P450 RGS: A Biomarker for Assessing the Toxicity of Environmental Samples, 1995 Environmental Conference Proceedings

Jack Anderson, Kristen Bothner, Stephen Vincent, David Edelman - Columbia Analytical Services

A reporter gene system (RGS) assay, has been engineered from a human liver cancer cell line so that the CYPlAl gene will produce luciferase instead of P450 when activated by an in-ducer compound. An organic extract of water, tissue or soil is applied, then the reaction is stopped 6 to 18 hours later by rinsing the cells. The cells are then lysed and the cytoplasm is measured for luminescence. Induction of this test system by such compounds as dioxin, dioxin-like PCB congeners (co-planar), and polyaromatic hydrocarbons (PAH) infers these xenobiotics are present at potentially toxic, carcinogenic, or mutagenic levels. Solvent extracts of aquatic sediments, soils, and mussel tissue have been directly applied to the assay sys-tem. Test results show significant RGS induction from environ-mental samples. Detection limits in a typical 40 g sample would be approximately: 0.05 ppb for dioxin; 10 to 5,000 ppb for a range of coplanar PCB congeners; and 100 to 2,000 ppb for a range of PAHs. Comparisons between the EPA Toxic Equivalent Factors (TEF) and those generated from P450 RGS testing differ considerably. Results presented will show that the P450 RGS assay is a rapid, sensitive, and specific test for dioxin, PCBs, and PAHs.