Pesticides, fertilizers threaten
brain development

UPdate Summer 2007

Children conceived in summer perform more poorly in school than other children. An Indiana research team has linked poor school results to pesticides and nitrate exposure in the early weeks and months of development. A study of more than 1.5 million children in grades 3 to 10 found that children conceived in the months when pesticide and fertilizer levels were highest achieved significantly lower results in standard math and English tests.

"The fetal brain begins developing soon after conception. The pesticides we use to control pests in fields and our homes and the nitrates we use to fertilize crops and even our lawns are at their highest level in the summer,” said lead researcher Dr. Paul Winchester, director of Newborn Intensive Care Services at St. Francis Hospital in Indianapolis.

The study supports other evidence that low levels of exposure to toxic chemicals at critical periods of development can have devastating and long lasting effects.

“Exposure to pesticides and nitrates can alter the hormonal milieu of the pregnant mother and the developing fetal brain," said Dr. Winchester. "Neurodevelopmental consequences of exposure to pesticides and nitrates may not be obvious for many decades.” The research was presented at the 2007 conference of the Pediatric Academic Society.

Dr. James Lemons, professor of pediatrics and director of neonatal-perinatal medicine at Indiana University School of Medicine notes the research has great significance. “I believe this work may lay the foundation for some of the most important basic and clinical research and public health initiatives of our time. To recognize that what we put into our environment has potential pandemic effects on pregnancy outcome and possibly on child development is a momentous observation, which hopefully will help transform the way humanity cares for its world,” Lemons commented.

Winchester and his research team also found links between pesticides and nitrate levels and two other infant health problems - premature births and birth defects. The team analyzed more than 27 million US live births from 1996- 2002. They found that preterm birth rates peaked when levels of pesticides and nitrates were highest, and were lowest when pesticide and nitrate levels were lowest. “Nitrates and pesticides can disrupt endocrine hormones and nitric oxide pathways in the developing fetus," Winchester explained.

In 2006, Dr Winchester reported results of a 4 year study, which showed that birth defects peak in Indiana and in the United States as a whole during April through July. Those babies would have been conceived in the months when pesticides and nitrates were at their maximum concentration in surface water.

"A growing body of evidence suggests that the consequence of prenatal exposure to pesticides and nitrates as well as to other environmental contaminants is detrimental to many outcomes of pregnancy. As a neonatologist, I am seeing a growing number of birth defects, and preterm births, and I think we need to face up to environmental causes," said Dr Winchester, who also serves as director of Newborn Intensive Care Services at St. Francis Hospital in Indianapolis.

Prior studies have identified a link between pesticide exposure and thyroid problems in pregnant women. Maternal thyroid problems are believed to affect the intelligence of an unborn child.