Benzo(a)pyrene induced micronucleus formation was modulated by persistent organic pollutants (POPs) in metabolically competent human HepG2 cells

Due to their bioaccumulation and their biological properties persistent organic pollutants (POPs) attract wide attention. In the present study we investigated the genotoxicity, cogenotoxicity and antigenotoxicity of three selected POPs (DDT, aroclor-1254 and toxaphene) in the HepG2 micronucleus assay. Exposure of HepG2 cells to DDT (17.8-60 muM) and aroclor-1254 (23-184 muM) alone did not increase the micronucleus-frequencies. A slight genotoxic effect could be observed after exposure to toxaphene (20-40 muM). Additionally, the ability of POPs to enhance/decrease the benzo(a)pyrene (BaP)-induced micronucleus formation was investigated. Exposure of HepG2 cells to 50 muM BaP alone led to a more than 2-fold increase of micronuclei (MN) compared with the background frequency. But when the cells were pretreated with 23-181 muM aroclor-1254 or 10-20 muM toxaphene, BaP exposure caused significantly more MN than BaP alone. In contrast, DDT (17.8-60 muM) reduced BaP-induced micronucleus induction by 6-38%. Mechanisms of action are discussed. (C) 2003 Elsevier Ireland Ltd. All rights reserved.