less than those of the controls. Feed consumption by exposed groups was similar to that by the controls. Leukocyte, segmented neutrophil, and lymphocyte counts of 4,000 ppm males were significantly greater than those of the controls. Leukocyte and segmented neutrophil counts of 2,000 or 4,000 ppm females were significantly greater than those of the controls. There were no histopathologic findings attributed directly to theophylline exposure. 14-WEEK GAVAGE STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were given 0, 75, 150, or 300 mg theophylline/kg body weight in corn oil by gavage for 14 weeks. Three males and all females receiving 300 mg/kg, one 75 mg/kg male, and one control female died before the end of the study. Final mean body weights and body weight gains of 150 and 300 mg/kg males were significantly less than those of the controls. Mean cell volume and mean cell hemoglobin of 300 mg/kg males were significantly greater than those of the controls. There were no histopathologic findings attributed directly to theophylline treatment. 2-YEAR GAVAGE STUDY IN RATS: Groups of 50 male and 50 female rats were given 7.5, 25, or 75 mg theophylline/kg body weight in corn oil by gavage for 2 years. Survival and Body Weights: There were no significant differences in survival between dosed and control groups. Final mean body weights of all groups of dosed males and females were significantly less than those of the controls. Pathology Findings: There were no significantly increased incidences of neoplasms in dosed rats. The incidence of chronic inflammation of the mesenteric arteries was significantly increased in males receiving 75 mg/kg compared to the controls. There were doserelated negative trends in the incidences of mammary gland fibroadenoma and fibroadenoma or carcinoma (combined) in females; these differences correlated with decreased body weights. 2-YEAR GAVAGE STUDY IN MICE: Groups of 50 male B6C3F1 mice were given 0, 15, 50, or 150 mg theophylline/kg body weight and groups of 50 female B6C3F1 mice were given 0, 7.5, 25, or 75 mg/kg in corn oil by gavage for 2 years. Survival and Body Weights: Survival of 150 mg/kg males was significantly less than that of the controls. The final mean body weights of 150 mg/kg males, 25 mg/kg females, and 75 mg/kg females were significantly less than those of the control groups. Pathology Findings: There were no treatment-related increases in incidences of nonneoplastic lesions or neoplasms. In males and females, there were decreased incidences of hepatocellular adenoma and of the combined incidences of hepatocellular adenoma or carcinoma compared to the controls. Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms in the liver consistent with Helicobacter hepaticus infection. The incidences of these liver lesions in 150 mg/kg males were significantly lower than those in control males. Increases in the incidences of hepatocellular neoplasms in male mice have been shown to be associated with H. hepaticus infection when hepatitis is also present. Because of this association, interpretation of the decreased incidence of liver neoplasms in male mice was more difficult. Incidences of lesions at other sites in this study were not considered to have been significantly impacted by H. hepaticus infection or its associated hepatitis. GENETIC TOXICOLOGY: Theophylline was not mutagenic in Salmonella typhimurium, with or without metabolic activation (S9). It induced sister chromatid exchanges but not chromosomal aberrations in cultured Chinese hamster ovary cells. The positive sister chromatid exchange response was noted only in the absence of S9. In vivo, a mouse bone marrow sister chromatid exchange test showed positive results at a standard 23-hour harvest time; however, this test was not repeated and the response is unconfirmed. An in vivo mouse bone marrow chromosomal aberrations test, that employed both standard and extended exposure protocols, gave negative results. The frequency of micronucleated erythrocytes was determined in peripheral blood of male and female mice exposed to theophylline in dosed feed or in corn oil by gavage for 14 weeks. No significant increases in the frequencies of micronucleated cells were seen in male or female mice in either of the studies. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of theophylline in male or female F344/N rats administered 7.5, 25, or 75 mg/kg. There was no evidence of carcinogenic activity of theophylline in male B6C3F1 mice administered 15, 50, or 150 mg/kg or female B6C3F1 mice administered 7.5, 25, or 75 mg/kg. Gavage administration of theophylline caused chronic inflammation of the mesenteric arteries in dosed male rats. Decreased incidences of mammary neoplasms in female rats were likely associated with lower body weights. There were dose-related decreases in the incidences of hepatocellular adenoma and hepatocellular carcinoma in male and female mice. Synonyms: 3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione; 1,3-dimethylxanthine; 1H-purine-2,6-dione; NSC 2066; pseusdotheophylline; theocin; theophyllin; theophylline, anhydrous Trade names: Accurbron; Aerobin; Aerolate III; Afonilum; Aminophylline; Aquaphyllin; Armophylline; Asmalix; Bilordyl; Bronchoretard; Bronkodyl; Cetraphylline; Constant-T; Diffumal; Duraphyl; Duraphyllin; Elixicon; Elixophyllin; Euphylline L.A.; Euphylong; LaBID; Labophylline; Lanophyllin; Lasma; Liquophylline; Optiphyllin; Parkophyllin; Phylocontin; Physpan; Pro-Vent; PulmiDur; Pulmo-Timelets; Quibron; Respbid; Rona-Phyllin; Sabidal; Slo-bid; Slo-Phyllin; Solosin; Sustaire; Tefamin; Teobid; Teofyllamin; Tesona; Theal tablets; Theo-24; Theobid; Theocap; Theochron; Theoclear; Theocontin; Theo-Dur; Theofol; Theograd; Theolair; Theolan; Theolix; Theophyl; Theoplus; Theo-Sav; Theosol; Theospan; Theostat; Theovent; TheoX; T-Phyl; Truphylline; Uni-Dur; Unifyl; Uniphyl; Uniphyllin; Xanthium

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of 1-Chloro-2-propanol (Technical Grade) (CAS NO. 127-00-4) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies.

1-Chloro-2-propanol and its positional isomer, 2-chloro-1-propanol, are used as chemical intermediates for the manufacture of propylene oxide, a starting material for production of polyurethane polyols and propylene glycol. The National Cancer Institute nominated 1-chloro-2-propanol for study because of potential for human exposure due to its residues in various foods that are fumigated with ethylene oxide or propylene oxide. Male and female F344/N rats and B6C3F1 mice were exposed to technical grade 1-chloro-2-propanol (75% to 76%% 1-chloro-2-propanol; 24% to 25%% 2-chloro-1-propanol) in drinking water for 14 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melanogaster, and mouse peripheral blood erythrocytes. Continuous breeding studies were conducted in Sprague-Dawley rats. 14-DAY STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 100, 330, 1,000, 3,300, or 10,000 ppm for 14 days. Two 10,000 ppm females died before the end of the study. The final mean body weights and body weight gains of 3,300 and 10,000 ppm rats were significantly less than those of the controls; rats in the 10,000 ppm groups lost weight. Water consumption by the 3,300 and 10,000 ppm groups was significantly less than that by the controls throughout the study. The thymus weights of 10,000 ppm rats were significantly less than those of the controls. Exposure to 1-chloro-2-propanol caused cytoplasmic alteration and degeneration of the acinar cells and fatty change in the pancreas, atrophy of the bone marrow, and atrophy and hematopoiesis of the spleen in males and females. 14-DAY STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 100, 330, 1,000, 3,300, or 10,000 ppm for 14 days. One male mouse in the 10,000 ppm group died before the end of the study. Mean body weight gains of 10,000 ppm mice were significantly less than those of the controls. Water consumption by 3,300 and 10,000 ppm males and females was significantly less than that by the controls throughout the study. Liver weights of 1,000, 3,300, or 10,000 ppm males and females were significantly greater and thymus weights of 10,000 ppm mice were significantly less than those of the controls. Exposure to 1-chloro-2-propanol caused hepatocellular vacuolization, cytoplasmic alteration and degeneration of the pancreas acinar cells, and atrophy of the spleen in males and females. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were administered 1-chloro-2-propanol at concentrations of 0, 33, 100, 330, 1,000, or 3,300 ppm (equivalent to average daily doses of approximately 5, 10, 35, 100, or 220 mg/kg) for 14 weeks. All rats survived to the end of the study. Mean body weight gains of 3,300 ppm rats were significantly less than those of the controls. Water consumption by the 3,300 ppm male and female rats was significantly less than that by the controls. A minimal to mild anemia was observed in exposed female rats. The cauda epididymis and epididymis weights of 3,300 ppm males were significantly less than those of the controls. The percentage of abnormal sperm in 3,300 ppm males and the concentration of epididymal sperm in 330 ppm males were significantly increased compared to the controls. Kidney and liver weights of males and females exposed to 100 ppm or more were generally greater than those of the controls. The incidences of acinar cell degeneration and fatty change of the pancreas in 1,000 and 3,300 ppm rats, hepatocytic metaplasia of the pancreatic islets in 3,300 ppm females, cytoplasmic vacuolization of the liver in 100, 1,000 and 3,300 ppm males, and renal tubule epithelium regeneration in 3,300 ppm females were increased compared to the controls. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were administered 1-chloro-2-propanol in drinking water at concentrations of 0, 33, 100, 33entrations of 0, 33, 100, 330, 1,000, or 3,300 ppm (equivalent to average daily doses of approximately 5, 15, 50, 170, or 340 mg/kg to males and 7, 20, 70, 260, or 420 mg/kg to females) for 14 weeks. One 330 ppm male died before the end of the study. Mean body weight gains of exposed groups were similar to those of the controls. A minimal anemia was observed in 3,300 ppm males. The right epididymis weight of 3,300 ppm males was significantly greater than that of the controls. Kidney weights of 3,300 ppm mice, liver weights of 1,000 ppm males and of all exposed groups of females, and thymus weights of 1,000 and 3,300 ppm females were greater than those of the controls. The incidences of pancreatic acinar cell degeneration and fatty change in 3,300 ppm males and females and cytoplasmic vacuolization of the liver in all groups of exposed females were significantly increased compared to the controls. The severities of renal tubule cytoplasmic vacuolization were greater in 1,000 and 3,300 ppm males than in the controls. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were administered drinking water containing 0, 150, 325, or 650 ppm 1-chloro-2-propanol (equivalent to average daily doses of approximately 15, 30, or 65 mg/kg during the first several months of the study and 8, 17, or 34 mg/kg for the remainder of the 2-year study) for up to 105 weeks. Survival of all exposed groups was similar to that of the controls. Mean body weights of exposed rats were generally similar to those of the controls throughout most of the study. Water consumption by all exposed groups was similar to that by the controls. No treatment-related neoplasms or nonneoplastic lesions were observed in this study. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were administered drinking water containing 0, 250, 500, or 1,000 ppm 1-chloro-2-propanol (equivalent to average daily doses of approximately 45, 75, or 150 mg/kg to males and 60, 105, or 210 mg/kg to females during the first several months of the study and 25, 50, or 100 mg/kg for the remainder of the 2-year study) for up to 105 weeks. Survival of all exposed groups was similar to that of the controls. The mean body weights of all exposed mice were generally similar to those of the controls throughout the study. Water consumption by all exposed groups was similar to that by the controls. No treatment- related neoplasms or nonneoplastic lesions were observed in this study. GENETIC TOXICOLOGY: 1-Chloro-2-propanol is a demonstrated mutagen in vitro. It was weakly mutagenic in S. typhimurium strain TA100 in the presence of hamster or rat liver S9 activation enzymes and was positive, with and without S9, in TA1535. No mutagenic activity was detected in strains TA97, TA98, and TA1537, with or without S9. In cytogenetic tests with Chinese hamster ovary cells, 1-chloro-2-propanol induced high levels of sister chromatid exchanges and chromosomal aberrations in the presence and the absence of S9. The marked ability of 1-chloro-2-propanol to induce chromosomal effects in vitro was not seen in vivo. Positive results were obtained in a test in D. melanogaster for induction of sex-linked recessive lethal mutations in germ cells of males administered 1-chloro-2-propanol via injection; however, negative results were obtained when males were administered 1-chloro-2-propanol in feed. A subsequent germ cell reciprocal translocation test in D. melanogaster yielded negative results. Further, no induction of micronucleated erythrocytes was observed in peripheral blood of male and female mice administered 1-chloro-2-propanol via drinking water for 14 weeks. CONCLUSIONS: Under the conditions of these 2-year drinking water studies, there was no evidence of carcinogenic activity of technical grade 1-chloro-2-propanol in male or female F344/N rats exposed to 150, 325, or 650 ppm. There was no evidence of carcinogenic activity of technical grade 1-chloro-2-propanol in male or female B6C3F1 mice exposed to 250, 500, or 1,000 ppm. Synonyms: 1-Chloro-2-hydroxypropane, 1-chloroisopropyl alcohol, propylene-α-chlorohydrin, sec-propylene chlorohydrin

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Tetrahydrofuran (CAS No. 109-99-9) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Tetrahydrofuran is used as a reaction medium for Grignard and metal hydride reactions; in the synthesis of butyrolactone, succinic acid, and 1,4-butanediol diacelate; in the fabrication of articles for packaging, transporting, and storing of foods; as a solvent for dyes and lacquers; and as a chemical intermediate in polymerization solvent for fat oils, unvulcanized rubber, resins, and plastics. Tetrahydrofuran is also an indirect food additive when it is in contact with the surface of articles intended for use in food processing. Tetrahydrofuran was nominated for study because of the potential for occupational exposure in humans. Male and female F344/N rats and B6C3F1 mice were exposed to tetrahydrofuran (approximately 99% pure) by inhalation for 13 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, Drosophila melanogaster, mouse bone marrow cells, and mouse peripheral blood cells erythrocites. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to 0 (chamber control), 66, 200, 600, 1,800, or 5,000 ppm tetrahydrofuran by inhalation, 6 hours per day, 5 days per week, for 14 weeks. All rats survived until the end of the study. Final mean body weights and mean body weight gains of exposed groups of male and female rats were similar to those of the chamber controls. Immediately after exposure, male and female rats in the 5,000 ppm groups exhibited ataxia. Hematologic and serum chemistry changes were minimal, with most values falling within physiologic ranges. Absolute and relative thymus and spleen weights of male and female rats exposed to 5,000 ppm were significantly less than those of the chamber controls. Absolute and relative liver weights of female rats exposed to 5,000 ppm were significantly greater than those of the chamber controls. Increased incidences of minimal to mild hyperplasia of the forestomach were observed in male and female rats exposed to 5,000 ppm. Minimal suppurative inflammation was associated with forestomach hyperplasia in two male rats and four female rats exposed to 5,000 ppm. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 66, 200, 600, 1,800, or 5,000 ppm tetrahydrofuran by inhalation, 6 hours per day, 5 days per week, for 14 weeks. Two male mice exposed to 5,000 ppm died during weeks 2 and 8 of the study; one male mouse from the 5,000 ppm group was killed in a moribund state during week 4. All female mice survived until the end of the study. The final mean body weights and mean body weight gains of all exposed groups of male mice were similar to those of the chamber controls. The final mean body weight and mean body weight gain of the 5,000 ppm female mice were significantly greater than those of the chamber controls. Male and female mice exposed to 1,800 or 5,000 ppm were observed in a state of narcosis (described by stupor) during exposure periods. Mice exposed to 1,800 ppm were fully awake and alert immediately after exposure; however, mice exposed to 5,000 ppm required up to 2 hours for recovery. Absolute and relative liver weights of male mice exposed to 600 ppm or greater and of female mice exposed to 1800 or 5,000 ppm were significantly greater than those of the chamber controls. Absolute and relative thymus weights of male mice exposed to 600, 1,800, or 5,000 ppm were significantly less than those of the chamber controls. The incidences of minimal to mild centrilobular cytomegaly of the liver in male and female mice exposed to 5,000 ppm were significantly greater than those in the chamber controls. The adrenal glands of all female mice exposed to 5,000 ppm had mild degeneration of the X-zone of the innermost cortex. Uterine atrophy was observed in all female mice exposed to 5,000 ppm. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to 0, 200, 600, or 1,800 ppm tetrahydrofuran by inhalation, 6 hours per day, 5 days per week, for 105 weeks. Survival, Body Weights, and Clinical Findings Survival and mean body weights of male and femand female rats exposed to tetrahydrofuran were similar to those of the chamber controls. Pathology Findings: The incidences of renal tubule epithelial adenoma or carcinoma (combined) in exposed males occurred with a positive trend, and the incidences in 600 and 1,800 ppm males exceeded the historical range for chamber controls in 2-year NTP inhalation studies. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to 0, 200, 600, or 1,800 ppm tetrahydrofuran by inhalation, 6 hours per day, 5 days per week, for 105 weeks. Survival, Body Weights, and Clinical Findings After week 36, the survival of male mice exposed to 1,800 ppm was significantly less than that of the chamber controls. Mean body weights of male and female mice exposed to tetrahydrofuran were similar to those of the chamber controls throughout the study. Male mice exposed to 1,800 ppm were observed to be in a state of narcosis during and up to 1 hour after the exposure periods. Pathology Findings: The incidences andmultiplicity of hepatocellular neoplasms were significantly greater in female mice exposed to 1,800 ppm than in the chamber controls. The incidence of nephropathy in 200 ppm male mice was significantly greater than that in the chamber control group. Male mice exposed to 1,800 ppm had significantly greater incidences of nonneoplastic lesions of the urogenital tract than did the chamber controls. The incidences of inflammation of the penis and urethra and necrosis of the urethra in 1,800 ppm males were slightly greater than those in the chamber controls; these may have been secondary effects of ascending urinary tract infection. GENETIC TOXICOLOGY: Tetrahydrofuran showed little evidence of mutagenic activity in a variety of in vitro and in vivo assays. It was not mutagenic in Salmonella typhimurium, and it did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro tests were conducted with and without exogenous metabolic activation from induced liver S9 enzymes. No increase in sex-linked recessive lethal mutations was detected in germ cells of male D. melanogaster exposed to tetrahydrofuran by feeding or injection. Results of in vivo assays for induction of chromosomal aberrations and sister chromatid exchanges in mouse bone marrow cells were negative. A micronucleus test in male and female mice exposed to tetrahydrofuran for 14 weeks showed no significant increases in the frequency of micronucleated erythrocytes in peripheral blood of female mice, but in male mice, analysis of micronucleated normochromatic erythrocyte levels revealed a small increase above baseline that was concluded to be equivocal. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of tetrahydrofuran in male F344/N rats based on increased incidences of renal tubule adenoma or carcinoma (combined). There was no evidence of carcinogenic activity of tetrahydrofuran in female F344/N rats exposed to 200, 600, or 1,800 ppm or male B6C3F1 mice exposed to 200, 600, or 1,800 ppm. There was clear evidence of carcinogenic activity of tetrahydrofuran in female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. Synonyms: Butylene oxide; cyclotetramethylene oxide; diethylene oxide; 1,4-epoxybutane; furanidine; hydrofuran; oxacyclopentane; oxolane; tetramethylene oxide

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Technical Grade Sodium Xylenesulfonate (CAS No. 1300-72-7) in F344/N Rats and B6C3F1 Mice (Dermal Studies).

Sodium xylenesulfonate is used as a hydrotrope, an organic compound that increases the ability of water to dissolve other molecules. Sodium xylenesulfonate is a component in a variety of widely used shampoos and liquid household detergents where it can constitute up to 10% of the total solution. Because of its widespread use, the potential for human exposure to sodium xylenesulfonate is great. Male and female F344/N rats and B6C3F1 mice were administered sodium xylenesulfonate in water or 50% ethanol dermally for 17 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, L5178Y mouse lymphoma cells, and cultured Chinese hamster ovary cells. 17-DAY STUDY IN RATS: Groups of five male and five female rats were administered 300 mL of 0, 5, 15, 44, 133, or 400 mg/mL sodium xylenesulfonate in distilled water by dermal application 5 days per week for 17 days. All rats survived to the end of the study. Final mean body weights and body weight gains of dosed rats were similar to those of the control groups. Dermal applications of 300 mL of 5, 15, 44, 133, and 400 mg/mL delivered average daily doses of approximately 10, 30, 90, 260, and 800 mg sodium xylenesulfonate/kg body weight to males and 13, 40, 120, 330, and 1,030 mg/kg to females. Clinical findings generally involved the skin of dosed animals and included tan or brown skin discoloration and crusty white deposits (presumed to be dried chemical) at the site of application. Neither of these observations were considered significant findings. The relative liver weights of 133 and 400 mg/mL male and female rats were significantly greater than those of the control groups, but the absolute liver weights were not increased and the biological significance of the relative differences in liver weight was unclear. In males and females, the few lesions observed grossly and microscopically were generally attributed to repeated clipping and were not considered related to chemical administration. 17-DAY STUDY IN MICE: Groups of five male and five female mice were administered 100 mL of 0, 5, 15, 44, 133, or 400 mg/mL sodium xylenesulfonate in distilled water by dermal application 5 days per week for 17 days. All mice survived to the end of the study. Final mean body weights and body weight gains of dosed mice were similar to those of the controls. Dermal applications of 5, 15, 44, 133, and 400 mg/mL delivered average daily doses of approximately, 20, 60, 190, 540, and 1,600 mg sodium xylenesulfonate/kg body weight to males and 26, 80, 220, 680, and 2,000 mg/kg to females. Clinical findings included crusty white deposits (presumed to be dried chemical) at the site of application in two 133 mg/mL males and in all 400 mg/mL males and females. The absolute and relative liver weights of 15 and 44 mg/mL males and 400 mg/mL males and females were significantly greater than those of the control groups, but the biological significance of these differences was unclear. The few skin lesions observed grossly and microscopically in males and females were generally attributed to repeated clipping and were not considered related to chemical administration. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 300 mL of 0, 5, 15, 44, 133, or 400 mg/mL sodium xylenesulfonate in 50% ethanol by dermal application for 14 weeks. For special hematology and clinical pathology studies, additional groups of 10 male and 10 female rats were administered 0, 5, 15, 44, 133, or 400 mg/mL sodium xylenesulfonate in 50% ethanol by dermal application for 14 weeks. All rats survived to the end of the study. Final mean body weights and body weight gains of dosed male and female rats were similar to those of the control groups. Dermal applications of 5, 15, 44, 133, and 400 mg/mL delivered average daily doses of approximately 6, 20, 60, 170, and 500 mg sodium xylenesulfonate/kg body weight to males and 10, 30, 90, 260, and 800 mg/kg to females. The only notable clinical finding was brown discoloration of the skin at the site of application in dosed animals. Hemaation in dosed animals. Hematology and clinical chemistry parameters of dosed groups of males and females were significantly different from those of the controls in several instances, but these differences were sporadic and did not demonstrate a treatment relationship. The absolute and relative liver weights of males receiving 44, 133, or 400 mg/mL were significantly less than those of the control group, but the biological significance of these differences was unclear, and there were no treatment-related histopathologic effects in the liver. There were no significant differences in liver weights in female rats. Minimal hyperplasia of the epidermis at the site of application occurred in both male and female rats in the control group as well as most dosed groups. The incidence of epidermal hyperplasia in 400 mg/mL males was possibly chemical related. 14-Week Study in Mice: Groups of 10 male and 10 female mice were administered 100 mL of 0, 5, 15, 44, 133, or 400 mg/mL sodium xylenesulfonate in 50% ethanol by dermal application for 14 weeks. There were no chemical-related deaths. The mean body weight gain of the 400 mg/mL males was significantly greater than that of the control group. Dermal applications of 5, 15, 44, 133, and 400 mg/mL delivered average daily doses of approximately 17, 40, 140, 440, and 1,300 mg sodium xylenesulfonate/kg body weight to males and 20, 60, 170, 530, and 1,630 mg/kg to females. There were no clinical findings related to sodium xylenesulfonate administration. Epidermal hyperplasia occurred in one 44 mg/mL female, two 133 mg/mL males, five 400 mg/mL males, and four 400 mg/kg females. Hyperplasia of the epidermis in 400 mg/mL males and females was probably related to chemical administration. Chronic inflammation of the skin occurred primarily in the control groups of males and females. These lesions consisted of mononuclear inflammatory cells in the dermis. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were dermally administered 0, 60, 120, or 240 mg sodium xylenesulfonate/kg body weight in 50% ethanol for 104 weeks. Survival, Body Weights, and Clinical Findings: Survival of dosed males and females was similar to that of the control groups. Mean body weights of dosed males and females were similar to those of the controls throughout the study. In male groups, there were no clinical findings considered treatment related. In females, clinical findings were limited to irritation at the site of application in one control female, four 120 mg/kg females, and two 240 mg/kg females. Pathology Findings: There were no neoplasms at any site (including the skin) that were considered treatment related.Low incidences of hyperplasia of the epidermis at the site of application occurred in males in the 60, 120, and 240 mg/kg groups. Low incidences of hyperplasia of the epidermis at the site of application also occurred in females in the 120 and 240 mg/kg groups, and they occurred with a significant positive trend. Low incidences of hyperplasia of the sebaceous gland occurred in control and 60 mg/kg males and in control, 120 mg/kg, and 240 mg/kg females. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were dermally administered 0, 182, 364, or 727 mg sodium xylenesulfonate/kg body weight in 50% ethanol for 104 to 105 weeks. Survival, Body Weights, and Clinical Findings: Survival of dosed males and females was similar to that of the control groups. Mean body weights of dosed males and females were generally similar to those of the controls throughout the study; however, the mean body weights of 727 mg/kg females were greater than those of the control group from week 85 to week 97. With the exception of irritation at the site of application in one 364 mg/kg female, there were no clinical findings related to sodium xylenesulfonate administration. Pathology Findings: There were no neoplasms at any site (including the skin) that were considered treatment related.Hyperplasia of the epidermis occurred in control,364 mg/kg, and 727 mg/kg males and in control and dosed females. In male mice, the incidences occurred with a significant positive trend. Focal ulceration occurred in one 727 mg/kg male and in one female in each dose group. In males and females from control and dosed groups, the incidences of hepatocellular adenoma, hepatocellular carcinoma, and hepato- cellular adenoma or carcinoma (combined) were generally higher than those expected by spontaneous occurrence. The incidences of hepatocellular neoplasms in some groups of males and females exceeded the NTP historical control range. Male mice had a pattern of nonneoplastic liver lesions along with silver stained positive helical organisms within the liver which suggests an infection with Helicobacter hepaticus. The findings in this study of sodium xylenesulfonate were not considered to have been significantly impacted by the infection with H. hepaticus or its associated hepatitis. GENETIC TOXICOLOGY: Sodium xylenesulfonate was not mutagenic in Salmonella typhimurium strain TA98, TA100, TA1535, or TA1537 with or without induced liver S9. Equivocal results were obtained in a mutation assay with mouse lymphoma cells in the presence of induced S9; no evidence of mutagenicity was noted without S9 in this assay. In cytogenetic tests with sodium xylenesulfonate in cultured Chinese hamster ovary cells, significant increases in sister chromatid exchanges were observed in the absence of S9 only, and no increases in chromosomal aberrations were observed with or without S9. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of sodium xylenesulfonate in male or female F344/N rats administered 60, 120, or 240 mg/kg or in male or female B6C3F1 mice administered 182, 364, or 727 mg/kg. Increased incidences of epidermal hyperplasia in female rats and male mice may have been related to exposure to sodium xylenesulfonate. Synonyms: Benzenesulfonic acid, dimethyl-, sodium salt; xylenesulfonic acid, sodium salt; sodium dimethylbenzenesulfonate; xylenesulfonic acid, sodium salt Trade names: Conco SXS; Cyclophil; SXS 30; Eletesol SX 30; Naxonate; Naxonate G; Richonate SXS; Stepanate SXS; Stepanate X; SXS 40; Ultrawet 40SX

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Cobalt Sulfate Heptahydrate (CAS No. 10026-24-1) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Cobalt sulfate is used in the electroplating and electro chemical industries. It is also used as a coloring agent for ceramics and as a drying agent in inks, paints, varnishes, and linoleum. Cobalt sulfate may be added to animal feed as a mineral supplement and has been used as a top dressing on pasture lands. Cobalt sulfate was nominated by the National Cancer Institute for study based on a lack of information on the toxicity of soluble salts. Male and female F344/N rats and B6C3F1 mice were exposed to cobalt sulfate heptahydrate (approximately 99% pure) by inhalation for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium. The results of prechronic inhalation toxicity studies were reported previously (Bucher et al., 1990; NTP, 1991). 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate heptahydrate 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of exposed male and female rats were similar to those of the chamber controls throughout the study. Pathology Findings The incidences and severities of proteinosis, alveolar epithelial metaplasia, granulomatous alveolar inflammation, and interstitial fibrosis were markedly greater in all exposed groups of male and female rats than in the chamber controls. The incidences of alveolar epithelial hyperplasia in all groups of exposed males and in females exposed to 3.0 mg/m3 were significantly greater than those in the chamber control groups, as were the incidences of squamous metaplasia in 1.0 mg/m3 females and atypical alveolar epithelial hyperplasia in 3.0 mg/m3 females. In 3.0 mg/m3 males, the combined incidence of alveolar/ bronchiolar neoplasms (adenoma and/or carcinoma) was significantly greater than in the chamber controls. In female rats exposed to 1.0 or 3.0 mg/m3, the incidences of alveolar/bronchiolar neoplasms were significantly greater than those in the chamber control group and exceeded the NTP historical control ranges. A squamous cell carcinoma was observed in one 1.0 mg/m3 and one 3.0 mg/m3 female. The incidences of benign, complex, or malignant pheochromocytoma (combined) in 1.0 mg/m3 males and in 3.0 mg/m3 females were significantly greater than those in the chamber controls and exceeded the historical control ranges. Hyperplasia of the lateral wall of the nose, atrophy of the olfactory epithelium, and squamous metaplasia of the epiglottis were observed in all exposed groups of males and females, and the severities of these lesions increased with increasing exposure concentration. The incidences of squamous metaplasia of the lateral wall of the nose and metaplasia of the olfactory epithelium were increased in 3.0 mg/m3 males and females. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate heptahydrate 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of 3.0 mg/m3 male mice were less than those of the chamber controls from week 96 until the end of the study. The mean body weights of all exposed groups of female mice were generally greater than those of the chamber controls from week 20 until the end of the study. Pathology Findings The incidences of diffuse histiocytic cell infiltration in 3.0 mg/m3 males and of focal histiocytic cell infil tration in 3.0 mg/m3 females were significantly greater than those in the chamber controls. The incidences of alveolar/bronchiolar neoplasms in 3.0 mg/m3 males and females were significantly greater than those in the chamber control groups. The combined incidences of alveolar/bronchiolar adenoma or carcinoma and the incidences of alveolar/bronchiolar carcinoma in 3.0 mg/m3 males and females and the incidence of alveolar/bronchiolar adenoma in 3.0 mg/m3 females exceeded the NTP historical crical control ranges for inhalation studies. The incidences of atrophy of the olfactory epithelium in 1.0 and 3.0 mg/m3 males and females and hyper plasia of the olfactory epithelium in 3.0 mg/m3 males and females were significantly greater than in the chamber controls. Squamous metaplasia of the larynx was observed in all exposed groups of males and females. Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms within the liver, characteristic of an infection with Helico bacter hepaticus. In NTP studies with H. hepaticus- associated hepatitis, increased incidences of hemangiosarcoma were seen in the liver of male mice. In this study of cobalt sulfate heptahydrate, incidences of hemangiosarcoma were increased in exposed groups of male mice. Because of the above association, interpretation of the increased incidences of hemangiosarcoma in the livers of male mice was confounded. Incidences of lesions at other sites in this study of cobalt sulfate heptahydrate were not considered to have been significantly impacted by the infection with H. hepaticus or its associated hepatitis. GENETIC TOXICOLOGY: Cobalt sulfate heptahydrate was mutagenic in S. typhimurium strain TA100 with and without liver S9 metabolic activation enzymes; no mutagenic activity was detected in strain TA98 or TA1535, with or without S9. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of cobalt sulfate heptahydrate in male F344/N rats based on increased incidences of alveolar/bronchiolar neoplasms. Marginal increases in incidences of pheochromocytomas of the adrenal medulla may have been related to exposure to cobalt sulfate heptahydrate. There was clear evidence of carcinogenic activity in female F344/N rats based on increased incidences of alveolar/bronchiolar neo-plasms and pheochromocytomas of the adrenal medulla in groups exposed to cobalt sulfate heptahydrate. There was clear evidence of carcinogenic activity of cobalt sulfate heptahydrate in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms. Exposure to cobalt sulfate heptahydrate caused a spectrum of inflammatory, fibrotic, and proliferative lesions in the respiratory tract of male and female rats and mice. Synonyms: Bieberite; cobalt(II) sulfate (1:1) heptahydrate; cobalt monosulfate heptahydrate; cobalt(II) sulphate heptahydrate; sulfuric acid, cobalt(2+) salt (1:1) heptahydrate

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Oxazepam (CAS No. 604-75-1) in F344/N Rats (Feed Studies).

Oxazepam and related benzodiazepine drugs are used in the treatment of anxiety. All benzodiazepines currently in use share a number of effects, including sedation, hypnosis, decreased anxiety, muscle relaxation, amnesia, and anticonvulsant activity. Oxazepam and four other benzodiazepines (chlordiazepoxide, chlorazepate, diazepam, and flurazepam) were nominated for study by the Food and Drug Administration (FDA) and by the NIEHS based on their widespread use, use by pregnant women, and the lack of adequate rodent carcinogenicity studies. Oxazepam was evaluated in 14-week and 2-year studies by the NTP, and Technical Report No. 443 contains the results of the studies performed with the Swiss-Webster and B6C3F1 strains of mice. Studies with rats were not initiated at the same time as the mouse studies because adequate carcinogenicity studies of oxazepam with the Sprague-Dawley rat strain had been submitted to the FDA. Subsequently, because of the marked neoplastic responses found in the two mouse strains, the NTP initiated 2-year studies of oxazepam with the F344/N rat. Groups of male and female F344/N rats were exposed to oxazepam (greater than 99% pure) in feed for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells, and mouse peripheral blood samples were analyzed for the frequency of micronucleated normochromatic erythrocytes. 2-YEAR STUDY: Groups of 50 male and 50 female F344/N rats were fed diets containing 0, 625, 2,500, or 5,000 ppm oxazepam for up to 105 weeks. A stop-exposure group of 50 males and 50 females received 10,000 ppm oxazepam in feed for 26 weeks, after which animals received undosed feed for the remainder of the 2-year study. The continuous-exposure concentrations resulted in average daily doses of 25, 100, or 250 mg oxazepam/kg body weight to males and 25, 110, or 220 mg/kg to females. Stop- exposure males and females received an average daily dose of 630 mg/kg during the exposure period. Survival, Body Weights, and Clinical Findings: All 5,000 ppm continuous-exposure and 10,000 ppm stop-exposure males died before the end of the study. Survival of 2,500 ppm continuous-exposure males and females was significantly less than that of the controls. The mean body weight gains of 2,500 and 5,000 ppm males and females were less than those of the controls throughout the study. The mean body weights of 10,000 ppm stop-exposure males were generally less than those of the controls throughout the study; those of 10,000 ppm stop-exposure females were less than those of the controls during the exposure portion of the study but increased steadily after the cessation of dosing at week 27. Feed consumption by exposed groups was similar to that by the controls after week 1 of the study. Treatment-related eye/nasal discharge, hyperactivity when handled, and/or ataxia were observed in exposed male and female rats on or about day 2 of exposure but were no longer apparent after day 7. Plasma Oxazepam Determinations: Plasma oxazepam concentrations were measured at the end of the study. The concentrations ranged from approximately 0.5 (625 ppm males) to 2.8 &mgr;g/mL (5,000 ppm females). Pathology Findings: In the standard histopathologic evaluation, the incidence of renal tubule adenoma was slightly increased in male rats exposed to 2,500 ppm and was at the upper limit of the historical control range for this neoplasm in 2-year NTP feed studies. In an extended evaluation (step section) of the kidneys of male rats, the incidences of renal tubule adenoma occurred with a positive trend in exposed groups. In standard and step sections (combined), male rats exposed to 2,500 or 5,000 ppm showed a significant increase in the incidences of renal tubule adenoma and hyperplasia. In addition, the incidences of renal tubule adenoma and hyperplasia were significantly increased in the 10,000 ppm stop-exposure group. The incidences of nephropathy in continuously exposed female rats were significantly greater than in the controls, and the severity of nephropathy increased wised with increasing exposure concentration in males. The incidences of epithelial hyperplasia and chronic inflammation of the forestomach in males exposed to 2,500 and 5,000 ppm and of ulcers in 2,500 ppm males were significantly greater than in the controls. Incidences of mineralization of the glandular stomach in 5,000 ppm and 10,000 ppm (stop-exposure) males and of erosion of the duodenum in 5,000 ppm males were significantly greater than in the controls. Female rats exposed to 2,500 ppm had greater incidences of epithelial hyperplasia, chronic inflammation, and ulcers of the forestomach and of erosion in the glandular stomach. Centrilobular hepatocyte hypertrophy occurred more frequently in 2,500 and 5,000 ppm males and females than in the controls. GENETIC TOXICOLOGY: Oxazepam was not mutagenic in any of several strains of S. typhimurium, nor did it induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro tests were performed with and without S9 metabolic activation. Results from an in vivo mouse peripheral blood micronucleus test performed on B6C3F1 mice used in a 14-week study were also negative. CONCLUSIONS: In summary, under the conditions of these 2-year dosed-feed studies, there was equivocal evidence of carcinogenic activity in male F344/N rats, based on small increases in the incidences of renal tubule adenomas in exposed groups also exhibiting significantly enhanced nephropathy. There was no evidence of carcinogenic activity of oxazepam in female F344/N rats exposed to feed containing 625, 2,500, or 5,000 ppm for 2 years or 10,000 ppm for 6 months. Administration of oxazepam to rats resulted in nonneoplastic lesions in the forestomach, glandular stomach, and small intestine as well as centrilobular hypertrophy of hepatocytes in the liver. In addition, nephropathy was increased in incidence in female rats and was markedly increased in severity in male rats, resulting in early mortality at the higher exposure concentrations. Synonym: 7-Chloro-1,3-dihydro-3-hydroxy-5-phenyl-2H-1,4-benzodiazepin-2-one Trade Names: Tazepam, Wy-3498, Serax

Journal Article↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Chloroprene (CAS No. 126-99-8) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Chloroprene is used almost exclusively in the manufacture of neoprene (polychloroprene). Chloroprene was chosen for study because it is a high-volume production chemical with limited information on its carcinogenic potential and because it is the 2-chloro analogue of 1,3-butadiene, a potent, multi-species, multi-organ carcinogen. Male and female F344/N rats and B6C3F1 mice were exposed to chloroprene (greater than 96% pure) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Drosophila melanogaster, and B6C3F1 mice (bone marrow cells and peripheral blood erythrocytes).

Journal Article↗
PubMed1997

NTP Toxicology and Carcinogenesis Studies of D&C Yellow No. 11 (CAS No. 8003-22-3) in F344/N Rats (Feed Studies).

D&C Yellow No. 11 is used to color topical drug preparations and cosmetics. It is also used in spirit lacquers, polystyrenes, polycarbonates, polyamides, acrylic resins, colored smokes, and hydrocarbon solvents. D&C Yellow No. 11 was nominated to the NTP for toxicity and carcinogenesis studies as part of a larger regulatory effort mandated by Congress and undertaken by the Food and Drug Administration to determine the safety of a number of provisionally listed dyes. D&C Yellow No. 11 is currently regulated for external use. The recommendation to study D&C Yellow No. 11 by dietary exposure was based on the fact that it is a contaminant of D&C Yellow No. 10, a candidate for permanent listing as a chemical for which there is a potential for ingestion. First-generation (F(0)) male and female F344/N rats were given D&C Yellow No. 11 (approximately 99% pure) in feed for up to 19 weeks and then mated, and exposure of second-generation (F(1)) males and females began in utero and continued for 2 years after weaning at 28 days of age. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood. REPRODUCTIVE TOXICITY STUDY: Groups of 60 male and 60 female F(0) rats were given 0, 500, 1,700, or 5,000 ppm D&C Yellow No. 11 in feed for up to 19 weeks, which resulted in average daily doses of 35, 120, or 350 mg D&C Yellow No. 11/kg body weight to males and 35, 120, or 370 mg/kg to females. All F(0) males and females survived until the end of the study. Prior to cohabitation, mean body weight gains of males given 500, 1,700, or 5,000 ppm and of females given 5,000 ppm were significantly lower than those of the controls. The mean body weight gains of exposed females during gestation and lactation were generally similar to those of the controls. Feed consumption by exposed groups of rats was generally similar to that by the control groups prior to cohabitation. The duration of gestation, the average litter size, the number of live pups on days 4 (precull) and 21, and the percentage of male pups for each exposure group were similar to those of the controls. The mean body weights of exposed litters were significantly less than those of the control litters on days 14 and 21; this effect was considered to be related to D&C Yellow No. 11 exposure. 2-YEAR STUDY: Groups of 60 male and 60 female F(1) rats were given 0, 500, 1,700, or 5,000 ppm D&C Yellow No. 11 in feed for 105 (males) or 106 (females) weeks after weaning (day 28); 6 to 10 rats per group were evaluated at 12 months. These exposure concentrations resulted in average daily doses of approximately 25, 85, or 250 mg D&C Yellow No. 11/kg body weight to males and 25, 100, or 280 mg/kg to females. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of males given 1,700 or 5,000 ppm was significantly less than that of the controls, and survival of 1,700 ppm females was significantly greater than that of the controls. Mean body weights of 1,700 and 5,000 ppm males and females were generally lower than those of the controls throughout the study. Feed consumption by exposed groups was similar to that by the controls. Chemical-related clinical findings included yellow discoloration of the entire body in all exposed males and females from day 1 and head swelling and edema in 1,700 and 5,000 ppm males. One 1,700 ppm and five 5,000 ppm males were moribund and were killed between weeks 49 and 81; these deaths were attributed to extensive edema. Hematology: A few minimal hematology changes occurred in male rats at the 12-month interim evaluation. There was evidence of minimal anemia in exposed males; this anemia was characterized by decreased hematocrit values, hemoglobin concentrations, and erythrocyte counts. The minimal anemia was characterized as normocytic, normochromic, and nonresponsive. There were no biologically or statistically significant differences in hematology parameters between control and exposed females. Pathology Findings: Absolute and relative liver weights of all exposed groups of md relative liver weights of all exposed groups of males and females were significantly greater than those of the controls at 12 months. At 2 years, the incidences of hepatocellular adenoma in 5,000 ppm males and of hepatocellular adenoma or carcinoma (combined) in 5,000 ppm females were significantly greater than those in the controls. At 12 months, the incidences of clear cell foci in 1,700 and 5,000 ppm females were significantly greater than that in the controls. At 2 years, the incidences of mixed cell foci in exposed males and of clear cell foci in exposed males (except 500 ppm) and females were significantly greater than those in the controls. Incidences of cytologic alterations (basophilia and granularity) of hepatocytes, and pigmentation in bile duct epithelium, hepatocytes, and Kupffer cells in exposed males and females were greater than those in the controls at both 12 months and 2 years. Renal tubule adenomas were observed in two 5,000 ppm males, and one renal tubule carcinoma was observed in a 1,700 ppm male. During an extended evaluation, renal tubule adenomas were observed in two additional 5,000 ppm males, four 1,700 ppm males, and two 500 ppm males. Renal tubule hyperplasia was observed in exposed groups of males but not in controls, and the incidences in 1,700 ppm males from both standard and extended evaluations were significantly greater than those in the controls. Necrosis and regeneration of the renal tubule epithelium were observed in all control and exposed male rats and in most female rats at 12 months and 2 years. The severity of nephropathy in exposed males and females was significantly greater than that in the controls. In exposed males and 1,700 ppm females at 2 years, the incidences of hyperplasia of the transitional epithelium in the kidney, which commonly accompanies advanced nephropathy, were greater than those of the controls, and the severity of this lesion in exposed males and females was greater than that in the controls. The incidences of renal tubule pigmentation in all exposed groups of males and females at 12 months and 2 years were significantly greater than those in the controls. Squamous cell carcinomas of the tongue were observed in one 500 ppm male at 12 months and one 5,000 ppm female at 2 years, and one squamous cell carcinoma of the oral mucosa was observed in each group of exposed males and in one 5,000 ppm female at 2 years. At 2 years, squamous cell papillomas were observed in the oral cavity (oral mucosa or tongue) of one control, one 500 ppm, two 1,700 ppm, and four 5,000 ppm males; this lesion was also observed in one control and one 500 ppm female. GENETIC TOXICOLOGY: Results of mutagenicity tests with D&C Yellow No. 11 in Salmonella typhimurium were equivocal in one study, based on responses observed in strain TA100 with induced rat liver S9, and weakly positive in a second study, based on responses observed in strains TA98 and TA100 with induced rat or hamster liver S9. D&C Yellow No. 11 induced sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells, with and without S9. No increase in the frequency of micronucleated normochromatic erythrocytes was observed in peripheral blood samples from male and female B6C3F(1) mice administered D&C Yellow No. 11 in feed for 13 weeks. CONCLUSIONS: Under the conditions of this perinatal exposure followed by a 2-year dosed feed study, there was some evidence of carcinogenic activity of D&C Yellow No. 11 in male F344/N rats based on increased incidences of hepatocellular adenoma, renal tubule neoplasms, and squamous cell neoplasms of the oral cavity. There was some evidence of carcinogenic activity in female F344/N rats based on increased inci dences of hepatocellular neoplasms. Incidences of uncommon squamous cell carcinoma of the oral cavity in females may have been related to chemical treatment. Exposure of rats to D&C Yellow No. 11 in feed for 2 years resulted in increased incidences of nonneoplastic liver lesions including clear cell foci, increased basophilia and granularity in the cytoplasm of hepatocytes, and bile duct, hepatocyte, and Kupffer cell pigmentation in males and females and mixed cell foci in males. In the kidney, there were increased incidences of renal tubule pigmentation and transitional epithelial hyperplasia in males and females and renal tubule hyperplasia in males. The severity of nephropathy was increased in exposed males and females. Synonyms: 2-(2-Quinolinyl)-1H-indene-1,3-(2H)-dione; 2-(2-quinolyl)-1,3-indandione Trade names: Arlosol Yellow S, Chinoline Yellow D (soluble in spirits), Chinoline Yellow ZSS, C.I. 47000, C.I. Solvent Yellow 33, Nitro Fast Yellow SL, Oil Yellow SIS, Petrol Yellow C, Quinoline Yellow A Spirit Soluble, Quinoline Yellow Base, Quinoline Yellow Spirit Soluble, Quinoline Yellow SS, Solvent Yellow 33, Waxoline Yellow T

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