title: Bioassay of tetraethylthiuram disulfide for possible carcinogenicity.
abstract: A bioassay of technical-grade tetraethylthiuram disulfide for possible carcinogenicity was conducted by administering the test chemical in feed to F344 rats and B6C3F1 mice. Groups of 50 rats of each sex were administered tetraethylthiuram disulfide in the diet at one of two doses, either 300 or 600 ppm, for 107 weeks. Groups of 50 mice of each sex were administered the test chemical at one of two doses, either 500 or 2,000 ppm for the males and either 100 or 500 ppm for the females, for 108 weeks. Matched controls consisted of 20 untreated rats and 20 untreated mice of each sex. All surviving animals were killed at the ends of the periods of administration of the test chemical. Mean body weights of the dosed rats and mice of each sex were lower than those of corresponding controls and were dose related throughout most of the bioassay. Mortality was not significantly affected by administration of the test chemical to either the rats of the mice, except for the female rats, in which the mortality was higher in the control group than in the dosed groups; however, the survival at the end of the bioassay was 65% or greater in all dosed and control groups of rats and mice of either sex, and sufficient numbers of animals were at risk in each group for the development of late-appearing tumors. No tumors occurred in the rats or mice of either sex at incidences that were significantly higher in dosed groups than in corresponding control groups. It is concluded that under the conditions of this bioassay, tetraethylthiuram disulfide was not carcinogenic for F344 rats or B6C3F1 mice of either sex.