Babies exposed to high levels of common pesticides in the womb have lower I.Q. scores than their peers by the time they reach school age, according to three new studies.
The research, based on data collected in New York and California from about 1,000 pregnant women and their babies, is certain to set off a new debate about the benefits of organic produce and the risks of chemicals found in the food supply and consumer products. The pesticides, called organophosphates, are commonly sprayed on food crops and are often used to control cockroaches and other pests in city apartments.
The latest findings are based on three separate but similar studies financed by the National Institute of Environmental Health Sciences and the federal Environmental Protection Agency. Two were conducted by researchers at Mount Sinai School of Medicine and Columbia University and studied urban families in New York; the third was done by researchers at the School of Public Health at the University of California, Berkeley, and focused on children in Salinas, Calif., an agricultural area. All three were published online on Thursday in the journal Environmental Health Perspectives.
Each study began about a decade ago, when researchers recruited pregnant women who gave blood and urine samples that were used to measure pesticide exposure. In some instances, umbilical cord blood was tested. After the babies were born, the researchers continued to monitor the health of the children and also obtained regular urine samples to determine exposure to pesticides.
Over all, the studies found that women who had higher exposures to pesticides during pregnancy gave birth to children who eventually had lower I.Q. scores once they reached school age. In the Berkeley study, for instance, children with the highest levels of prenatal pesticide exposure scored 7 points lower on intelligence tests compared with children with the lowest levels of exposure. In that study, every 10-fold increase in organophosphate exposure detected during pregnancy corresponded to a 5.5 point drop in overall I.Q. scores.
“I think these are shocking findings,” said Dr. Philip Landrigan, a professor of pediatrics and director of the Children’s Environmental Health Center at Mount Sinai. “Babies exposed to the highest levels had the most severe effects. It means these children are going to have problems as they go through life.”
Dr. Landrigan compared the findings with research in the 1980s that linked childhood lead exposure to lower intelligence, dyslexia, higher risk for dropping out of school and a range of behavioral and developmental problems. As a result of that research, lead was removed from gasoline to prevent exposure from car exhaust, and it was also removed from paints and other consumer products.
The drop in I.Q. scores shown in the pesticide studies is similar to the drops shown in the earlier lead research, Dr. Landrigan said.
“When we took lead out of gasoline, we reduced lead poisoning by 90 percent, and we raised the I.Q. of a whole generation of children by four or five points,’’ said Dr. Landrigan. “I think these findings about pesticides should generate similar controversy, but I’m cautiously optimistic that they will have the effect of having the E.P.A. sharply reduce the use of organophosphate pesticides.”
Individuals can also do more to limit their own exposure. In homes with pest problems, sealing up cracks and crevices in baseboards and cleaning up food residue has been shown to be more effective at controlling cockroaches than using pesticides.
Caleb Kenna for The New York TimesSteps can also be taken to minimize exposure to pesticides in foods, particularly among pregnant women. Buying organic foods can help because certified organic fruits and vegetables aren’t grown with organophosphate pesticides. Better washing and peeling of conventionally grown produce can also reduce exposure.
The Environmental Working Group offers a shopper’s guide showing which foods have the highest and lowest rates of pesticide exposure. Strawberries, peaches, celery, apples and spinach typically have the highest levels of pesticide residue among commercially grown fruits and vegetables. Onions, avocado, frozen corn and pineapple had the lowest levels of pesticide residue.
