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T9 PM Pyrethroid Insecticides in Urban and Agricultural Environments
(HOL-1117-835568) National Exposure Analysis of Pyrethroids (Part 1); Spatial Proximity of Agriculture to Surface Water.
Holmes, C1, Matella, M1, 1 Waterborne Environmental, Inc., Leesburg, VA, USA
ABSTRACT- This three-part presentation describes a national exposure analysis that was undertaken to characterize watersheds in the conterminous US for relative risk to pyrethroid exposure. Part 1 relates to the quantification of spatial proximity of agriculture to surface water as an indicator of potential exposure from agricultural spray drift. Surface water from the National Hydrography Dataset (NHD) was separated into four classes and the area proximate to each class was generated in a GIS. The National Land Cover Dataset (NLCD) was used to determine the spatial location of agricultural land, and how much of this crop area was proximate to surface water. In addition, the 2002 Census of Agriculture was used to provide information on the specific crop types (e.g., corn, cotton) and the area grown within each county. These datasets were combined to estimate the amount of corn and cotton grown within close proximity to surface water (up to 480m). Finally, over 60,000 watersheds from the USGS Enhanced River Reach File dataset were combined with the crop proximity information to generate a distribution of potential exposure from corn and cotton to surface water within each watershed. The results represent a national distribution of potential spray drift exposure suitable for identifying areas for detailed analysis. In addition, they provide the ability to place detailed analysis results into the broader context of US agriculture and potential surface water exposure. The spatial results of this study could be used with additional crops, alternate land cover data, or alternate watersheds. Subsequent presentations will describe the potential exposure to surface water related to erosion risk, and also an examination of the relative sensitivities to pyrethroid exposure for both spray drift and erosion factors.
Key words: GIS, spatial, proximity, exposure
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