CORRELATION TECHNIQUES FOR ESTIMATING PESTICIDE VOLATILIZATION FLUX AND DOWNWIND CONCENTRATIONS

Because of growing concerns over the potential risks from exposure to airborne pesticides that have acute and chronic human and ecological h earth impacts, information on concentrations in air downwind of emissi on sources is being increasingly required, especially in populated are as. A simple and cost-effective approach to estimating downwind air co ncentrations from emissions was developed by relating physicochemical properties of various pesticides and other organics with their publish ed volatilization rates (flux) from treated soil, plant foliage, and w ater. The resulting set of In-in correlations was used to estimate flu x for pesticides with known physicochemical properties. These estimate d flux values were used as source strengths in the EPA's SCREEN-2 disp ersion model to calculate downwind concentrations near treated fields for time periods soon after application. Using estimated flux values f or carbofuran, oxydemeton-methyl, methidathion, azinphos-methyl, and m olinate, downwind concentrations were calculated that compared well wi th concentrations measured near treated fields far these pesticides ap plied to field crops, orchards, and rice fields. This approach is usef ul for prioritizing pesticides that pose potential health hazards and for which monitoring should be considered.