HUMAN BIOASSAYS TO ASSESS ENVIRONMENTAL GENOTOXICITY - DEVELOPMENT OFA DNA BREAK BIOASSAY IN HEPG2 CELLS

Objectives: Increasing interest in environmental health issues has cre ated a demand for improved methods for the assessment of pollutant eff ects on humans. Our laboratory has developed an in vitro assay for the quantification of genotoxicity, monitored as DNA single strand breaks (SSB), in the HepG2 human hepatoma cell line. Design and Methods: Thi s assay procedure, which is based upon alkaline unwinding and hydroxyl apatite DNA chromatography, is both rapid and simple to perform. Resul ts: HepG2 cells responded to the standard mutagen, 4-nitroquinoline N- oxide, demonstrating SSB formation at concentrations above 0.1 mu mol/ L. Phenanthrene-9,10-quinone, a component of diesel exhaust, mediated SSB formation at concentrations above 250 nmol/L. Finally, an extract of contaminated sediment from the Great Lakes Basin mediated SSB forma tion in a dose-dependent manner. Conclusions: These results illustrate the utility of this human genotoxicity assay for future use in screen ing of environmental pollutants.