MUTAGENIC POTENTIAL OF ENVIRONMENTAL-SAMPLES BEFORE AND AFTER REMEDIATION OF A SOLVENT-CONTAMINATED SITE

Soil, sediment, and paint sludge samples were collected during a 4-yea r period from an abandoned solvent recovery site prior to and after si te remediation. Samples were sequentially extracted with methylene chl oride and methanol and redissolved in dimethyl sulfoxide for biologica l analysis. The mutagenic potential of the extracts was evaluated usin g the Salmonella/microsome assay with and without metabolic activation . Noncontaminated background soil samples collected off-site induced s pecific mutagenic activities that ranged from below detection to 28 ne t revertants per milligram of residue. Although several sludge samples induced specific activities that were relatively low, the maximum mut agenic response induced by a sludge sample was 1,258 net revertants pe r milligram of residue. Compared to background soil, elevated levels o f mutagenic activity were also detected in the extracts of several sam ples collected from a drainage area downgradient from the waste storag e pad and in the extract of sediment samples from a downgradient storm -water retention pond. The weighted activity of the noncontaminated ba ckground soil samples ranged from below detection to 15 revertants per gram of soil. The combined weighted activity of the sludge sample ext racts ranged from below detection to 43,567 revertants per gram. The c ombined weighted activity of the extracts of samples collected after s ite remediation ranged from below detection to 1,273 revertants per gr am. A visual inspection of the site following remediation suggested th at all obvious signs of chemical contamination had been removed. Howev er, the results from biological analysis indicate that soil collected following site remediation induced a weighted activity more than 30 ti mes the maximum weighted activity observed in the noncontaminated back ground soil. These data suggest that additional site remediation is re quired if the genotoxic potential of soil is to be reduced to levels a pproximating those of noncontaminated background soil.