EVALUATION OF THE GENOTOXICITY OF ENVIRONMENTAL CONTAMINANTS IN SEDIMENTS TO RAINBOW-TROUT HEPATOCYTES

Rainbow trout hepatocytes were used as an in vitro bioassay to assess the genotoxic potential of single chemicals and marine sediment extrac ts. Freshly prepared trout hepatocytes were exposed to either benzo[a] pyrene, N-methyl-N'-nitro-N-nitrosoguanidine, beta-naphtoflavone, or o rganic extracts of marine sediments for 24 h at 15 degrees C, Genotoxi city was assayed using the nick translation assay, wh ich makes use of a nonradioactive nucleotide (biotin-dUTP), and the DNA alkaline preci pitation assay followed by fluorometric detection of DNA strands. Expo sure to benzo[a]pyrene or methyl-N'-nitro-N-nitrosoguanidine, known in direct- and direct-acting genotoxins respectively, produced genotoxici ty to rainbow trout hepatocytes with both assays. beta-Naphtoflavone d isplayed genotoxic activity in trout hepatocytes. Sediment extracts an d reference sediment extracts displayed high toxicity and genotoxicity to trout hepatocytes. Chemical analyses showed that these sediments c ontained significant amounts of organochlorine pesticides, polychlorin ated biphenyls, and polycyclic aromatic hydrocarbons. Cell toxicity wa s correlated with total levels of organochlorine pesticides and polych lorinated biphenyls but not total levels of polycyclic aromatic hydroc arbons, No positive correlation was found with the nick translation as say between total levels of chemicals and genotoxicity in marine sedim ents. Genotoxicity obtained with the alkaline precipitation assay was correlated with levels of the organochlorine pesticide DDT. However, m ore tests would be required to further substantiate possible links wit h other specific chemicals. (C) 1995 by John Wiley and Sons, Inc.