The insecticide chlorpyrifos, which has been almost entirely banned for home use, but still used in commercial farming and landscaping, has been linked to structural changes in the brains of young children.
In the new study, the researchers used MRI machines to scan the brains of 40 children aged 5 to 11 years. The mothers of 20 of them had high levels of exposure to the insecticide while they were pregnant with the children. The mothers of the other 20 kids had low levels of exposure.
The brains of the kids with high exposure were more likely to have certain enlarged structures in the brain. They also had thinning in some parts of the brain.
Study author, Virginia Rauh, deputy director of the Columbia Center for Children's Environmental Health at Columbia University acknowledged that the study doesn't prove a direct cause-and-effect link between the insecticide and the differences in the brains between the children.
Yet, the findings are worrisome said Rauh because the differences in brain structure appear to be harmful. "An abnormal enlargement would not necessarily be a good thing." In addition, there are links between the sizes of parts of the brain and problems with behavior and thinking, she said.
Dr. Bruce Lanphear, a professor of health sciences who studies environmental risks at Simon Fraser University in Vancouver, British Columbia, said, "even though this paper is not the final word, it builds on existing studies that basically say [Silent Spring author] Rachel Carson was right: Widespread exposure to toxins is likely to cause fairly severe disease."
He added, "Are we willing to sacrifice our children's brains for profits? That's the choice we're making, whether we know it or not."
Commenting on the study, Stephanie Engel, an associate professor of epidemiology at the University of North Carolina at Chapel Hill, said: "The general lesson here is that the dangers that chemicals pose to child development are not always understood. These children were exposed during a period when chlorpyrifos was deemed safe for residential use. So it just makes good sense for pregnant women to be cautious about the chemicals they use during pregnancy. Even ones that we are told are 'safe' may later turn out to be harmful."
Chlorpyrifos Use Continues
While no longer being used in homes, chlorpyrifos is widely used in farming to kill insects on used on corn, some fruits, many types of leafy green vegetables and cotton. It's also used to control pests on golf courses, road medians, Christmas tree farms and other commercial applications.
People should wash their fruits and vegetables very carefully before eating, and pregnant women should not be working in agricultural settings where there might be an occupational exposure, said Rauh.