DETECTING GENOTOXIC ACTIVITY IN INDUSTRIAL EFFLUENTS USING THE SOS CHROMOTEST MICROPLATE ASSAY

The SOS Chromotest, a cost-effective short-term bacterial genotoxicity screening assay, was performed to appraise its capacity for detecting the presence of soluble genotoxic activity in industrial effluent sam ples (organic and inorganic chemical plants, metallurgical plants, pul p and paper mills, municipal wastewater treatment plants). An optimize d methodology, based on criteria taking into account beta-galactosidas e activity (the indicator of SOS gene induction), alkaline phosphatase activity (the indicator of cytotoxicity), and two genotoxicity measur ement end points (minimum genotoxic concentration and maximum inductio n factor), was employed to generate reliable results that overcame the potential interferences inherent to complex wastewaters. Of 48 efflue nt samples tested, 37 (77%) elicited a significant induction of the Es cherichia coli PQ37 SOS response. Effluents from inorganic chemical pl ants and pulp and paper mills displayed the most potent responses, wit h and without metabolizing enzymes (S9 mix). In general, chemical data available for some wastewaters supported SOS Chromotest positive resp onses. The genotoxic activity of whole effluents subjected to a 5-day aeration treatment was as high as that of native (unaerated) samples, suggesting that soluble genotoxicants are relatively recalcitrant to o xidation, although reductions in genotoxic activity did occur. This st udy indicates that the SOS Chromotest is sufficiently sensitive to scr een for the presence of soluble DNA-damaging agents in a wide variety of unconcentrated wastewater samples. (C) 1996 by John Wiley & Sons, I nc.