TOXICOLOGICAL SCREENING OF CHEMICAL-EMISSIONS FROM MUNICIPAL SOLID-WASTE LANDFILLS - APPLICATION OF A PREDICTIVE FRAMEWORK TO A STATE-OF-THE-ART FACILITY

A screening-level risk assessment was used to identify chemicals of po tential health concern emitted during die normal operation of an hypot hetical state-of-the-art municipal solid waste landfill. Data on the a mount of contaminants (carcinogens, non-carcinogenic systemic toxicant s, odorous compounds, and particulate-bound metals) were obtained from existing facilities and used to estimate ground-level air concentrati ons of airborne chemicals at the point of maximum impact (property lin e) and at year 20 (year of maximum emissions from the landfill). Conce ntrations of leachate components present in tile corresponding underly ing aquifer were also estimated. Intakes of chemicals experienced by a series of human receptors were then computed using either single-medi a or multi-media algorithms. Carcinogens of concern were selected as t hose contributing to a lifetime excess cancer risk (LECR) greater than 10(-6); for non-carcinogenic systemic toxicants and odorous volatiles an Exposure Ratio (ER = intake or concentration/RfD, RfC, odor thresh old) greater than 0.1 was used as cut-off: The results obtained identi fied a final set of air emission components (n = 25) constituted mainl y of carcinogenic and odorous substances whereas 2 leachate components were retained, Additional analysis using more refined risk-based appr oaches are necessary to verify the relevance of these projections.