This research was initiated to provide toxicologic and range finding data sufficient for setting dose levels for the chronic phase testing of chloroform in drinking water of male Osborne-Mendel rats and female B6C3F1 mice. A 90-day subchronic study was designed to investigate the effects of chloroform in drinking water at levels of 200, 400, 600, 900, and 1800 ppm in both the rats and mice, and 2700 ppm level in the mice. Body weights, water consumption, chloroform concentration in blood serum, kidney fat-to-kidney weight ratios (for rats), liver fat-to-liver weight ratios (in mice), and gross and microscopic pathology findings were examined. Results showed that the body weights of both rats and mice receiving the high chloroform levels were affected by treatment, but the variances were low and the mice body weights returned to that of controls after one week. There was no effect on the percentage of kidney fat (rats) but a significant increase in liver fat (mice) was seen in the 2700 ppm group. Data in this study indicated that all chloroform levels examined in the 90-day study are acceptable for use in the chronic study.

"Mammalian Toxicology Program, SRI International." "July 1980." "Contract no. 68-03-2616." "Project Officers Richard J. Bull, Merrel Robinson, Toxicological Assessment Branch. and Carrie E. Whitmire, Carcinogenesis Testing program."