EVIDENCE OF GENOTOXIC SUBSTANCES IN THE NIAGARA RIVER WATERSHED

The SOS chromotest was used to detect genotoxicity of sediment samples from seven locations in the Welland River, Ontario, Canada, in December 1986 and April 1987. DMSO extracts of sediment samples from one location situated directly below the discharge pipe of a polyvinyl chloride plant showed a statistically significant (p < 0.01) genotoxic effect. It was concluded that genotoxic contaminants were associated with vinyl chloride contaminated sediments from this location. At a distance of 5 m downstream of the polyvinyl chloride plant's discharge, the mean SOS induction factor was 2.05, while 100 m further downstream the SOS induction factor had dropped to 1.54. The Ames test was used to detect genotoxicity of samples that gave positive responses in the SOS chromotest. The results of the Ames test were negative. This may suggest that the SOS chromotest is more sensitive than the Ames test for testing genotoxicity in these types of samples.