Concern Over Pesticide Exposure During Pregnancy Linked to Lower IQ in Children

May 3, 2011

Exposure to pesticides is known to carry health risks in both adults and children, but a new study at the University of California, Berkeley’s School of Public Health, has found a clear link between intelligence rates and prenatal exposure to organophosphate pesticides.

Organophosphates (OP) are a class of pesticides that are widely used on food crops and are well documented neurotoxicants. Indoor use of chlorpyrifos and diazinon, two common OP pesticides, has been phased out over the past decade, primarily because of health risks to children. However, this is the first time that exposure to their use has been linked to lower intelligence scores in children when they reach the age of 7.

The researchers found that every tenfold increase in measures of organophosphates detected during a mother’s pregnancy corresponded to a 5.5 point drop in overall IQ scores in the 7-year-olds. Children in the study with the highest levels of prenatal pesticide exposure scored seven points lower on a standardized measure of intelligence compared with children who had the lowest levels of exposure.

What this means in practice is that those children who have been exposed are also potentially being handicapped by having below average IQ rates and may possibly need more specialised education and support at school.

This is not an isolated study but part of a trio on pesticide exposure and childhood IQ that was published online April 21 in the journal Environmental Health Perspectives. The other two studies — one at Mt. Sinai Medical Center, the other at Columbia University — examined urban populations in New York City, while the UC Berkeley study focused on children living in Salinas, an agricultural center in Monterey County, California. The researchers sampled pesticide metabolites in maternal urine and umbilical cord blood levels of a specific pesticide, chlorpyrifos. A previous study also found an association between prenatal pesticide exposure and attention problems in children at age 5.

What is unusual is that these figures appear not just in urban areas but are consistent across all the population, which means that these pesticides have entered the food chain and are being consumed by everyone.

However, the really significant finding is that while markers of prenatal OP pesticide exposure were significantly correlated with childhood IQ, exposure to pesticides after birth was not. This suggests that exposure during fetal brain development was more critical than childhood exposure.

The most at risk occupations are exposure are farm workers, gardeners, florists, pesticide applicators and anyone working at a manufacturer of such products.
A simple precaution that pregnant women could take would be to switch to as organic diet as possible, particularly for grains, vegetables and meat products. At home, or in the garden, then use natural nonchemical insecticides and pesticides.


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