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Last Edited: 8/20/07

Maternal Residence Near Agricultural Pesticide Applications and Autism Spectrum Disorders Among Children in the California Central Valley
Written: Jul 2007


Background: Ambient levels of pesticides ("pesticide drift") are detectable at residences near agricultural field sites.

Objective: To evaluate the hypothesis that maternal residence near agricultural pesticide applications during key periods of gestation could be associated with the development of Autism Spectrum Disorders (ASD) in children.

Methods: We identified 465 children with ASD born during 1996-1998 using the California Department of Developmental Services electronic files and matched them by maternal date of last menstrual period to 6,975 live born, normal birthweight, term infants as controls. Proximity to pesticide applications was determined using California Department of Pesticide Regulation records refined using Department of Water Resources land use polygons. A staged analytic design applying a priori criteria to the results of conditional logistic regressions was employed to exclude associations likely due to multiple testing error.

Results: Of 249 unique hypotheses, four that described organochlorine pesticide applications—specifically those of dicofol and endosulfan—occurring during the period immediately prior to and concurrent with CNS embryogenesis (clinical weeks 1 through 8) met a priori criteria and were unlikely to be a result of multiple testing. Multivariate a posteriori models comparing children of mothers living within 500 m of field sites with the highest non-zero quartile of organochlorine poundage to those with mothers not living near field sites suggested an odds ratio for ASD of 6.1 (95%-confidence interval 2.4-15.3). ASD risk increased with poundage of organochlorine applied and decreased with distance from field sites.

Conclusions: The association between residential proximity to organochlorine pesticide applications during gestation and ASD among children should be further studied.

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Suggested Citation

  • Roberts EM, English PB, Grether JK, Windham GC, Somberg L, Wolff CD. Maternal Residence Near Agricultural Pesticide Applications and Autism Spectrum Disorders Among Children in the California Central Valley. Environ Health Perspect doi:10.1289/ehp.10168, July, 2007.