New York City’s low-income neighborhoods and California’s Salinas Valley, where 80 percent of the United States’ lettuce is grown, could hardly be more different. But scientists have discovered that children growing up in these communities — one characterized by the rattle of subway trains, the other by acres of produce and vast sunny skies — share a pre-natal exposure to pesticides that appears to be affecting their ability to learn and succeed in school.
Three studies undertaken independently, but published simultaneously last month, show that prenatal exposure to organophosphate pesticides — sprayed on crops in the Salinas Valley and used in Harlem and the South Bronx to control cockroaches and other insects — can lower children’s IQ by an average of as much as 7 points. While this may not sound like a lot, it is more than enough to affect a child’s reading and math skills and cause behavioral problems with potentially long-lasting impacts, according to the studies.
“This is not trivial,” said Virginia Rauh, one of the study authors, speaking from Columbia University, where she is deputy director of the university’s Center for Children’s Environmental Health and professor of population and family health. What is particularly significant, she said, is that these studies involved so many children from such different communities, yet produced consistent evidence of the pesticides’ effects on cognitive skills and short-term memory.
Rauh said that the new studies were prompted by the long-standing awareness of the neurotoxicity of these pesticides on animals and the chemicals’ widespread use. Given science’s growing knowledge about the measurable effects of neurotoxic chemicals and elements, such as lead, on children’s cognition and behavior, the three recent studies were a logical next step in such research, Rauh explained.
The studies in New York and California were a continuation of research that has been ongoing for 12 years. Two of the studies, led by researchers at Columbia University and the Mount Sinai School of Medicine in New York City, looked at more than 660 children, ages six to nine, living in the South Bronx, Harlem, and other inner city neighborhoods. The New York mothers were exposed primarily indoors, as they lived in buildings where these pesticides were used in public areas and inside apartments. Previous studies of pregnant women in the same New York City neighborhoods had found organophosphate pesticides in all indoor air samples and in the majority of umbilical cord blood taken from these women when they gave birth.
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Learning more about the specific mechanisms by which individual chemicals act — and and the effects they trigger — can point the way to which insecticides should be banned. In their next studies, Rauh and her colleagues plan to follow the children in their study group as they progress through school, using brain-imaging studies, blood analysis, and continued intellectual testing. Engel’s group plans to examine additional genetic factors that may help explain susceptibility to organophosphates.
Two generations after the U.S. stopped widely using the pesticides that Rachel Carson wrote about in Silent Spring, scientists are just beginning to get a distinct picture of how replacement pesticides are affecting the health of children. “We now have additional safety regulations for pesticides,” says Lanphear, ”but that doesn’t mean they’re safe.”
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