Actual pesticide exposures in 96 preschool children were measured for one whole class of pesticides (organophosphorus (OP)) by carefully measuring all the metabolites of this class of pesticides in the children’s urine. "The use of urinary metabolites as biomarkers provides an estimate of exposure by all routes (dermal, respiratory, and oral) and assesses actual rather than potential absorption." Of course, the researchers chose OP pesticides because the metabolites are known and measurable down to minuscule amounts. However, other excellent reasons for studying this class of pesticides are "their widespread use, acute toxicity, and neurotoxic properties."

The children were recruited from two Seattle health-care facilities: one public-funded and the other private. They serve two quite different areas of Seattle. One is densely populated with lower- to middle-income families, many of whom live in apartments. The second area "is predominantly inhabited by middle- to upper middle-income families in single-family dwellings."

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Every child, except one, had metabolites of organophosphorus pesticides in their urine. . . . This one child’s parents "reported buying exclusively organic produce and did not use any pesticides at home."

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Two urine samples were taken for each child, one in the spring and the other in the fall. The researchers determined that pesticide use is heaviest at these times in the Seattle area. The parents were carefully instructed in the collection and refrigeration of the urine and the samples were promptly collected and delivered to the researchers. A questionnaire on pesticide use in the home, the garden, and on pets, was filled out at the time of the first urine collection in the spring.

Every child, except one, had metabolites of organophosphorus pesticides in their urine. In regard to quantity of the metabolites, they found statistically significant increases in the urine of children, where the parents reported that pesticides were used in the garden, compared to families with gardens, who reported no pesticide use. We know that small children crawl around and when pesticides are used outside, they are tracked into the home and settle into carpet, where they can degrade slowly. "Ingestion of soil or house dust containing pesticide residues may contribute to the exposure of young children because children spend more time on the floor than adults and may engage in hand-to-mouth and object-to-mouth behaviors."

No significant differences in the quantities of the organophosphorus pesticide metabolites were observed between the two areas studied; between boys and girls; between spring and fall samples; or in terms of the children’s age differences or family income differences.

In this whole study of 96 children, only one child "showed no measurable concentration of any of the [OP] metabolites in the spring and fall samples." This one child’s parents "reported buying exclusively organic produce and did not use any pesticides at home."

*Lu, C., et al, "Biological Monitoring Survey of Organophosphorus Pesticide Exposure among Preschool Children in the Seattle Metropolitan Area," Environmental Health Perspectives, 109(3): 299-303, March 2001.