Ntp Toxicity Study Reports

Technical Report on Toxicology and Carcinogenesis Studies of Sodium Dichromate Dihydrate (CAS No. 7789-12-0) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies)

Chromium is a metal that exists in a variety of valence states, depending on surrounding conditions and what other atoms it is bound to. The most stable forms are metallic chromium, trivalent chromium (chromium III), and hexavalent chromium (chromium VI). Chromium VI has been shown to cause cancer when inhaled in the air. Because compounds containing chromium VI occur as contaminants in drinking water, scientists studied the effects of sodium dichromate dihydrate (SDD) in drinking water on rats and mice to identify potential toxic or cancer-related hazards. Results showed that rats exposed to SDD had carcinomas of the mouth, but none occurred in the control rats. Mice receiving SDD had greatly increased rates of cancer of the small intestine. Illus.

National Toxicology Program Annual Report for Fiscal Year ...

Technical Report on Toxicology and Carcinogenesis Studies of Formamide (CAS No. 75-12-7) in F344/N Rats and B6C3F1 Mice (Gavage Studies)

Formamide has a variety of uses, including as a softener for paper, gums, and glues. This report details the study of the effects of formamide on male and female rats and mice to identify potential toxic or cancer-related hazards. Solutions containing formamide in deionized water were deposited directly into the stomachs of male and female rats and mice. Groups of 50 animals received 20, 40, or 80 milligrams of formamide per kilogram body weight 5 days per week for 2 years; groups of animals receiving water alone served as the control groups. At the end of the study, tissues from more than 40 sites were examined for every animal. The only effects observed in male and female rats were lower body weight in animals receiving the highest dose of formamide and a slight increase in bone marrow hyperplasia in male rats. The study concludes that exposure to formamide did not cause cancer in male or female rats, but it did produce hemangiosarcomas in the liver of male mice and may have been related to an increase in liver tumors in female mice. Increased incidence of bone marrow hyperplasia in male rats and testicular mineralization in male mice were also associated with formamide exposure. Illus.