Human Bioassays to Assess Environmental Genotoxicity: Development of a DNA Break Bioassay in HepG2 Cells

Objectives: Increasing interest in environmental health issues has created a demand for improved methods for the assessment of pollutant effects on humans. Our laboratory has developed anin vitro assay for the quantification of genotoxicity, monitored as DNA single strand breaks (SSB), in the HepG2 human hepatoma cell line. Design and Methods: This assay procedure, which is based upon alkaline unwinding and hydroxylapatite DNA chromatography, is both rapid and simple to perform. Results: HepG2 cells responded to the standard mutagen, 4-nitroquinolineN -oxide, demonstrating SSB formation at concentrations above 0.1 μmol/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 formation in a dose-dependent manner. Conclusions: These results illustrate the utility of this human genotoxicity assay for future use in screening of environmental pollutants.