Neoplastic transformation of Syrian hamster cells by putative epoxide metabolites of commercially utilized chloroalkenes.

The transforming ability of six epoxides of structurally related chloroalkenes was determined with a quantitative Syrian hamster embryo cell model. The epoxides used were cis-1-chloropropene oxide (c-CPO), trans-1-chloropropene oxide (t-CPO), cis-1,3-dichloropropene oxide, trans-1,3-dichloropropene oxide, trichloroethylene oxide (TCEO), and tetrachloroethylene oxide (PCEO). All six epoxides induced morphologic transformation of Syrian hamster embryo cells and caused cell lethality as reflected in the reduced cloning efficiency; in all instances, transformation was observed with less than 25% toxicity. The potency of the various epoxides was influenced by the difference in stability of the compounds. The results with c-CPO, t-CPO, TCEO, and PCEO were consistent with a linear dose response. The transformation results reflect the carcinogenicity of the parental chloroalkenes tested thus far. Furthermore, if the epoxides are metabolic intermediates of the chloropropene parent chloropropenes, the epoxides are probably proximate carcinogens.