Pesticides tied to lower IQ in children
Children exposed in the womb to substantial levels of neurotoxic pesticides have somewhat lower IQs by the time they enter school than do kids with virtually no exposure. A trio of studies screened women for compounds in blood or urine that mark exposure to organophosphate pesticides such as chlorpyrifos, diazinon and malathion.
These bug killers, which can cross the human placenta, work by inhibiting brain-signaling compounds. Although the pesticides' residential use was phased out in 2000, spraying on farm fields remains legal.
The three new studies began in the late 1990s and followed children through age 7. Pesticide exposures stem from farm work in more than 300 low-income Mexican-American families in California, researchers from the University of California, Berkeley and their colleagues report. In two comparably sized New York City populations, exposures likely trace to bug spraying of homes or eating treated produce.
Among the California families, the average IQ for the 20 percent of children with the highest prenatal organophosphate exposure was 7 points lower compared with the least-exposed group.
A Columbia University study followed low-income black and Hispanic families. Here, each additional 4.6 picrograms of chlorpyrifos per gram of blood in a woman during pregnancy correlated with a drop of 1.4 percent in her youngster's IQ and 2.8 percent in a measure of the child's working memory.