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National Toxicology Program

Publications and source records attributed to National Toxicology Program.

At least 415 records · Page 23Linked to original sources
PubMed1989

NTP Toxicology and Carcinogenesis Studies of Dichlorvos (CAS No. 62-73-7) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis studies of dichlorvos (99% pure), a contact and stomach poison for control of insects and parasites, were conducted by administering dichlorvos in corn oil by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 13 weeks or 2 years. Previous feed studies were done by the National Cancer Institute using Osborne-Mendel rats and B6C3F1 mice. Thirteen-Week Studies: Thirteen-week studies with groups of 10 rats of each sex were conducted at doses of 0, 2, 4, 8, 16, 32, or 64 mg/kg dichlorvos in corn oil. All rats that received 32 or 64 mg/kg dichlorvos and 4/10 females that received 16 mg/kg died before the end of the studies. Final mean body weights of dosed and vehicle control rats were similar. Thirteen-week studies with groups of 10 mice of each sex were conducted at doses of 0, 5, 10, 20, 40, 80, or 160 mg/kg. All 10 male mice and 9/10 female mice that received 160 mg/kg and 5/10 male mice that received 80 mg/kg dichlorvos died before the end of the studies. Final mean body weights of dosed and vehicle control mice were similar. No compound-related gross or microscopic pathologic effects were observed in rats or mice. Two-year studies of dichlorvos were conducted by administering 0, 4, or 8 mg/kg dichlorvos, 5 days per week for 103 weeks, to groups of 50 F344/N rats of each sex. Groups of 50 male B6C3F1 mice were administered 0, 10, or 20 mg/kg dichlorvos on the same schedule, and groups of 50 B6C3F1 female mice were administered 0, 20, or 40 mg/kg dichlorvos. Body Weight and Survival in the Two-Year Studies: Mean body weights of dosed and vehicle control rats and mice were similar. No significant differences in survival were observed between any groups of rats or mice of either sex (rats--male: vehicle control, 31/50; low dose, 25/50; high dose, 24/50; female: 31/50; 26/50; 26/50; mice-- male: 35/50; 27/50; 29/50; female: 26/50; 29/50; 34/50). Neoplastic Effects in the Two-Year Studies: Adenomas of the exocrine pancreas occurred at greater incidences in dosed rats than in vehicle controls (male: vehicle control, 25/50; low dose, 30/49; high dose, 33/50; female: 2/50; 3/47; 6/50). Mononuclear cell leukemia in both dosed groups of male rats occurred more frequently than in vehicle controls (11/50; 20/50; 21/50). Mammary gland fibroadenomas and fibroadenomas or adenomas (combined) in dosed female rats occurred at increased incidences relative to the vehicle controls (9/50; 19/50; 17/50). Multiple fibroadenomas occurred in dosed female rats but not in vehicle controls (0/50; 6/50; 3/50); carcinomas occurred in two vehicle control and two low dose female rats. In mice, incidences of squamous cell papillomas of the forestomach were increased in the high dose groups compared with those in the vehicle controls (male: 1/50; 1/50; 5/50; female: 5/49; 6/49; 18/50). Two high dose female mice developed forestomach squamous cell carcinomas. Genetic Toxicology: Dichlorvos was mutagenic in Salmonella typhimurium strain TA100 with and without metabolic activation but was not mutagenic in strain TA98. Dichlorvos was mutagenic in the mouse lymphoma L5178Y/TK+/- assay without metabolic activation. Dichlorvos induced sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cells in the absence and presence of metabolic activation. Conclusions: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of dichlorvos for male F344/N rats, as shown by increased incidences of adenomas of the exocrine pancreas and mononuclear cell leukemia. There was equivocal evidence of carcinogenic activity of dichlorvos for female F344/N rats, as shown by increased incidences of adenomas of the exocrine pancreas and mammary gland fibroadenomas. There was some evidence of carcinogenic activity of dichlorvos for male B6C3F1 mice, as shown by increased incidences of forestomach squamous cell papillomas. There was clear evidence of carcinogenic activity of dichlorvos for female B6C3F1 mice, as shown by increased incidences of forestomach squamous cell papils cell papillomas. Synonyms: 2,2-dichloroethenyl dimethyl phosphate; 2,2-dichlorovinyl dimethyl phosphate; O,O-dimethyl-O-(2,2-dichlorovinyl)phosphate; DDVP Trade Names: BAY-19149; DDVF; ENT-20738; OMS-14; SD 1750; Canogard®.; Crossman's Fly-Cake®.; Dedevap®.; De-Pester Insect Strip®.; Estrosol®.; Herkol®.; Kill-fly Resin Strip®.; Lethalaire®.; Mafu®.; Misect®.; Nogos®.; Nuvan®.; No-Pest Strip®.; Oko®.; Phoracide®.; Phosvit®.; Vapona®.; Vaponicide®.; Vaporette Bar®. Anthelmintics: Atgard®.; Dichlorman®.; Equigard®.; Task®.

Journal Article↗
PubMed1989

NTP Toxicology and Carcinogenesis Studies of Nitrofurantoin (CAS No. 67-20-9) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Nitrofurantoin was studied and evaluated because of its widespread use as a drug for treating urinary tract infections in humans, its structural relationship to known carcinogenic 5-nitrofuran compounds, and the lack of adequate studies to assess its carcinogenicity. Toxicology and carcinogenesis studies of nitrofurantoin were conducted by administering nitrofurantoin (greater than 99% pure) in feed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: None of the rats (at dietary concentrations up to 20,000 ppm) died before the end of the 14-day studies. Rats that received 5,000, 10,000, or 20,000 ppm lost weight. Four of five male and 4/5 female mice that received 10,000 ppm and 1/5 females that received 5,000 ppm nitrofurantoin died before the end of the studies. Mice that received 5,000 ppm and male mice that received 10,000 ppm lost weight. In the 13-week studies, final mean body weights of rats that received 2,500, 5,000, or 10,000 ppm were 10%, 34%, or 47% lower than that of the controls for males and 15%, 31%, or 41% lower for females. Feed consumption by dosed and control rats was generally similar. Degeneration of the germinal epithelium of the seminiferous tubules of the testis was observed in male rats that received 2,500 to 10,000 ppm nitrofurantoin. Necrosis of the ovarian follicles was observed in 8/10 female rats that received 10,000 ppm, in 3/10 females that received 5,000 ppm, and in 1/10 that received 2,500 ppm. For mice, final mean body weights of the 5,000-ppm groups were 13% lower than that of the controls for males and 15% lower for females. Two of 10 male mice that received 5,000 ppm and 1/10 males that received 300 ppm died before the end of the 13-week studies. Estimated feed consumption was similar for dosed and control groups. Degeneration of the germinal epithelium of the testis was observed in males that received 1,300 to 5,000 ppm; necrosis of the ovarian follicles was observed in females that received 5,000 ppm but not in the lower dose groups. Necrosis of the renal tubular epithelium was observed in 2/9 males that received 5,000 ppm. Based on these results, 2-year studies of nitrofurantoin were conducted by feeding diets containing 0, 1,300, or 2,500 ppm nitrofurantoin to groups of 50 male F344/N rats and to groups of 50 male and female B6C3F1 mice for 103 weeks. Groups of 50 female F344/N rats were fed diets containing 0, 600, or 1,300 ppm nitrofurantoin on the same schedule. Body Weight and Survival in the Two-Year Studies: Mean body weight and average daily feed consumption of dosed male and female rats were similar to those of the controls throughout the studies. The average amount of nitrofurantoin consumed per day was estimated to be 60 and 110 mg/kg for low and high dose male rats and 30 and 60 mg/kg for low and high dose female rats. No significant differences in the number of rats surviving to the end of the studies were observed between any groups of rats of either sex (male: control, 24/50; low dose, 27/50; high dose, 26/50; female: 25/50; 26/50; 31/50). Mean body weights of high dose male and female mice were up to 12% lower than those of the controls throughout most of the studies. The average daily feed consumption by dosed mice ranged from 93% to 100% that by controls. The average amount of nitrofurantoin consumed per day was estimated to be 280-300 mg/kg and 570-580 mg/kg for low and high dose mice. The survival of the control group of female mice was lower than that of the dosed groups (control, 19/50; low dose, 37/50; high dose, 37/50). The decrease in survival was most likely related to the increase in microbial infection in the reproductive tract observed in the controls. Groups of male mice had similar survival (28/50; 29/50; 34/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Organs showing toxicity from nitrofurantoin exposure identified in the short-term studies were the testis in male rats and mice, the ovary in female rats and mice, and the kidney in male mice. Lesions oband mice, the ovary in female rats and mice, and the kidney in male mice. Lesions observed in the 2-year studies were in the testis in male rats and mice, ovary in female mice, and kidney in male rats. Chronic nephropathy was observed in nearly all rats, but the severity of the lesions was judged to be greater in dosed male rats. Hyperplasia of the transitional cell epithelium (control, 0/50; low dose, 5/50; high dose, 2/50) and hydronephrosis of the renal pelvis (0/50; 5/50; 2/50) were also observed in dosed male rats. In the standard single sections of the left and right kidney from each rat, tubular cell adenomas were observed in one low dose and two high dose males; a tubular cell carcinoma was observed in another high dose male. Because the number of renal tubular cell neoplasms identified by standard procedures in the dosed male rats was low, additional step-sections of the kidney were evaluated. The incidences of tubular cell adenomas derived from the step-sections and original sections (combined) were significantly increased in dosed male rats (adenomas: 3/50; 11/50; 19/50); tubular cell carcinomas occurred in two high dose males only. Lesions considered to be associated with the nephropathy and nitrofurantoin exposure were observed in male rats and included hyperplasia of the parathyroid glands (3/49; 18/47; 23/49), fibrous osteodystrophy of the bone (0/50; 5/50; 5/50), and mineralization of the glandular stomach (1/49; 8/50; 14/50). Atypical cells of the epididymis (0/50; 0/50; 12/50) and degeneration of the testis (0/50; 0/50; 36/50) were observed in high dose male rats. Fibrinoid necrosis of arterioles (1/50; 8/50; 15/50) and perivascular infiltration of mononuclear cells (3/50; 9/50; 19/50) were also observed in the testis of male rats. Interstitial cell adenomas of the testis occurred with a negative trend (47/50; 45/50; 21/50), and no adenomas or carcinomas of the preputial gland were seen in high dose male rats (12/48; 11/50; 0/47). The incidence of clitoral gland neoplasms was increased in low dose female rats (5/44; 10/38; 4/42). Osteosarcomas were observed in the bone of one low dose and two high dose male rats. The historical incidence of osteosarcomas in untreated male F344/N rats is 8/1,937 (0.4%). The incidences of subcutaneous tissue neoplasms in dosed male rats were greater than that in the controls (1/50; 7/50; 5/50). No neoplastic lesions in dosed female rats or male mice were considered to be compound related at the doses of nitrofurantoin administered. For female mice, ovarian atrophy was observed in 48/50 low dose and 49/50 high dose mice but not in controls. Tubular cell adenomas of the ovary (0/50; 0/50; 5/50), benign mixed tumors (tubular and stromal) (0/50; 0/50; 4/50), and granulosa cell tumors (0/50; 3/50; 2/50)) were observed in dosed female mice. One granulosa cell tumor in the high dose group was malignant. Ovarian abscesses (18/50) and suppurative inflammation of the uterus (11/50) were observed in control female mice but not in dosed female mice and are believed to be related to indigenous microbial infections and most likely were the cause of early deaths in this group. Adenocarcinomas of the uterus were seen in one low dose and in one high dose mouse. Testicular aspermatogenesis (1/49; 1/49; 16/50), degeneration of the germinal epithelium (0/49; 3/49; 23/50), and atypical cells (0/50; 0/49; 26/50) and depletion (1/50; 1/49; 15/50) of the epididymis were observed at increased incidences in high dose male mice. Spindle cell hyperplasia of the adrenal cortex was observed in dosed female mice (3/50; 41/50; 45/50). A spindle cell adenoma (adrenal capsule adenoma) was seen in one low dose female mouse, and a spindle cell carcinoma (adrenal capsule carcinoma) was seen in one low dose male mouse. Mineralization of the renal medulla (male: 0/50; 0/50; 17/50; female: 0/50; 0/50; 7/50) and dilatation of the renal tubules (male: 0/50; 0/50; 14/50) were observed in high dose mice. Hepatocellular neoplasms (adenomas or carcinomas, combined) were observed at an increased incidence in high dose female mice (2/50; 2/50; 8/50). An Ito cell tumor of the liver was observed in one low dose and one high dose female mouse. Malignant lymphomas occurred in female mice (12/50; 19/50; 24/50). Genetic Toxicology: Nitrofurantoin was mutagenic in Salmonella typhimurium strains TA98 and TA100, with and without metabolic activation, but was not mutagenic for strains TA1535 or TA1537. Nitrofurantoin induced forward mutations at the TK+/- locus of L5178Y mouse lymphoma cells in the absence of metabolic activation (it was not tested with activation). Nitrofurantoin induced increased numbers of sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells with and without metabolic activation. Results of the sex-linked recessive lethal assay in Drosophila were negative after administration of nitrofurantoin by feeding or by injection. Conclusions: Under the conditions of these 2-year feed studies, there was some evidence of carcinogenic activity of nitrofurantoin for male F344/N rats as shown by increased incidences of uncommon kidney tubular cell neoplasms. Uncommon osteosarcomas of the bone and neoplasms of the subcutaneous tissue were observed in dosed male rats. Incidences of interstitial cell adenomas of the testis and neoplasms of the preputial gland were decreased in the 2,500-ppm group of male rats. There was no evidence of carcinogenic activity of nitrofurantoin for female F344/N rats fed diets containing 600 ppm or 1,300 ppm for 2 years. Female rats may have been able to tolerate higher doses. There was no evidence of carcinogenic activity of nitrofurantoin for male B6C3F1 mice fed diets containing 1,300 ppm or 2,500 ppm for 2 years. There was clear evidence of carcinogenic activity of nitrofurantoin for female B6C3F1 mice as shown by increased incidences of tubular adenomas, benign mixed tumors, and granulosa cell tumors of the ovary. Nonneoplastic lesions considered related to nitrofurantoin exposure were chronic nephropathy and associated lesions (hyperplasia of the parathyroid gland, fibrous osteodystrophy of the bone, and mineralization of the glandular stomach) in male rats and testicular degeneration in male rats and mice. Ovarian atrophy and hyperplasia of the adrenal cortex spindle cells were observed in dosed female mice. Synonyms: 1-(((5-nitro-2-furanyl)methylene)amino-2,4-imidazolidinedione); 1-(5-nitro-2-furfurylideneamino)-hydantoin; N-(5-nitro-2-furfurlidene)-1-aminohydantoin; 1-((5-nitrofurfurylidene)amino)hydantoin Trade Names: Benkfuran; Benkfurin; Chemiofuran; Cyantin; Dantafur; Furadantin; Furadantine; Furadantoin; Furadonin; Furadonine; Furantoin; Furatoin; Furobactina; Ituran; Macrodantin; Nifurantin; NSC 2107; N-Toin; Orafuran; Parafuran; Urizept; USAF EA-2; Welfurin; Zoofurin

Journal Article↗
PubMed1989

NTP Toxicology and Carcinogenesis Studies of Roxarsone (CAS No. 121-19-7) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Roxarsone is a veterinary drug used as a growth promoter and as an anticoccidial agent and for treatment of swine dysentery. Toxicology and carcinogenesis studies were conducted by administering roxarsone (greater than 99.4% pure) in feed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: In the 14-day studies, the diets fed to rats contained 0 or 100-1,600 ppm roxarsone, and those fed to mice contained 0 or 60-1,000 ppm. Deaths occurred in rats and mice that received the highest doses. Rats that received 800 or 1,600 ppm lost weight. Male mice that received 1,000 ppm and female mice that received 500 ppm lost weight. In the first 13-week studies, roxarsone was fed to rats and mice at dietary concentrations of 0 or 50-800 ppm. Decreases (more than 10%) in final mean body weights of dosed rats relative to those of controls were observed for males that received 200, 400, or 800 ppm and for females that received 400 or 800 ppm. Deaths occurred in groups that received 800 ppm. Clinical signs of toxicity (trembling, ataxia, and pale skin) were seen primarily in rats that received 800 ppm. Kidney lesions were observed in rats that received 800 ppm. These lesions were characterized by tubular necrosis and mineralization in the rats that died during the studies and by tubular dilatation and casts, interstitial inflammation, and tubular epithelial cell regeneration in the rats that lived to the end of the studies. Additional 13-week studies were conducted in rats at dietary concentrations of 0, 100, or 400 ppm to demonstrate the absorption of roxarsone from the gastrointestinal tract; to determine its distribution in liver, kidney, and blood; and to study its effects on various hematologic and clinical chemical values. No deaths occurred. Renal lesions of minimal severity observed in male rats that received 400 ppm were characterized by tubular epithelial cell degeneration and regeneration, tubular casts, and mineralization. Arsenic levels in urine, blood, kidney, and liver of dosed rats increased (140%-300%) with time on study and were proportional to the dietary concentrations of roxarsone. No compound-related hematologic or clinical chemical effects were observed in rats. In the first 13-week studies, final mean body weights of mice that received 800 ppm were 11%-18% lower than those of controls. Deaths occurred in males and females receiving 400 and 800 ppm. No compound-related gross or histopathologic lesions were observed. In the second 13-week studies in mice, no compound-related hematologic or clinical chemical effects were observed. At the end of the studies, arsenic concentrations in dosed mice ranged from 0.45 to 0.99 ug/g of liver and from 0.85 to 2.98 ug/g of kidney. No arsenic was detected in the liver or kidney of control mice. Because of kidney lesions, lower body weight gain, and increased mortality in rats and lower body weight gain and increased mortality in mice in the short-term studies, dietary concentrations of roxarsone selected for the 2-year studies were 0, 50, or 100 ppm for rats and 0, 100, or 200 ppm for mice. Body Weight and Survival in the Two-Year Studies: Mean body weights of dosed rats were generally within 5% of those of controls. No significant differences in survival were observed between any groups of rats of either sex, although survival in males was lower than usual (final survival--male: control, 24/50; low dose, 18/50; high dose, 18/50; female: 27/50; 35/50; 32/50). The average feed consumption by high dose rats was 95% that of controls for males and 88% for females. The average amount of roxarsone consumed per day was approximately 2 mg/kg for low dose rats and 4 mg/kg for high dose rats. Mean body weights of high dose male mice were generally 5%-8% higher than those of the controls, whereas those of female mice were generally 6%-15% lower than those of the controls. The survival of the control group of male mice was lower than that of the low dose group after month 22; survival for females was low (final survir than that of the low dose group after month 22; survival for females was low (final survival--male: 27/50; 40/50; 33/50; female: 14/50; 18/50; 17/50). The low survival in females was due in part to utero-ovarian infection, with more than 50% of the animals in each dose group having suppurative inflammation at this site. The average daily feed consumption by dosed mice was 105%-110% that by the controls. The average amount of roxarsone consumed per day was approximately 21 or 43 mg/kg for low dose or high dose male mice and 27 or 54 mg/kg for low dose or high dose female mice. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Although the incidence of adenomas of the exocrine pancreas in high dose male rats was not statistically greater than that in the controls (control, 1/50; low dose, 1/50; high dose, 5/50), it was greater than that seen in any historical control group of male F344/N rats. The historical rate is 1/437 (0.2%) for the study laboratory and 5/1,871 (0.3%) throughout the Program. The incidences of hyperplasia were 2/50; 0/50; 3/50. No hyperplasia oradenomas were observed in the exocrine pancreas of female rats. Clitoral gland adenomas in female rats occurred with a marginally positive trend (1/44; 3/47; 6/48; P=0.049). One carcinoma was also observed in each of the groups. The incidences of adenomas or of adenomas or carcinomas (combined) in the dosed groups were not significantly different from those in the controls. This marginal effect was not considered to be related to roxarsone administration. No chemical-related increases in neoplastic or nonneoplastic lesions occurred in male or female mice. Lymphomas in female mice occurred with a negative trend; the incidences in the dosed groups were lower than that in the controls (13/50; 2/50; 3/50; P≤0.01). Genetic Toxicology: Roxarsone was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without metabolic activation. Roxarsone induced trifluorothymidine (Tft) resistance in mouse lymphoma L5178Y cells in the absence of metabolic activation; it was not tested with activation. Exposure of adult male Drosophila melanogaster to roxarsone by injection or by feeding did not cause an increase in sex--linked recessive lethal mutations. Audit: The data, documents, and pathology materials from the 2-year studies of roxarsone have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year feed studies, there was equivocal evidence of carcinogenic activity of roxarsone for male F344/N rats, as indicated by a marginally increased incidence of adenomas of the exocrine pancreas. There was no evidence of carcinogenic activity for female F344/N rats fed diets containing 50 or 100 ppm roxarsone for 2 years. There was no evidence of carcinogenic activity for male or female B6C3F1 mice fed diets containing 100 or 200 ppm roxarsone for 2 years. Synonyms: 4-hydroxy-3-nitrophenylarsonic acid; 4-hydroxy-3-nitrobenzenearsonic acid; 2-nitro-1-hydroxybenzene-4-arsonic acid; nitrophenolarsonic acid; 3-nitro-4-hydroxybenzenearsonic acid; 3-nitro-4-hydroxyphenylarsonic acid Trade Names: Ristat; Ren-O-sal; 3-nitro; 3-nitro-10; 3-nitro-20; 3-nitro-50; 3-nitro-80

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of 2-Amino-4-Nitrophenol (CAS No. 99-57-0) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

2-Amino-4-nitrophenol is used to color semipermanent hair dyes and in the manufacture of mordant dyes for leather, nylon, silk, wool, and fur. 2-Amino-4-nitrophenol was nominated by the National Cancer Institute for toxicology and carcinogenesis studies because of widespread human exposure associated with its manufacture and use. Toxicology and carcinogenesis studies were conducted by administering 2-amino-4-nitrophenol (98% pure) in corn oil by gavage, 5 days per week, to groups of F344/N rats and B6C3F1 mice of each sex in 15-day, 13-week, and 2-year studies. Fifteen-Day and Thirteen-Week Studies: During the 15-day studies, rats and mice received doses of 0, 313, 625, 1,250, 2,500, or 5,000 mg/kg. All rats that received 2,500 or 5,000 mg/kg and all female rats that received 1,250 mg/kg died before the end of the studies. Final mean body weights of chemically exposed rats surviving to the end of the studies were comparable to those of vehicle controls. Diarrhea was observed in all groups of exposed rats except those receiving 313 mg/kg. All mice that received 2,500 or 5,000 mg/kg, 2/5 males and all females that received 1,250 mg/kg, and 1/5 females that received 313 mg/kg died before the end of the studies. Final mean body weights of exposed mice surviving until the end of the studies were comparable to those of vehicle controls. In 13-week studies, F344/N rats and B6C3F1 mice of each sex received 2-amino-4-nitrophenol at doses of 0, 62.5, 125, 250, 500, or 1,000 mg/kg. All rats that received 1,000 mg/kg and 2/10 males and 2/10 females that received 500 mg/kg died before the end of the studies. The final mean body weight of male rats that received 500 mg/kg was reduced 10% compared with that of vehicle controls; final mean body weights of all other surviving exposed rat groups were comparable to those of vehicle controls. Diarrhea and lethargy were observed for rats that received 500 or 1,000 mg/kg. All male mice and most females that received 1,000 mg/kg and 4/10 females that received 500 mg/kg died before the end of the studies. Final mean body weights of chemically exposed mice were comparable to those of vehicle controls. No compound-related clinical signs were observed in mice during the studies. Mineralization of the renal cortex and degeneration of the renal tubular epithelium were observed in male and female rats that received 1,000 mg/kg and in males that received 500 mg/kg. Degeneration and necrosis of the renal tubular epithelium was observed in 5/10 male and 3/10 female mice that received 1,000 mg/kg. Body Weight and Survival in the Two-Year Studies: In the 2-year studies, rats and mice received 2-amino- 4- nitrophenol at doses of 0, 125, or 250 mg/kg. Mean body weights of male rats that received 250 mg/kg were 8%-10% lower than those of vehicle controls throughout most of the 2-year study. Mean body weights of female rats were comparable to those of vehicle controls. Soft stools and occasional diarrhea were observed in chemically exposed rats starting 6 months after the beginning of the studies. Survival of male rats that received 250 mg/kg was markedly lower than that of vehicle controls after week 89 (final survival: vehicle control, 32/50; 125 mg/kg group, 24/50; 250 mg/kg group, 10/50). Survival of female rats was comparable among all groups (final survival: 25/50; 27/50; 31/50). Mean body weights of male and female mice that received 250 mg/kg were comparable to those of vehicle controls; the mean body weights of female mice that received 125 mg/kg were as much as 17% greater than that of vehicle controls. Survival of all mouse groups was comparable during the 2-year studies (final survival: male-- 28/50; 29/50; 23/50; female--28/50; 31/50; 30/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Pigmentation of the small and large intestines was present in exposed rats but not in vehicle controls. Ulcers and erosive lesions of the digestive tract were observed in male rats that received 250 mg/kg and to a lesser extent in male rats that received 125 mg/kg. A carcinoma of the colon occurrkg. A carcinoma of the colon occurred in one male rat that received 250 mg/kg; no other neoplasms were observed in the gastrointestinal tract of rats. No pigmentation, ulcers, or erosive lesions were found in the digestive tract of mice. The severity of nephropathy was markedly greater in exposed male rats than in vehicle controls. Associated with the nephropathy were nonneoplastic lesions indicative of reduced renal function and secondary hyperparathyroidism, including parathyroid hyperplasia, mineralization of various organs, and fibrous osteodystrophy. Renal tubular cell hyperplasia (1/50; 4/48; 5/50) and renal cortical (tubular cell) adenomas (0/50; 1/48; 3/50) occurred in male rats. Renal cortical adenomas are infrequently observed in male F344/N rats (historical incidence, 0.5%). More preputial gland adenomas or carcinomas (combined) were observed in low dose male rats than in vehicle controls (3/50; 10/48; 3/50), whereas the incidences of clitoral gland neoplasms were decreased in dosed female rats (9/50; 6/50; 1/49). Hemangiomas or hemangiosarcomas (combined) occurred in male mice that received 2-amino-4-nitrophenol (0/50; 1/50; 5/50); each tumor was present at a different site. The historical control incidence is 11% at the study laboratory and 6% in 2-year NTP studies. Genetic Toxicology: 2-Amino-4-nitrophenol was mutagenic in Salmonella typhimurium strains TA98 and TA100 with metabolic activation. 2-Amino-4-nitrophenol was not mutagenic in strains TA1535 or TA1537. 2-Amino-4-nitrophenol was mutagenic in the mouse lymphoma L5178Y/TK± assay without metabolic activation. It was not tested with activation. 2-Amino-4-nitrophenol induced sister chromatid exchanges (SCEs) and chromosomal aberrations in Chinese hamster ovary cells in the presence and absence of metabolic activation. Audit: The data, documents, and pathology materials from the 2-year studies of 2-amino-4-nitrophenol were audited at the NTP Archives. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of 2-amino-4-nitrophenol for male F344/N rats, as shown by increased incidences of renal cortical (tubular cell) adenomas. The incidences of renal tubular cell hyperplasia were also increased in male rats exposed to 2-amino-4-nitrophenol. The survival of male rats that received 2-amino-4-nitrophenol was reduced compared with survival of vehicle control male rats. There was no evidence of carcinogenic activity of 2-amino-4-nitrophenol for female F344/N rats or for male or female B6C3F1 mice that received 125 or 250 mg/kg per day.

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Erythromycin Stearate (CAS No. 643-22-1) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Toxicology and carcinogenesis studies of erythromycin stearate (USP grade, greater than 96% pure) were conducted by administering the antibiotic in feed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Erythromycin stearate was studied because of its widespread use in humans as a broad-spectrum macrolide antibiotic and because of the lack of adequate long-term studies for carcinogenicity. Fourteen-Day and Thirteen-Week Studies: In the 14-day studies, none of the rats (at dietary concentrations up to 50,000 ppm) and 2/5 female mice that received 50,000 ppm died before the end of the studies. Final mean body weights of male rats that received 12,500, 25,000, or 50,000 ppm were 10%, 30%, or 36% lower, respectively, than that of controls; final mean body weights of female rats were 10%, 12%, or 32% lower. None of the dosed mouse groups gained weight. The final mean body weight of male mice that received 50,000 ppm was 10% lower than that of controls. In the 13-week studies, none of the rats or mice (at dietary concentrations up to 20,000 ppm) died before the end of the studies. Final mean body weights of the 20,000-ppm groups of rats were more than 12% lower than that of the controls for males and 7% lower for females. Final mean body weights of mice that received 10,000 or 20,000 ppm were 15% or 19% lower than that of controls for males and 5% or 14% lower for females. Multinucleated syncytial hepatocytes were observed in 10/10 male rats that received 20,000 ppm but in 0/10 male rats that received 10,000 ppm. No compound-related gross or microscopic pathologic effects were observed in mice. Based on these results, 2-year studies of erythromycin stearate were conducted by feeding diets containing 0, 5,000, or 10,000 ppm erythromycin stearate to groups of 50 rats of each sex for 103 weeks. Diets containing 0, 2,500, or 5,000 ppm were fed to groups of 50 mice of each sex for 103 weeks. Body Weight and Survival in the Two-Year Studies: Mean body weights of high dose male rats were comparable to those of controls throughout the studies. Mean body weights of high dose female rats were 5%-10% lower than those of controls. Mean body weights of dosed and control mice were comparable. The average daily feed consumption was similar for dosed and control male and female rats. For mice, estimated daily feed consumption by low and high dose males was similar to that of the controls and by low and high dose females was 92% that of the controls. The average amount of erythromycin stearate consumed per day was approximately 180 or 370 mg/kg for male rats and 210 or 435 mg/kg for female rats; for mice, the average amounts were 270 or 545 mg/kg for males and 250 or 500 mg/kg for females. No significant differences in survival were observed between any groups of rats or mice of either sex (final survival-- male rats: control, 28/50; low dose, 23/50; high dose, 27/50; female rats: 29/50; 30/50; 38/50; male mice: 34/50; 33/50; 40/50; female mice: 38/50; 34/50; 40/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Granulomas of the liver were observed at increased incidences in high dose rats (male: 1/50; 2/50; 10/50; female: 18/50; 27/50; 43/50). Granulomatous inflammation or granulomas of the spleen were observed in dosed female rats (0/48; 1/49; 3/50). Reticulum cell hyperplasia in the bone marrow occurred at increased incidences in high dose female rats (10/50; 14/50; 25/50). Squamous cell papillomas of the oral mucosa were observed in 1/50 control, 2/50 low dose, and 3/50 high dose female rats. These tumors were considered to be marginal and not related to exposure. Hyperplasia of the oral mucosa was not observed. Pheochromocytomas of the adrenal gland in female rats occurred with a positive trend (1/50; 4/49; 5/50). The incidences in the dosed groups are similar to the average historical incidence (9%) of this tumor in untreated control female F344/N rats at the study laboratory. This marginal tumor increase is not considered to be biologically important. No increases in incidences of study laboratory. This marginal tumor increase is not considered to be biologically important. No increases in incidences of neoplasms were observed at any site in dosed male rats. Inflammation in the glandular stomach was observed at increased incidences in dosed male mice (1/49; 4/50; 6/50). Lymphoid hyperplasia in the urinary bladder was observed at increased incidences in dosed female mice (1/50; 9/47; 7/48). No increases in incidences of neoplasms were observed at any site in dosed male or female mice. Genetic Toxicology: Erythromycin stearate was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 when tested both with or without exogenous metabolic activation. Erythromycin stearate demonstrated equivocal mutagenicity in the mouse L5178Y lymphoma cell assay in the absence of exogenous metabolic activation (S9); erythromycin stearate was not mutagenic in the presence of S9. Treatment of cultured Chinese hamster ovary cells with erythromycin stearate did not produce an increase in the frequency of sister chromatid exchanges or chromosomal aberrations in either the presence or absence of metabolic activation. Audit: The data, documents, and pathology materials from the 2-year studies of erythromycin stearate have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year studies, there was no evidence of carcinogenic activity of erythromycin stearate for male or female F344/N rats administered erythromycin stearate in the diet at 5,000 or 10,000 ppm. There was no evidence of carcinogenic activity of erythromycin stearate for male or female B6C3F1 mice administered erythromycin stearate in the diet at 2,500 or 5,000 ppm. Dose-related increases in the incidences of granulomas of the liver were observed in male and female rats. The absence of any biologically important chemical-associated effects in mice suggests that higher doses could have been given to male and female mice. Synonyms: erythrocin stearate; erythromycin octadecanoate Trade Names: Abbotcine; Bristamycin; Dowmycin E; Eratrex; Erypar; Ethril; Gallimycin; HSDB 4178; OE 7; Pantomicina; Pfizer-E; SK-Erythromycin; Wyamycin S

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Nitrofurazone (CAS No. 59-87-0) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Nitrofurazone is a synthetic furan derivative, active against a broad spectrum of bacteria, which has been widely used in veterinary and human medicine. Toxicology and carcinogenesis studies were conducted by feeding diets containing nitrofurazone (99% pure) to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: Groups of five males and five females of each species were fed diets containing 0, 630, 1,250, 2,500, 5,000, or 10,000 ppm for 14 consecutive days. Early deaths occurred in all groups of rats receiving 5,000 or 10,000 ppm nitrofurazone. The surviving rats in the lower two dose groups gained weight, but weight gain was decreased as the dose of nitrofurazone was increased. Feed consumption by rats of each sex was decreased at all doses above 630 ppm. In all dosed groups, clinical signs of toxicity included rough hair coats and lethargy. At doses of 2,500 ppm and above, rats of each sex exhibited intermittent episodes of seizures and lethargy. All mice that received 2,500, 5,000, or 10,000 ppm nitrofurazone and 3/5 males that received 1,250 ppm died before the end of the 14-day studies; the surviving dosed mice (except females at 630 ppm) lost weight. A dose-related decrease in feed consumption was observed at all doses above 630 ppm. Clinical signs included rough hair coats and convulsive seizures. In the 13-week studies, groups of 10 rats of each sex were given diets containing 0, 150, 310, 620, 1,250, or 2,500 ppm nitrofurazone. No deaths were observed and all animals gained weight, but the magnitude of weight gain was dose dependent with decrements in final mean body weight for the highest dose group reaching 55% in males and 36% in females. Other evidence of chemically related toxicity included convulsive seizures, osteoporosis, degenerative arthropathy, and gonadal hypoplasia in both sexes at the two highest doses. Groups of 10 mice of each sex were given diets containing 0, 70, 150, 310, 620, or 1,250 ppm nitrofurazone for 13 weeks. Early deaths were observed in the two highest dose groups of each sex. The final mean body weights of male and female mice in the 1,250-ppm groups were about 20% lower than those of the controls; weight gains of the other dosed mice were comparable to those of the controls. Stimulus-induced convulsive seizures were observed for all mice in the two highest dose groups. Testicular hypoplasia was observed in the two highest dose groups of male mice. Body Weight and Survival in the Two-Year Studies: Dietary concentrations for the 2-year studies were 0, 310, or 620 ppm for rats and 0, 150, or 310 ppm for mice (50 animals per dose group). Mean body weights of high dose male rats were lower than those of the controls after week 39; mean body weights of low dose male rats and of the controls were comparable throughout the study. Final mean body weights of low and high dose female rats were 9% and 21% lower than those of the controls. Dosed rats consumed less feed than did the controls. The average amount of nitrofurazone consumed per day was approximately 11-12 or 24-26 mg/kg by low or high dose male and female rats. The survival of the high dose group of male rats was lower than that of the controls after week 92 (final survival-- male: control, 33/50; low dose, 30/50; high dose, 20/50; female: 28/50; 37/50; 31/50). Mean body weights of dosed mice were similar to or somewhat greater than those of controls throughout most of the studies. The average daily feed consumption by dosed mice was similar to that of controls. The average amount of nitrofurazone consumed per day was approximately 14-16 or 29-33 mg/kg for low or high dose male and female mice. The survival of the high dose group of male mice was lower than that of the controls after week 88 (final survival-- male: 39/50; 31/50; 27/50; female: 39/50; 40/50; 35/50). In mice of each sex, nitrofurazone administration induced stimulus-sensitive convulsive seizures beginning at week 4 or 5 for high dose mice and week 24 for low dose female mice. These seizures were low dose female mice. These seizures were observed primarily in the first year of the study. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Degenerative changes involving the vertebral and femoro-tibial (knee) joints were observed at increased incidences in dosed rats. The degenerative changes primarily affected the articular cartilage and were similar to those seen in the 13-week studies. Degeneration of the sternal synchondroses was increased in high dose female rats. The osteoporosis seen in the 13-week studies was not observed in the 2-year studies. Testicular degeneration, characterized by atrophy of the germinal epithelium and aspermatogenesis, was observed at increased incidences in dosed male rats (control, 12/50; low dose, 49/50; high dose, 47/50). Adenomas of the sebaceous glands and trichoepitheliomas or sebaceous adenomas (combined) of the skin were observed in high dose male rats (0/50; 0/50; 5/50). Carcinomas of the preputial gland were increased in dosed male rats (1/50; 8/50; 5/50). The incidences of preputial gland adenomas or carcinomas (combined) in dosed male rats were not statistically greater than that in the controls (9/50; 16/50; 7/50). However, in the low dose group, the incidence is greater than the highest incidence observed in historical untreated control groups (9/50). In addition, hyperplasia of the preputial gland was observed in six low dose male rats in which neither adenomas nor carcinomas occurred. The incidence of mesotheliomas of the tunica vaginalis in low dose male rats was greater than that in the controls (0/50; 7/50; 2/50). Fibroadenomas of the mammary gland occurred at markedly increased incidences in dosed female rats (8/49; 36/50; 36/50). Three adenocarcinomas were also observed (1/49; 0/50; 2/50). Ovarian atrophy (7/47; 44/50; 38/50) and tubular cell hyperplasia of the ovary (1/47; 23/50; 21/50) were observed at markedly increased incidences in dosed female mice. The incidences of benign mixed tumors (0/47; 17/50; 20/50), granulosa cell tumors (1/47; 4/50; 9/50), and granulosa cell tumors or luteomas (combined) (3/47; 6/50; 9/50) of the ovary were increased in exposed female mice. Mononuclear cell leukemia in rats occurred with negative trends (male: 21/50; 23/50; 6/50; female: 15/49; 2/50; 2/50). In female mice, the incidences of adenomas or carcinomas (combined) of the anterior pituitary gland occurred with a negative trend (10/50; 7/50; 2/49). The incidences of testicular interstitial cell tumors were decreased in dosed male rats (45/50; 30/50; 28/50). Genetic Toxicity: Nitrofurazone was mutagenic in Salmonella typhimurium strains TA98 and TA100 both with and without exogenous metabolic activation. The responses in strains TA1535 and TA1537 were more varied: nitrofurazone was mutagenic in strain TA1535 only in the presence of S9 and produced no consistent increase in gene reversions in strain TA1537 with or without S9. In the absence of metabolic activation, nitrofurazone induced forward mutations at the TK+/- locus of mouse L5178Y lymphoma cells; the chemical was not tested with S9. Treatment of cultured Chinese hamster ovary cells with nitrofurazone in the absence of S9 produced a dose-related increase in sister chromatid exchanges and chromosomal aberrations; with S9, sister chromatid exchanges were increased, but no induction of chromosomal aberrations was observed. Audit: The data, documents, and pathology materials from the 2-year studies of nitrofurazone were audited at the NTP Archives. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year feed studies, there was equivocal evidence of carcinogenic activity of nitrofurazone for male F344/N rats as shown by the occurrence of sebaceous gland adenomas and trichoepitheliomas of the skin, mesotheliomas of the tunica vaginalis, and preputial gland tumors. There was clear evidence of carcinogenic activity of nitrofurazone for female F344/N rats as shown by a markedly increased incidence of fibroadenomas of the mammary gland. There was no evidence of carcinogenic activity for male B6C3F1 mice fed diets containing nitrofurazone at concentrations of 150 or 310 ppm. There was clear evidence of carcinogenic activity of nitrofurazone for female B6C3F1 mice as shown by increased incidences of benign mixed tumors and granulosa cell tumors of the ovary. Administration of nitrofurazone was associated with decreased incidences of mononuclear cell leukemia in male and female rats, testicular interstitial cell tumors in male rats, and pituitary gland neoplasms in female mice. Convulsive seizures in mice of each sex, ovarian atrophy in female mice, testicular degeneration in rats, and degeneration of articular cartilage in rats were all associated with the administration of nitrofurazone. Synonyms: 5-nitro-2-furaldehyde semicarbazone; 2-[(5-nitro-2-furanyl)methylene]hydrazine carboximide Trade Names: Aldomycin; Amifur; Chemfuran; Coxistat; Furacin; Furacinetten; Furaplast; Furazol W; Furesol; Furracoccid; Mammex; Nefco; Nifuzon; Nitrofural; Vabrocid

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Penicillin VK (CAS No. 132-98-9) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Penicillin VK, a widely used antibiotic for treatment of gram-positive coccal infections, was nominated for study by the National Cancer Institute because rodent carcinogenicity studies for this drug had not been performed. The chemical (94% or 98% pure, USP grade) was administered orally (by gavage in corn oil) because oral administration is the primary route used to treat infections in humans. Fourteen-day, 13-week, and 2-year studies were conducted in F344/N rats and B6C3F1 mice. Additional studies were performed to evaluate the potential for genetic damage in bacteria and mammalian cells. Fourteen-Day and Thirteen-Week Studies: In the 14-day studies, penicillin VK was administered at doses of 150-2,400 mg/kg. No compound-related deaths or dose-related histopathologic lesions were seen in rats or mice. Final mean body weights of dosed male rats were 5%-17% lower than that of controls; weights of dosed and control female rats were comparable. Final mean body weights of dosed mice were 5%-9% lower than those of controls. Diarrhea was observed in all dosed groups of rats and mice. In the 13-week studies, male and female rats received doses of 180-3,000 mg/kg and male and female mice received doses of 250-3,000 mg/kg. No compound-related deaths were seen in rats or mice. Final mean body weights of rats that received 3,000 mg/kg were 11% lower than those of the vehicle controls for males and 6% lower for females. For mice, mean body weights were comparable. Diarrhea occurred in male rats at doses of 750 mg/kg and above and in female rats at doses of 1,500 and 3,000 mg/kg. Mucous cell metaplasia of the glandular stomach was observed in male and female rats receiving 1,500 and 3,000 mg/kg. Lesions of the glandular stomach (inflammation, mucous cell metaplasia, and eosinophilic cytoplasmic change) and the forestomach (papillary hyperplasia and hyperkeratosis) were seen in all groups of dosed mice. The severity of lesions at 1,000 mg/kg or below was considered minimal. Based on these results, doses selected for rats and mice in the 2-year studies were 0, 500, or 1,000 mg/kg. Body Weight and Survival in the Two-Year Studies: Mean body weights of dosed and vehicle control male and female rats and male mice were comparable. Mean body weights of dosed female mice were 4%-16% lower than those of the vehicle controls from week 28 to the end of the study. Diarrhea was observed for dosed male and female rats and for dosed male mice. Survival of low and high dose male rats and high dose female rats was reduced (male rats: vehicle control, 34/50; low dose, 19/50; high dose, 16/50;female rats: 29/50; 26/50; 16/50). Survival of male and female mice was comparable to that of the vehicle controls (male mice: 24/50; 36/50; 26/50; female mice: 36/50; 32/50; 32/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Nonneoplastic lesions occurred at low incidences in the nasal mucosa, lung, and forestomach of dosed male rats and in the nasal mucosa and lung of dosed female rats. Congestion and aspiration pneumonia occurring in dosed rats dying before week 104 was the principal cause of death in these animals. Nonneoplastic lesions of the gastric fundal gland (eosinophilic cytoplasmic change and dilatation) and glandular stomach (cyst, chronic focal inflammation, hyperplasia, fibrosis, and squamous metaplasia) were seen in dosed male and female mice, and lesions of the gallbladder (eosinophilic cytoplasmic change) were seen in male mice. Slight increases in the incidences of adenomas of the pituitary gland in high dose male rats and of fibroadenomas or adenomas (combined) of the mammary gland in low dose female rats were observed. These were not considered to be compound-related lesions. The incidence of hepatocellular adenomas was decreased in high dose male mice (14/50; 15/49; 4/49). No compound-related neoplasms were seen in female mice. Genetic Toxicology: Penicillin VK was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without exogenous metabolic activation. The chemical was mutagenic onl exogenous metabolic activation. The chemical was mutagenic only with activation in the mouse lymphoma L5178Y/TK± forward mutation assay. Incubation of Chinese hamster ovary cells with penicillin VK resulted in increased frequencies of sister chromatid exchanges and chromosomal aberrations in the absence of metabolic activation under the conditions of delayed harvest to compensate for chemical-induced cell cycle delay, no effects from penicillin VK exposure were observed in these cells in the presence of S9. Audit: The data, documents, and pathology materials from the 2-year studies of penicillin VK were audited. The audit findings show that the conduct of the studies is documented and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of penicillin VK for F344/N rats or for B6C3F1 mice administered 500 or 1,000 mg/kg penicillin VK in corn oil gavage, 5 days per week for 2 years. Nonneoplastic lesions were seen in the glandular stomach of dosed mice. Decreased survival of low and high dose male rats and of high dose female rats reduced the sensitivity of the studies for determining the presence or absence of a carcinogenic response in this species. Synonyms: 4-thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 3,3-dimethyl-7-oxo-6-(2-phenoxy-acetamide)-, monopotassium salt; penicillin V potassium; penicillin V potassium salt; D-a-phenoxymethylpenicillinate K salt; phenoxymethylpenicillin potassium; PVK Trade Names: Antibiocin; Apsin VK; Aracil; Arcasin; Aspin VK; Beromycin; Beromycin 400; Betapen VK; Calciopen K; Cliacil; Compocillin VK; Distakaps V-K; Distaquaine V-K; Dowpen V-K; DQV-K; Fenoxypen; Icipen; Isocillin; Ispenoral; Ledercillin VK; Megacillin oral; Oracil-VK; Orapen; Ospeneff; Pedipen; Penagen; Pencompren; Pen-Vee K; Pen-V-K powder; Penvikal; Pfizerpen VK; Qidpen VK; Robicillin VK; Rocillin-VK; Roscopenin; SK-Penicillin VK; Stabilin VK Syrup 125; Stabilin VK Syrup 62.5; Sumapen VK; Suspen; Uticillin VK; V-Cil-K; V-Cillin K; Veetids; Vepen

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of C.I. Acid Orange 3 (CAS No. 6373-74-6) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

C.I. Acid Orange 3 is a dinitrodiphenylamine derivative used exclusively as a dye (up to 0.2%) in semipermanent hair coloring products. This study was one of a series on semipermanent hair dyes, which included HC Blue No. 1 (NTP TR 271), HC Blue No. 2 (NTP TR 293), HC Red No. 3 (NTP TR 281), and C.I. Disperse Blue 1 (NTP TR 299). Toxicology and carcinogenesis studies of C.I. Acid Orange 3 (90% pure, containing 10% water for short-term studies and containing 6%-8% water and 2%-4% acetone for 2-year studies) were conducted by administering the dye in corn oil by gavage to F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: In the 14-day studies (at 94-1,500 mg/kg in rats and 62-1,000 mg/kg in mice), no compound-related deaths or body weight changes were observed and no adverse effects were observed at necropsy. In the 13-week studies (at 94-1,500 mg/kg in rats and 31-2,000 mg/kg in mice), compound-related kidney lesions were observed in rats and mice of each sex. These lesions included variable degrees of degeneration and necrosis of epithelial cells in the proximal convoluted tubules, regeneration of tubular epithelium, and granular casts in the tubules. In a few female rats of the highest dose group, necrosis of the renal papillae and suppurative inflammation were also observed. Mean body weights were generally comparable among groups of rats and mice. Mice receiving 2,000 mg/kg had body weights 11%-12% lower than those of vehicle controls. Five of 10 female rats that received the highest dose of 1,500 mg/kg died before the end of the study, but no compound-related deaths occurred in male rats or mice of either sex. Based on these results, 2-year studies of C.I. Acid Orange 3 were conducted by administering the dye by gavage in corn oil at 0, 375, or 750 mg/kg to groups of 50 F344/N rats of each sex, 5 days per week for 103 weeks. Groups of 50 male B6C3F1 mice were administered 0, 125, or 250 mg/kg C.I. Acid Orange 3 on the same schedule, and groups of 50 female B6C3F1 mice were administered 0, 250, or 500 mg/kg. These doses were selected on the basis of the nature and severity of the renal lesions in both species. Body Weights and Survival in the Two-Year Studies: Mean body weights of high dose rats were generally more than 10% lower than those of vehicle controls after week 52 for males and week 70 for females. Mean body weights forlow dose groups were comparable to those of vehicle controls. The survival of high dose male (after week 33) and female (after week 14) rats was lower (P<0.05) than that of vehicle controls and was attributed to nephrotoxicity (final survival-- male: vehicle control, 36/50; low dose, 30/50; high dose, 0/50; female: 43/50; 34/50; 7/50). Mean body weights of dosed male and female mice were lower than those of vehicle controls (high dose, 5%-11% after week 74; low dose, 7%-17% after week 48). Survival of both the low dose (after week 102) and high dose (after week 100) groups of male mice was lower than that of the vehicle controls (final survival: 38/50; 25/50; 26/50). Although survival was lower than usual, no notable differences in survival were observed between groups of female mice (final survival: 23/50; 23/50; 24/50). Nonneoplastic and Neoplastic Lesions in the Two-Year Studies: For both species, the kidney was the major target organ for C.I. Acid Orange 3. These findings are summarized in the accompanying table. The incidences of renal pelvic epithelial hyperplasia were increased in dosed rats of each sex. No renal neoplasms were observed in dosed male rats, but a tubular cell adenocarcinoma was observed in a vehicle control male rat. Six transitional cell carcinomas of the kidney were observed in high dose female rats; kidney transitional cell neoplasms have not been observed in 1,697 corn oil vehicle control female F344/N rats. Nonneoplastic lesions characteristic of secondary renal hyperparathyroidism or secondary to uremia also occurred in dosed rats. The lesions included parathyroid hyperplasia, fibrous dysplasia of boia also occurred in dosed rats. The lesions included parathyroid hyperplasia, fibrous dysplasia of bone, erosion and ulcers of the glandular stomach, and mineralization of the aorta and glandular stomach. Epithelial hyperplasia of the urinary bladder was observed in one low dose and three high dose female mice. A squamous cell carcinoma was seen in the urinary bladder of one low dose female mouse. Even though no squamous cell urinary bladder neoplasms have been observed in 1,665 corn oil vehicle control female B6C3F1 mice, this single neoplasm in a low dose animal was not considered to be related to the administration of C.I. Acid Orange 3. Genetic Toxicology: C.I. Acid Orange 3 was mutagenic with and without exogenous metabolic activation in Salmonella typhimurium strains TA97; TA98; and TA100; no mutagenicity was observed for strain TA1535. Audit: The data, documents, and pathology materials from the 2-year studies of C.I. Acid Orange 3 have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of C.I. Acid Orange 3 for male F344/N rats administered 375 mg/kg; because of a marked reduction in survival and no indication of carcinogenicity, the 750 mg/kg group was considered to be inadequate for assessment of carcinogenic activity. There was clear evidence of carcinogenic activity of C.I. Acid Orange 3 for female F344/N rats as shown by the occurrence of transitional cell carcinomas of the kidney in the 750 mg/kg group; this group had reduced survival and chemically related nonneoplastic lesions of the kidney. There was no evidence of carcinogenic activity of C.I. Acid Orange 3 for male B6C3F1 mice administered 125 or 250 mg/kg or for female B6C3F1 mice administered 250 or 500 mg/kg. Nonneoplastic lesions of the kidney were observed in both dose groups of both sexes of rats and mice. Synonyms: 2-anilino-5-(2,4-dinitroanilino)-benzenesulfonic acid, monosodium salt; 5[(2,4-dinitrophenol)amine]-2-(phenylamine)-benzenesulfonic acid, monosodium salt; C.I. 10385; Tetracid Light Yellow 2R

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of 2-Amino-5-Nitrophenol (CAS No. 121-88-0) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

2-Amino-5-nitrophenol is used as a colorant in semipermanent hair dyes and in the manufacture of C.I. Solvent Red 8, an azo dye for synthetic resins, lacquers, and wood stains. 2-Amino-5-nitrophenol was nominated for toxicology and carcinogenesis studies by the National Cancer Institute because of widespread human exposure associated with its use in hair dyes. Toxicology and carcinogenesis studies were conducted by administering 2-amino-5-nitrophenol (98% pure) by gavage in corn oil 5 days per week to groups of F344/N rats and B6C3F1 mice of each sex in 16-day, 13-week, and 2-year studies. In the 2-year studies, male and female rats were given doses of 0, 100, or 200 mg/kg and male and female mice were given doses of 0, 400, or 800 mg/kg. Sixteen-Day and Thirteen-Week Studies: During the 16-day studies, F344/N rats of each sex received 0, 156, 313, 625, 1,250, or 2,500 mg/kg 2-amino-5-nitrophenol by gavage in corn oil vehicle. One of the five males that received 2,500 mg/kg, 1/5 females that received 1,250 mg/kg, and 2/5 females that received 313 mg/kg died before the end of the studies. Final mean body weights of rats that received 1,250 or 2,500 mg/kg were 11% and 30% lower than that of vehicle controls for males and 9% and 13% lower for females. B6C3F1 mice of each sex received doses of 0, 313, 625, 1,250, 2,500, or 5,000 mg/kg 2-amino-5-nitrophenol. Two of five males and 5/5 females that received 5,000 mg/kg, 3/5 males and 3/5 females that received 2,500 mg/kg, 3/5 females that received 1,250 mg/kg, 1/5 females that received 625 mg/kg, and 2/5 male vehicle controls died before the end of the studies. Final mean body weights of chemically exposed mice were not different from those of the vehicle controls. Rats that received 625, 1,250, or 2,500 mg/kg and male mice that received 5,000 mg/kg had loose stools. In 13-week studies, F344/N rats and B6C3F1 mice of both sexes received 0, 100, 200, 400, 800, or 1,600 mg/kg 2-amino-5-nitrophenol by gavage in corn oil. Five of 10 male and 2/10 female rats that received 1,600 mg/kg, 1/10 male and 3/10 female rats that received 800 mg/kg, and 1/10 male rats that received 400 mg/kg died before the end of the studies. Final mean body weights of males that received 400, 800, or 1,600 mg/kg were 10%, 25%, and 43% lower than that of vehicle controls. The final mean body weight of females that received 1,600 mg/kg was 16% lower that of vehicle controls. Four of 10 male and 3/10 female mice that received 1,600 mg/kg died before the end of the 13-week studies. The final mean body weight of male mice that received 1,600 mg/kg was 11% lower than that of vehicle controls; male and female mice that received 1,600 mg/kg appeared lethargic. During the 13-week studies, acute/chronic perivasculitis of vessels of the cecum and colon was observed in rats that received 400, 800, or 1,600 mg/kg and in mice that received 1,600 mg/kg. Body Weight and Survival in the Two-Year Studies: Mean body weights of rats receiving 200 mg/kg were 5%-10% lower than those of vehicle controls after week 33 for males and 4%-5% lower than those of vehicle controls after week 93 for females. Survival of male rats was significantly lower than that of vehicle controls after week 99 for the 100 mg/kg dose group and after week 75 for the 200 mg/kg dose group (final survival: vehicle control, 33/50; 100 mg/kg group, 16/50; 200 mg/kg group, 4/50). Survival of female rats was comparable to that of vehicle controls (30/50; 32/50; 29/50). Loose or poorly formed stools were observed for male rats and occasionally for females that received 200 mg/kg. Mean body weights of mice that received 800 mg/kg were 8%-11% lower than those of vehicle controls between weeks 29 and 74 for males and 8%-13% lower than those of vehicle controls after week 69 for females; mean body weights of mice that received 400 mg/kg were greater than those of vehicle controls after week 69 for males and 5%-9% lower than those of vehicle controls after week 69 for females. Survival of mice that received 800 mg/kg was significantly reduced compared with that of ose of vehicle controls after week 69 for females. Survival of mice that received 800 mg/kg was significantly reduced compared with that of vehicle controls after week 20 for males and week 22 for females and was not considered adequate to evaluate a carcinogenic response (final survival--male: vehicle control, 31/50; 400 mg/kg group, 36/50; 800 mg/kg group, 12/50; female: 37/50; 36/50; 10/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Pigmentation was present at increased incidences in all groups of chemically exposed animals and was characterized by varying amounts of an orange, granular pigment present in the fibrous connective tissue of the lamina propria, in the submucosa, and around vessels in the submucosa of the cecum and colon. Pigmentation of the rectum was observed at increased incidences in male rats that received 100 mg/kg, male and female rats that received 200 mg/kg, and both groups of chemically exposed mice. No pigmentation was found in the intestines of vehicle control rats or mice. Associated with pigmentation was an increased incidence of acute/chronic inflammation in the cecum and colon of all groups chemically exposed rats and mice; this inflammation was similar to that observed in the 13-week studies but was of greater severity. Acute/chronic inflammation was also present in the rectum of male rats that received 100 mg/kg, male and female rats that received 200 mg/kg, and male mice that received 800 mg/kg. The incidence of pancreatic acinar cell adenomas was significantly increased (P&le;0.002) in male rats that received 100 mg/kg 2-amino-5-nitrophenol (vehicle control, 1/50; 100 mg/kg, 10/50; 200 mg/kg, 3/49); the increase was considered to be associated with chemical exposure. The reduced survival of male rats that received 200 mg/kg markedly reduced the sensitivity of this group for detecting the presence of neoplasms. The incidences of adenomas or carcinomas (combined) of the preputial or clitoral glands were marginally increased in male or female rats that received 200 mg/kg 2-amino-5-nitrophenol (preputial gland: 3/50; 2/50; 5/50; clitoral gland: 3/50; 3/50; 7/50). Neoplasms found in the intestinal tract of 3/50 male rats that received 100 mg/kg (one leiomyoma of the small intestine, one adenocarcinoma of the jejunum, one leiomyoma of the cecum), 2/50 male rats that received 200 mg/kg (one lipoma and one osteosarcoma of the cecum), and 1/50 female rats that received 200 mg/kg (one leiomyoma of the cecum) were not considered to be the result of chemical exposure. No compound-related neoplasms were found in mice exposed to 2-amino-5-nitrophenol in the 2-year studies. Genetic Toxicology: 2-Amino-5-nitrophenol was mutagenic in Salmonella typhimurium strains TA98, TA100, and TA1537 when tested in a preincubation protocol with and without exogenous metabolic activation, and it exhibited equivocal mutagenic activity in strain TA1535 in the presence of induced liver S9. 2-Amino-5-nitrophenol induced forward mutations in mouse L5178Y lymphoma cells in the absence of metabolic activation; it was not tested with S9. An increase in chromosomal aberrations and sister chromatid exchanges was observed in cultured Chinese hamster ovary (CHO) cells following incubation with 2-amino-5-nitrophenol both in the presence and absence of exogenous metabolic activation. Data Audit: The data, documents, and pathology materials from the 2-year studies of 2-amino-5-nitrophenol were audited at the NTP Archives. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity for male F344/N rats that received 100 mg/kg 2-amino-5-nitrophenol, as shown by the increased incidence of acinar cell adenomas of the pancreas. Reduced survival of male F344/N rats that received 200 mg/kg decreased the sensitivity of this group for detecting a carcinogenic response. There was no evidence of carcinogenic activity for female rats that received 100 or 200 mg/kg per day. Marginally increased incidences of preputial or clitoral gland adenomas or carcinomas (combined) occurred in male and female F344/N rats administered 200 mg/kg 2-amino-5-nitrophenol. There was no evidence of carcinogenic activity for B6C3F1 mice that received 400 mg/kg 2-amino-5-nitrophenol; reduced survival of B6C3F1 mice that received 800 mg/kg caused this group to be considered inadequate for detecting a carcinogenic response.

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of N-Phenyl-2-naphthylamine (CAS No. 135-88-6) in F344/N Rats and B6C3F1 Mice (Feed Studies).

N-Phenyl- 2- naphthylamine, formerly used as a antioxidant in the rubber industry, was selected for toxicology and carcinogenesis studies because at the time of nomination (1976) it had a large annual production and widespread human exposure. Additional reasons for selection included it structural similarity and possible metabolism to the known human urinary bladder carcinogen, 2-naphthylamine. Toxicology and carcinogenesis studies were conducted by feeding diets containing N-phenyl-2-naphthylamine (approximately 98% pure and containing less than 1 ppm 2-naphthylamine) at various concentrations to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: In 14-day studies, 3/5 male and 4/5 female rats that received 50,000 ppm N-phenyl-2-naphthylamine died before the end of the studies. Final mean body weights of rats that received 12,500 ppm or more were considerably lower (18%-57%) than those of the controls. Arched backs, rough coats, and diarrhea were observed for males that received 12,500 ppm or more and for females that received 25,000 or 50,000 ppm. All mice were alive at the end of the studies, and no compound-related clinical signs of toxicity were observed in mice given feed containing up to 20,000 ppm. In 13-week studies, deaths occurred in 4/10 male and 9/10 female rats that received the highest dose (40,000 ppm) of N-phenyl-2-naphthylamine. Final mean body weights of rats that received 5,000-40,000 ppm were 9%-60% lower than those of the controls. The liver weight to body weight ratios increased with increasing dose, with the ratios for male rats at 10,000 ppm or more and for female rats at 5,000 ppm being greater (P<0.05) than those of controls. A compound-related nephropathy occurred in rats and was characterized by renal tubular epithelial degeneration and hyperplasia. Other effects in rats included hematopoietic hypoplasia or atrophy of the femoral bone marrow, testicular hypospermatogenesis, lymphoid degeneration of the thymus, and lymphoid depletion of the spleen. In mice, 2/10 males and 7/10 females that received 40,000 ppm died before the end of the 13-week studies. The final mean body weights of mice that received 10,000, 20,000, or 40,000 ppm were 9%-32% lower than those of the controls. The liver weight to body weight ratios for mice increased with increasing dose. Those for male mice at 10,000 ppm or more and for female mice at 20,000 ppm or more were greater (P<0.05) than those for the controls. Nephropathywas observed at increased incidences and severity in dosed mice. Because of kidney lesions, liver enlargement, lower weight gain, and increased mortality in the shorter term studies, dietary concentrations of N-phenyl-2-naphthylamine selected for the 2-year studies in rats and mice were 0, 2,5000, and 5,000 ppm. Body Weight and Survival in the Two-Year Studies: The mean body weights of dosed rats were lower than those of the controls throughout the studies (12% and 16% lower for dosed males and 15% and 31% lower for dosed females at the end of the studies). The average daily feed consumption for rats was 94%-87% that of the controls for dosed males and 88% that of the controls for dosed females. The estimated average amount of N-phenyl-2-naphthylamine consumed per day was 100 mg/kg and 225 mg/kg for male rats and 120 mg/kg and 260 mg/kg for female rats. The survival of the high dose group of male rats was greater (P<0.05) than that of the controls after week 101 (male: control, 24/50; low dose, 28/50; high dose, 34/50; female: 26/50; 44/50; 38/50). Final mean body weights of high dose male and female mice were lower (male, 9%; female, 23%) than those of the controls. The estimated average daily feed consumption by dosed mice was within 10% that of the controls. The average amount of N-phenyl-2-naphthylamine consumed per day was approximately 500 or 1,000 mg/kg for male mice and 450 or 900 mg/kg for female mice. No significant differences in survival were observed between any groups of mice of either sex (male: control, 33/50; male mice. No significant differences in survival were observed between any groups of mice of either sex (male: control, 33/50; low dose, 36/50; high dose, 28/50; female: 36/50; 30/50; 35/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: As in the 13-week studies, the kidney was the principal target for toxic effects of N-phenyl-2-naphthylamine. Mineralization of the kidney, necrosis of the renal papilla, and epithelial hyperplasia and calculi of the kidney pelvis were observed at increased incidences in high dose female rats. Hydronephrosis, atrophy, fibrosis, and chronic focal inflammation of the kidney were observed at increased incidences in high dose female rats. Cysts and acute suppurative inflammation of the kidney were observed at increased incidences in dosed male and high dose female rats. No compound-related renal neoplasms were observed in rats. Nuclear enlargement of renal tubular epithelial cells and nephropathy were observed at increased incidences in high dose female mice. Atypical tubular cell hyperplasia occurred in two high dose female mice. A tubular cell adenoma was found in one high dose female mouse, and a tubular cell adenocarcinoma was found in another high dose female mouse. No renal neoplasms were observed in dosed male mice. Neoplasms of several organs occurred in rats with negative trends and/or at significantly lower incidences in high dose groups. These included thyroid gland C-cell neoplasms in males and females and mammary gland fibroadenomas, pituitary gland adenomas, and mononuclear cell leukemia in females. The lack of carcinogenicity in rats may be related to an inability to metabolize this compound to the known animal and human carcinogen 2-napththylamine. Genetic Toxicity: N-Phenyl-2-naphthylamine was not mutagenic in the Salmonella typhimurium/microsome assay with strains TA97, TA98, TA100, or TA1535 with or without induced hamster or rat liver S9. The chemical did not induce chromosomal aberrations in cultured Chinese hamster ovary (CHO) cells with or without metabolic activation. No increase in sister chromatid exchanges (SCEs) was observed in the absence of metabolic activation; in the presence of rat liver S9, the SCE results were judged to be equivocal. Data Audit: The data, documents, and pathology materials from the 2-year studies of N-phenyl-2-naphthylamine were audited at the NTP Archives. The audit findings show thatthe conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity for male or female F344/N rats fed diets containing 2,500 or 5,000 ppm N-phenyl-2-naphthylamine. Decreased incidences of several neoplasms were observed in dosed rats: thyroid gland C-cell neoplasms in males and females and mononuclear cell leukemia, pituitary gland adenomas, and mammary gland fibroadenomas in females. There was no evidence of carcinogenic activity for male B6C3F1 mice fed diets containing 2,500 or 5,000 ppm N-phenyl-2-naphthylamine. There was equivocal evidence of carcinogenic activity of N-phenyl-2-naphthylamine for female B6C3F1 mice as indicated by the occurrence of two rare kidney neoplasms. Chemical-related nonneoplastic lesions (nephropathy, karyomegaly, and hyperplasia) occurred in the kidney of rats and mice. Synonyms: N-(2-naphthyl)aniline; 2-naphthylphenylamine; b-naphthylphenylamine; 2-phenylaminonaphthalene; phenyl-b-naphthylamine; N-phenyl-b-naphthylamine Trade Names: Aceto PBN; Agerite Powder: Antioxidant 116; Neosone D; Neozon D; Nilox PBNA; Nonox D; PBNA; Stabilizator AR

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of 2-Mercaptobenzothiazole (CAS No. 149-30-4) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toxicology and carcinogenesis studies of technical-grade 2-mercaptobenzothiazole (96%-97% pure), a rubber accelerant and preservative, were conducted by administering the chemical by gavage in a corn oil vehicle to groups of F344/N rats and B6C3F1 mice of each sex for 16 days, 13 weeks, or 2 years. 2-Mercaptobenzothiazole was nominated for study by the National Institute of Environmental Health Sciences and the National Institute for Occupational Safety and Health. Sixteen-Day and Thirteen-Week Studies: In 16-day studies, mean body weight gains of rats receiving 2,500 mg/kg were 6-7 g lower than those of vehicle controls; 4/5 male and 5/5 female mice dosed with 3,000 mg/kg and 4/5 female mice dosed with 1,500 mg/kg died; lethargy and prostration occurred in most of these animals after gavage. Based on these results, doses were selected for both species in the 13-week studies were 0, 94 (mice only), 188, 375, 750, and 1,500 mg/kg. In the 13-week studies, no chemical-related deaths occurred in rats, but body weight gains in males dosed with 1,500 mg/kg and in females dosed with 750 or 1,500 mg/kg were lower than those in the vehicle control groups. Hepatomegaly occurred at the two highest doses in males and at all doses in females; however, no microscopic pathologic changes were noted in any tissue. More than half the mice dosed with 1,500 mg/kg died, but no compound-related body weight changes occurred. Clinical signs in mice were dose related and included lethargy in animals dosed with 375 mg/kg and lacrimation, salivation, and clonic seizure in some dosed with 750 or 1,500 mg/kg. No association between these clinical signs of toxicity and gross or microscopic pathologic effects were observed. Doses selected for the 2-year studies were 0, 375, and 750 mg/kg for male rats and for mice of each sex and 0, 188, or 375 mg/kg for female rats. Body weight and Survival in the Two-Year Studies: Fifty animals of each species and sex were administered 2-mercaptobenzothiazole in corn oil by gavage 5 days per week for 103 weeks. Administration of 2-mercaptobenzothiazole resulted in decreased survival in dosed male rats (vehicle control, 42/50; low dose, 22/50; high dose, 20/50) and in the high dose group of female mice (37/50; 39/50; 22/50) but not in female rats (28/50; 31/50; 25/50) or in male mice (38/50; 33/50; 30/50). No effect on body weight gain in dosed rats was observed; in dosed mice, minor reductions occurred between weeks 3 and 64, withrecovery thereafter. Postgavage lethargy and prostration occurred frequently in dosed rats and mice. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: The severity of nephropathy was increased in dosed male rats. Ulcers and inflammation of the forestomach were prevalent in dosed rats, as were increased incidences of epithelial hyperplasia and hyperkeratosis in male rats, but no neoplasms of the forestomach were observed. There were no increases of nonneoplastic lesions in mice which were considered to be compound related. The incidences of a variety of tumors were increased in rats dosed with 2-mercaptobenzothiazole; some of the increased incidences were not dose related. In low dose male rats, increased incidences (P<0.01) were observed for mononuclear cell leukemia (7/50; 16/50; 3/50) and pancreatic acinar cell adenomas (2/50; 13/50; 6/49). Increased tumor incidences with dose-related trends (P<0.05) included pituitary gland adenomas in females (15/49; 24/50; 25/50), preputial gland adenomas or carcinomas (combined) in males (1/50; 6/50; 5/50), adrenal gland pheochromocytomas or malignant pheochromocytomas (combined) in males (18/50; 27/50; 24/49), and pheochromocytomas in females (1/50; 5/50; 6/50). These tumors were observed at significantly greater incidences (P</=0.05) in the high dose groups than in the vehicle controls. An increased incidence (P=0.028) of hepatocellular adenomas or carcinomas (combined) was observed only in low dose female mice (4/50; 12/49; 4/50). No significant increases in tumor incidences were seen in male mice. Genetic Toxicology: 2-Mercaptobenzothgy: 2-Mercaptobenzothiazole was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without metabolic activation. In the presence of rat liver S9, 2-mercaptobenzothiazole increased the frequency of chromosomal aberrations and sister chromatid exchanges (SCEs) in Chinese hamster ovary (CHO) cells, as well as mutations at the TK locus of mouse L5178Y lymphoma cells. Audit: The data, documents, and pathology materials from the 2-year studies of 2-mercaptobenzothiazole were audited at the NTP Archives. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of 2-mercaptobenzothiazole for male F344/N rats, indicated by increased incidences of mononuclear cell leukemia, pancreatic acinar cell adenomas, adrenal gland pheochromocytomas, and preputial gland adenomas or carcinomas (combined). There was some evidence of carcinogenic activity for female F344/N rats, indicated by increased incidences of adrenal gland pheochromocytomas and pituitary gland adenomas. There was no evidence of carcinogenic activity of 2-mercaptobenzothiazole for maleB6C3F1 mice dosed with 375 or 750 mg/kg. There was equivocal evidence of carcinogenic activity for female B6C3F1 mice, indicated by increased incidences of hepatocellular adenomas or carcinomas (combined). Synonyms and Trade Names: Captax; Dermacid; Mertax; Thiotax; 2(3H)-benzothiazolethione; 2-benzothiazolyl mercaptan

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Malonaldehyde, Sodium Salt (3-Hydroxy-2-propenal, Sodium Salt) (CAS No. 24382-04-5) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Malonaldehyde occurs as a natural metabolic byproduct of prostaglandin biosynthesis and as an end product of polyunsaturated lipid peroxidation. Toxicology and carcinogenesis studies of malonaldehyde were conducted by administering the chemical as malonaldehyde, sodium salt, a stabilized form of malonaldehyde, in distilled water by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, and two years. The study material was 63%-79% malonaldehyde, sodium salt, 22%-38% water, and 1% or less other impurities. The water content was taken into account when the dose mixtures were prepared. Fourteen-Day and Thirteen-Week Studies: In the 14-day studies, groups of five rats and five mice of each sex were dosed with 250, 500, 750, 1,000, or 1,500 mg/kg malonaldehyde, sodium salt. Controls were untreated. Rats and mice that received 1,500 mg/kg malonaldehyde, sodium salt, did not survive to the end of the 14-day studies. No compound-related gross lesions were seen in the dosed animals. In the 13-week studies, groups of 10 males and 10 females of each species were administered 0, 30, 60, 125, 250, or 500 mg/kg malonaldehyde, sodium salt. Nine of 10 male rats, 10/10 female rats, 3/10 male mice, and 1/10 female mice that received 500 mg/kg malonaldehyde, sodium salt, died before the end of the studies. Body weights were reduced by more than 15% in rats receiving 250 or 500 mg/kg and in mice receiving 500 mg/kg. Compound-related nonneoplastic lesions were present in the stomach, testis, and kidney of rats and in the pancreas, stomach, and testis of mice. Focal and multifocal erosive lesions were observed in the gastric mucosa of the glandular stomach in the 500 mg/kg groups of male and female rats. Dilatation of the gastric glands of the stomach mucosa occurred in the 500 mg/kg male mice. Lesions of the kidney included membranous glomerular nephropathy in the 250 and 500 mg/kg male rats and the 125, 250, and 500 mg/kg female rats and mineralization in the 250 and 500 mg/kg male rats and the 60, 125, 250, and 500 mg/kg female rats. Degeneration of the testicular germinal epithelium was observed in male rats and male mice receiving 250 and 500 mg/kg. Atrophy of the exocrine pancreas was seen in the 125, 250, and 500 mg/kg male and the 250 and 500 mg/kg female mice. Based on these results, 2-year studies of malonaldehyde, sodium salt, were conducted by exposing groups of 50F344/N rats of each sex at doses of 0, 50, or 100 mg/kg, administered 5 days per week for 103 weeks. Doses of 0, 60, or 120 mg/kg were administered in the same schedule to groups of 50 male and 50 female B6C3F1 mice. Body Weight and Survival in the Two-Year Studies: Final mean body weights at the end of the study were reduced by 26% and 36% for high dose male and female rats compared with those for the vehicle controls. The final mean body weight of high dose male mice was 92% that of the vehicle controls. The final mean body weights of low dose male mice, low dose rats, and all groups of female mice were comparable to those of the vehicle controls. The survival of high dose male and female rats was significantly lower than that of the vehicle controls, with survival declining rapidly after week 76 for high dose males and after week 59 for high dose females (survival-- male: vehicle control, 37/50; low dose, 33/50; high dose, 15/50; female: 37/50; 37/50; 14/50). Survival of all groups of male mice was low (male: 24/50; 20/50; 14/50; female: 41/50; 38/50; 30/50). Survival of the high dose groups of male mice was significantly lower than that of the vehicle controls; no other significant differences in survival were observed between any groups of mice. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: The incidences of a variety of nonneoplastic lesions were increased in dosed rats of each sex, primarily in the high dose male and female rat groups. These lesions were ulceration and inflammation of the glandular stomach; epithelial hyperplasia of the forestomach; inflammation of the cornea, retinal atrophy, and cataracts of the crysttion of the cornea, retinal atrophy, and cataracts of the crystalline lens; focal lipoid degeneration of the adrenal cortex; and diffuse pancreatic atrophy. Cytoplasmic vacuolization and cystic degeneration in the liver occurred at increased incidences in the high dose rat groups; in addition, the incidences of bile duct hyperplasia and bile duct fibrosis were increased in the high dose female and male rat groups, respectively. Bone marrow hematopoietic hyperplasia, hematopoiesis of the spleen, and ultimobranchial cysts of thyroid gland occurred with increased incidences in high dose female rats. The incidences of thyroid gland follicular cell adenomas or carcinomas (combined) were significantly increased in high dose male (vehicle control, 4/50; low dose, 8/49; high dose, 13/50) and female (2/50; 1/50; 7/50) rats. Follicular cell hyperplasia of the thyroid gland also occurred at an increased incidence in high dose female rats (10/50; 10/50;26/50) but not in male rats (9/50; 7/49; 7/50). The incidence of pancreatic islet cell adenomas was increased in low dose male rats (0/49; 9/50; 1/49). Adenomas and adenomas or carcinomas (combined) of the anterior pituitary gland occurred at significantly lower incidences in high dose rats than those in vehicle controls (combined incidence--male: 20/47; 14/49; 8/49; female: 18/49; 10/49; 2/48). Nonneoplastic lesions that occurred at increased incidences in dosed mice included atrophy of the pancreatic acinus and dilatation of the uterus. Depigmentation of hair shafts and change of coat color from agouti to gray were observed in high dose mice. No compound-related neoplasms were observed in dosed mice. Genetic Toxicology: Malonaldehyde, sodium salt, was not mutagenic in the Salmonella typhimurium/microsome assay when tested at doses of up to 10,000 ug/plate in a preincubational protocol using the excision-repair deficient strains TA98, TA100, TA1535, and TA1537 with or without S9 metabolic activation. The chemical induced forward mutations in mouse L5178Y lymphoma cells in the absence of S9; it was not tested with S9. Malonaldehyde, sodium salt was not mutagenic in the Drosophila melanogaster sex-linked recessive lethal mutagenicity test in which adult male flies were exposed either by feeding or by abdominal injection. In cytogenetic assays with cultured Chinese hamster ovary (CHO) cells, malonaldehyde, sodium salt, produced a dose-related increase in the frequency of sister-chromatid exchanges both in the presence and absence of rat liver S9; no increase in the number of chromosomal aberrations was observed in CHO cells in the absence or presence of S9. Audit: The data, documents, and pathology materials from the 2-year studies of malonaldehyde, sodium salt, have been audited. The audit found no special circumstances or significant deficiencies in the conduct or documentation of the studies which needed to be taken into consideration for reporting purposes. Conclusions: Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity for male and female F344/N rats administered malonaldehyde, sodium salt, as shown by the increased incidences of follicular cell adenomas or carcinomas (combined) of the thyroid gland. Pancreatic islet cell adenomas were also observed at an increased incidence in low dose male rats. There was no evidence of carcinogenic activity for B6C3F1 mice administered 60 or 120 mg/kg malonaldehyde, sodium salt, in distilled water by gavage 5 days per week for 2 years. Chemically related increased incidences of nonneoplastic lesions included ulcers and inflammation of the glandular stomach and epithelial hyperplasia of the forestomach; corneal inflammation, retinal atrophy, and cataracts of the crystalline lens; and cystic degeneration of the liver, bile duct fibrosis, and bile duct hyperplasia in rats. Most of these nonneoplastic lesions as well as the thyroid gland follicular cell neoplasms occurred primarily in the high dose rat groups, in which survival and final body weights were reduced in high dose male and female rats. Increased incidences of atrophy of the pancreatic acinus and pigmentation loss in hair shafts were seen in high dose mice. Synonyms: malonaldehyde, enol, sodium salt; propanedial, sodium; 3-hydroxy-2-propenal, sodium salt; sodium b-oxyacrolein

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of 4-Hexylresorcinol (CAS No. 136-77-6) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

4-Hexylresorcinol, which is used as an anthelmintic and antiseptic, was nominated by the National Cancer Institute for study. Toxicology and carcinogenesis studies were conducted by administering 4-hexylresorcinol (greater than 99% pure) in corn oil by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 16 days, 13 weeks, or 2 years. Sixteen-Day and Thirteen-Week Studies: In the 16-day studies, groups of five rats and five mice of each sex were administered 0, 31.3, 62.5, 125, 250, or 500 mg/kg 4-hexylresorcinol. Survival was not affected. Decreased body weights were seen in male rats that received 250 or 500 mg/kg 4-hexylresorcinol. No other effects were observed. In the 13-week studies, groups of 10 rats and 10 mice of each sex were administered 0, 62.5, 125, 250, 500, or 1,000 mg/kg of the chemical, 5 days per week. All rats and male mice and 9/10 female mice that received 1,000 mg/kg died before the end of the studies. Final mean body weights of male rats that received 250 or 500 mg/kg were 22% or 38% lower than that of the vehicle controls; final mean body weights of female rats that received 250 or 500 mg/kg were 16% or 9% lower. No compound-related gross or microscopic pathologic effects were observed in rats. No body weight effects were observed for mice. Mild to moderate nephropathy was dose related in male and female mice. Based on these results, 2-year toxicology and carcinogenesis studies of 4-hexylresorcinol were conducted by administering 0, 62.5, or 125 mg/kg to groups of 50 F344/N rats and 50 B6C3F1 mice of each sex, 5 days per week. Body Weight and Survival in the Two-Year Studies: Mean body weights of high dose male rats were 7%-11% lower than those of the vehicle controls throughout the study. Mean body weights of low dose male and dosed female rats were similar to those of the vehicle controls. The body weights of dosed male and dosed female mice were comparable to those of vehicle controls except during the last 16 weeks of the studies, when body weights were 6%-16% lower in the dosed groups. No significant differences in survival were observed between any groups of rats or mice of either sex (male rats: vehicle control, 30/50; low dose, 29/50; high dose, 33/50; female rats: 28/50; 32/50; 30/50; male mice: 36/50; 26/50; 30/50; female mice: 35/50; 32/50; 35/50). Nonneoplastic and Neoplastic Lesions in the Two-Year Studies: Two astrocytomas and an oligodendroglioma were observed in high dose male rats, a glioma was observed in one low dose male rat, and an oligodendroglioma was observed in one vehicle control male rat. These neoplasms were not considered to be related to 4-hexylresorcinol administration. Focal medullary hyperplasia of the adrenal gland was observed at increased incidences in dosed male mice (5/50; 16/50; 10/49). Pheochromocytomas in male mice occurred with a marginal upward trend (1/50; 2/50; 5/49). Historically, these neoplasms are observed in about 1% of corn oil vehicle control B6C3F1 male mice. The incidences of neoplasms of the harderian gland in male mice were slightly increased over those in the vehicle controls (adenomas or carcinomas, combined: 0/50; 4/50; 3/50). Decreases were observed in the incidences of mononuclear cell leukemia in dosed male (12/49; 7/50; 1/50) and female (16/50; 3/50; 2/50) rats, hepatocellular adenomas or carcinomas (combined) in dosed male mice (21/50; 9/50; 9/50), and circulatory system tumors in male (10/50; 4/50; 2/50) and female (6/50; 2/49; 0/50) mice. These decreased incidences of tumors in rats and mice are considered to be possibly related to 4-hexylresorcinol administration. The incidences and severity of nephropathy (male: 39/50; 43/50; 47/50; female: 7/50; 40/49; 47/50) and incidences of osteosclerosis (male: 5/50; 5/50; 15/50; female: 21/50; 25/49; 40/50) were increased in both dosed male and female mice and are considered to be related to chemical exposure. Genetic Toxicology: 4-Hexylresorcinol was not mutagenic for Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without S9 metabolic activation. 4-Hexylre, TA1535, or TA1537 with or without S9 metabolic activation. 4-Hexylresorcinol induced forward mutations at the TK locus in mouse L5178Y cells in the presence of S9; no response was observed in the absence of metabolic activation. In cytogenetic assays with cultured Chinese hamster ovary (CHO) cells, 4-hexylresorcinol caused an increase in the frequency of sister chromatid exchanges (SCEs) in the absence of metabolic activation; no induction of SCEs was observed in the presence of S9. Chromosomal aberrations were not induced in CHO cells with or without metabolic activation. Data Audit: The data, documents, and pathology materials from the 2-year studies of 4-hexylresorcinol were audited at the NTP Archives. The audit findings show that the conduct of the studies is documented appropriately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity of 4-hexylresorcinol for male or female F344/N rats given doses of 62.5 or 125 mg/kg. There was equivocal evidence of carcinogenic activity of 4-hexylresorcinol for male B6C3F1 mice, as shown by marginally increased incidences of pheochromocytomas (and hyperplasia) of the adrenal medulla and of harderian gland neoplasms. There was no evidence of carcinogenic activity for female B6C3F1 mice given doses of 62.5 or 125 mg/kg 4-hexylresorcinol. Decreased incidences of three tumors types were considered related to 4-hexylresorcinol administration: mononuclear cell leukemia in male and female rats, hepatocellular neoplasms in male mice, and circulatory system tumors in male and female mice. Synonyms: 4-hexyl-1,3-benzenediol; 4-hexyl-1,3-dihydroxybenzene

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of 1,2-Epoxybutane (CAS No. 106-88-7) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

1,2-Epoxybutane was selected for study because it is a short-chain epoxide that had been shown to be mutagenic and because no carcinogenicity data were available. Approximately 8 million pounds of 1,2-epoxybutane are produced annually in the United States. The chemical is used primarily as a stabilizer in chlorinated hydrocarbon solvents. Single-Exposure, Fourteen-Day, and Thirteen-Week Studies: Single-exposure, 14-day, 13-week, and 2-year studies were conducted in F344/N rats and B6C3F1 mice. The chemical was greater than 99% pure and was administered as a vapor by the inhalation route to mimic worker exposure; room air was used as the control exposure during these studies. Exposures were 6 hours per day (5 days per week), except in the single-exposure studies (4 hours). Additional studies were performed to evaluate the potential for genetic damage in bacteria and in mammalian cells. In the single-exposure studies, the chemical was administered at exposure concentrations of 400-6,550 ppm in rats and 400-2,050 ppm in mice. In the 14-day studies, rats and mice were exposed at 400-6,400 ppm, and in the 13-week studies, rats and mice were exposed at 50-800 ppm. All rats in the single-exposure studies at 6,550 ppm died; compound-related deaths were not seen in other dosed groups. All mice at 2,050 ppm and 4/5 mice of each sex at 1,420 ppm died; compound-related mortality was not seen in other dosed groups. In the 14-day studies, all rats at 3,200 and 6,400 ppm and 2/5 female rats at 1,600 ppm died; all mice at 1,600, 3,200, and 6,400 and 1/5 male mice at 800 ppm died. Final mean body weights of surviving rats exposed at 800 or 1,600 ppm were 12%-33% lower than those of the controls; final mean body weights of surviving mice at 800 ppm were 10%-12% lower than those of the controls. Compound-related lesions included pulmonary hemorrhage and rhinitis in rats at 1,600 ppm and nephrosis in mice at 800 and 1,600 ppm. In the 13-week studies, no compound-related mortality was observed in rats; all mice exposed at 800 ppm died. No compound-related clinical signs were seen in rats or in surviving mice. The final mean body weight of rats exposed at 800 ppm was 23% lower than that of controls for males and 16% lower for females. Final body weights of surviving mice were unaffected by exposure. Inflammation of the nasal turbinates was seen in rats at 800 ppm but not at lower exposure concentrations. Renal tubular necrosis was seen in mice at 800 ppm but not at lowerconcentrations. Inflammation of the nasal turbinates was observed in female mice at 100, 200, 400, and 800 ppm and in male mice at 200, 400, and 800 ppm. The highest exposure concentration selected for the 2-year studies in rats was 400 ppm because of body weight effects and nasal lesions observed at 800 ppm. The highest concentration selected for the 2-year studies in mice was 100 ppm because the nasal lesions seen at 200 and 400 ppm were considered to be potentially life threatening. Two-Year Studies: The 2-year toxicology and carcinogenesis studies of 1,2-epoxybutane were conducted by exposing groups of 50 animals per species and sex to the chemical by inhalation, 6 hours per day 5 days per week. Rats were exposed at concentrations of 0, 200, or 400 ppm for 103 weeks and mice at 0, 50, or 100 ppm for 102 weeks. Body Weight and Survival in the Two-Year Studies: The survival of all groups of dosed rats was at least 50% until week 98, but final survival was reduced in the dosed groups (final survival-- male: control, 30/50; low dose, 18/50; high dose, 23/50; female: 32/50; 21/50; 22/50). Mean body weights of control and exposed male rats were similar until week 86; thereafter, mean body weights of high dose male rats were 4%-8% lower than those of controls. Mean body weights of high dose female rats were 5%-10% lower than those of controls after week 22. Survival in male mice was comparable among groups (final survival: 41/50; 45/50; 33/50). Survival in female mice was greater than 50% in all groups at week 86 and then was reduced in high dose females toward the end of the stin all groups at week 86 and then was reduced in high dose females toward the end of the study (final survival: 29/50; 25/50; 9/50). This decreased survival was associated with suppurative inflammation of the ovary and uterus. Klebsiella oxytoca was isolated from these ovarian/uterine lesions. Mean body weights of high dose male mice were 10&percnt;-14&percnt; lower than those of the controls after week 69; mean body weights of low dose male mice were 4&percnt;-8&percnt; lower than those of the controls after week 86. Mean body weights of high dose female mice were 13&percnt;-23&percnt; lower than those of the controls after week 60, and mean body weights of low dose female mice were 12&percnt;-16&percnt; lower than those of the controls after week 73. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Dosed rats had nonneoplastic lesions of the nasal cavity including inflammation, epithelial hyperplasia, squamous metaplasia, hyperostosis of the nasal turbinate bone, and atrophy of the olfactory epithelium. Seven papillary adenomas of the nasal cavity were seen in highdose male rats and two in high dose female rats. The historical incidences of nasal cavity adenomas in untreated male and untreated female F344/N rats are less than 0.1&percnt;. The incidences of alveolar/bronchiolar carcinomas (0/50; 1/50; 4/49) and adenomas or carcinomas (combined) (0/50; 2/50; 5/49) were increased in high dose male rats; no increased incidences of these tumors were observed in dosed female rats. Dosed mice had increased incidences of nonneoplastic lesions of the nasal cavity but no significant increase in the incidence of neoplastic lesions of the nasal cavity. The nonneoplastic lesions included suppurative inflammation (empyema), epithelial hyperplasia, erosion, regeneration, and squamous metaplasia in the nasal cavity; atrophy of the olfactory sensory epithelium; hyperplasia of the nasal gland (Bowman's glands); and inflammation and hyperplasia of the nasolacrimal duct. A single squamous cell papilloma was seen in the incisive duct of one high dose male mouse. Genetic Toxicology: 1,2-Epoxybutane was mutagenic in Salmonella typhimurium strains TA100 and TA1535 when tested with a preincubational protocol with or without rat liver S9, indicating that it is a direct-acting mutagen capable of inducing base-pair substitutions in prokaryotes; it did not cause gene reversion in strains TA1537 or TA98. 1,2-Epoxybutane induced forward mutations at the TK locus of cultured mouse L5178Y lymphoma cells with and without metabolic activation. Both chromosomal aberrations andsister chromatid exchanges were induced in cultured Chinese hamster ovary cells after exposure to 1,2-epoxybutane in the presence and absence of metabolic activation. 1,2-Epoxybutane, when fed to male Drosophila, caused significant increases in the number of sex-linked recessive lethal mutations and reciprocal translocations in the germ cells. Data Audit: An audit of the experimental data was conducted for the 2-year studies of 1,2-epoxybutane. No data discrepancies were found that influenced the final interpretations. Conclusions: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of 1,2-epoxybutane for male F344/N rats, as shown by an increased incidence of papillary adenomas of the nasal cavity, alveolar/bronchiolar carcinomas, and alveolar/bronchiolar adenomas and carcinomas (combined). There was equivocal evidence of carcinogenic activity for female F344/N rats, as shown by the presence of papillary adenomas of the nasal cavity. There was no evidence of carcinogenic activity for male or female B6C3F1 mice exposed at 50 or 100 ppm. 1,2-Epoxybutane exposure was associated with adenomatous hyperplasia and inflammatory lesions of the nasal cavity in rats and inflammatory lesions of the nasal cavity in mice. Synonyms: 1-butene oxide; 1,2-butene oxide; butylene oxide; 1,2-butylene oxide; ethyl ethylene oxide; ethyl oxirane

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Trichloroethylene (CAS No. 79-01-6) in Four Strains of Rats (ACI, August, Marshall, Osborne-Mendel) (Gavage Studies).

Trichloroethylene is an industrial solvent used primarily for vapor degreasing and cold cleaning. It was selected for study because of its industrial use and for potential for human exposure. (An estimated 3.5 million workers are exposed to trichloroethylene.) In an earlier study trichloroethylene (stabilized with epichlorohydrin and 1,2-epoxybutane) administered by gavage caused hepatocellular carcinomas in male and female B6C3F1 mice. Trichloroethylene administration did not increase the incidence of tumors in male or female Osborne-Mendel rats. However, the survival of dosed rats was reduced, thereby compromising the sensitivity of the study to detect a carcinogenic effect. The studies described in this report were conducted to compare the sensitivities of four strains of rats (ACI, August, Marshall, and Osborne-Mendel) to diisopropylamine-stabilized trichloroethylene. The results of the present studies demonstrate that long-term administration of trichloroethylene produces nephrotoxicity in four strains of rats and that the susceptibilities of these strains to the nephrotoxic effects of the chemical are similar. Because of chemically induced toxicity, reduced survival, and incomplete documentation of the experimental data, the studies are considered inadequate for either comparing or assessing trichloroethylene-induced carcinogenesis in these strains of rats. Toxicology and carcinogenesis studies of trichloroethylene (more than 99% pure, stabilized with 8 ppm diisopropylamine) were conducted by administering the chemical in corn oil gavage at doses of 0, 500, or 1,000 mg/kg per day, 5 day per week, for 103 weeks to groups of 50 male and 50 female ACI, August, Marshall, and Osborne-Mendel rats. The doses were selected on the basis of results from 13-week gavage studies in which groups of 10 male and 10 female ACI, August, and Marshall rats received daily doses or trichloroethylene (male: 125-2,000 mg/kg; female: 63-1,000 mg/kg). Doses for Osborne-Mendel rats were selected to conform with doses used in an earlier carcinogenicity study in that strain (TR-2). In the 13-week studies, male ACI and August rats receiving 2,000 mg/kg trichloroethylene and male and female Marshall rats receiving 1,835 mg/kg had final mean body weights 12%-17% lower than those of the vehicle controls. All other dose groups had body weights comparable to those of the vehicle controls. Three male August rats dosed with 2,000 mg/kg died. Histopathologic evaluation of tissues revealed no lesions attributable to trichloroethylene administration in the 13-week studies. This absence of histopathologic findings did not accurately predict the nephrotoxic effects of long-term administration of trichloroethylene to rats. Body Weight and Survival in the Two-Year Studies: In the 2-year studies, all dosed groups exhibited some reduction in mean body weights relative to the vehicle controls. Survival relative to vehicle controls was significantly reduced in 7/16 dosed groups (see page 6 of the Technical Report). Also, the survival of high dose male Marshall rats was reduced by a large number of accidental deaths. Nephrotoxicity, reduced survival, and central nervous system toxicity (characterized by sedation, loss of consciousness, tremors, and convulsions) showed that the doses of trichloroethylene selected for the 2-year studies were too high. Renal Effects in the Two-Year Studies: Trichloroethylene caused tubular cell cytomegaly in 82%-100% of all dosed animals. In addition, trichloroethylene produced toxic nephropathy (which was distinguishable from age-related nephropathy) in 17%-80% of the dosed animals. Cytomegaly, karyomegaly, or toxic nephropathy was not found in untreated or vehicle control animals. Trichloroethylene administration was also associated with increased incidences of renal tubular cell adenomas and adenocarcinomas. The incidences of renal lesions are shown in the following table (see page 7 of Technical Report). Other Pathologic Effects in the Two-Year Studies: An increased incidence of interstitial cell tumors of the testis was observinterstitial cell tumors of the testis was observed in high dose male Marshall rats (untreated control, 16/46; vehicle control, 17/46; low dose, 21/48; high dose, 32/48; P=0.002). The incidences of pheochromocytomas of the adrenal gland were significantly reduced in male ACI, female August, female Marshall, and male and female Osborne-Mendel rats. Genetic Toxicology: Trichloroethylene did not cause mutations in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without metabolic activation. In Chinese hamster ovary cells, trichloroethylene did not induce chromosomal aberrations; the results for sister chromatid exchanges were considered positive. Trichloroethylene was mutagenic to mouse L5178Y lymphoma cells in the presence of rat liver S9. Data Audit: Audits of the experimental data for these 2-year studies of trichloroethylene were conducted by the National Toxicology Program (see Appendix Q of the Technical Report). The results of the audits revealed evidence that the doses of trichloroethylene were too high. In addition, there was insufficient documentation of animal breeding, clinical observations, environmental conditions, and analytical chemistry data. Also, individual animal identification was not always verifiable. Conclusions: Under the conditions of these 2-year gavage studies of trichloroethylene in male and female ACI, August, Marshall, and Osborne-Mendel rats, trichloroethylene administration caused renal tubular cell cytomegaly and toxic nephropathy in both sexes of the four strains. However, these are considered to be inadequate studies of carcinogenic activity because of chemically induced toxicity, reduced survival, and deficiencies in the conduct of the studies. Despite these limitations, tubular cell neoplasms of the kidney were observed in rats exposed to trichloroethylene and interstitial cell neoplasms of the testis were observed in Marshall rats exposed to trichloroethylene. Synonyms: acetylene trichloride; 1-chloro-2,2-dichloroethylene; 1,1-dichloro-2-chloroethylene; ethinyl trichloride; ethylene trichloride; 1,1,2-trichloroethylene; trichloroethene Trade names of formulations: Algylen; Anamenth; Benzinol; Blacosolv; Blancosolv; Cecolene; Chlorilen; Chlorylea; Chorylen; Circosolv; Crawhaspol; Densinfluat; Dow-Tri; Dukeron; Fleck-Flip; Flock Flip; Fluate; Gemalgene; Germalgene; Lanadin; Lethurin; Narcogen; Narkogen; Narkosoid; Nialk; Perma-A-Chlor; Perm-A-Clor; Petzinol; Philex; Threthylen; Threthylene; Trethylene; Tri; Triad; Trial; Triasol; Trichloran; Trichloren; Triclene; Tri-Clene; Trielene; Trielin; Triklone; Trilen; Trilene; Triline; Trimar; Triol; TRI-plus; TRI-plus M; Vestrol; Vitran; Westrosol Target Organs & Incidences from 2-year Studies

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Monuron (CAS No. 150-68-5) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Carcinogenesis studies of monuron (greater than 99% pure), a substituted urea herbicide, were conducted by feeding diets containing 0, 750, or 1,500 ppm monuron to groups of 50 F344/N rats of each sex and 0, 5,000, or 10,000 ppm to groups of 50 B6C3F1 mice of each sex for 103 weeks. Survivors then were fed a control diet for 1 week, killed, and examined. Throughout most of the studies, mean body weights of dosed rats and mice of each sex were lower than those of the controls. Survival rates of low dose female rats and high dose male and female mice were increased relative to those of the controls. In 13-week toxicity studies, the lympho/hematopoietic system of rats and mice was the primary site affected. The lymphoid depletion found in these animals was not seen in rats or mice surviving to the end of the 104-week studies. Nonneoplastic changes associated with the long-term administration of monuron to rats included renal tubular cell cytomegaly, mainly involving the proximal convoluted tubules in male and female rats, and dose-related hepatic cytoplasmic changes in male rats. In the 104-week study, the kidneys and liver of male rats were the primary tissues affected. Long-term administration of monuron was associated with an increase in renal tubular cell adenomas (control, 0/50; low dose, 2/50; high dose, 7/50) and renal tubular cell adenocarcinomas (0/50; 1/50; 8/50). Administration of monuron to male rats was associated with increased incidences of neoplastic nodules of the liver (1/50; 6/49; 7/50) and of neoplastic nodules or carcinomas (combined) of the liver (1/50; 6/49; 9/50). Dosed male and female rats had decreased incidences of mononuclear cell leukemia; dosed male rats had lower incidences of pheochromocytomas of the adrenal glands and C-cell carcinomas of the thyroid gland; dosed female rats had reduced incidences of mammary gland fibroadenomas. In male mice, dose-related decreases occurred in the incidences of hepatocellular carcinomas (6/50; 5/49; 2/50) and hepatocellular adenomas or carcinomas (12/50; 8/49; 6/50); incidences of hepatocellular tumors in low dose female mice were reduced in dosed female mice (16/50; 8/50; 7/50). Monuron was not mutagenic in Salmonella strains TA98, TA100, TA1535, or TA1537 in the presence or absence of Aroclor 1254-induced rat liver S9. Monuron did induce chromosomal aberrations and sister chromatid exchanges in cultured Chinese hamster ovary cells. The data, documents and pathology materials from the 2-year studies of monuron have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenicity for male F344/N rats in that monuron caused increased incidences of tubular cell adenocarcinomas of the kidney, tubular cell adenomas of the kidney, and neoplastic nodules or carcinomas (combined) of the liver. Monuron induced cytomegaly of the renal tubular epithelial cells in both male and female F344/N rats. There was no evidence of carcinogenicity for female F344/N rats or for male or female B6C3F1 mice. Synonyms and Trade Names: N'-(4-chlorophenyl)-N,N-dimethylurea; 1,1-dimethyl-3-(p-chlorophenyl)urea; CMU; Karmex Monuron Herbicide; Telvar

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Crocidolite Asbestos (CAS No. 12001-28-4) In F344/N Rats (Feed Studies).

Carcinogenesis studies of crocidolite asbestos were conducted with male and female F344/N rats. This form of asbestos was administered at a concentration of 1% in pelleted diet for the lifetime of the rats, starting with the dams of the study animals. The studies were started in January 1978 and ended in December 1980. Group sizes were 118 for male and female controls and 250 for male and female crocidolite asbestos-exposed rats. The offspring from mothers exposed to crocidolite asbestos and the controls were similar in size at birth but were slightly smaller at weaning and remained so throughout their life. Feed consumption and survival were comparable in the exposed and control groups. No overt toxicity was observed in the crocidolite asbestos-exposed animals. There was an elevated (P<0.05) incidence of thyroid gland C-cell adenomas (control, 4/117, 3%, vs. exposed, 23/250, 9%) and of thyroid gland C-cell carcinomas (12/117, 10%, vs. 46/250, 18%) in crocidolite asbestos-exposed female rats relative to concurrent controls. Because these control incidences were low relative to control incidences observed in other contemporary studies at this laboratory (21% for thyroid gland C-cell tumors), this slight increase was not regarded as being biologically important. The data, documents, and pathology materials from the lifetime studies of crocidolite asbestos have been audited. The audit findings show that the conduct of these studies is documented adequately and support the data and results presented in this Technical Report. Conclusions: Under the conditions of these feed studies, crocidolite asbestos was not overtly toxic and did not cause a carcinogenic response when ingested at a concentration of 1% in the diet by male and female F344/N rats for their lifetime. Levels of Evidence of Carcinogenicity: Male Rats: Negative Female Rats: Negative

Journal Article↗
PubMed1988

NTP Toxicology and Carcinogenesis Studies of Rotenone (CAS No. 83-79-4) in F344/N Rats and B6C3F1 Mice (Feed Studies).

Toxicology and carcinogenesis studies of rotenone (more than 98% pure), a pesticide, were conducted in B6C3F1 mice and F344/N rats for 14 days, 13 weeks, and 2 years. Results of the Fourteen-Day Studies: In the 14-day studies (dietary rotenone concentrations of 0-600 ppm in the first 14-day studies and 0-4,800 ppm in the second 14-day studies), rough hair coats and dose-related decreases in mean body weight gain were observed in rats. Rats fed diets containing rotenone at concentrations of 1,200 ppm or higher lost weight. No compound-related toxic effects were observed in mice. Results of the Thirteen-Week Studies: In the 13-week studies (concentrations of 0-1,200 ppm rotenone in feed for rats and 0-50,000 ppm for mice), compound-related effects included lower body weight gain in rats at 150 ppm or more; and bone marrow atrophy and inflammation and hyperplasia of the forestomach in male rats at 300 ppm or more and in female rats at 150 ppm or more. These findings were used to establish the dietary concentrations of rotenone for the 2-year studies. Experimental Design for the Two-Year Studies: Two-year studies of rotenone were conducted by administering diets containing 0, 38, or 75 ppm rotenone to groups of 50 F344/N rats of each sex for 103 weeks. Groups of 50 B6C3F1 mice of each sex were administered diets containing 0, 600, or 1,200 ppm rotenone on the same schedule. The estimated average amount of rotenone consumed per day was 1.7 mg/kg or 3.5 mg/kg for low dose or high dose rats and 115 mg/kg or 250 mg/kg for low dose and high dose mice. Survival and Mean Body Weight in the Two-Year Studies: Survival of control and dosed rats was similar (male: control, 22/50; low dose. 31/50; high dose, 30/50; female: control, 27/50; low dose, 32/50; high dose, 31/50). Mean body weights of dosed and control male rats were comparable. Mean body weights of high dose female rats were 5%-9% lower than those of the controls between weeks 58 and 88. Survival of high dose male mice was significantly greater than that of the controls (male: 29/50; 36/50; 47/50; female: 37/50; 42/50; 45/50). Final mean body weights of dosed mice were lower than those of the controls by 8%-13% for males and 17%-24% for females. Neoplastic Effects in the Two-Year Studies: Parathyroid gland adenomas were observed in 1/41 control, 0/44 low dose, and 4/44 high dose male rats. The historicalincidence of this uncommon tumor in untreated control male rats in NTP studies is 4/1,314 (0.3%). Because these tumors are rare and because the highest incidence ever seen in a control group is 1/50, the increase in these tumors may have been related to rotenone administration. The incidence of subcutaneous tissue fibromas, fibrosarcomas, sarcomas, myxosarcomas, or neurofibrosarcomas (combined) in low dose female rats was greater (P<0.05) than that in the controls (0/50; 5/50; 3/50). These tumors were combined because of their possible common histiogenic origin from fibroblasts or undifferentiated mesenchymal cells. The incidence of those tumors in the low dose females was greater than the historical rats at this laboratory (9/337, 3% +/- 1%) and throughout the Program (50/2,021, 2% +/- 2%). Because of the lack of a significant dose-related trend and because statistical significance was attained only by combining tumors of differing morphology, the subcutaneous tissue tumors in female rats were not considered to be chemically related. The incidences of these tumors in dosed male rats were not significantly different from that in the controls. Hepatocellular adenomas or carcinomas (combined) occurred in male mice with a negative (P<0.02) trend, and the incidence in the high dose group was lower than that in the controls (12/47; 12/49; 1/50). Because this low rate of combined liver tumors is unusual, this decrease may have been related to rotenone administration. Subcutaneous tissue fibromas, sarcomas, fibrosarcomas, or neurofibrosarcomas (combined) in male mice occurred with a significant (P<0.05) negative trend (8/49; 4/50; 2/50). The incidence in the high dose group was signignificant (P<0.05) negative trend (8/49; 4/50; 2/50). The incidence in the high dose group was significantly lower than that in the controls by the life table test (P=0.01). Genotoxicity: Rotenone was not mutagenic when tested according to a preincubational protocol with Salmonella typhimurium strains TA100, TA1535, TA1537, and TA98 with or without metabolic activation by rat or hamster liver S9. Rotenone induced forward mutations in the mouse L5178Y/TK&plusmn; lymphoma assay without activation; it was not tested in the presence of S9. Results of tests with rotenone in Chinese hamster ovary cells were negative for induction of sister chromatid exchanges (SCEs) in the absence of exogenous metabolic activation (at concentrations at which the chemical was very toxic), equivocal for SCEs in the presence of rat liver S9 (due to a nonrepeatable positive response when tests were conducted up to toxic concentrations), and negative for chromosomal aberrationsin both the presence and absence of metabolic activation. Data Audit: An audit of the experimental data was conducted for the 2-year studies of rotenone. No data discrepancies were found that influenced the final interpretations. Conclusions: Under the conditions of these 2-year feed studies, there was equivocal evidence of carcinogenic activity of rotenone for male F344/N rats, as indicated by an increased incidence of parathyroid gland adenomas (uncommon tumors). There was no evidence of carcinogenic activity in female F344/N rats fed diets containing 38 or 75 ppm rotenone. There was no evidence of carcinogenic activity for male or female B6C3F1 mice fed diets containing 600 or 1,200 ppm rotenone for 2 years. The decreased incidence of liver neoplasms in male mice may have been related to the administration of rotenone. Synonym: 1,2,12,12a-tetrahydro-8,9-dimethoxy-2-1-methylethenyl)-[1]benzopyrano[3,4-b]furo2,3-h][1]benzopyran-6(6H)-one Trade Names of Formulations: Derrin; Derris; Tubatoxin; Nicouline; Prentox; Noxfish; Rotocide; Barbasco; Cube Root; Haiari; Dactinol

Journal Article↗