Identifying populations potentially exposed to agricultural pesticides using remote sensing and a geographic information system

pesticides used in agriculture may cause adverse health effects among the p opulation living near agricultural areas. However, identifying the populati ons most likely to be exposed is difficult. We conducted a feasibility stud y to determine whether satellite imagery could be used to reconstruct histo rical crop patterns. We used historical Farm Service Agency records as a so urce of ground reference data to classify a late summer 1984 satellite imag e into crop species in a three-county area in south central Nebraska. Resid ences from a population-based epidemiologic study of non-Hodgkin lymphoma w ere located on the crop maps using a geographic information system (GIS). C orn, soybeans, sorghum, and alfalfa were the major crops grown in the study area. Eighty-five percent of residences could be located, and of these 22% had one of the four major crops within 500 m of the residence, an intermed iate distance for the range of drift effects from pesticides applied in agr iculture. We determined the proximity of residences to specific crop specie s and calculated crop-specific probabilities of pesticide use based on avai lable data. This feasibility study demonstrated that remote sensing data an d historical records on crop location can be used to create historical crop maps. The crop pesticides that were likely to have been applied can be est imated when information about crop-specific pesticide use is available. Usi ng a GIS, zones of potential exposure to agricultural pesticides and proxim ity measures can be determined for residences in a study.