Mutagenic and carcinogenic risks associated with halogenated olefins.

Recent experimental evidence indicates that structural analogs of vinyl chloride namely, vinylidene chloride and trichloroethylene, are mutagenic. Carcinogenic response also has been observed in experimental animals following exposure to vinylidene chloride, trichloroethylene, and perchloroethylene. More recent observations demonstrate low-level vinyl chloride-induced mammary carcinoma. An additional chlorinated olefin, chloroprene, has demonstrated a mutagenic response in several test systems. Likewise, several studies have indicated significant excesses of chromosomal aberrations as well as adverse effects on reproductive function following male exposure to chloroprene. Although reports have indicated an increased incidence of lung and skin cancer among workers occupationally exposed to chloroprene, adequately designed studies have not been carried out which would allow the development of valid inferences regarding its carcinogenicity. The question facing the scientific community and society is whether observations in subhuman species are adequate to institute prudent public health practice by controlling these agents as carcinogens or mutagens or whether, once again, epidemiologic enumeration of the toll will be required.