Organophosphorus pesticide exposure of urban and suburban preschool children with organic and conventional diets - Children's Health

Environmental Health Perspectives, March, 2003 by Cynthia L. Curl, Richard A. Fenske, Kai Elgethun

Individual dimethyl OP pesticide doses were calculated assuming that all exposure came either from oxydemeton-methyl, malathion, azinphosmethyl, or phosmet (Table 4). Doses for children with conventional diets were significantly higher than doses for children with organic diets for all four pesticides (Mann Whitney U-test, p = 0.0002). If all exposure were assumed to be from oxydemeton-methyl, 88% of the children with organic diets and 100% of the children with conventional diets would exceed the U.S. EPA chronic reference dose. Conversely, if either malathion or phosmet were assumed to be the source of all exposure, no child from either group would exceed the RfD. However, if azinphosmethyl were the only source, one child with an organic diet (6%) and 11 children with conventional diets (52%) would surpass the RfD.

Discussion

This study demonstrates that dietary choice can have a significant effect on children's pesticide exposure. To our knowledge, no other studies have tested this hypothesis. Our finding that children who consume primarily organic: produce exhibit lower pesticide metabolite levels in their urine than children who consume conventional produce is consistent with known agricultural practice, because organic foods are grown without pesticides. Consumption of organic produce represents a relatively simple way for parents to reduce their children's pesticide exposure.

Exposure pathways. Diet appears to have been the primary pathway for OP pesticide exposure for this population. One-third of the conventional diet families and one-sixth of the organic diet families reported some use of OP pesticides for residential pest control. However, residential pesticide use did not appear to confound the analysis; the results were unchanged when participants reporting residential OP pesticide use were excluded. Drinking water is another potential source of pesticide exposure. However, virtually all participants in this study reside in the Seattle metropolitan area and receive their water from a municipal water system. Further, a previous study of OP pesticide exposure in Seattle did not detect residues in drinking water (Kedan 1999).

Dose estimation. Very different conclusions regarding risk can be drawn depending on the pesticide to which the dose is attributed. If a more toxic pesticide is chosen, such as oxydemeton-methyl, nearly all of the estimated daily doses are above the U.S. EPA chronic reference dose. Alternatively, if a less toxic pesticide is chosen, such as phosmet or malathion, none of the daily doses are above the RfD. However, if all exposure is attributed to a relatively toxic and commonly applied pesticide, azinphosmethyl, consumption of organic produce and juice can shift most of the doses from above the RfD to below it. It is unlikely that these doses stemmed from azinphosmethyl exposure alone, but this analysis demonstrates that consumption of organic produce and juice may be able to shift children's exposure from a range of uncertain risk to a range of negligible risk within the context of the U.S. EPA's current risk framework.