The objective was to determine PON1 status as a predictor for organophosphorus insecticide sensitivity in a cohort of Latina mothers and newborns from the Salinas Valley, California, an area with high levels of organophosphorus insecticide use. PON1 status was established for 130 pregnant Latina women and their newborns using a high-throughput two substrate activity/analysis method which plots rates of diazoxon (DZO) hydrolysis against rates of paraoxon (PO) hydrolysis. Arylesterase activity (AREase) was determined using phenylacetate as a substrate, allowing comparison of PON1 levels across PON1 192 genotypes in mothers and children. Phenylacetate hydrolysis is not affected by the Q192R polymorphism. Among newborns, levels of PON1 (AREase) varied by 26-fold (4.3–110.7 U/ml) and among mothers by 14-fold (19.8–281.4 U/ml). On average, children's PON1 levels were four-fold lower than the mothers' PON1 levels (P<0.001). Average PON1 levels in newborns were comparable with reported hPON1 levels in transgenic mice expressing human PON1Q192 or PON1R192, allowing for prediction of relative sensitivity to chlorpyrifos oxon (CPO) and DZO. The predicted range of variability in sensitivity of mothers and children in the same Latino cohort was 65-fold for DZO and 131 to 164-fold for CPO. Overall, these findings indicate that many of the newborns and some of the mothers in this cohort would be more susceptible to the adverse effects of specific organophosphorus pesticide exposure due to their PON1 status. Of particular concern are exposures of pregnant mothers and newborns with low PON1 status.
aDepartments of Genome Sciences and Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington
bCenter for Children's Environmental Health, School of Public Health, University of California, Berkeley, California, USA
Correspondence and requests for reprints to Clement Furlong, University of Washington, Division of Medical Genetics, Box 357720, Seattle, WA 98195-7720, USA
Tel: +1 206 543 1193; fax: +1 206 543 3050;
Sponsorship: This study was supported by 2 P01 ES009605, ES11387, ES09883, P30 ES01896, EPA-R82670901-5, P60 MD00222, and NIEHS ES09601/EPA: RD-83170901. The contents of this paper are solely the responsibility of the authors and do not necessarily represent official views of the NIH, or the EPA.
Received 26 July 2005 Accepted 13 October 2005
*The first two authors contributed equally to this work.