In vitro genotoxicity of polychlorinated butadienes (Cl4-Cl6).

Tetrachlorinated butadienes (TetraCBDs), pentachlorinated butadienes (PentaCBDs) and hexachloro-1,3-butadiene (hexachlorobutadiene or HexaCBD) are environmental contaminants that can occur in groundwater and drinking water at specific sites. While some toxicological data exist for HexaCBD, only few or no toxicity data are available for TetraCBDs and PentaCBDs. In view of structural alerts for potential genotoxicity and carcinogenicity, the genotoxicity of these substances was examined in the Salmonella typhimurium mutagenicity assay (Ames test) and in the in vitro chromosome aberration test. All of the tested polychlorinated butadienes induced chromosome aberrations. Such an effect of HexaCBD is reported here for the first time. In addition, 1,1,3,4-TetraCBD and 1,2,3,4-TetraCBD were positive in the Ames test while the other polychlorinated butadienes including HexaCBD were negative. From these findings it is concluded that certain incompletely chlorinated butadienes have a different genotoxic profile than the completely halogenated HexaCBD, which is of relevance for the risk assessment of these compounds.