Pesticides may impair children's brain function

Pesticides may impair children's brain function

Dramatic deficits in brain function are seen in rural children with long-term exposure to pesticides compared with children not similarly exposed, according to a recent study in the US publication Environmental Health Perspectives.

The study compared two groups of four- and five-year-old children in the Yaqui Valley of Sonora, Mexico, a region and population that allowed researchers to compare children who are very similar except in their levels of pesticide exposure. The children share a genetic and cultural background, eat the same foods and drink the same water.

Thirty-three of those studied live in the valley, a farming area where pesticide use is relatively intense. Farmers reported that two crops a year may be planted, with up to 45 pesticide applications per crop. Organophosphates, organochlorines and pyrethroids are among the chemicals used, according to the study.

In addition, household insecticides are usually applied each day throughout the year.

Contamination of the local population has been documented, with women's breast milk containing concentrations of lindane, heptachlor, benzene hexachloride, aldrin and endrin all above limits established by the UN Food and Agricultural Organisation.

The second study group (17 children) live in the foothills, where most families are involved in ranching and pesticide use is minimal.

Foothill residents use traditional methods of intercropping for pest control in gardens and rarely use insecticides indoors. Residents stated that their only exposure to pesticides is annual government spraying of DDT to combat malaria (this program is also carried out in the valley).

Using a variety of games and tests, researchers found that children who live in the valley had significantly less stamina and hand-eye coordination, poorer short-term memory and were less adept at drawing a person than were children in the foothills.

According to paediatrician Philip Landrigan of Mount Sinai Medical Center in New York, the study raises "very important concerns about the toxic effects of pesticides on children's nervous systems".

Bernard Weiss of the Department of Environmental Medicine at the University of Rochester School of Medicine and Dentistry stated that the study highlights the need for more research. "It doesn't seem a surprise that you would see an effect, knowing what we know about pesticides and the elevated vulnerability of the developing brain."

[From Pesticide Action Network North America Updates Service.]

From GLW issue 326