ACUTE AND GENETIC TOXICITY OF MUNICIPAL LANDFILL LEACHATE

The large number of municipal solid waste (MSW) landfills and the many hazardous materials which they contain pose a serious environmental threat to our groundwater reserves. The present study was conducted to assess the environmental hazards that four MSW landfill leachates pose to the groundwater. Genetic toxicities of the landfill leachate and groundwater samples were assessed using the Salmonella/microsome (Ames test) mutagenicity bioassay, the Bacillus subtilis DNA repair bioassay, and the diploid Aspergillus nidulans chromosome damage bioassay. Acute toxicities of the leachate samples were assessed using the Microtox test. The leachate and groundwater samples were also analyzed for organic constituents using gas chromatography and gas chromatography/mass spectrometry. The chemical data were used to calculate the estimated cumulative cancer risk for each sample. All leachate samples were acutely toxic, and three of the four leachate samples were genetically toxic. Two of the four leachate samples and the groundwater sample contained concentrations of USEPA priority pollutants in excess of promulgated standards for potable water. Two of the leachates had mean estimated cumulative cancer risks on the same order of magnitude (10(-4)) as leachates from co-disposal and hazardous waste landfills. The use of a battery of acute and genetic toxicity bioassays, chemical analysis, and an estimated cancer risk calculation resulted in evidence that MSW landfill leachates are as acutely and chronically toxic as co-disposal and hazardous waste landfill leachates.