Student Research: Nancy J. Simcox

, , 1993
Faculty Advisor: Richard A. Fenske

Organophosphorous Pesticide Residues in Soil as a Potential Source of Exposure among Children of Agricultural Families


Much of the research regarding organophosphorous insecticides in soil has focused on insecticide efficacy/degradation for agricultural production, potential groundwater leaching and the establishment of worker reentry levels. Recently, concerns regarding children's pesticide exposure in and around the home have increased with the reported association between pesticide use and childhood leukemia. Pesticide residues in soil of children's play areas that are in close proximity to orchards may be an important source of exposure for small children and toddlers.

In July and August, 1992, soil samples of children's play areas were collected from fifty-nine families in Eastern Washington: 26 farmer, 22 farmworker and 11 control nonfarm residences. The majority of the farm families lived within 200 feet of an operating orchard (apple, cherry, pear, and/or apricot) whereas the control homes were located at least a quarter of a mile from an orchard.

Samples were extracted with sonication and four organophosphorous insecticides commonly used during the spray season were targeted for GC/MSD. Recovery efficiencies of the sonication extraction method for chlorpyrifos, ethyl parathion, phosmet, and azinphos-methyl were 92%, 110%, 98%, and 90% respectively. Quantifiable levels of these four insecticides ranged from 11 - 1202 ng/g in the soil samples of the farmer/farmworker families. One or more of the target insecticides was found in the soil of 58% of the farmer/farmworker residences. A surprising finding was that twenty-three percent of the samples from the agricultural families contained more than one of the targeted organophosphates. Azinphos-methyl was the most frequently detected insecticide found for the farm family homes. Chlorpyrifos was the only insecticide detected for control families.

This is the first study to examine levels of organophosphates in the soil from children's play areas among agricultural families. The results suggest that children of agricultural families have a higher potential for exposure to organophosphates in soil than control families. As is evident from this study, more than one organophosphate may be present around the home and children's cumulative exposure to this class warrants further investigation.