Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0001430 (adenoma)
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Methyleugenol is used as a flavoring agent in jellies, baked goods, nonalcoholic beverages, chewing gum, candy, pudding, relish, and ice cream. It is also used as a fragrance in perfumes, creams, lotions, detergents, and soaps. Methyleugenol has also been used as an insect attractant in eradication programs and as an anesthetic in rodents. Methyleugenol was nominated for testing because of its widespread use and because of its structural resemblance to safrole, a known carcinogen, and isosafrole and estragole. Male and female F344/N rats and B6C3F1 mice received methyleugenol (approximately 99% pure) in 0.5% methylcellulose by gavage for 14 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse peripheral blood erythrocytes. 14-WEEK STUDY IN RATS: Groups of 9 or 10 male and 10 female F344/N rats were administered 0, 10, 30, 100, 300, or 1,000 mg methyleugenol/kg body weight in 0.5% methylcellulose by gavage 5 days per week for 14 weeks. A water control group of 10 male and 10 female rats received deionized water by gavage. All rats survived until the end of the study. The final mean body weights of 300 and 1,000 mg/kg males and of all dosed groups of females were significantly less than those of the vehicle controls. Erythrocyte microcytosis was demonstrated by decreased mean cell volumes in 300 mg/kg males and 1,000 mg/kg males and females. There was evidence of a thrombocytosis at all time points, demonstrated by increased platelet counts in the 100 mg/kg or greater groups. The serum activities of alanine aminotransferase and sorbitol dehydrogenase were increased in the 100 mg/kg or greater rats at various time points, suggesting hepatocellular injury. Additionally, bile acid concentrations were generally increased in the 300 and 1,000 mg/kg groups at all time points, consistent with cholestasis or altered hepatic function. A hypoproteinemia and hypoalbuminemia, evidenced by decreased total protein and albumin concentrations, occurred in rats in the 300 and 1,000 mg/kg groups at all time points. Liver weights of 100, 300, and 1,000 mg/kg males and 300 and 1,000 mg/kg females and testis weights of 1,000 mg/kg males were significantly increased. Increased incidences of liver lesions occurred in 300 and 1,000 mg/kg males and females and hepatocellular adenoma occurred in one 1,000 mg/kg male. The incidences of atrophy and chronic inflammation of the mucosa of the glandular stomach were significantly increased in rats administered 300 or 1,000 mg/kg. Increased incidences of adrenal gland cortical hypertrophy and/or cytoplasmic alteration in the submandibular gland occurred in the 100 mg/kg or greater groups. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice received methyleugenol in 0.5% methylcellulose by gavage at doses of 0, 10, 30, 100, 300, or 1,000 mg/kg, 5 days per week for 14 weeks. A water control group of 10 male and 10 female mice received deionized water by gavage. All but one male and all females receiving 1,000 mg/kg died before the end of the study. The mean body weight gains of mice in the 300 mg/kg groups were significantly less than those of the vehicle controls. The only clinical finding was toxicity manifested as generalized morbidity in mice administered 1,000 mg/kg. Liver weights of 30, 100, and 300 mg/kg males and of 300 mg/kg females were significantly increased. Male mice administered 10 or 30 mg/kg had significantly lower cauda epididymis, epididymis, and testis weights; males receiving 100 mg/kg had significantly lower spermatozoal concentrations. Increased incidences of liver lesions occurred in 1,000 mg/kg males and 300 and 1,000 mg/kg females. The incidences of lesions of the glandular stomach were increased in one or more groups administered 30 mg/kg or greater. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats received methyleugenol in 0.5% methylcellulose by gavage at doses of 37, 75, or 150 mg/kg, 5 days per week for 105 weeks; groups of 60 male and 60 female rats received the 0.5% me60 female rats received the 0.5% methylcellulose vehicle only. Stop-exposure groups of 60 male and 60 female rats received 300 mg/kg in 0.5% methylcellulose by gavage for 52 weeks followed by just the 0.5% methylcellulose vehicle for the remaining 53 weeks of the study. Special study groups of 10 male and 10 female rats administered 36, 75, 150, or 300 mg/kg were designated for toxicokinetic studies. Survival and Body Weights: All 150 and 300 mg/kg males died before the end of the study, and survival of 150 mg/kg females was slightly less than that of the vehicle controls. Mean body weights of all dosed groups of rats were less than those of the vehicle controls throughout most of the 2-year study. Pathology Findings: Chemical-related liver neoplasms occurred in all dosed groups of rats and included hepatocellular adenoma, hepatocellular carcinoma, hepatocholangioma, and hepatocholangiocarcinoma; at 2 years, there were positive trends in the incidences of hepatocellular adenoma, carcinoma, and adenoma or carcinoma (combined) in core study rats and in the numbers of rats with multiple liver neoplasms. Nonneoplastic lesions included eosinophilic and mixed cell foci, hepatocellular hypertrophy, oval cell hyperplasia, cystic degeneration, and bile duct hyperplasia (females); the incidences of these lesions in dosed groups of male and female rats were increased at 6 months, 12 months, and/or 2 years. Chemical-related neoplasms and nonneoplastic lesions of the glandular stomach included benign and malignant neuroendocrine tumors in the 150 and 300 mg/kg groups and females in the 75 mg/kg group. In all dosed groups of rats at all time points, the incidences of mucosal atrophy were significantly greater than in the vehicle controls. Neuroendocrine cell hyperplasia was observed in females at 6 months and males and females at 12 months and at 2 years. In core study female rats, there was a positive trend in the incidences of squamous cell papilloma or carcinoma (combined) of the forestomach, and the incidence in the 150 mg/kg group exceeded the historical control range. The incidences of renal tubule proliferative lesions in male rats were suggestive of a neoplastic effect in the kidney. Therefore, additional step sections of the kidneys of male rats were prepared. The incidences of renal tubule hyperplasia and adenoma in the extended evaluation and the combined incidences of standard and step sections in the 75, 150, and 300 mg/kg groups were greater than those in the vehicle controls. The incidences of nephropathy were increased in all dosed groups of females, and the increase was significant in the 300 mg/kg group. In dosed groups of male rats, there was a positive trend in the incidences of malignant mesothelioma, and the incidences were significantly greater in 150 and 300 mg/kg males than in the vehicle controls. The incidences of mammary gland fibroadenoma in 75 and 150 mg/kg males were significantly increased. The incidences of fibroma of the subcutaneous tissue in 37 and 75 mg/kg males and the combined incidences of fibroma or fibrosarcoma in 37, 75, and 150 mg/kg males were significantly increased. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice received methyleugenol in 0.5% methylcellulose by gavage at doses of 0, 37, 75, or 150 mg/kg for 105 weeks. Special study groups of 10 male and 10 female mice administered 37, 75, or 150 mg/kg were designated for toxicokinetic studies. Survival and Body Weights: Survival of all dosed groups of male mice was similar to that of the vehicle controls. Survival of dosed groups of females was significantly less. Mean body weights of dosed mice were generally less than those of the vehicle controls throughout the studies. Pathology Findings: Chemical-related increases in the incidences of liver neoplasms and nonneoplastic lesions in mice included hepatocellular adenoma and carcinoma, hepatoblastoma, hepatocholangiocarcinoma, eosinophilic foci, oval cell hyperplasia, bile duct hyperplasia, hemosiderin pigmentation, chronic active inflammation, and hematopoietic cell proliferation. In all dosed groups ofmales and females, the incidences of hepatocellular neoplasms and the multiplicity of neoplasms were generally greater than in the vehicle controls. The incidences of hepatoblastoma were significantly increased in all dosed groups of females and slightly increased in 150 mg/kg males. Hepatocholangiocarcinoma was observed in 150 mg/kg females. The incidences of eosinophilic foci, oval cell hyperplasia, portal hypertrophy, hepatocyte necrosis, hematopoietic cell proliferation, bile duct hyperplasia, and hemosiderin pigmentation were significantly increased in two or more dosed groups of male and/or female mice. The incidences of glandular ectasia, mucosal atrophy, chronic active inflammation, epithelial hyperplasia, and neuroendocrine cell hyperplasia of the glandular stomach were increased in one or more dosed groups of male and female mice. In addition, malignant neuroendocrine tumors were observed in the glandular stomach of two 150 mg/kg male mice; one male in this group had a carcinoma. TOXICOKINETIC STUDIES: Methyleugenol is rapidly absorbed following oral administration to rats and mice. The kinetic data are consistent with rapid clearance from the blood, metabolism in the liver, and excretion of the parent and various metabolites in the urine. GENETIC TOXICOLOGY: Methyleugenol was not mutagenic in S. typhimurium strain TA98, TA100, TA1535, or TA1537, with or without exogenous metabolic activation (S9). In cytogenetic tests with cultured Chinese hamster ovary cells, methyleugenol induced sister chromatid exchanges in the presence of S9, but no induction of chromosomal aberrations was noted in cultured Chinese hamster ovary cells following exposure to methyleugenol, with or without S9. In vivo, no increase in the frequency of micronucleated normochromatic erythrocytes was seen in male or female mice administered methyleugenol by gavage for 14 weeks. PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL: A physiologically based pharmacokinetic (PBPK) model resulting from intravenous and oral exposure was created to characterize tissue concentrations of methyleugenol in rats and mice. Data used to create the model were obtained from the literature or from current studies. The primary conclusions that can be reached from the PBPK model are: 1) absorption of oral doses of methyleugenol in rats and mice is rapid and complete, 2) distribution of methyleugenol to tissues is not hampered by capillary permeability, and 3) metabolism of methyleugenol is saturable and must have some extrahepatic component in the mouse. Model-based plasma methyleugenol concentrations were not found to be good dosimeters for evaluating neoplasm dose-response data. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity of methyleugenol in male and female F344/N rats based on the increased incidences of liver neoplasms and neuroendocrine tumors of the glandular stomach in male and female rats and the increased incidences of kidney neoplasms, malignant mesothelioma, mammary gland fibroadenoma, and subcutaneous fibroma and fibroma or fibrosarcoma (combined) in male rats. A marginal increase in the incidence of squamous cell neoplasms of the forestomach may have been related to methyleugenol administration in female rats. There was clear evidence of carcinogenic activity of methyleugenol in male and female B6C3F1 mice based on the increased incidences of liver neoplasms. Neuroendocrine tumors of the glandular stomach in male mice were also considered related to methyleugenol administration. In male and female rats and mice, methyleugenol administration caused significant increases in nonneoplastic lesions of the liver and glandular stomach. Synonyms: 1-Allyl-1,2-dimethoxybenzene; 4-allylveratrole; 4-allyl-1,2-dimethoxy-benzene; 1,2-dimethoxy-4-allylbenzene; 3,4-dimethoxyallylbenzene; ENT 21040; 1-(3,4-dimethoxyphenyl)-2-propene; eugenol methyl ether; 1,3,4-eugenol methyl ether; veratrole methyl ether.
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PMID:NTP Toxicology and Carcinogenesis Studies of Methyleugenol (CAS NO. 93-15-2) in F344/N Rats and B6C3F1 Mice (Gavage Studies). 1256 49

Primidone is used alone or with other anticonvulsants in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy. Primidone was nominated by the National Cancer Institute for 2-year toxicology and carcinogenicity studies due to its human use as an anticonvulsant. Male and female F344/N rats and B6C3F1 mice received primidone (greater than 99% pure) in feed for 14 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse bone marrow cells. 14-DAY STUDY IN RATS: Five male and five female rats were exposed to 0, 1,250, 2,500, 5,000, 10,000 or 20,000 ppm primidone (equivalent to average daily doses of approximately 120, 240, 500, 970, or 1,100 mg primidone/kg body weight to males and 120, 240, 500, or 900 mg/kg to females) in feed for 14 days. All 20,000 ppm females died before the end of the study as did one 10,000 ppm male and two 20,000 ppm males. The mean body weights of 10,000 ppm males and females and 20,000 ppm males were significantly less than those of the controls. Feed consumption by all exposed rats was generally similar to that by the controls. Males and females in the 10,000 and 20,000 ppm groups were observed to have eye discharge, ataxia, and abnormal posture and were thin and lethargic. 14-DAY STUDY IN MICE: Five male and five female mice were exposed to 0, 625, 1,250, 2,500, 5,000 or 10,000 ppm primidone (equivalent to average daily doses of approximately 100, 200, 400, or 800 mg/kg body weight to males and 100, 250, 500, or 900 mg/kg to females) in feed for 14 days. All mice in the 10,000 ppm groups and one male and one female mouse in the 5,000 ppm groups died on day 3 of the study. The mean body weights of mice in the 625, 1,250, 2,500, and 5,000 ppm groups were similar to those of the controls. Feed consumption by all exposed mice was generally similar to that by the controls. Males and females in the 10,000 ppm groups were observed to have abnormal posture, ataxia, and lethargy. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to 0, 300, 600, 1,300, 2,500, or 5,000 ppm primidone (equivalent to average daily doses of approximately 20, 40, 100, 200, or 400 mg/kg) in feed for 14 weeks. All rats survived to the end of the study. The mean body weights of male and female rats in the 2,500 and 5,000 ppm groups were significantly less than those of the controls. Feed consumption by all exposed rats was generally similar to that by the controls. A minimal to mild exposure-related thrombocytosis occurred on day 22 and at week 14 in all exposed groups of male rats and in females in the 1,300 ppm or greater groups. A minimal decrease in hemoglobin concentration occurred in 2,500 and 5,000 ppm male and female rats on day 22 and at week 14. The incidences of centrilobular hepatocyte hypertrophy in male rats exposed to 600 ppm or greater and in female rats exposed to 1,300 ppm or greater were significantly greater than those in the controls. The severity of chronic nephropathy in male rats exposed to 1,300 ppm or greater increased with increasing exposure concentration. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to 0, 300, 600, 1,300, 2,500, or 5,000 ppm primidone (equivalent to average daily doses of approximately 50, 100, 200, 400, or 1,000 mg/kg to males and 60, 120, 220, 440, or 1,100 mg/kg to females) in feed for 14 weeks. Three male and two female mice in the 5,000 ppm group died during week 1 of the study. The final mean body weights of all exposed groups were similar to those of the controls. Feed consumption by male mice in the 5,000 ppm group was slightly greater than that by the controls; this may have been due to feed spillage. Male and female mice in the 5,000 ppm groups were ataxic and lethargic. Compared to controls, the estrous cycle lengths of females exposed to 1,300, 2,500, or 5,000 ppm were significantly longer. The liver weights of male and female mice exposed to 600 po 600 ppm or greater were significantly greater than those of the controls. The incidences of centrilobular hepatocyte hypertrophy in all exposed males and in females exposed to 600 ppm or greater and the incidences of cytoplasmic alteration of the adrenal gland and hematopoietic cell proliferation of the spleen in 2,500 and 5,000 ppm males and in 5,000 ppm females were significantly greater than in the controls. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 600, 1,300, or 2,500 ppm primidone (equivalent to average daily doses of approximately 25, 50, or 100 mg/kg) in feed for 2 years. Survival, Body Weights, and Feed Consumption Survival of the 1,300 and 2,500 ppm males was sig nificantly less than that of the controls. The mean body weights of males and females in the 2,500 ppm groups were less than those of the controls, beginning at week 29 for males and week 17 for females; the mean body weights of 1,300 ppm males and females were less than those of the controls during the second year of the study. Feed consumption by all exposed groups of rats was generally similar to that by the controls. Pathology Findings Male rats exposed to primidone had increased inci dences of thyroid gland follicular cell neoplasms (adenoma and/or carcinoma). All exposed groups of male rats had follicular cell adenomas or carcinomas (combined) at incidences above the historical control range, with the highest incidence in the 1,300 ppm group. Hepatocyte cytoplasmic vacuolation and centrilobular hypertrophy were associated with primidone exposure in male and female rats. These changes were more severe in females than in males and the incidences in all exposed groups of females were significantly greater than those in the controls. Females in the 2,500 ppm group had an increased incidence of hepatocellular eosinophilic foci. In 2,500 ppm males, the incidence of renal tubule hyperplasia was greater than that in the controls in the standard evaluation. Additional hyperplasias were found in the extended evaluation, and the incidences in exposed groups of males were significantly greater than that in the controls. In the extended evaluation, the incidence of renal tubule adenoma in 2,500 ppm males was significantly increased. The incidence of adenoma or carcinoma (combined) in 2,500 ppm males in the combined standard and extended evaluations were marginally increased over those in the controls. Male rats had an exposure-related increase in the severity of chronic nephropathy, which probably accounted for the reduced survival in the 1,300 and 2,500 ppm groups. The incidences of kidney cysts were increased in 1,300 and 2,500 ppm males. Hyperparathyroidism, secondary to the loss of renal function, was present in many exposed male rats. The incidences of parathyroid gland hyperplasia in all groups of exposed males were significantly greater than that in the controls. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to dietary levels of 0, 300, 600, or 1,300 ppm primidone (equivalent to average daily doses of approximately 30, 65, or 150 mg/kg to males and 25, 50, or 100 mg/kg to females) in feed for 2 years. Survival, Body Weights, Feed Consumption, and Clinical Findings Survival of the 1,300 ppm males was significantly less than that of the controls. During the second year of the study, the mean body weights of 1,300 ppm male and female mice were less than those of the controls. The final mean body weights of 600 ppm males and females were less than those of the controls. Feed consumption by all exposed groups of mice was similar to that by the controls. During the latter part of the study, a treatment-related increase in the number of animals with swelling of the abdominal area was observed; necropsy revealed that the swelling was due to liver nodules/masses. Pathology Findings The liver was a target organ in both male and female mice. The incidences and multiplicities of hepatocellular neoplasms (hepatocellular adenoma, hepatocellular carcinoma, and hepatoblastoma) in all exposed groups of males and females (except hepatoblastoma in females) were significantly greater than those in the controls. The incidences of hepatocellular adenoma or carcinoma (combined) and hepatocellular adenoma, hepatocellular carcinoma, or hepatoblastoma (combined) in all exposed groups exceeded the historical control ranges in 2-year NTP studies. The incidences of centrilobular hepatocyte hypertrophy were increased in exposed groups of males and females, and the severities increased with increasing exposure concentration. The incidences of cytoplasmic vacuolization were increased in all exposed groups of females and in 300 ppm males. Incidences of eosinophilic focus in all exposed groups of females were significantly greater than those in the controls. Proliferative changes occurred in the thyroid gland in an exposure-related manner in male and female mice. Incidences of follicular cell hyperplasia were increased in all exposed groups of males and in 600 and 1,300 ppm females, but incidences of follicular cell adenomas were increased only in male mice. GENETIC TOXICOLOGY: Primidone was mutagenic in Salmonella typhimurium strain TA1535 in the absence of S9 activation only; no mutagenicity was detected in strain TA98, TA100, or TA1537, with or without S9. Primidone did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells, with or without S9. The single in vivo study with primidone, a mouse bone marrow micronucleus test, also gave negative results. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was equivocal evidence of carcinogenic activity of primidone in male F344/N rats based on a marginal increase in thyroid gland follicular cell neoplasms, primarily adenomas, and a marginal increase in renal tubule neoplasms. There was no evidence of carcinogenic activity of primidone in female F344/N rats exposed to 600, 1,300, or 2,500 ppm. There was clear evidence of carcinogenic activity of primidone in male B6C3F1 mice based on the increased incidences of hepatocellular neoplasms, and the increased incidence of thyroid gland follicular cell adenomas was also considered to be chemical related. There was clear evidence of carcinogenic activity of primidone in female B6C3F1 mice based on the increased incidences of hepatocellular neoplasms. Exposure of rats to primidone resulted in increased incidences of hepatocyte cytoplasmic vacuolization and centrilobular hypertrophy in males and females and eosinophilic foci in females. The increased severity of nephropathy and increased incidence of renal tubule hyperplasia in male rats were related to primidone exposure. Exposure of male mice to primidone resulted in hepatocyte centrilobular hypertrophy and thyroid gland follicular cell hyperplasia. Exposure of female mice to primidone resulted in hepatocyte centrilobular hypertrophy and cytoplasmic vacuolization, eosinophilic focus, and thyroid gland follicular cell hyperplasia. Synonyms: 5-Aethyl-5-phenyl-hexahydropyrimidin-4,6-dion; 2-deoxyphenobarbital; 2-desoxyphenobarbital; desoxyphenobarbitone; 5-ethyldihydro-5-phenyl-4,6 (1H,5H)-pyrimidinedione; 5-ethylhexahydro-4,6-dioxo-5-phenylphrimidine; 5-ethylhexahydro-5-phenylpyrimidine-4,6-dione; 5-ethyl-5-phenylhexahydropyrimidine-4,6-dione Trade names: Cyral; Hexadiona; Hexamidine; Lepimidin; Lepsiral; Majsolin; Midone; Milepsin; Misodine; Misolyne; Mizodin; Mizolin; Mylepsin; Mylepsinum; Mysedon; Mysoline; Prilepsin; Primacione; Primaclone; Primacone; Primakton; Primadon; Prysoline; Pyrimidone; ROE 101; Sertan
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PMID:NTP Toxicology and Carcinogenesis Studies of Primidone (CAS No. 125-33-7) in F344/N Rats and B6C3F1 Mice (Feed Studies). 1257 87

Nitromethane is used as a rocket and engine fuel; as a synthesis intermediate for agricultural fumigants, biocides, and other products; as a solvent; and as an explosive in mining, oil-well drilling, and seismic exploration. It has been detected in air, in surface and drinking water, and in cigarette smoke. Nitromethane was studied because of the potential for widespread human exposure and because it is structurally related to the carcinogens 2-nitropropane and tetranitromethane. Male and female F344/N rats and B6C3F1 mice received nitromethane (purity 98% or greater) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and peripheral blood erythrocytes of mice. 16-DAY STUDY IN RATS: Groups of five male and five female rats were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 16 days. All rats survived until the end of the study. The mean body weight gain of male rats in the 1,500 ppm group was slightly but significantly less than that of the controls; the final mean body weights and mean body weight gains of exposed females were similar to those of the controls. Clinical findings in all male and female rats in the 1,500 ppm groups included increased preening, rapid breathing, hyperactivity early in the study, and hypoactivity and loss of coordination in the hindlimbs near the end of the study. The relative liver weights of all exposed groups of male rats and the absolute and relative liver weights of females exposed to 375 ppm or greater were significantly greater than those of the controls. Minimal to mild degeneration of the olfactory epithelium was observed in the nose of males and females exposed to 375 ppm or greater. Sciatic nerve degeneration was present in all male and female rats exposed to 375 ppm or greater; rats exposed to 750 or 1,500 ppm also had reduced myelin around sciatic axons. 16-DAY STUDY IN MICE: Groups of five male and five female mice were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 16 days. All mice survived to the end of the study. The final mean body weights and weight gains of exposed males and females were similar to those of the controls. Clinical findings included hypoactivity and tachypnea in male and female mice in the 1,500 ppm groups. Absolute and relative liver weights of male mice in the 750 and 1,500 ppm groups and female mice in all exposed groups and the relative liver weight of males in the 375 ppm group were significantly greater than those of the controls. Degeneration of the olfactory epithelium of the nose was observed microscopically in all males and females exposed to 375 ppm or greater; this lesion was of minimal severity in males and minimal to mild severity in females. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 13 weeks. All rats survived to the end of the study. The final mean body weight and weight gain of male rats in the 1,500 ppm group were significantly less than those of the controls. Clinical findings included hindlimb paralysis in rats in the 750 and 1,500 ppm groups. Inhalation exposure of rats to nitromethane resulted in an exposure concentration-dependent, microcytic, responsive anemia; anemia was most pronounced in males and females exposed to 375 ppm or greater. The presence of schistocytes, Heinz bodies, and spherocytes and increased mean cell hemoglobin concentration and methemoglobin concentration were evidence that a hemolytic process was occurring; this hemolytic process could have accounted, in part, for the anemia. Thrombocytosis accompanied the anemia and would be consistent with a reactive bone marrow or could have been due to the erroneous inclusion of small erythrocyte fragments as part of the platelet count. On day 23, transient decreases in serum triiodothyronine, thyroxine, and fr and free thyroxine were observed in male rats exposed to 375 ppm or greater and female rats exposed to 750 or 1,500 ppm. There was little or no pituitary response to the thyroid hormone decreases, as evidenced by the lack of significantly increased concentrations of thyroid-stimulating hormone in exposed rats. No biologically significant differences in organ weights were observed. The forelimb and hindlimb grip strengths of males in the 1,500 ppm group were significantly less than those of the controls. The hindlimb grip strengths of females in the 750 and 1,500 ppm groups were also significantly less than the control value. Minimal to mild hyperplasia of the bone marrow was observed microscopically in male rats in the 750 and 1,500 ppm groups and in females exposed to 188 ppm or greater. Nasal lesions in exposed males and females included olfactory epithelial degeneration in males and females exposed to 375 ppm or greater and in one female exposed to 188 ppm and respiratory epithelial hyaline droplets and goblet cell hyperplasia in males and females in the 750 and 1,500 ppm groups; the severity of nasal lesions in males and females was minimal to mild. Males and females exposed to 375 ppm or greater had minimal to mild degeneration of the sciatic nerve and the lumbar spinal cord. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to 0, 94, 188, 375, 750, or 1,500 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 13 weeks. All mice survived to the end of the study. The final mean body weights and weight gains of exposed mice were generally similar to those of the controls. There were no treatment-related clinical findings. The absolute right kidney weights of all groups of exposed male mice except the 1,500 ppm group and of females exposed to 188 ppm or greater and the relative right kidney weights of all groups of exposed males and of females in the 750 and 1,500 ppm groups were significantly greater than those of the controls. The absolute liver weight of male mice in the 750 ppm group and the relative liver weights of males exposed to 375 ppm or greater were significantly greater than those of the controls. Olfactory epithelial degeneration and respiratory epithelial hyaline droplets were observed microscopically in all male and female mice exposed to 375 ppm or greater. Degeneration also occurred in females in the 188 ppm group, and hyaline droplets occurred in females in the 94 and 188 ppm groups. The average severity of the nasal lesions ranged from minimal to mild in males. In females, the average severity of olfactory epithelial degeneration ranged from minimal to mild and the severity of respiratory epithelial hyaline droplets ranged from minimal to moderate. All males and nine females in the 1,500 ppm groups also had minimal extramedullary hematopoiesis of the spleen. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to 0, 94, 188, or 375 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 103 weeks. Survival,Body Weights, and Clinical Findings: There were no significant differences in survival rates between exposed and control male or female rats. The mean body weight of females in the 375 ppm group was slightly greater than that of the control group; the mean body weights of exposed males were generally similar to the mean body weight of the controls throughout the study. Clinical findings were consistent with incidences of mammary gland neoplasms in females exposed to 188 or 375 ppm; no hindlimb paralysis, as occurred in rats in the 13-week study, was observed in male or female rats in the 2-year study. Pathology Findings: The incidences of mammary gland fibroadenoma and fibroadenoma, adenoma, or carcinoma (combined) in female rats in the 188 and 375 ppm groups were significantly greater than those in the controls. Additionally, the incidences of mammary gland carcinoma in the 375 ppm group were significantly greater than those in the controls. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to 0, 188, 375, or 750 ppm nitromethane by inhalation, 6 hours per day, 5 days per week, for 103 weeks. Survival,Body Weights, and ClinicalFindings The survival rate of females in the 750 ppm group was marginally greater than that of the controls. The mean body weights of exposed females were generally slightly greater than the mean body weights of the controls during the study but were generally similar to the mean body weight of the controls at the end of the study. The mean body weights of exposed males were similar to those of the controls throughout the study. Clinical findings included swelling around the eyes and exophthalmos in exposed males and females; these findings were coincident with harderian gland neoplasms. Pathology Findings: The incidences of harderian gland adenoma and adenoma or carcinoma (combined) in exposed mice increased with increasing exposure concentration and were significantly greater in males and females in the 375 and 750 ppm groups than those in the controls. The incidences of harderian gland carcinoma in males and females in the 375 and 750 ppm groups were also slightly greater than those in the controls. Female mice in the 188 and 750 ppm groups had significantly greater incidences of hepatocellular adenoma and hepatocellular adenoma or carcinoma (combined) than the controls. The incidences of liver eosinophilic focus increased with increasing exposure concentration, and the incidences in the 375 and 750 ppm groups were significantly greater than the control incidence. The incidences of alveolar/bronchiolar carcinoma in male mice in the 750 ppm group and female mice in the 375 ppm group were significantly greater than those in the controls. Females in the 750 ppm group also had a significantly greater incidence of alveolar/bronchiolar adenoma or carcinoma (combined) and a slightly greater incidence of alveolar/bronchiolar adenoma than the controls. Females in the 375 ppm group had a significantly greater incidence of cellular infiltration of histiocytes in the lung than the controls. The incidences of degeneration and metaplasia of the olfactory epithelium and hyaline degeneration of the respiratory epithelium were significantly greater in exposed male and female mice than those in the controls. Additionally, males in the 375 and 750 ppm groups had significantly greater incidences of inflammation of the nasolacrimal duct than did the controls. GENETIC TOXICOLOGY: Nitromethane was not mutagenic in any tests performed by the NTP. It did not induce mutations in Salmonella typhimurium, with or without S9 metabolic activation, and no induction of sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells exposed to nitromethane was noted with or without S9. No increase in the frequency of micronucleated erythrocytes was observed in peripheral blood samples of male and female mice at the end of the 13-week inhalation study of nitromethane. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of nitromethane in male F344/N rats exposed to 94, 188, or 375 ppm. There was clear evidence of carcinogenic activity of nitromethane in female F344/N rats based on increased incidences of mammary gland fibroadenomas and carcinomas. There was clear evidence of carcinogenic activity of nitromethane in male B6C3F1 mice based on increased incidences of harderian gland adenomas and carcinomas. There was clear evidence of carcin ogenic activity in female B6C3F1 mice, based on increased incidences of liver neoplasms (primarily adenomas) and harderian gland adenomas and carcinomas. Increased incidences of alveolar/bronchiolar adenomas and carcinomas in male and female mice exposed to nitromethane were also considered to be related to chemical administration. Exposure to nitromethane by inhalation for 2 years resulted in increased incidences of nasal lesions including degeneration and metaplasia of the olfactory epithelium and degeneration of the respiratory epithelium in male and female mice. Synonym: Nitrocarbol
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PMID:NTP Toxicology and Carcinogenesis Studies of Nitromethane (CAS No. 75-52-5) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). 1258 15

Estragole is a natural organic compound that is used as an additive, flavoring agent, or fragrance in a variety of food, cleaning, and cosmetic products; as an herbal medicine; as an antimicrobial agent against acid-tolerant food microflora; and to produce synthetic anise oil. Estragole was nominated for toxicity testing by the National Institute of Environmental Health Sciences to characterize its toxicity when administered by gavage to F344/N rats and B6C3F1 mice and to determine how similar its effects might be to those of the structurally related compound, methyleugenol. Male and female F344/N rats and B6C3F1 mice were given estragole (greater than 99% pure) in corn oil by gavage for 3 months. Genetic toxicology studies were conducted in Salmonella typhimurium and mouse peripheral blood erythrocytes. Core and special study (rats only) groups of 10 male and 10 female rats and mice were administered 37.5, 75, 150, 300, or 600 mg estragole/kg body weight in corn oil by gavage, 5 days per week. The core study groups were given estragole for 3 months and the special study groups for 30 days. All core study rats survived the 3-month exposure period. Mean body weights of the 300 and 600 mg/kg groups were 73% to 92%, respectively, of those of the vehicle control groups. A staining pattern on the ventral surface anterior to the genitalia beginning at week 9 in the 300 and 600 mg/kg groups was attributed to residue of estragole or metabolites in the urine. Alterations in the erythron related to estragole administration occurred in male and female rats; male rats demonstrated a stronger response. The changes in the erythron were characterized as a microcytic, normochromic, nonresponsive anemia. There were decreases in serum iron concentration in the 300 mg/kg females and 600 mg/kg males and females. The average percent saturation of total iron binding capacity was decreased in the 600 mg/kg males and females. Dose-related increases in platelet counts occurred in most of the dosed groups of rats; the effect appeared to be stronger in males. The increase could be consistent with a reactive thrombocytosis. Increases in the serum alanine aminotransferase and sorbitol dehydrogenase activities suggested a hepatocellular effect (increased leakage) and were consistent with the morphological liver changes observed. There were dose-related increases in serum bile salt concentration in most treated male rats at all time points; females were less affected. Absolute and relative liver weights were significantly increased in 300 and 600 mg/kg males and in 75 mg/kg or greater females. Relative kidney weights were significantly increased in all dosed groups of male rats and in female rats given 75 mg/kg or greater. Absolute and relative testis weights of 300 and 600 mg/kg males were significantly decreased. Two 600 mg/kg male rats had multiple cholangiocarcinomas in the liver and a third had an hepatocellular adenoma. All 600 mg/kg males exhibited cholangiofibrosis. All 75 mg/kg or greater males and all 150 mg/kg or greater females had hepatocellular hypertrophy. Incidences of bile duct hyperplasia, oval cell hyperplasia, and chronic periportal inflammation were significantly increased in all dosed groups. Incidences of basophilic and mixed cell foci were significantly increased in 150 mg/kg or greater males and females. Incidences of eosinophilic focus were significantly increased in 300 and 600 mg/kg males and 600 mg/kg females. Incidences of cellular infiltration of the periportal region by histiocytes increased significantly in all dosed groups of males and in 150 mg/kg or greater females. Incidences of bone marrow hyperplasia were significantly increased in 75, 300, and 600 mg/kg male rats. Incidences of renal tubule papillary mineralization were significantly increased in 300 mg/kg males and females and 600 mg/kg males. Incidences of cortical renal tubule pigmentation were significantly increased in 150 mg/kg or greater males, and the incidence of renal tubule regeneration was significantly increased in 600 mg/kg females. Incidences of degeneration of the olfactory epithelium in the nose were significantly increased in 300 and 600 mg/kg rats. Incidences of hypertrophied chromophobe cells in the pars distalis of the pituitary gland were significantly increased in 300 and 600 mg/kg males. Cytoplasmic alteration of the submandibular salivary gland occurred in all 75 mg/kg or greater rats. Incidences of atrophy of the gastric glands in the stomach were significantly increased in 150 mg/kg or greater rats. Bilateral degeneration of the germinal epithelium in the testes and bilateral hypospermia of the epididymis occurred in all 300 and 600 mg/kg males. In the special study, serum gastrin concentration and stomach pH were significantly increased in rats exposed to 600 mg/kg for 30 days. Gastric gland atrophy was significantly increased in the stomach of 300 and 600 mg/kg rats. Hepatic 7-pentoxyresorufin-O-deethylase activity was significantly increased in all exposed groups except 37.5 mg/kg females, and the increases were generally dose related. In the mouse core study, a 600 mg/kg male died during week 9, and all 600 mg/kg female mice died during week 1; the female deaths were attributed to liver necrosis caused by estragole exposure. Mean body weights of 300 and 600 mg/kg males and 75 mg/kg or greater females were 79% to 89% those of the vehicle control groups. Liver weights were generally increased in 75 mg/kg or greater males and in 300 mg/kg females. Relative thymus weights were significantly increased in all dosed groups of female mice. The incidences of hepatocellular hypertrophy and hepatocellular degeneration were significantly increased in 300 and 600 mg/kg male mice and 150 and 300 mg/kg female mice. Incidences of oval cell hyperplasia were significantly increased in 300 and 600 mg/kg males and in 75 mg/kg or greater females. Liver necrosis occurred in all 600 mg/kg female mice, along with a significant increase in the incidence of diffuse fatty change. In addition, 600 mg/kg females exhibited significant increases in the incidences of degeneration of the gastric glands of the glandular stomach, as well as squamous hyperplasia, mineralization, and ulcer in the forestomach. Degeneration of the olfactory epithelium in the nose occurred in all 300 and 600 mg/kg mice. Estragole was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 when tested in the presence or absence of exogenous metabolic activation enzymes. No increases in the frequencies of micronucleated normochromatic erythrocytes were observed in peripheral blood samples from male and female mice in the 3-month study. Under the conditions of these 3-month studies, estragole showed carcinogenic activity based on the occurrence of two cholangiocarcinomas and one hepatocellular adenoma in the liver of three of 10 male F344/N rats in the high dose group. Because rats and mice were exposed for only 3 months, these studies do not access the full carcinogenic potential of estragole. Nonneoplastic effects were observed in the liver, glandular stomach, nose, kidney, and salivary gland of male and female rats and in the testes, epididymides, and pituitary gland of male rats. Nonneoplastic effects were also observed in the liver and nose of male and female mice and in the stomach of female mice.
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PMID:NTP 3-month toxicity studies of estragole (CAS No. 140-67-0) administered by gavage to F344/N rats and B6C3F1 mice. 2144 3