Carcinogenicity of benzene hexachloride and its isomers.

Technical BHC and the alpha, beta, gamma and delta isomers of BHC are carcinogenic for the liver of mice and rats. Mice given the isomers of BHC developed carcinomas and hyperplastic nodules of the liver as early as 24 weeks. Several strains of mice (dd, ICR-JLC, CL1, DDY, IRC, DBA/Z, C3H/HEN, C57BL/6 were susceptible. Male mice were more susceptible to hepatic carcinogenesis than female mice and they appeared to be more susceptible to alpha-BHC. The incidence of neoplasms of the liver was increased when beta-, gamma-, or delta-BHC were each given together with alpha-BHC. PCB-5 promoted the induction of hepatic neoplasms when administered with beta-BHC. Technical BHC and its isomers are carcinogenic for the liver of male and female Wistar rats. Beta-BHC is carcinogenic for the liver of Osborne-Mendel male rats. Osborne-Mendel rats receiving delta-BHC developed cirrhosis of the liver, portal vein thrombosis, and focal necrosis of the skeletal muscle. Male rats ingesting technical BHC or the beta or delta isomers also had atrophic testes.