UMLS:C0023418 - FACTA Search

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Butyl benzyl phthalate is a plasticizer added to polymers to give flexibility and softness. It is used extensively in polyvinyl chloride and in cellulose plastics, polyvinyl acetate, polysulfides, and polyurethane. Butyl benzyl phthalate was nominated as part of a class study of phthalates. Previous studies of butyl benzyl phthalate by the NTP (1982a) resulted in chemical-related mortality in male rats beginning at about 14 weeks of exposure and, thus, were inadequate for evaluating carcinogenicity in male rats. The companion studies revealed a marginal increase in leukemia in female rats and no evidence of carcinogenicity in B6C3F1 mice. Consequently, the present evaluations were conducted only in F344/N rats. Male and female F344/N rats were given butyl benzyl phthalate (at least 97% pure) in feed for 10 weeks, 26 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, L5178Y mouse lymphoma cells, cultured Chinese hamster ovary cells, mouse bone marrow cells, and Drosophila melanogaster. 10-WEEK MODIFIED MATING STUDY IN RATS: Groups of 15 male F344/N rats were given 0, 300, 2,800, or 25,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 20, 200, or 2,200 mg butyl benzyl phthalate/kg body weight) in feed for 10 weeks. All rats survived to the end of the study. The final mean body weight and body weight gain of the 25,000 ppm group were significantly less than those of the controls. Feed consumption by the 25,000 ppm group was less than that by the controls at the end of the study. A few minimal hematology changes occurred in the 25,000 ppm male rats. There was some evidence of a minimal anemia characterized by a decreased erythrocyte count and increases in mean cell hemoglobin and platelet count. The absolute and relative prostate gland weights of the 25,000 ppm males were significantly less than those of the controls. Degeneration of the seminiferous tubule germinal epithelium was observed in all males from the 25,000 ppm group. The absolute right cauda, right epididymis, and right testis weights of the 25,000 ppm males were significantly less than those of the controls. The epididymal spermatozoal concentrations in 2,800 and 25,000 ppm males were significantly less than that in the controls. Although 10 females mated to 25,000 ppm males were initially found to be sperm positive, none of these females were pregnant at necropsy. The fertility indices of males and females in the 25,000 ppm group were significantly lower than those of the controls. The maternal body weights of females mated to 300 and 2,800 ppm males were similar to those of females mated to control males. There were no significant differences in litter data between the controls and the 300 and 2,800 ppm groups. 26-WEEK STUDY IN RATS: Groups of 15 male F344/N rats were given 0, 300, 900, 2,800, 8,300, or 25,000 ppm butyl benzyl phthalate in feed for 26 weeks. Dietary levels of 300, 900, 2,800, and 8,300 ppm delivered average daily doses of approximately 30, 60, 180, and 550 mg butyl benzyl phthalate/kg body weight. The final mean body weight and body weight gain of the 25,000 ppm males were significantly less than those of the controls. Except for the 25,000 ppm males, feed consumption by all exposed groups was similar to that by the controls. An exposure-related macrocytic responsive anemia was present in the 25,000 ppm group at all time points. Additionally, minimal erythrocyte count decreases occurred sporadically in the 2,800 and 8,300 ppm groups at various time points. Reticulocyte counts were increased on days 60 and 90. Increases in mean cell hemoglobin and mean cell hemoglobin concentrations occurred in the 8,300 and 25,000 ppm rats. The absolute right cauda, right epididymis, and right testis weights and the sperm concentration of 25,000 ppm males were significantly less than those of the controls. The incidences of hypospermia and of atrophy of the seminiferous tubule in the testis and of hypospermia in the epididymis in 25,000 ppm males were significantly greater than those in the in the controls. Degenerative changes of the testis and epididymis in the 25,000 ppm males were qualitatively and quantitatively similar to those observed in males in the 10-week modified mating study. 2-YEAR STUDY IN RATS: Groups of 60 male F344/N rats were given 0, 3,000, 6,000, or 12,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 120, 240, or 500 mg butyl benzyl phthalate/kg body weight), and groups of 60 female F344/N rats were given 0, 6,000, 12,000, or 24,000 ppm butyl benzyl phthalate (equivalent to average daily doses of approximately 300, 600, or 1,200 mg/kg) in feed for 2 years. Survival, Body Weights, and Feed Consumption: Survival of all exposed groups of male and female rats was similar to that of the controls. Mean body weights of the 12,000 ppm males and 24,000 ppm females were less than those of the controls throughout most of the study. Feed consumption by the females exposed to 24,000 ppm was less than that by the controls at the beginning of the study, but was similar to that by the controls by week 6. Hematology and Hormone Assays: In general, hematology changes were sporadic and minor. At 6 months, a minimal decrease in erythrocyte count and an increase in mean cell hemoglobin, similar to that which occurred in the 26-week study, occurred in male rats in the 12,000 ppm group. In female rats, a decreased hematocrit value occurred at 15 months in the 24,000 ppm group. There was also a mild decrease in triiodothyronine concentrations in the 24,000 ppm females at 6 and 15 months and at the end of the study. Pathology Findings: of pancreatic acinar cell adenoma and adenoma or carcinoma (combined) in 12,000 ppm males were significantly greater than those in the controls. The incidences of adenoma and of adenoma or carcinoma (combined) in 12,000 ppm males exceeded the ranges of historical controls from NTP 2-year feed studies. One carcinoma was observed in one 12,000 ppm male, and two adenomas were observed in 24,000 ppm females. At 2 years, the incidence of focal hyperplasia of the pancreatic acinar cell in 12,000 ppm males was significantly greater than that in the controls. At 2 years, transitional epithelial papillomas in the urinary bladder were observed in one control female and in two 24,000 ppm females. The incidence of this neoplasm exceeded the range of historical controls from NTP 2-year feed studies. The incidence of transitional epithelial hyperplasia in 24,000 ppm females was significantly greater than that in the controls. The absolute right kidney weight of 12,000 ppm females and the relative right kidney weights of all exposed groups of males and of 24,000 ppm females were significantly greater than those of the controls at the 15-month interim evaluation. The severities of renal tubule pigmentation in 12,000 ppm males and in 24,000 ppm females were greater than those in the controls at 15 months and 2 years. At 2 years, the incidences of kidney mineralization in 6,000 and 24,000 ppm females were significantly less than that in the controls, and the severity was decreased in exposed females. The incidence of preputial gland adenoma or carcinoma (combined) in 12,000 ppm male rats was significantly less than in the controls, and the incidences occurred with a negative trend. GENETIC TOXICOLOGY: Results from in vitro mutagenicity tests with butyl benzyl phthalate were uniformly negative. No mutagenic response was obtained in any of several strains of Salmonella typhimurium treated with up to 11,550 mg/plate butyl benzyl phthalate, with or without S9 metabolic activation enzymes. Negative results were also obtained in in vitro studies of mammalian cell systems with and without S9. No induction of trifluorothymidine resistance in L5178Y mouse lymphoma cells or sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells were observed. These assays also were conducted with and without S9. No significant increase in sex-linked recessive lethal mutations was observed in germ cells of male Drosophila melanogaster after administration of butyl benzyl phthalate either in feed or by injection. In contrast to the negative results obtained in vitro and in Drosophila, butyl benzyl phthalate gave positive responses in two in vivo studies with mice. Results of a mouse bone marrow sister chromatid exchange test were positive at sample times of 23 and 42 hours, but no confirmatory test was conducted. Chromosomal aberrations were induced in bone marrow cells of male mice sampled 17 hours after intraperitoneal injection of 5,000 mg/kg butyl benzyl phthalate. CONCLUSIONS: Under the conditions of this 2-year feed study, there was some evidence of carcinogenic activity of butyl benzyl phthalate in male F344/N rats based on the increased incidences of pancreatic acinar cell adenoma and of acinar cell adenoma or carcinoma (combined). There was equivocal evidence of carcinogenic activity of butyl benzyl phthalate in female 344/N rats based on the marginally increased incidences of pancreatic acinar cell adenoma and of transitional epithelial papilloma of the urinary bladder. Exposure of rats to butyl benzyl phthalate in feed for 2 years resulted in focal hyperplasia in the pancreas in male rats and in transitional epithelial hyperplasia in the urinary bladder of female rats. Synonyms: A13-14777; BBP; 1,2-benzenedicarboxylic acid butyl phenylmethyl ester (9CI); benzyl n-butyl phthalate; n-butyl benzyl phthalate; butyl phenylmethyl 1,2-benzenedicarboxylate; NCI-C54375; phthalic acid benzyl butyl ester (8CI) Trade names: Palatinol BB; Santicizer 160; Sicol 160; Unimoll BB
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PMID:NTP Toxicology and Carcinogenesis Studies of Butyl Benzyl Phthalate (CAS No. 85-68-7) in F344/N Rats (Feed Studies). 1258 18

Salicylazosulfapyridine is widely used for the treatment of ulcerative colitis and Crohn's disease. It has been beneficial in the treatment of psoriasis and rheumatoid arthritis, and it has been used in veterinary medicine for the treatment of granulomatous colitis. Salicylazosulfapyridine was nominated for toxicity and carcinogenicity testing by the National Cancer Institute on the basis of its widespread use in humans and because it is a representative chemical from a class of aryl sulfonamides. Salicylazosulfapyridine is a suspect carcinogen because reductive cleavage of the azo linkage yields a p-amino aryl sulfonamide (sulfapyridine), and a related p-amino aryl sulfonamide (sulfamethoxazole) has been shown to produce thyroid neoplasms in rats. Toxicology and carcinogenicity studies were conducted in F344/N rats and B6C3F1 mice. Rats and mice were administered salicylazosulfapyridine (96% to 98% pure) in corn oil by gavage for 16 days, 13 weeks, or 2 years. The gavage route of administration was selected for these studies because it approximates the typical route of human exposure to the chemical. Genetic toxicology studies were conducted in vitro in Salmonella typhimurium and cultured Chinese hamster ovary cells and in vivo in rat and mouse bone marrow and mouse peripheral blood cells. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. All rats survived to the end of the study. With the exception of the 675 mg/kg male group, the final mean body weights of all dosed groups of males and females were significantly lower than those of controls. Mean body weight gains of all dosed groups were less than those of controls. Clinical findings included ruffled fur and distended abdomens in male and female rats receiving 2,700 mg/kg. Hypothyroidism, evidenced by decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentrations, occurred in 2,700 mg/kg male and female rats. The absolute and relative thymus weights of male rats receiving,350 or 2,700 mg/kg and female rats receiving 2,700 mg/kg were significantly lower than those of controls. At necropsy, all dosed rats had enlarged cecae/large intestines. Male rats receiving 1,350 mg/kg and male and female rats receiving 2,700 mg/kg had red, enlarged thyroid glands. Chemical-related microscopic lesions were present in the forestomach, thymus, thyroid gland, and pituitary gland. Minimal to mild hyperplasia of the forestomach mucosa was present in the 1,350 and 2,700 mg/kg male and female groups. Lymphoid depletion was observed in the thymus of three male and three female rats in the 2,700 mg/kg groups. Male and female rats receiving 1,350 and 2,700 mg/kg had thyroid gland follicular cell hyperplasia and an increase in thyroid-stimulating hormone producing cells in the pars distalis of the pituitary gland. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 16 days excluding weekends. There were no chemical-related deaths, and final mean body weights of dosed mice were similar to those of controls. No chemical-related clinical findings were noted for male or female mice. There were no differences in triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice. There were no biologically significant differences in absolute or relative organ weights between dosed and control male and female mice. At necropsy, male mice receiving 2,700 mg/kg had enlarged cecae/large intestines. There were no biologically significant histopathologic lesions attributed to salicylazosulfapyridine administration. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 0, 84, 168.8, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All rats survived to the end of the study. The finaludy. The final mean body weights of dosed male rats were similar to those of controls; the final mean body weights and body weight gains of dosed females were significantly lower than those of controls. No chemical-related clinical findings were noted in dosed male or female rats during the 13-week study. No significant differences in hematology or urinalysis parameters between control and dosed rats were observed. The absolute and relative right kidney weights of 337.5 mg/kg females were significantly greater than those of controls. At necropsy, some 337.5 mg/kg male rats had red, enlarged thyroid glands. Histopathologic changes were noted primarily in the thyroid gland and pituitary gland of males and females in the 337.5 mg/kg groups. The thyroid gland lesions observed were similar to those present in the 16-day study. Nine male rats receiving 168.8 mg/kg and ten male and seven female rats receiving.5 mg/kg had minimal but consistent changes in thyroid gland follicular cells. In the pituitary gland of 337.5 mg/kg males and females, the thyroid-stimulating hormone producing cells were enlarged and contained pale-staining cytoplasm and prominent Golgi complexes. Decreased serum triiodothyronine and thyroxine concentrations and increased thyroid-stimulating hormone concentration, similar to differences observed in the 16-day study, occurred in 337.5 mg/kg male rats; thyroid hormone concentrations were not affected in female rats. Sperm motility of all dosed groups of males was significantly lower than that of controls. Vaginal cytology parameters of dosed groups of females were similar to those of controls. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for 13 weeks. All mice survived to the end of the study. The final mean body weights of dosed male and female mice were similar to those of controls. The mean body weight gains of 1,350 and 2,700 mg/kg male mice were less than that of controls. No chemical-related clinical findings were noted in dosed male or female mice during the 13-week study. There was minimal evidence of a responsive anemia in mice in the 13-week study. The anemia was probably related to a methemoglobinemia. There were minimal decreases in thyroxine concentration in all dosed groups of male and female mice in the -week study. There were, however, no differences in triiodothyronine and thyroid-stimulating hormone concentrations between dosed and control animals. Absolute and relative liver weights of all groups of dosed male and female mice were significantly greater than those of controls. There were no chemical-related gross lesions. Microscopic evaluation of the liver revealed centrilobular hypertrophy in five 1,350 mg/kg and all 2,700 mg/kg male mice. The right cauda weight of the 1,350 mg/kg group and the right epididymis weights of all dose groups were significantly lower than those of controls. There was no evidence of chemical-related alteration in the vaginal cytology parameters of female mice. 2-YEAR STUDY IN RATS: Groups of 60 male and 60 female rats were administered 84, 168, or 337.5 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 105 weeks. Groups of 70 male and 60 female rats were administered the corn oil vehicle by gavage for up to 105 weeks. A stop-exposure group of 70 male rats was administered 337.5 mg/kg salicylazosulfapyridine in corn oil by gavage for 6 months, after which animals received the corn oil vehicle by gavage for the remainder of the 2-year study. Ten animals from the vehicle control male group and 10 animals from the 337.5 mg/kg stop-exposure group were evaluated at 6 months; animals from each core-study group were evaluated at 15 months. Survival, Body Weights, and Clinical Chemistry: Survival of 337.5 mg/kg male core-study rats was significantly lower than that of controls; survival of 84 and 168 mg/kg core-study males, all groups of dosed females, and the stop-exposure male group was similar to controls. Mean body weights of core-study males and stop-exposure males were similar to controls throughout the study. From week 45 to the end of the study, females in the 337.5 mg/kg group had mean body weights that were lower than those of controls. The serum thyroxine concentration in 337.5 mg/kg core-study males at study termination was minimally lower than that of controls; the serum thyroid-stimulating hormone, triiodothyronine, and reverse triiodothyronine concentrations of dosed males and females were similar to those of controls. Pathology Findings: Administration of salicylazosulfapyridine for 2 years was associated with transitional epithelial papilloma in the urinary bladder of male rats and may have been associated with transitional epithelial papilloma of the kidney and of the urinary bladder of female rats. Nonneoplastic effects in the urinary bladder and kidney of male and female rats and in the spleen of male rats were also observed. Dosed male and female rats had increased incidences of grossly and microscopically observed urinary bladder concretions (diagnosed grossly as calculi at necropsy); male and female rats that developed transitional epithelial papillomas of the urinary bladder had grossly observed concretions (calculi) in the urinary bladder at necropsy. The microscopic neoplastic and nonneoplastic urinary bladder and kidney effects observed in dosed male rats during the 2-year continuous study did not occur in dosed rats during the 2-year stop-exposure study, nor were there gross observations of concretions (calculi) at necropsy. The incidences of mononuclear cell leukemia in male and female rats were decreased. The thyroid gland hyperplasia seen in the -week study was not observed in the 2-year study, and there was no evidence of chemical-related thyroid gland follicular cell adenomas or carcinomas. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice were administered 0, 675, 1,350, or 2,700 mg salicylazosulfapyridine/kg body weight in corn oil by gavage for up to 104 weeks. Ten animals from each group were evaluated at 15 months. Survival, Body Weights,and Clinical Chemistry: Survival of all the dosed groups of male and female mice was similar to that of controls. Mean body weights of 675 and 1,350 mg/kg male and female mice were similar to controls throughout the study. From week 12 to the end of the study, 2,700 mg/kg male mice had mean body weights that were lower than those of controls. From week 14 to the end of the study, the 2,700 mg/kg female mice had mean body weights that were lower than those of controls. There were no chemical-related differences in triiodothyronine, reverse triiodothyronine, thyroxine, or thyroid-stimulating hormone concentrations between dosed and control mice at the 15-month evaluation. Pathology Findings: Exposure of mice to salicylazosulfapyridine in corn oil by gavage for 2 years was associated with increased incidences of hepatocellular neoplasms in males and females. Nonneoplastic effects in the liver and spleen were also observed in male and female mice. The incidences of forestomach squamous cell papilloma in females and forestomach hyperplasia in males and females were decreased. GENETIC TOXICOLOGY: Salicylazosulfapyridine was not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535, and it did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells. These in vitro assays were performed with and without S9 metabolic activation enzymes. Results from in vivo mouse bone marrow chromo somal aberration tests were uniformly negative, while results of micronucleus assays performed on male or female mice exposed to salicylazosulfapyridine for periods ranging from 3 days to weeks were positive. Micronucleus tests in male mice for shorter exposure times (1 to 2 days) yielded negative or very weakly positive results. A three-treatment (72-hour exposure time) micronucleus test performed in male rats yielded equivocal results. Overall, results of these in vivo assays indicate that salicylazosulfa pyridine is capable of inducing chromosomal damage, possibly in the form of aneuploidy, in mouse bone marrow cells after multiple administrations. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of salicylazosulfapyridine in male and female F344/N rats based on increased incidences of neoplasms in the urinary tract. There was an increased incidence of transitional epithelial papilloma of the urinary bladder in males and a low incidence of rare transitional epithelial papillomas of the kidney and of the urinary bladder in females. There was clear evidence of carcinogenic activity of salicylazosulfapyridine in male and female B6C3F1 mice based on increased incidences of hepatocellular neoplasms. Increased incidences of nonneoplastic lesions of the urinary bladder and kidney in male and female rats and of the spleen in male rats were observed. Increased incidences of nonneoplastic lesions of the liver and spleen in male and female mice were observed. Decreased incidences of mononuclear cell leukemia in male and female rats were related to salicylazosulfapyridine administration. Decreased incidences of forestomach squamous cell papilloma in female mice and forestomach hyperplasia in male and female mice were related to salicylazosulfapyridine administration. Synonyms: 2-Hydroxy-5-[[4-[2-(pyridinylamino)sulfonyl]phenyl]azo]benzoic acid; 5-[p- (2-pyridylsulfamoyl)phenylazo]salicylic acid; sulfasalazine; salazosulfapyridine; 5-[4-(2-pyridylsulfamoyl)phenylazo]-2-hydroxybenzoic acid; 4-(pyridyl-2-amidosulfonyl)-3'-carboxy-4'-hydroxyazobenzene; sulphasalazine Trade names: Azopyrin, Azulfidine, Benzosulfa, Colo-Pleon, Reupirin, Salazopyrin
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PMID:NTP Toxicology and Carcinogenesis Studies of Salicylazosulfapyridine (CAS No. 599-79-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies). 1258 19

o-Nitroanisole is used as an intermediate for the preparation of o-anisidine and in the manufacture of azo dyes. Toxicology and carcinogenesis studies were conducted by administering o-nitroanisole (>99% pure) in the diet to groups of male and female F344 rats and B6C3F1 mice for 14 days, 13 weeks, and 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Chinese hamster ovary cells, and mouse lymphoma cells. 14-DAY STUDIES: Groups of five male and five female F344 rats received diets containing 0, 583, 1,166, 2,332, 4,665, or 9,330 ppm o-nitroanisole. Mean body weight gains and final mean body weights of males in the 4,665 and 9,330 ppm groups were lower than those of the controls. Absolute liver weights were significantly increased in males receiving 1,166 ppm or more and in females receiving 583 ppm or more. Groups of five male and five female B6C3F1 mice received diets containing 0, 250, 500, 1,000, 2,000, or 4,000 ppm o-nitroanisole. Mean body weight gains and final mean body weights of males that received 250 ppm and females that received 4,000 ppm were significantly lower than those of the controls. No other chemical-associated effects were observed. 13-WEEK STUDIES: Groups of 10 male and 10 female F344 rats received diets containing 0, 200, 600, 2,000, 6,000, or 18,000 ppm o-nitroanisole. Final mean body weights and feed consumption by male and female rats receiving 6,000 and 18,000 ppm were lower than those of the controls. Hemoglobin and hematocrit values were significantly lower and methemoglobin levels significantly higher in males in the 6,000 and 18,000 ppm groups than in controls. Absolute liver weights were significantly increased in females that received 200, 600, 2,000, and 6,000 ppm, absolute kidney weights were significantly increased in males that received 600, 2,000, and 6,000 ppm, and absolute spleen weights were significantly increased in males and females that received 6,000 and 18,000 ppm. Groups of 10 male and 10 female B6C3F1 mice received diets containing 0, 60, 200, 600, 2,000, or 6,000 ppm o-nitroanisole. Final mean body weight gains, final mean body weights, and feed consumption by male and female mice receiving 6,000 ppm were lower than those of the controls. Hemoglobin and hematocrit values in males and females that received 2,000 or 6,000 ppm were significantly lower than those in the controls. The absolute and relative liver weights of females in the 600 ppm group and relative liver weights of males and females in the 2,000 and 6,000 ppm groups were significantly greater than those of controls. Lesions associated with exposure to o-nitroanisole were present in the urinary bladder, spleen, kidney, liver, testis, and uterus of rats. Diffuse hyperplasia of the transitional epithelium of the urinary bladder occurred in all male and female rats that received 6,000 and 18,000 ppm. A transitional cell papilloma occurred in one male and transitional cell carcinomas occurred in two males and three females receiving 18,000 ppm. Congestion of the red pulp and capsular hyperplasia of the spleen and hepatocellular hypertrophy of the liver were present in males and females from the 18,000 ppm groups. Multifocal degeneration and necrosis of the renal tubule epithelium with infiltration of mononuclear inflammatory cells were present in male rats that received 600, 2,000, and 6,000 ppm. At the 18,000 ppm level, degeneration of the seminiferous epithelium accompanied by loss of spermatogenic cells and decreased numbers of spermatozoa were observed in the testes of male rats, while uterine atrophy was observed in female rats. Hepatocyte hypertrophy of the centrilobular and midzonal regions of liver lobules was present in mice that received 200 ppm and increased in severity at higher exposure levels. 2-YEAR STUDIES: The doses selected for the 2-year study of o-nitroanisole in rats were based on lower mean body weights, reduced feed consumption, and increased severity of regenerative anemia in male and female rats receiving 6,000 and 18,000 ppm during the 13-week study. Groups of 6roups of 60 male and 60 female F344 rats received diets containing 0, 222, 666, or 2,000 ppm o-nitroanisole. Groups of 60 male and 60 female B6C3F1 mice received diets containing 0, 666, 2,000, or 6,000 ppm o-nitroanisole. After 15 months, up to 10 animals from each group were evaluated for chemical-related lesions. Survival, Body Weights, Feed Consumption, and Clinical Findings: Survival of male rats receiving 2,000 ppm was significantly lower than that of the controls due to increased severity of nephropathy. Survival of 222 and 666 ppm male rats and all exposed female rats was similar to that of the controls. Survival of groups of exposed male and female mice was similar to that of the controls. The final mean body weight of male rats receiving 2,000 ppm was lower than that of the controls. Final mean body weights of male and female mice that received 2,000 and 6,000 ppm were lower than those of the controls. Feed consumption by male and female rats was similar to that by the controls. The only clinical finding in male or female mice attributable to chemical administration was discolored urine. Neoplasms and Nonneoplastic Lesions: The incidence of mononuclear cell leukemia was significantly increased in male rats that received 666 and 2,000 ppm and in female rats that received 2,000 ppm (males: 0 ppm, 26/50; 222 ppm, 25/50; 666 ppm, 42/50; 2,000 ppm, 34/50; females: 14/50, 11/50, 14/50, 26/50). Nephropathy occurred in all male rats; the severity increased with exposure level. Focal hyperplasia of the renal tubule epithelium was present in three males receiving 222 ppm and two males receiving 2,000 ppm. Renal tubule adenomas occurred in one male from each of the 222, 666, and 2,000 ppm groups, and renal tubule carcinomas occurred in two males from the 2,000 ppm group. Focal hyperplasia of the transitional epithelium of the urinary bladder was present in one female rat that received 222 ppm and two male rats and six female rats that received 2,000 ppm. A transitional cell papilloma occurred in the urinary bladder of one female rat from the 2,000 ppm group, and a transitional cell carcinoma occurred in another female from the 2,000 ppm group. The incidence of forestomach ulcers increased in male rats that received 2,000 ppm, and the incidence of focal hyperplasia of the forestomach increased with exposure level in male and female rats. In addition, squamous cell papillomas of the forestomach were present in one female receiving 222 ppm, one male receiving 666 ppm, and one male and one female receiving 2,000 ppm, while squamous cell carcinomas were present in one male receiving 666 ppm and one male and one female receiving 2,000 ppm. The incidences of pituitary gland adenomas in male rats and mammary gland fibroadenomas in female rats decreased with exposure level. The incidence of cellular alteration in the liver was significantly increased in exposed groups of male and female mice. The incidences of hepatocellular adenoma, hepatocellular adenoma or carcinoma (combined), and hepatocellular carcinoma or hepatoblastoma (combined) were significantly increased in male mice receiving 2,000 and 6,000 ppm. The incidences of hepatocellular adenoma or carcinoma were significantly increased in female mice that received 2,000 ppm. STOP-EXPOSURE STUDY: Groups of 60 male and 60 female F344 rats received diets containing 0, 6,000, or 18,000 ppm o-nitroanisole for 27 weeks and were then maintained on control feed without further chemical exposure for up to an additional 77 weeks. Up to 10 rats from each group were evaluated for the presence of chemical-related lesions at 3, 6, 9, and 15 months. Survival and Body Weights: Survival of exposed male and female rats was significantly lower than that of the controls as a result of moribund deaths associated with significantly increased incidences of urinary bladder neoplasms, primarily transitional cell carcinomas. All male rats that received 18,000 ppm were dead by week 48 and all females that received 18,000 ppm were dead by week 61. Mean body weights of exposed male and female rats were lower than those of the controls throughout the study. Neoplasms and Nonneoplastic Lesions: Hyperplasia of the transitional epithelium of the urinary bladder was present in nearly all exposed male and female rats examined at the interim evaluations. A transitional cell carcinoma was first observed at the 3-month interim evaluation in a male rat that received 18,000 ppm. At the 6- and 9-month interim evaluations, transitional cell papillomas or carcinomas were observed in both exposed groups of male rats. Transitional cell carcinomas were observed at the 6-month interim evaluation in females receiving 18,000 ppm and at the 9-month interim evaluation in females receiving 6,000 and 18,000 ppm. Adenomatous polyps of the large intestine were observed in a small number of exposed rats at the 6-, 9-, and 15-month interim evaluations. At the end of the study, the incidence of adenomatous polyps of the large intestine was significantly increased in all exposed groups and carcinomas of the large intestine were present in four males and two females from the 18,000 ppm groups. The incidence of hyperplasia of the transitional epithelium of the kidney pelvis was significantly increased in exposed male and female rats and transitional cell papillomas were present in three males and one female that received 18,000 ppm. Transitional cell carcinomas of the kidney were present in one male receiving 6,000 ppm and six males and one female receiving 18,000 ppm. Transitional cell carcinomas of the urinary bladder were seen in nearly all exposed male and female rats. Of the males and females receiving 6,000 ppm which were without carcinomas, three males and one female had transitional cell papillomas. Generalized centrilobular hypertrophy, focal hepatocellular necrosis, multifocal hepatocellular cytoplasmic vacuolation, and Kupffer cell pigmentation were observed in the livers of male and female rats at the 3- and 6-month interim evaluations; however, only Kupffer cell pigmentation was observed at the end of the study. Congestion of the red pulp of the spleen was observed in nearly all exposed male and female rats at the 3-, 6-, and 9-month interim evaluations but the incidence was only slightly increased in the 18,000 ppm groups at the end of the study. Degeneration and atrophy of the seminiferous tubule epithelium of the testes were observed at the 3- and 6-month interim evaluations in all male rats receiving 18,000 ppm. GENETIC TOXICOLOGY: o-Nitroanisole was tested in two laboratories for mutagenicity in Salmonella typhimurium strains TA97, TA98, TA100, TA1535, and TA1537 with and without exogenous metabolic activation (S9). Positive responses were observed at both laboratories in TA100 with and without S9 activation. One laboratory found no increase in mutations, while the second laboratory detected a weakly positive response in TA1535 without S9. No mutagenic activity was observed in the other tester strains. o-Nitroanisole was positive in the mouse lymphoma assay for induction of trifluorothymidine resistance in L5178Y cells without S9 activation. In cytogenetic tests with Chinese hamster ovary cells, o-nitroanisole induced a significant increase in chromosomal aberrations at the highest dose tested in the presence of S9 activation; sister chromatid exchanges were induced both with and without S9. CONCLUSIONS: Under the conditions of these feed studies there was clear evidence of carcinogenic activity of o-nitroanisole in male and female F344 rats that received diets containing 6,000 or 18,000 ppm for 6 months based on overall increased incidences of benign and malignant neoplasms of the urinary bladder, transitional cell neoplasms of the kidney, and benign and malignant neoplasms of the large intestine. There was a chemical-related increased incidence of mononuclear cell leukemia in male and female rats receiving diets containing 222, 666, or 2,000 ppm o-nitroanisole for 2 years. Marginally increased incidences of uncommon renal tubule neoplasms in male rats and forestomach neoplasms in male and female rats were considered uncertain findings. There was clear evidence of carcinogenic activity of o-nitroanisole in male B6C3F1 mice based on increased incidences of benign and malignant hepatocellular neoplasms. There was some evidence of carcinogenic activity of o-nitroanisole in female B6C3F1 mice based on increased incidences of hepatocellular adenomas. Increased severity of nephropathy in male rats, and increased incidences of focal hyperplasia of the renal tubule epithelium and forestomach ulcers in male rats, and of transitional cell hyperplasia of the urinary bladder, focal hyperplasia of the forestomach, and hyperplasia of transitional epithelium of the kidney pelvis in male and female rats were associated with exposure to o-nitroanisole. Synonyms: Methoxynitrobenzene, nitrophenyl methyl ether
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PMID:NTP Toxicology and Carcinogenesis Studies of o-Nitroanisole (CAS No. 91-23-6) in F344 Rats and B6C3F1 Mice (Feed Studies). 1261 95

The types and levels of fats in the diet are known to affect the incidence of certain neoplasms in humans and rodents. In long-term toxicity and carcinogenicity studies in rodents, the level of dietary fat is altered by using oil as a vehicle to administer unpalatable or volatile chemicals. Control male rats receiving a corn oil vehicle have a higher incidence of pancreatic proliferative lesions and a lower incidence of mononuclear cell leukemia than untreated control males. Therefore, the National Toxicology Program (NTP) designed studies to evaluate the role of several oils in altering cancer rates in male rats. The NTP study reported here was part of a larger program that included cooperative agreements with Dartmouth Medical School, Northwestern Medical School, and the University of Missouri. The program was designed to study the mechanisms by which corn oil induces pancreatic cancer. To evaluate corn oil as well as two other gavage vehicles for potential toxicity, corn oil, safflower oil, and tricaprylin were administered by gavage to male F344/N rats for 2 years. The rats that received corn oil were also made available to the university investigators for study of the corn oil-induced pancreatic lesions. Each vehicle was administered by gavage at volumes of 2.5, 5, or 10 mL/kg body weight once daily for 5 days per week. In the corn oil study, a control of 10 mL saline/kg was also included. To evaluate the potential role of corn oil in promoting a pancreatic proliferative effect, 500 mg dichloromethane/kg body weight was administered in 2.5, 5, or 10 mL corn oil/kg body weight for 2 years to male F344/N rats. Dichloromethane was chosen because the chemical appeared to cause pancreatic proliferative lesions when administered by gavage in a corn oil vehicle but not when the exposure was by inhalation. In each of these studies, the term "dose" refers to the volume of gavage vehicle administered. 2-YEAR STUDIES OF CORN OIL, SAFFLOWER OIL, AND TRICAPRYLIN: Survival and Body Weights: Two-year survival was increased in male rats receiving corn oil (untreated control, 26/50; saline control, 32/50; 2.5 mL/kg, 33/50; 5 mL/kg, 38/50; 10 mL/kg, 40/50) primarily due to a dose-related decreased incidence of mononuclear cell leukemia. The mean body weights of all dosed groups were at least 5% higher than those of the untreated and saline controls by week 48, but the mean body weights of groups receiving 2.5 or 5 mL corn oil/kg decreased during the final weeks of the study (after week 89) and were similar to those of the controls at the end of the study. Two-year survival was slightly increased in male rats receiving safflower oil relative to that of the controls (untreated control, 30/50; 2.5 mL/kg, 33/50; 5 mL/kg, 40/50; 10 mL/kg, 36/50). The mean body weight of male rats receiving 10 mL safflower oil/kg was at least 5% greater than that of the controls after week 45 and was 16% greater by the end of the study. Two-year survival of high-dose tricaprylin males was lower than that of the controls (untreated control, 31/50; 2.5 mL/kg, 30/50; 5 mL/kg, 31/50; 10 mL/kg, 23/53) due to moribund kills and deaths that appeared to be related to toxicity. The mean body weight of the high-dose group was lower than that of the controls throughout the study, although the difference was less than 5% after week 61. Pathology Findings: In the corn oil study, there were significant dose-related increased incidences of pancreatic exocrine hyperplasia and adenoma (hyperplasia: 8/50, 28/47, 28/50, 35/50; adenoma: 1/50, 8/47, 10/50, 23/50; carcinoma: 0/50, 0/47, 1/50, 0/50 in the untreated control, 2.5, 5, and 10 mL/kg groups, respectively). The incidence and severity of nephropathy decreased with dose (incidence [mean severity grade]: 47/50 [2.1], 43/48 [1.8], 45/50 [1.4], 40/49 [1.2]). The incidences of pheochromocytomas (benign, malignant, or complex) of the adrenal medulla were also decreased in dosed rats (23/49, 21/50, 5/50, 9/50). The incidence of mononuclear cell leukemia was significantly decreased in rats dosed with corn oil (27/50, 16/50, 11h corn oil (27/50, 16/50, 11/50, 7/50). In rats receiving safflower oil, the incidences of pancreatic exocrine hyperplasia and adenoma increased significantly with dose (hyperplasia: 8/50, 14/50, 29/49, 30/50; adenoma: 1/50, 7/50,15/49, 28/50; carcinoma: 0/50, 0/50, 0/49, 1/50 in the untreated control, 2.5, 5, and 10 mL/kg groups, respectively). There was a decrease in the severity, but not in the incidence, of nephropathy, a common lesion in aging F344/N rats (incidence [mean severity grade]: 49/50 [2.0], 50/50 [1.8], 47/50 [1.1], 49/49 [1.1]). There were decreased incidences of mononuclear cell leukemia (33/50, 19/50, 18/50, 7/51). In the tricaprylin study, there were significant dose-related increased incidences of pancreatic exocrine hyperplasia and adenoma (hyperplasia: 8/49, 9/49, 18/49, 28/50; adenoma: 2/49, 6/49,13/49,18/50 in the untreated control, 2.5, 5, and 10 mL/kg groups, respectively). The incidence of proliferative lesions of the forestomach increased significantly with dose (basal cell hyperplasia: 4/50, 7/50, 12/49, 21/52; squamous cell papilloma: 0/50, 0/50, 3/50, 10/53). The incidence of nephropathy was significantly decreased in high-dose rats, and the severity of nephropathy decreased with dose (incidence [mean severity grade]: 46/50 [2.0], 42/50 [1.5], 45/50 [1.7], 27/49 [0.9]). In high-dose rats, the incidence of mononuclear cell leukemia was decreased (23/50, 28/50, 22/50, 9/53). 2-YEAR STUDY OF DICHLOROMETHANE IN CORN OIL: Survival and Body Weights: Two-year survival increased slightly with dose in the three groups receiving 500 mg dichloromethane/kg in 2.5, 5, or 10 mL corn oil/kg (23/50, 28/50, 31/50) due to a dose-related decrease in the incidence of mononuclear cell leukemia. The rats receiving 500 mg dichloromethane/kg without corn oil were sacrificed within the first 3 weeks of the study due to the severe toxicity of dichloromethane. The final mean body weight of the high-dose rats was greater than the final mean body weights of groups receiving dichloromethane in 2.5 or 5 mL corn oil/kg. Pathology Findings: There was a dose-related increase in the incidence of pancreatic proliferative exocrine lesions in rats receiving dichloromethane in 2.5, 5, and 10 mL corn oil/kg (hyperplasia: 28/50, 38/50, 44/50; adenoma: 9/50,19/50, 41/50; carcinoma: 0/50,1/50, 3/50). The incidences of pancreatic exocrine hyperplasia and adenoma in rats receiving dichloromethane in 5 or 10 mL, but not 2.5 mL, corn oil were increased compared to the incidences in rats receiving comparable volumes of corn oil alone (hyperplasia: 2.5 mL, 28/47; 5 mL, 28/50;10 mL, 35/50; adenoma: 8/47,10/50, 23/50; carcinoma: 0/47,1/50, 0/50). There were significantly increased incidences of pituitary gland pars distalis adenoma in rats receiving dichloromethane in corn oil (20/50, 18/49, 16/49) when compared to those in rats receiving comparable volumes of corn oil alone (10/50, 6/49, 7/50). The incidence of mammary gland adenoma and fibroadenoma (combined) was significantly increased in rats receiving dichloromethane in 10 mL corn oil/kg (7/50) when compared to rats receiving dichloromethane in 2.5 mL corn oil/kg (1/50), but was not significantly increased when compared to the group receiving 10 mL of corn oil alone (3/50). The incidences of mammary gland adenoma and fibroadenoma (combined) were 7/50 for the untreated safflower oil controls and 6/50 for the untreated tricaprylin controls. The incidence of mononuclear cell leukemia decreased in the group receiving dichloromethane in 10 mL corn oil/kg (13/50,14/50, 5/50). GENETIC TOXICOLOGY: Neither safflower oil nor corn oil was mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, or TA1535, with or without S9. Tricaprylin, in contrast, was mutagenic in strain TA1535 with, but not without, S9. Tricaprylin did not induce mutations in strains TA97, TA98, or TA100, with or without S9. SUMMARY: These studies were designed to evaluate the effects of various concentrations of an oil very high in polyunsaturated fat (safflower oil), an oil containing high levels of polyunsaturated and monounsaturated fats (corn oil), and an oil containing saturated medium-chain fatty acids (tricaprylin) on the incidence and pattern of neoplasms in the F344/N rat. In addition, safflower oil and tricaprylin were evaluated as replacements for the corn oil vehicle. These studies demonstrate that safflower oil and tricaprylin do not offer significant advantages over corn oil as a gavage vehicle in long-term rodent studies. Corn oil, safflower oil, and tricaprylin each caused hyperplasia and adenoma of the exocrine pancreas, decreased incidences of mononuclear cell leukemia, and reduced incidences or severity of nephropathy in male F344/N rats. There was an increased incidence of squamous cell papillomas of the forestomach in F344/N rats receiving 10 mL tricaprylin/kg. Further, the use of corn oil as a gavage vehicle may have a confounding effect on the interpretation of chemical-induced proliferative lesions of the exocrine pancreas and mononuclear cell leukemia in male F344/N rats. Synonyms: Corn Oil - Maize oil, Maydol Tricaprylin - Trioctanoin; 1,2,3-trioctanoyl glycerol; Glycerol trioctanoate
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PMID:NTP Comparative Toxicology Studies of Corn Oil, Safflower Oil, and Tricaprylin (CAS Nos. 8001-30-7, 8001-23-8, and 538-23-8) in Male F344/N Rats as Vehicles for Gavage. 1261 5

Furan serves as an intermediate in the synthesis and preparation of numerous linear polymers used to prepare temperature-resistant structural laminates and to prepare copolymers used in machine dishwashing products as alternatives to phosphorus- and nitrogen-containing detergents. Toxicology and carcinogenesis studies were conducted by administering furan (purity > 99%) in corn oil by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 16 days, 13 weeks, and 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Drosophila melanogaster, mouse bone marrow cells, mouse L5178Y lymphoma cells, and Chinese hamster ovary cells. 16-Day Studies: Groups of five male rats received doses of 0, 5, 10, 20, 40, or 80 mg of furan per kg of body weight and groups of five female rats and five mice of each sex received doses of 0, 10, 20, 40, 80, and 160 mg/kg in corn oil by gavage. All male and female mice and female rats that received 160 mg/kg, all male and female rats and all male and four female mice that received 80 mg/kg, and three male mice that received 40 mg/kg died by day 8. Final mean body weights of male rats that received 20 mg/kg and of male and female rats that received 40 mg/kg were significantly lower than controls. Final mean body weights of male mice that received 10 or 20 mg/kg were significantly greater than controls. Mottled and enlarged livers were observed at necropsy in male rats that received 20, 40, or 80 mg/kg and in females that received 40, 80, or 160 mg/kg. No lesions were observed at necropsy that were considered related to furan administration in mice. 13-Week Studies: Groups of 10 rats of each sex and groups of 10 female mice received doses of 0, 4, 8, 15, 30, or 60 mg of furan per kg of body weight, and groups of 10 male mice received doses of 0, 2, 4, 8, 15, or 30 mg/kg in corn oil by gavage. Nine male and four female rats that received 60 mg/kg died before the end of the studies. There were no chemical-related deaths in mice. Final mean body weights of male rats that received 15 or 30 mg/kg and female rats that received 60 mg/kg were significantly lower than controls. Final mean body weights of male mice that received 60 mg/kg were significantly lower than controls. Relative and absolute liver weights in both sexes of rats and mice were increased in groups that received furan, as were relative and absolute kidney weights in female rats that received furan. Thymus weights were decreased in all groups of rats that received furan. Toxic lesions of the liver (bile duct hyperplasia, cholangiofibrosis, cytomegaly and degeneration of hepatocytes, and nodular hyperplasia of hepatocytes) were associated with furan administration in all dose groups of rats; the severity of the lesions increased with dose. Kidney lesions (tubule dilatation and necrosis of tubule epithelium) were present in rats that received 30 or 60 mg/kg. Thymic atrophy and testicular or ovarian atrophy were also observed in rats exposed to 60 mg/kg furan. Toxic liver lesions (cytomegaly, degeneration, and necrosis of hepatocytes) were also present in all groups of furan-exposed mice. Bile duct hyperplasia and cholangiofibrosis were observed in groups of mice receiving 30 or 60 mg/kg. Doses selected for the 2-year studies of rats and mice were based on the hepatotoxicity associated with exposure to furan. 2-Year Studies: Groups of 70 rats of each sex were administered 2, 4, or 8 mg furan per kg body weight in corn oil by gavage 5 days per week for 2 years. After 9 and 15 months of chemical exposure, 10 rats per group were evaluated for the presence of treatment-associated lesions. Groups of 50 mice of each sex received doses of 8 or 15 mg/kg furan 5 days per week for 2 years. Body Weight and Survival: Mean body weights of male rats that received 8 mg/kg furan were lower than controls from approximately week 73 to the end of the study. Survival of male and female rats that received 8 mg/kg was lower than controls from approximately week 85 to the end of the studies as a result of moribund condition associatedassociated with liver and biliary tract neoplasms and mononuclear cell leukemia. Mean body weights of male and female mice that received 15 mg/kg furan were lower than controls during the studies. Survival of low- and high-dose male and high-dose female mice was lower than controls from approximately week 80 to the end of the studies as a result of moribund condition associated with liver neoplasms. Neoplastic and Nonneoplastic Lesions: Cholangiocarcinoma of the liver occurred in all groups of dosed rats (males: control, 0/50; low dose, 43/50; mid dose, 48/50; high dose, 49/50; females: 0/50; 49/50; 50/50; 48/50) and was present in many rats of each sex at the 9- and 15-month interim evaluations (9-month: males - 0/10, 5/10, 7/10, 10/10; females - 0/10, 4/10, 9/10, 10/10; 15-month: males - 0/10, 7/10, 9/10, 6/10; females - 0/10, 9/10, 9/10, 7/10). Hepatocellular adenomas or carcinomas (combined) were significantly increased in male rats after 2 years of chemical administration (1/50, 5/50, 22/50, 35/50) and hepatocellular adenomas were significantly increased in female rats (0/50, 2/50, 4/50, 7/50); hepatocellular neoplasms were not observed at the 9- or 15-month interim evaluations. Increased incidences of numerous nonneoplastic liver lesions were present in rats administered furan. These lesions included biliary tract fibrosis, hyperplasia, chronic inflammation, and proliferation and hepatocyte cytomegaly, cytoplasmic vacuolization, degeneration, nodular hyperplasia, and necrosis. The incidence of mononuclear cell leukemia was increased in male and female rats that received 4 or 8 mg/kg furan (males: 8/50, 11/50, 17/50, 25/50; females: 8/50, 9/50, 17/50, 21/50); the incidence in the 8 mg/kg groups of each sex exceeded the historical control ranges for corn oil gavage studies. The severity of nephropathy increased with dose and the incidence was significantly increased in all groups of dosed rats; this increased severity was accompanied by an associated increased incidence of parathyroid hyperplasia (renal secondary hyperparathyroidism). The incidence of forestomach hyperplasia was increased in male and female rats (males: 1/50, 4/49, 7/50, 6/50; females: 0/50, 2/50, 5/50, 5/50) and the incidence of subacute inflammation of the forestomach was increased in female rats (0/50, 1/50, 5/50, 6/50). No forestomach neoplasms were observed in males; a squamous papilloma was present in one low-dose female. The incidences of hepatocellular adenomas and carcinomas were significantly increased in mice receiving furan (males: adenoma - 20/50, 33/50, 42/50; carcinoma - 7/50, 32/50, 34/50; females: adenoma - 5/50, 31/50, 48/50; carcinoma - 2/50, 7/50, 27/50). The incidences of numerous nonneoplastic hepatocellular lesions were increased in dosed mice. These lesions included hepatocyte cytomegaly, degeneration, necrosis, multifocal hyperplasia, and cytoplasmic vacuolization and biliary tract dilatation, fibrosis, hyperplasia, and inflammation. The incidences of benign pheochromocytoma and focal hyperplasia of the adrenal medulla were increased in low- and high-dose male and in high-dose female mice (benign pheochromocytoma: males - 1/49, 6/50, 10/50; females - 2/50, 1/50, 6/50). The incidences of squamous papilloma, focal inflammation, and papillary hyperplasia of the forestomach were increased in male mice (squamous papilloma: 0/49, 1/50, 3/50; focal inflammation: 9/49, 13/50, 21/50; papillary hyperplasia: 7/49, 14/50, 22/50). Stop-Exposure Study: A separate 2-year study was conducted in which 50 male rats were administered 30 mg/kg furan in corn oil by gavage 5 days per week for 13 weeks and then maintained for the remainder of the 2 years without additional furan administration. Groups of 10 animals were evaluated for the presence of treatment-related lesions at the end of the 13-week period of furan administration and at 9 and 15 months. Neoplastic and Nonneoplastic Lesions: Cholangiocarcinoma of the liver occurred with an overall incidence of 100&percnt; (40/40) and hepatocellular carcinoma occurred with an overall incidence of 15&percnt; (6/40) in stop-exposure male rats that survived at least 9 months. Cholangiocarcinoma was observed in all 10 males at both the 9-month and 15-month interim evaluations. Hepatocellular carcinoma was first observed in 2 males at the 15-month interim evaluation. Genetic Toxicology: Furan was negative for induction of gene mutations in Salmonella typhimurium strains TA100, TA1535, TA1537, and TA98 in the presence and the absence of exogenous metabolic activation (S9). Furan was negative for the induction of sex-linked recessive lethal mutations in germ cells of male Drosophila melanogaster when administered either by feeding or by injection. In vitro tests for genotoxicity in mammalian cells, however, were positive. Furan induced trifluorothymidine resistance in mouse L5178Y lymphoma cells in the absence of S9, and sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cells, with and without S9. Furan administered to male B6C3F1 mice by intraperitoneal injection induced chromosomal aberrations but not sister chromatid exchanges in bone marrow cells. Conclusions: Under the conditions of these 2-year gavage studies there was clear evidence of carcinogenic activity of furan in male and female F344/N rats based on increased incidences of cholangiocarcinoma and hepatocellular neoplasms of the liver and on increased incidences of mononuclear cell leukemia. There was clear evidence of carcinogenic activity of furan in male and female B6C3F1 mice based on increased incidences of hepatocellular neoplasms of the liver and benign pheochromocytomas of the adrenal gland. Nonneoplastic liver lesions associated with furan administration in rats and mice included biliary tract fibrosis, hyperplasia, inflammation, and proliferation, as well as hepatocellular cytomegaly, degeneration, hyperplasia, necrosis, and vacuolization. In rats, increased severity of nephropathy with an associated increased incidence of parathyroid hyperplasia was associated with exposure to furan. Synonyms: Divinylene oxide, tetrole, furfuran, oxole, 1,4-epoxy-1,3-butadiene, axole, oxacyclopentadiene
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PMID:Toxicology and Carcinogenesis Studies of Furan (CAS No. 110-00-9) in F344 Rats and B6C3F1 Mice(Gavage Studies). 1262 16

1-Amino-2,4-dibromoanthraquinone is an anthraquinone-derived vat dye, a member of a class of insoluble dyes that are impregnated into textile fibers. Five anthraquinone-derived dyes with representative and diverse structures, as well as the parent chemical, anthraquinone, were selected for NTP Toxicology and Carcinogenesis evaluation. Similar to the benzidine dye initiative, the rationale for selecting these vat dyes was to generate sufficient toxicologic data to permit more reliable predictions of carcinogenicity to be made on other chemicals in this class, thereby eliminating or reducing the need to study every anthraquinone dye. 1-Amino-2,4-dibromoanthraquinone is the last anthraquinone-derived dye in this group to be studied. Groups of male and female F344/N rats and B6C3F1 mice were exposed to 1-amino-2,4-dibromoanthraquinone (87% to 97% pure) for 13 weeks or for 9, 15, or 24 months. Because 1-amino-2,4-dibromoanthraquinone was predicted to be carcinogenic, these studies were designed to evaluate the potential for tumor progression and regression. Absorption and excretion studies were carried out in male F344/N rats. Genetic toxicity was determined in vitro using Salmonella typhimurium and cultured Chinese hamster ovary cells. Extensive chemical analyses were performed to identify and characterize impurities of the 1-amino-2,4-dibromoanthraquinone used in these studies. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were given 0, 2,500, 5,000, 10,000, 25,000, or 50,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 13 weeks. These levels correspond to approximately 150 to 3,200 mg 1-amino-2,4-dibromoanthraquinone/kg body weight per day for males and to approximately 170 to 3,200 mg/kg for females. Chemical-related mortality was limited to one male and one female in the 50,000 ppm groups. Final mean body weights and body weight gains of all exposed groups of rats were significantly lower than those of the controls. Feed consumption by all exposed groups was less than that by the controls throughout the study and generally decreased with increasing exposure concentration. Pink-red staining of the fur and tail was observed in all exposed groups. Absolute and relative liver weights of all exposed groups were generally significantly greater than those of the controls. Chemical-related lesions were present in the liver, kidney, and spleen of male and female rats. Nonneoplastic lesions in the liver included foci of hepatocellular alteration, diffuse hepatocellular hypertrophy (cytomegaly), hepatocellular cytoplasmic vacuolation, bile duct hyperplasia, inflammation, and pigmentation. These differences were observed primarily in the 25,000 and 50,000 ppm groups of males and females; the spectrum of proliferative lesions of the bile ducts (hyperplasia, fibrosis, and necrotizing cholangitis) in the 25,000 and 50,000 ppm groups was morphologically consistent with the lesion described as cholangiofibrosis. Pigmentation was present in the renal tubule epithelium of all groups of exposed rats; nuclear enlargement (karyomegaly) was also present in the renal tubule epithelium in some of the exposed rats. Accumulation of hyaline droplets in the cytoplasm of the renal tubule epithelium and tubule lumina was present in 2,500, 5,000, 10,000, and 25,000 ppm males. Incidences of hematopoiesis of the spleen in exposed groups of males and females were increased compared to those in the controls. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were given 0, 2,500, 5,000, 10,000, 25,000, or 50,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 13 weeks. These levels correspond to approximately 500 to 10,600 mg 1-amino-2,4-dibromoanthraquinone/kg body weight per day for males and approximately 660 to 11,700 mg/kg per day for females. There was no chemical-related mortality. Feed consumption and final mean body weights of exposed groups were similar to those of the controls. Red staining of the fur was observed in all exposed groups. Absolute and relative liver weights of the exposed groups were greater than those er than those of the controls except for the absolute liver weight of 2,500 ppm males. Absolute and relative kidney weights of 25,000 and 50,000 ppm males were lower than those of the controls. Chemical-related lesions were limited to the livers of males and consisted of pigmentation of hepatocytes at all exposure concentrations and centrilobular hepatocellular hypertrophy at 10,000, 25,000, and 50,000 ppm. Minimal pigment was present in the liver of one female in the 25,000 ppm group and in one female in the 50,000 ppm group. 2-YEAR STUDY IN RATS: Groups of 70 male and 70 female rats were given 0, 5,000, or 10,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 103 weeks. In addition, groups of 50 male and 50 female rats were given 2,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 104 weeks. These exposure concentrations were approximately equal to 90, 240, or 490 mg 1-amino-2,4-dibromoanthraquinone/kg body weight for males and 110, 285, or 600 mg/kg for females. Ten animals from each group were evaluated for histopathology at 9 months. Additional groups of 10 animals from the 0 and 10,000 ppm groups were evaluated for histopathology at 15 months. Survival, Body Weights, Feed Consumption, and Clinical Findings In the 2-year study, survival of the 10,000 ppm males and females was significantly lower than that of the controls. Survival of the 2,000 and 5,000 ppm groups was similar to that of the controls. During the last year of the study, the mean body weights of exposed males were 80&percnt; to 91&percnt; those of controls, and the mean body weights of exposed females were 67&percnt; to 84&percnt; those of controls. Feed consumption among exposed groups was generally similar, but was less than that by controls. The fur and urine of all exposed male and female groups were discolored. Pathology Findings In the 2-year study, 1-amino-2,4-dibromoanthraquinone was associated with significant chemical-related increases in the incidences of benign and malignant neoplasms in the liver, large intestine, kidney, and urinary bladder of males and females. Chemical-related nonneoplastic proliferative and degenerative lesions occurred in the liver, kidney, urinary bladder, and forestomach of males and females. The incidences of foci of hepatocellular alteration and pigmentation in the liver of males and females were increased at the 9-month interim evaluation, and a hepatocellular adenoma was present in one 5,000 ppm male. At the 15-month interim evaluation, hepatocellular adenoma or carcinoma (combined) occurred in all males and nine females in the 10,000 ppm groups. By the end of the 2-year study, hepatocellular adenoma, carcinoma, cholangioma, or cholangiocarcinoma were observed in males and females in the 5,000 and 10,000 ppm groups. In the 2,000 ppm groups, similar liver neoplasms were present in 63&percnt; of the males and in 83&percnt; of the females. Of the hepatocellular carcinomas in the 5,000 and 10,000 ppm groups of males and females, 31&percnt; to 49&percnt; were metastatic to the lungs or other sites. Increases in the incidences of foci of hepatocellular alteration (basophilic, eosinophilic, and clear cell) and pigmentation of the liver were also observed in exposed groups of males and females. Adenomatous polyps (adenoma) of the large intestine were present in six 10,000 ppm males at the 15-month interim evaluation. Incidences of adenomatous polyp (adenoma) and carcinoma of the large intestine were significantly increased in exposed groups of males and females after 2 years; multiple benign and malignant intestinal neoplasms were observed in many of these rats. In the kidney, incidences of renal tubule adenoma and carcinoma were significantly increased in exposed groups of males and females after 2 years. Renal tubule adenomas were present in two 10,000 ppm males at 15 months. There were also chemical-related increases in the incidences and severities of renal tubule epithelial hyperplasia, pigmentation, and transitional cell hyperplasia in the kidney of males and females. Hyaline droplet accumulation was present in all exposed male rats at 9 months. Incidences of transitional cell papilloma and carcinoma of the urinary bladder were increased at 2 years in males and females in the 10,000 ppm groups. Transitional cell hyperplasia was observed in exposed males and females at the 15-month interim evaluation. Other nonneoplastic lesions observed in the urinary bladder at 2 years included metaplasia of the transitional epithelium and submucosal stromal tissue. In the forestomach, the incidences and severities of inflammation, ulceration, hyperkeratosis, and hyperplasia of the squamous mucosa were increased in all exposed groups of males and females at 2 years, but not at the 9- or 15-month interim evaluations. In exposed males and females, the incidences of mononuclear cell leukemia were significantly decreased. The incidences of atrophy of the seminal vesicle were increased in exposed male rats in the 2-year study. Stop-Exposure Evaluation in Rats Groups of 40 male and 40 female rats were given 20,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 9 or 15 months. At 9 months, 10 males and 10 females were evaluated for histopathology (9-month interim evaluation groups). After 9 months of exposure, an additional 10 males and 10 females were fed control diet until the end of the 15-month evaluation (9-month stop-exposure groups), and 20 males and 20 females continued to receive 20,000 ppm 1-amino-2,4-dibromoanthraquinone until the end of the evaluation (15-month exposure groups). The approximate daily consumption of 1-amino-2,4-dibromoanthraquinone was 1,335 mg/kg for males and 1,790 mg/kg for females in the 9-month stop-exposure groups and 1,115 mg/kg for males and 1,435 mg/kg for females in the 15-month exposure groups. Survival was similar among groups except for the females in the 15-month exposure group; the survival of this group was lower than that of the controls. Lower mean body weights were related to increased exposure duration. The mean body weights of exposed males were 76&percnt; to 82&percnt; that of controls, and the mean body weights of exposed females were 73&percnt; to 84&percnt; that of controls. For the stop-exposure evaluation, similar chemical-related neoplasms and nonneoplastic lesions were observed in the same sites as in the 2-year study: liver, large intestine, kidney, urinary bladder, and forestomach. After 9 months of dietary exposure to a concentration of 20,000 ppm 1-amino-2,4-dibromoanthraquinone, hepatocellular adenoma and carcinoma occurred in males and females. Nonneoplastic chemical-related lesions in the liver of exposed rats included pigmentation, focal hepatocellular alteration, and bile duct hyperplasia. Neoplasms at other sites in males included one adenomatous polyp (adenoma) in the large intestine and one transitional cell papilloma in the urinary bladder. Hyaline droplet accumulation was present in the kidney of exposed males at 9 months. In the stop-exposure groups examined at 15 months, hepatocellular adenoma and carcinoma were present in most males and females. Adenomatous polyp (adenoma) of the colon, renal tubule cell adenoma, and urinary bladder transitional cell papilloma and carcinoma also occurred in males and females. Nonneoplastic chemical-related lesions included foci of hepatocellular alteration in the liver and hyperplasia of the renal tubule epithelium and urinary bladder transitional epithelium. Hyperplasia, hyperkeratosis, inflammation, and ulceration were observed in the forestomach of some male and female rats continuously exposed for 15 months. 2-YEAR STUDY IN MICE: Groups of 60 male and 60 female mice were given 0, 10,000, or 20,000 ppm 1-amino-2,4-dibromoanthraquinone in feed for 104 weeks. The daily compound consumption was approximately 1,690 or 3,470 mg 1-amino-2,4-dibromoanthraquinone/kg body weight for males and 1,950 or 4,350 mg/kg for females. Ten animals from each group were evaluated for histopathology at 15 months. Survival, Body Weights, Feed Consumption, and Clinical Findings In the 2-year study, survival of exposed males was significantly lower than that of the controls. Survival of exposed females was similar to that of the controls. The final mean body weights of exposed males were 83&percnt; to 85&percnt; that of controls, and the final mean body weights of exposed females were 81&percnt; to 86&percnt; that of controls. Feed consumption by exposed groups was generally similar to that by controls. Discoloration of the fur, urine, and feces was observed in all exposed groups. Pathology Findings In the 2-year study, 1-amino-2,4-dibromoanthraquinone was associated with significant chemical-related increases in the incidences of benign and malignant neoplasms in the liver, forestomach, and lung of males and females. Incidences of hepatocellular adenoma and carcinoma were increased in exposed groups at the 15-month interim evaluation and at 2 years. At 2 years, there were significant increases in the incidences of multiple hepatocellular adenoma and carcinoma in males and females and in the incidences of hepatoblastoma in males. Centrilobular hypertrophy of hepatocytes in males and foci of hepatocellular alteration and pigmentation in the liver of males and females were also chemical-related changes. Sqamous cell papilloma of the forestomach mucosa occurred in 10,000 ppm females and 20,000 ppm males and females at the 15-month interim evaluation, and the incidences of squamous cell papilloma and carcinoma were significantly increased in exposed groups of males and females at 2 years. Chemical-related hyperplasia of forestomach epithelium was also present at 15 months and at 2 years. Alveolar/bronchiolar adenomas were present only in the exposed groups of males and females at 15 months, and the incidences of alveolar/bronchiolar adenoma were significantly increased in exposed males and females at 2 years. The incidences of multiple alveolar/bronchiolar adenomas were also increased in exposed males. In the kidney, pigmentation was present in the renal tubules of most mice after 2 years of exposure. DISPOSITION AND METABOLISM STUDIES: Adult male F344/N rats were given [14C]-labeled 1-amino-2,4-dibromoanthraquinone as a single intravenous dose of 0.4 mg/kg body weight or as a single oral dose of 2, 23, 118, 814, or 1,473 mg/kg. A 6-hour bile cannulation study was also performed. From day 0 through day 3 after intravenous administration, about 50&percnt; of the 14C was excreted in the feces, 15&percnt; in the urine, and 6&percnt; in expired air. Unmetabolized 1-amino-2,4-dibromoanthraquinone accounted for less than 3&percnt; of the excreted 14C after intravenous administration. For oral doses administered, the amount of the dose that was absorbed fit the equation: absorbed dose = 6.6 x log(dose). After intravenous administration, the metabolites of 1-amino-2,4-dibromoanthraquinone in blood were primarily in the plasma fraction (blood:plasma ratio of approximately 0.5:1). The highest concentrations of 14C in tissues 15 minutes after intravenous dosing were in excretory organs, lung, kidney, small intestine, liver, adipose tissue, and adrenal gland. GENETIC TOXICOLOGY: 1-Amino-2,4-dibromoanthraquinone was mutagenic in Salmonella typhimurium strains TA98 and TA1537 in the absence of S9; with S9, an equivocal response was observed in TA1537. 1-Amino-2,4-dibromoanthraquinone resulted in an equivocal response in TA100 with and without S9, and no mutagenic activity was detected with strain TA1535. In cultured Chinese hamster ovary cells, 1-amino-2,4-dibromoanthraquinone induced sister chromatid exchanges with and without S9; chromosomal aberrations were induced in the absence of S9. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenic activity of 1-amino-2,4-dibromoanthraquinone in male and female F344/N rats based on increased incidences of neoplasms in the liver, large intestine, kidney, and urinary bladder. There was clear evidence of carcinogenic activity of 1-amino-2,4-dibromoanthraquinone in male and female B6C3F1 mice based on increased incidences of neoplasms in the liver, forestomach, and lung. Exposure of male and female rats to 1-amino-2,4-dibromoanthraquinone for 2 years was associated with basophilic focus (males only), clear cell focus, eosinophilic focus, and pigmentation in the liver; renal tubule hyperplasia, renal tubule pigmentation, and transitional cell hyperplasia in the kidney; transitional cell hyperplasia, squamous metaplasia, and stromal metaplasia (females only) in the urinary bladder; squamous hyperplasia, hyperkeratosis, ulceration, and inflammation of the forestomach mucosa; and seminal vesicle atrophy. Exposure of male and female mice to 1-amino-2,4-dibromoanthraquinone for 2 years was associated with centrilobular hepatocellular hypertrophy (males only), basophilic focus, clear cell focus (females only), eosinophilic focus, and pigmentation in the liver; pigmentation in the kidney; and hyperplasia, basal cell hyperplasia, hyperkeratosis, and inflammation of the forestomach mucosa. Synonym: ADBAQ
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PMID:NTP Toxicology and Carcinogenesis Studies of 1-Amino-2,4-Dibromoanthraquinone (CAS No. 81-49-2) in F344/N Rats and B6C3F1 Mice (Feed Studies). 1269 53

Benzene ranks 16th in production volume for chemicals produced in the United States, with approximately 9.9 billion pounds being produced in 1984, 9.1 billion pounds in 1983, and 7.8 billion pounds in 1982. This simplest aromatic chemical in used in the synthesis of styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes (detergents), chlorobenzenes, and other products used in the production of drugs, dyes, insecticides, and plastics. Benzene, along with other light, high-octane aromatic hydrocarbons, such as toluene and xylenes, is a component of motor gasoline. Benzene is also used as a solvent, but for most applications, it has been replaced by less hazardous solvents. During the 17-week studies, groups of 10 or 15 male and female F344/N rats and B6C3F1 mice were gavaged 5 days per week with benzene in corn oil (5 ml/kg) at doses of 0 to 600 mg/kg. No benzene-related deaths occurred; in rats that received benzene, final mean body weights were 14%-22% lower compared with vehicle controls and in mice, slight dose-related reductions were observed (less than 10% differences). Doses for the 2-year studies were selected based on clinical observations (tremors in higher dosed mice), on clinical pathologic findings (lymphoid depletion in rats and leukopenia in mice), and on body weight effects. Two-year toxicology and carcinogenesis studies of benzene (greater than 99.7% pure) were conducted in groups of 50 F344/N rats and 50 B6C3F1 mice of each sex and for each dose. Doses of 0, 50, 100, or 200 mg/kg body weight benzene in corn oil (5 ml/kg) were administered by gavage to male rats, 5 days per week, for 103 weeks. Doses of 0, 25, 50, or 100 mg/kg benzene in corn oil were administered by gavage to female rats and to male and female mice for 103 weeks. Ten additional animals in each of the 16 groups were killed at 12 months and necropsies were performed. Hematologic profiles were performed at 3-month intervals. These studies were designed and conducted because of large production volume and potential human exposure, because of the epidemiologic association with leukemia, and because previous experiments were considered inadequate or inconclusive for determining potential carcinogenicity in laboratory animals. In the 2-year studies, mean body weights of the 200 mg/kg male rats (-23%) and the 100 mg/kg mice (-14% to -19%) were lower than those of the vehicle controls, and survival of dosed groups decreased with increasing dose (rats--male: vehicle control, 32/50; low dose, 29/50; mid dose, 25/50; high dose, 16/50; female: 46/50; 38/50; 34/50; 25/50; mice--male: 28/50; 23/50; 18/50; 7/50; female: 30/50; 26/50; 24/50; 18/50). At week 92 for rats and week 91 for mice, survival was greater than 60% in all groups; most of the dosed animals that died before week 103 had neoplasia. Compound-related nonneoplastic or neoplastic effects on the hematopoietic system, Zymbal gland, forestomach, and adrenal gland were found both for rats and mice. Further, the oral cavity was affected in rats, and the lung, liver, harderian gland, preputial gland, ovary, and mammary gland were affected in mice. Significantly increased (P<0.05) incidences of neoplasms were observed at multiple sites for male and female rats and for male and female mice. Primary neoplasms observed in rats and mice are summarized in Table 1 (see page 12 of the Technical Report). Hematologic data from vehicle control and dosed rats and mice were obtained at 3-month intervals from 0 to 24 months. Reliably identifiable hematologic effects were limited to lymphocytopenia and associated leukocytopenia in benzene-dosed rats and mice. These effects were seen from 3 to 18 months in dosed male rats and in dosed male mice; a similar but less pronounced response was observed in dosed female rats during this same time period. The effect in female mice was limited to 12-18 months. The technical quality of certain of these data was questionable; thus, more detailed analyses (e.g., investig questionable; thus, more detailed analyses (e.g., investigation of the association between hematologic and pathologic changes) are deemed inappropriate for these data. Benzene increased the frequency of micronucleated normchromatic peripheral erythrocytes in male and female mice (rats were not examined); males were more sensitive than females. The hematopoietic system of rats and mice of each sex was affected by benzene in the 2-year studies. The incidences of malignant lymphomas in all dosed groups of mice were greater than those in the vehicle controls (male: 4/49; 9/48; 9/50; 15/49; female: 15/49; 24/45; 24/50; 20/49). Lymphoid depletion of the splenic follicles (rats) and thymus (male rats) was observed at increased incidences. Bone marrow hematopoietic hyperplasia was observed at increased incidences in dosed mice of each sex (male: 0/49; 11/48; 10/50; 25/49; female: 3/49; 14/45; 8/50; 13/49). The incidences of Zymbal gland carcinomas in mid and high dose male rats and in dosed female rats were greater than those in the vehicle controls (male: 2/32; 6/46; 10/42; 17/42; female: 0/45; 5/40; 5/44; 14/46). The incidences of Zymbal gland carcinomas in mid and high dose male mice and in high dose female mice were greater than those in the vehicle controls (male: 0/43; 1/34; 4/40; 21/39; female: 0/43; 0/32; 1/37; 3/31). In mid and high dose male mice and in high dose female mice, the incidences of epithelial hyperplasia of the Zymbal gland were also increased (male: 0/43; 3/34; 12/40; 10/39; female: 1/43; 1/32; 2/37; 6/31). Hyperplasia of the adrenal capsule was observed at increased incidences in dosed mice of each sex (male: 2/47; 32/48; 14/49; 4/46; female: 5/49; 19/44; 34/50; 30/48). The incidence of pheochromocytomas in mid dose male mice was greater than that in the vehicle controls (male: 1/47; 1/48; 7/49; 1/46), whereas the incidences in dosed female mice were lower than that in the vehicle controls (female: 6/49; 1/44; 1/50; 1/48). Hyperplasia of the zona fasciculata of the adrenal cortex was observed at increased incidences in low dose rats of each sex (male: 0/50; 13/49; 0/48; 2/49; female: 0/50; 17/50; 0/47; 0/49). Benzene was associated with increased incidences of neoplasms of the skin and oral cavity of rats. The incidences of squamous cell papillomas and squamous cell carcinomas of the skin in high dose male rats were greater than those in the vehicle controls (squamous cell papilloma: 0/50; 2/50; 1/50; 5/50; squamous cell carcinoma: 0/50; 5/50; 3/50; 8/50). Increased incidences of uncommon squamous cell papillomas or squamous cell carcinomas (combined) of the oral cavity were observed in dosed male and female rats (male: 1/50; 9/50; 16/50; 19/50; female: 1/50; 5/50; 12/50; 9/50). Incidences of squamous cell papillomas or carcinomas (combined) (male: 2/45; 2/42; 3/44; 5/38; female: 1/42; 3/40; 6/45; 5/42), hyperkeratosis, and epithelial hyperplasia of the forestomach were increased in some dosed groups of male and female mice; incidences of hyperkeratosis and acanthosis were increased in high dose male rats. Compound-related effects in the lung, harderian gland, preputial gland, ovary, mammary gland, and liver were seen in mice but not in rats. Administration of benzene was associated with increased incidences of alveolar epithelial hyperplasia in mid and high dose mice (male: 2/49; 3/48; 7/50; 10/49; female: 1/49; 1/42; 9/50; 6/49). Increased incidences of alveolar/bronchiolar carcinomas and alveolar/bronchiolar adenomas or carcinomas (combined) were observed in high dose male mice (carcinomas: 5/49; 11/48; 12/50; 14/49; adenomas or carcinomas: 10/49; 16/48; 19/50; 21/49). Alveolar/bronchiolar adenomas were seen at increased incidences in high dose female mice (4/49; 2/42; 5/50; 9/49), as were alveolar/bronchiolar carcinomas (0/49; 3/42; 6/50; 6/49) and alveolar/bronchiolar adenomas or carcinomas combined (4/49; 5/42; 10/50; 13/49) in mid and high dose female mice. The incidences of focal or diffuse hyperplasia of the harderian gland were increased in dosed mice of each sex (male: 0/49; 5/46; 11/49; 7/48; female: 6/48; 10/44; 11/50; 10/47). The incidences of harderian gland adenomas (0/49; 9/46; 13/49; 11/48) in dosed male mice were greater than that in the vehicle controls. A marginal increase in the incidence of adenomas or carcinomas (combined) of the harderian gland was seen in high dose female mice (5/48; 6/44; 10/50; 10/47). The administration of benzene to male mice was associated with increased incidences of hyperplasia (1/21; 18/28; 9/29; 1/35) and squamous cell carcinomas (0/21; 3/28; 18/29; 28/35) of the preputial gland. Increased incidences of mammary gland carcinomas were found in mid dose and high dose female mice (0/49; 2/45; 5/50; 10/49) and carcinosarcomas in high dose female mice (0/49; 0/45; 1/50; 4/49). Increased incidences of various uncommon neoplastic and nonneoplastic lesions of the ovary (papillary cystadenoma, luteoma, granulosa cell tumor, tubular adenoma, benign mixed tumor, epithelial hyperplasia, and senile atrophy) were associated with the administration of benzene to female mice. In mid and high dose female mice, the incidences of granulosa cell tumors (1/47; 1/44; 6/49; 7/48) and benign mixed tumors (0/47; 1/44; 12/49; 7/48) were greater than those in the vehicle controls. Increased incidences of hepatocellular adenomas were observed in low dose female mice (1/49; 8/44; 5/50; 4/49) and hepatocellular adenomas or carcinomas (combined) in low dose and mid dose female mice (4/49; 12/44; 13/50; 7/49). An audit of the experimental data was conducted for these 2-year carcinogenesis studies on benzene. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of benzene for male F344/N rats, for female F344/N rats, for male B6C3F1 mice, and for female B6C3F1 mice. For male rats, benzene caused increased incidences of Zymbal gland carcinomas, squamous cell papillomas and squamous cell carcinomas of the oral cavity, and squamous cell papillomas and squamous cell carcinomas of the skin. For female rats, benzene caused increased incidences of Zymbal gland carcinomas and squamous cell papillomas and squamous cell carcinomas of the oral cavity. For male mice, benzene caused increased incidences of Zymbal gland squamous cell carcinomas, malignant lymphomas, alveolar/bronchiolar carcinomas and alveolar/bronchiolar adenomas or carcinomas (combined), harderian gland adenomas, and squamous cell carcinomas of the preputial gland. For female mice, benzene caused increased incidences of malignant lymphomas, ovarian granulosa cell tumors, ovarian benign mixed tumors, carcinomas and carcinosarcomas of the mammary gland, alveolar/bronchiolar adenomas, alveolar/bronchiolar carcinomas, and Zymbal gland squamous cell carcinomas. Dose-related lymphocytopenia was observed for male and female F344/N rats and male and female B6C3F1 mice. Synonyms: benzol, cyclohexatriene, pyrobenzol
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PMID:NTP Toxicology and Carcinogenesis Studies of Benzene (CAS No. 71-43-2) in F344/N Rats and B6C3F1 Mice (Gavage Studies). 1274 14

Diallyl phthalate is a widely used crosslinking agent for unsaturated polyesters. Diallyl phthalate or diallyl phthalate polyester blends are used primarily as plasticizers and carriers for adding catalysts and pigments to polyesters and in molding, electrical parts, laminating compounds, and impregnation of metal castings. Rubber compounds, epoxy formulations, and polyurethane foams may also contain diallyl phthalate. Annual production of diallyl phthalate in the United States exceeds 5,000 pounds; precise figures are not available. A NTP Carcinogenesis bioassay of diallyl phthalate (99% pure) was conducted by administering 0 (vehicle control), 150, or 300 mg/kg diallyl phthalate in corn oil by gavage, 5 days per week for 103 weeks, to groups of 50 male and 50 female B6C3F1 mice. Survival rates and mean body weights of dosed mice were not different from those of the controls, and pathological lesions unrelated to proliferative changes were not observed. Therefore, a maximally tolerated dose for the purposes of carcinogenicity testing may not have been achieved. The incidences of lymphoma and either lymphoma or leukemia in dosed male mice were no significantly greater than those in the controls according to pairwise comparisons (P=0.051 to P=0.096), but the trend tests were statistically significant by either life table or incidental tumor analysis (P=0.031 to P=0.045). The incidence of lymphomas in the high-dose male mice was 12/50 (24%) in comparison with 6/50 (12%) in the controls. Recent historical incidences at the performing laboratory and in the NTP Bioassay Program were 18/120 (15%) and 71/661 (11%), respectively. Since the incidence of high-dose male mice with leukemia was not significantly greater than that of concurrent or historical controls at the performing laboratory by pairwise comparisons, this marginal increase was considered only to be equivocally related to diallyl phthalate administration. Increased incidences of squamous cell papillomas, hyperplasia, and inflammatory lesions of the forestomach were observed in diallyl phthalate-dosed mice of both sexes in a dose-related manner. Papillomas of the forestomach were observed in 0%, 2%, and 4% of the control, low-dose, and high-dose mice of both sexes. The recent historical incidence of this tumor in gavage control mice from both the performing laboratory and other laboratories within the Bioassay Program was less than 1%. Forestomach hyperplasia was diagnosed in 0%, 15%, and 18%, and in 8%, 2%, and 29% of the control, low-dose, and high-dose male and female mice, respectively; chronic inflammation of the forestomach was diagnosed in 0%, 9%, and 16% and in 4%, 2%, and 18% of the control, low-dose, and high-dose male and female mice, respectively. Because of the numerical elevation of the forestomach papillomas in the high-dose mice of both sexes, the concomitant observation of dose related forestomach hyperplasia, and the rarity of this tumor in corn oil (gavage) control B6C3F1 mice, the development of squamous cell papillomas of the forestomach may have been related to diallyl phthalate administration. Under the conditions of this bioassay, the development of chronic inflammation and hyperplasia of the forestomach in both male and female B6C3F1 mice was considered to be related to the administration of diallyl phthalate. The development of squamous cell papillomas of the forestomach may also have been related to chemical administration, but the available data are insufficient to indicate a clear cause and effect relationship. An increase in the incidence of male mice with lymphomas was observed, but this increase was considered only to be equivocally related to diallyl phthalate administration. The results of this bioassay, therefore, do not indicate that diallyl phthalate is carcinogenic in B6C3F1 mice, although a maximum tolerated dose may not have been achieved. A carcinogenicity study by the National Toxicology Program of diallyl phthalate in male and female Fisher 344/N rats, employing daily gavage doses of 0 (vehicle control), 50, or 100 mg/kg boicology Program of diallyl phthalate in male and female Fisher 344/N rats, employing daily gavage doses of 0 (vehicle control), 50, or 100 mg/kg body weight is currently being evaluated. Levels of Evidence of Carcinogenicity: Male Mice: Equivocal Female Mice: Equivocal
...
PMID:NTP Carcinogenesis Bioassay of Diallyl Phthalate (CAS No. 131-17-9) in B6C3F1 Mice (Gavage Study). 1275 Jul 51

The tumour suppressor p53 induces cell death by launching several pathways that are either dependent on or independent of gene transcription. Accumulation of the sphingolipid ceramide and reactive oxygen species are among these pathways. Crossregulation of these two pathways is possible owing to the demonstrated inhibition of neutral sphingomyelinase by glutathione, the predominant cellular antioxidant, and has been observed in some cytokine-dependent cell-death models. In a model of irradiation-induced cell death of Molt-4 leukaemia cells, it was found that ceramide accumulation and glutathione depletion were dependent on p53 up-regulation. The loss of p53 owing to expression of the papilloma virus E6 protein inhibited both pathways after irradiation. However, in this model, these two pathways appeared to be independently regulated on the basis of the following observations: (1) glutathione supplementation or depletion did not alter irradiation-induced ceramide accumulation, (2) exogenous ceramide treatment did not induce glutathione depletion, (3) glutathione depletion was dependent on new protein synthesis, whereas ceramide accumulation was independent of it and (4) caspase activation was required for ceramide accumulation but not for glutathione depletion. Furthermore, caspase 9 activation, which is dependent on the release of mitochondrial cytochrome c, was not required for ceramide accumulation. This suggested that a caspase, other than caspase 9, was necessary for ceramide accumulation. Interestingly, Bcl-2 expression inhibited these pathways, indicating a possible role for mitochondria in regulating both pathways. These findings indicate that these two pathways exhibit cross-regulation in cytokine-dependent, but not in p53-dependent, cell-death models.
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PMID:Ceramide and glutathione define two independently regulated pathways of cell death initiated by p53 in Molt-4 leukaemia cells. 1296 22

Spontaneously arising tumor cells are not usually angiogenic at first. The phenotypic switch to angiogenesis is usually accomplished by a substet that induces new capillaries that then converge toward the tumor. The switch clearly involves more than simple upregulation of angiogenic activity and is thought to be the result of a net balance of positive and negative regulators. Tumor growth is although to require disruption of this balance and hence this switch must turned on for cancer progression. Progenitor endothelial cells, the crosstalk between angiogenic factors and their receptors and the interaction between vasculogenesis and lymphangiogenesis are all factors that may contribute to the switch. Its promotion is also the outcome of genetic instability resulting in the emergence of tumor cell lines. This review describes the history of the angiogenic switch illustrated in the literature and with particular reference to the three transgenic mouse models, namely RIP1-TAG2, keratin-14 (K14) (human papilloma virus) HPV16 and papilloma virus, used for stage-specific assessment of the effects of antiangiogenic and antitumorigenic agents.
Leukemia 2007 Jan
PMID:The history of the angiogenic switch concept. 1699 Jul 61

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