Relationship of pesticide exposure and pervasive developmental disorder

"Behavioral teratogens" are chemicals which affect cognitive and behavioral functioning of children due to exposure during fetal or child development. Some have hypoothesized that increases in learning disabilities, attentional deficits, childhood autism and other developmental disorders over the last generation may be due to the use of chemicals in the environment. More than thirty years ago, lead and alcohol were identified as "behavioral teratogens". One other class of chemicals which has been of particular concern is pesticides. Pesticides at high doses are well-known toxins to the nervous system, resulting in numerous poisonings to children and workers every year. Despite animal evidence suggesting neurotoxic effects of lower level exposure to pesticides, few published studies have investigated the neurodevelopmental toxicity of pesticides in humans. We investigated the relation of one important class of pesticides, organophosphates (OP) and the cognitive, motor and behavioral development of children from a low-income Mexican farmworker families in California. These children are participates of the CHAMACOS birth cohort study. We measured metabolites of OP pesticides in urine collected from over 400 mothers twice during pregnancy and from children at the time of their neurodevelopmental assessments. We found that both prenatal and postnatal metabolites were associated with increased odds of maternal report at age two of pervasive developmental disorder. Results were similar when the children were 3.5 years old.  Recent evidence suggests that not all individuals are equially susceptible to effects of pesticide exposure. For example,  individuals with certain genotypes (PON1) may be more susceptible to OP pesticide exposure. It has also been hypothesized that these same genotypes may be related to risk for childhood autism. We will examine the inter-relationship of PON1 genotype and related enzyme levels and DAP levels and maternal report of maternal pervasive developmental disorder.