Study Shows Neurobehavioral Deficits in Children of Farmworkers Exposed to Organophosphate Pesticides

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Two scientific studies related to the effects of organophosphate pesticides on children.

Organophosphate Pesticide Exposure and Attention in Young Mexican-American Children: The CHAMACOS Study

http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1289%2Fehp.1002056

Editor’s Summary

Organophosphate (OP) pesticides are well-known neurotoxicants that have been associated with neurobehavioral deficits in children. Marks et al. (p. 1768) evaluated attention-related outcomes among Mexican-American children participanting in the CHAMACOS study (331 children 3.5 years and 323 children 5 years of age), and measured urinary dialkyl phosphate (DAP) metabolites in the children and in their mothers during pregnancy to determine OP exposure. The authors report that prenatal DAP levels were positively but not significantly associated with maternal reports of attention problems or attention deficit/hyperactivity disorder (ADHD) at 3.5 years, and were significantly associated with these outcomes at 5 years. Some associations appeared to be modified by sex, with associations found only among boys. There was also limited evidence of associations between the outcomes and DAP levels measured in the children. The authors conclude that in utero DAPs and, to a lesser extent, DAPs in children, were associated adversely with attention.

PON1 and Neurodevelopment in Children from the CHAMACOS Study Exposed to Organophosphate Pesticides in Utero

http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1289%2Fehp.1002234

Editor’s Summary

Maternal urinary concentrations of dialkyl phosphate (DAP) metabolites, a marker of in utero organophosphate (OP) pesticide exposure, were previously associated with poorer mental development and maternally reported symptoms consistent with pervasive developmental disorder (PDD) among 2-year-old children in the CHAMACOS study. Eskenazi et al. (p. 1775) extended this research by examining modification of these association by paraoxonase 1 (PON1), an enzyme that detoxifies oxon derivatives of OP pesticides. The authors report that children with the PON1-108T allele had poorer Bayley Mental Development Index scores and somewhat poorer Psychomotor Developmental Index scores, and that children were less likely to display symptoms of PDD when they or their mothers had higher PON1 activity. However, interactions between DAPs and PON1 polymorphisms or activity were not statistically significant, and the authors conclude that additional research is needed to confirm whether PON1 modifies associations between in utero OP exposure and neurodevelopment.