Acute and Subchronic Inhalation Toxicity of Chloroform in Rats and Mice

In order to better characterize acute and subchronic toxicities of chloroform and to provide its basic toxicity data for risk assessment of humans exposed to chloroform in work and living environments, mice and rats of both sexes were exposed by inhalation to chloroform at different concentrations from 500 to 8,000 ppm for 6 h/d x 5 d/wk × 2 wk and from 12 to 400 ppm for 6 h/d x 5 d/wk ×13 wk. The kidneys, liver and nasal cavity were primarily damaged by the inhalation exposure. Acute death occurred at 12 ppm in male mice, 1,OOO ppm in female mice and 2,000 ppm in male and female rats. The 13-wk exposures induced renal lesions in male mice, hepatic and nasal lesions in female mice and renal, hepatic and nasal lesions in male and female rats. Susceptibility to the acute and subchronic toxicities was higher in male mice than female mice, and higher in mice than in rats. No-observed-adverse-effect-levels (NOAELs) and lowest-observed-adverse-effect-levels (LOAELs) were determined for the renal, hepatic and nasal endpoints of animals exposed to chloroform for 13 wk. For the hepatic endpoint, NOAEL was 100 ppm in male mice, 50 ppm in female mice and female rats and 100 ppm in male rats. For the renal endpoint, LOAEL was 12 ppm in male mice, and NOAEL was 25 ppm in male rats and 1OO ppm in female rats. For the nasal endpoint, LOAEL was 12 ppm and 25 ppm in the mice and the rats of both sexes, res pectively.