Prenatal Pesticide Exposure Linked to Low IQ Later in Life

April 21, 2011— -- By age 2, Ali Bergstrom's son Chille had spent half his life in the hospital. Chille was born with a rare birth defect called Goldenhar syndrome. Now 6, he has already endured two open-heart surgeries and could face many more.

Bergstrom, a 34-year-old New York City-based blogger, will never know for certain what caused her son's deformities. But she suspects chemicals that she was exposed to during pregnancy are to blame.

"Knowing what I know now, in my first trimester I would have stayed inside," said Bergstrom. "I wouldn't have gardened. I wouldn't have allowed fertilizer on my lawn."

In recent years, chemicals in fertilizers and pesticides have been linked to autism, cancer, Lou Gehrig's disease and other illnesses. Some diseases, researchers say, could be caused by an unlucky mix of pollutants and genetic susceptibility. But conclusive evidence for the health hazards of certain chemicals is hard to find.

The latest research, published today as three independent studies in Environmental Health Perspectives, links prenatal pesticide exposure (measured in the urine of mothers-to-be) to a lower IQ in children by age 9. The research teams, from Mount Sinai School of Medicine, Columbia University's Mailman School of Public Health and the school of public health at the University of California, Berkeley, all conclude that pesticide exposure during pregnancy could negatively affect brain development.

But a lack of controlled trials, for obvious reasons, makes it impossible to determine whether there is cause and effect.

"The biggest problem with these studies is they attempt to demonstrate an association when there has not yet been a mechanism identified that would explain how pesticides cause any of the abnormalities," said Dr. Donna Seger, associate professor of medicine at Vanderbilt University Medical Center and director of the Tennessee Poison Center. "Because pesticide exposure and abnormal developmental occur in a specific patient population does not mean that one caused the other."