National Toxicology Program technical report series
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Natl Toxicol Program Tech Rep Ser · Mar 1992
NTP Toxicology and Carcinogenesis Studies of Ethylene Thiourea (CAS: 96-45-7) in F344 Rats and B6C3F1 Mice (Feed Studies).
Ethylene thiourea is a white crystalline solid used extensively in the rubber industry as an accelerator in the vulcanization of elastomers. It is also a trace contaminant and metabolic degradation product of a widely used class of ethylene bisdithiocarbamate fungicides. Ethylene thiourea is known to produce thyroid neoplasms in rats and liver neoplasms in mice following long-term administration; thus, it was chosen by the National Toxicology Program in an investigation of the potential value of perinatal exposures in assessing chemical carcinogenicity. ⋯ However, increasing perinatal exposure from 0 to 90 ppm had no effect on incidences of thyroid neoplasms in rats receiving adult exposure to 83 ppm. Increasing perinatal exposure from 0 to 330 ppm was associated with a marginally increased incidence of thyroid neoplasms in female mice receiving adult exposure to 330 ppm, but there were no enhancing effects of perinatal exposure in mice receiving adult exposure to 1,000 ppm. Synonyms: 2-Imidazolidinethione; Imidazoline-2-thiol; 2-mercaptoimidazoline; N,N'-ethylenethiourea; 1,3-ethylenethiourea; 2-imadazoline-2-thiol
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Natl Toxicol Program Tech Rep Ser · Sep 1991
NTP Toxicology and Carcinogenesis Studies of Titanocene Dichloride (CAS No. 1271-19-8) in F344/N Rats (Gavage Studies).
Titanocene dichloride is an organometallic compound composed of two cyclopentadienyl rings, titanium, and chloride. It is used as a cocatalyst in polymerization reactions. Toxicology and carcinogenesis studies were conducted by administering titanocene dichloride (greater than 98% pure) in corn oil by gavage to groups of F344/N rats for 14 days, 13 weeks, and 2 years. ⋯ There was equivocal evidence of carcinogenic activity of titanocene dichloride in female F344/N rats based on a marginal increase in the incidence of forestomach squamous cell papillomas. Nonneoplastic lesions associated with the administration of titanocene dichloride for up to 2 years included erosions and inflammation of the gastric mucosa, hyperplasia and metaplasia of the fundic glands with fibrosis of the lamina propria in the glandular stomach, and acanthosis (hyperplasia) and hyperkeratosis of the forestomach epithelium. Synonyms: Titanium ferrocene; biscyclopentadienyltitanium dichloride; dichlorodi-p-cyclopentadienyltitanium; dichlorobis(h5-2,4-cyclopentadien-1-yl)titanium; dicyclopentadienyltitanium dichloride; dichlorodicyclopentadienyltitanium; dichlorotitanocene; dicyclopentadienyldichlorotitanium; dichlorobis(p-cyclopentadienyl)titanium; bis (h5-cyclopentadienyl) titanium dichloride; dichlorobis(h5-cyclopentadienyl)titanium; dichlorobiscyclopentadienyl titanium; dichlorobis(1,3-cyclopentadiene)titanium; bis(cyclopentadienyl)dichlorotitanium
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Natl Toxicol Program Tech Rep Ser · Jun 1991
NTP Toxicology and Carcinogenesis Studies of 3,3'-Dimethylbenzidine Dihydrochloride (CAS No. 612-82-8) in F344/N Rats (Drinking Water Studies).
3,3'-Dimethylbenzidine dihydrochloride is one of five chemicals being evaluated in 2-year carcinogenicity and toxicity studies as part of the NTP's Benzidine Dye Initiative. This Initiative was designed to evaluate representative benzidine congeners, benzidine congener-derived dyes, and benzidine-derived dyes. 3,3'-Dimethylbenzidine dihydrochloride was nominated for study because of the potential for human exposure during production of bisazobiphenyl dyes and because benzidine, a structurally related chemical, is a known human carcinogen. Toxicology and carcinogenesis studies were conducted by administering 3,3'-dimethylbenzidine dihydrochloride (approximately 99% pure) in drinking water to groups of F344/N rats of each sex for 14 days, 13 weeks, or 9 or 14 months. ⋯ There was clear evidence of carcinogenic activity for female F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal's gland, clitoral gland, liver, oral cavity, small and large intestine, mammary gland, and lung. Increased incidences of neoplasms of the brain and mononuclear cell leukemia may have been related to chemical administration. Synonyms: o-tolidine dihydrochloride; 3,3'-dimethylbiphenyl-4,4'-diamine dihydrochloride; 3,3'-dimethylbiphenyl-4,4'-biphenyldiamine dihydrochloride; 4,4'-diamino-3,3'-dimethylbiphenyl dihydrochloride