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J Occup Health year 2002 volume 44 number 5 page 283 - 293
Classification Rapid Communication
Title Carcinogenicity and Chronic Toxicity in Rats and Mice Exposed to Chloroform by Inhalation
Author Seigo YAMAMOTO, Tatsuya KASAI, Michiharu MATSUMOTO, Tomoshi NISHIZAWA,
Heihachiro ARITO, Kasuke NAGANO and Taijiro MATSUSHIMA
Organization Japan Bioassay Research Center, Japan Industrial Safety and Health Association, Japan
Keywords Tumor, Chloroform, Rat, Mouse, NOAEL, Liver, Kidney, Occupational Exposure Limit
Correspondence S. Yamamoto, Japan Bioassay Research Center, 2445 Hirasawa, Hadano, Kanagawa 257-0015, Japan
Abstract Carcinogenicity and Chronic Toxicity in Rats and Mice Exposed to Chloroform by Inhalation: Seigo YAMAMOTO, et al. Japan Bioassay Research Center-A bioassay study of carcinogenicity and chronic toxicity of chloroform was undertaken by inhalation exposures of groups of 50 F344 rats and 50 BDF1 mice of both sexes to chloroform for 6 h/d x 5 d/wk x 104 wk. The exposure concentration was 0 (control), 10, 30 or 90 ppm for rats and 0, 5, 30 or 90 ppm for mice. Combined incidences of renal cell adenomas and carcinomas, and of hepatocellular adenomas and carcinomas increased in the exposed male and female mice, respectively. Incidences of atypical tubule hyperplasia, cytoplasmic basophilia and nuclear enlargement in the kidneys and fatty change in the liver increased in the exposed male mice. Increased incidence of altered cell foci in the exposed female mice was causally related to the hepatocellular adenomas and carcinomas. No significantly increased incidence of the kidney or liver tumors was observed in the exposed rats of either sex. Increased incidences of nuclear enlargement and dilatation of tubular lumen were found in the kidneys of exposed rats. No-observed-adverse-effect-levels (NOAELs) for the biologically significant endpoint were determined from the dose-response relationships of the present datasets. The NOAEL for the histopathological endpoint of the kidneys resulted in 5 ppm for mice and 10 ppm for rats. An occupational exposure limit for chloroform was discussed in light of the NOAELs.