Evaluation of the genetic toxicity of the organophosphate insecticide chlorpyrifos.

The genetic toxicity of chlorpyrifos [O,O,-diethyl-O-(3,5,6-trichloro-2- pyridinyl)phosphorothioate, C.A.S. Number: 2921-88-2)], an organophosphate insecticide, was examined by employing several end points such as gene mutations in bacteria (Ames test) and mammalian cell cultures (CHO/HGPRT assay), cytogenetic abnormalities in mammalian cells both in vitro (rat lymphocyte chromosomal aberration test, RLCAT) and in vivo (mouse bone marrow micronucleus test) and induction of DNA damage and repair in rat hepatocytes in vitro. There was no indication of genotoxic activity for chlorpyrifos in any of these assays. These results are consistent with the reported lack of carcinogenic potential for chlorpyrifos in both mice and rats.