New Studies About Children

Scientific research continues to prove that early environmental exposures can have major impacts on developing babies and young children. Here is an update on some of the worst pollutants, and what you can do to protect your child's health.

Mercury

This nervous-system toxicant, passed from mother to child in utero, produced permanent damage to specific brain functions such as memory and language, according to a study conducted in the Faeroe Islands that appeared in the February 2004 Journal of Pediatrics. "If mercury toxicity at some point interrupts development, then you don't get a second chance to fix it," says lead investigator Philippe Grandjean, M.D., adjunct professor at the Harvard School of Public Health.

Another study by the same authors found that 7-year-olds with higher mercury levels had elevated blood pressure. "We think that mercury contributes to heart disease by affecting the nervous-system control of the heart," Grandjean says.

Pesticides

An EPA ban on the residual use of two common insecticides—chlorpyrifos (Dursban) and diazinon—has resulted in rapid and dramatic improvements in infant birth weight, according to researchers at Columbia University who tested levels of these organophosphate pesticides in the blood of pregnant women and their infants before and after the ban. The babies of women who had been exposed to the greatest amount of the pesticides were on average 6.6 ounces lighter than those of women with lower exposures, researchers reported in the May 2004 Environmental Health Perspectives (EHP). In a related study published in the March EHP, infants delivered at New York's Mount Sinai Hospital had a small but significant reduction in head circumference when their mothers had chlorpyrifos in their blood and urine.

Because low birth weight has been linked to developmental problems, it's very good news that babies born after the phaseout of chlorpyrifos and diazinon in 2001-3 had "substantially lower cord blood levels of the pesticides," says Frederica P. Perera, Ph.D., director of Columbia University's Center for Children's Environmental Health. "It is a very nice illustration of the direct benefits of an intervention at the policy level," Perera says.

A child's exposure to pesticides and herbicides in the first year of life was also associated with the risk of developing asthma, according to University of Southern California researchers in the May 2003 EHP.

Air Pollution

The air we breathe often contains more than one pollutant, and researchers are starting to respond. "Most studies have looked at one exposure at a time, but in the real world there is combined exposure to multiple pollutants," says Perera. Reporting in the April 2003 EHP, Columbia University investigators studying pregnant women's exposures to polycyclic aromatic hydrocarbons (PAHs) and secondhand smoke found that the babies had lower birth weights and smaller head size. "We found that newborns who had both exposures during their time in utero were smaller at birth. The effect of the combined exposures was greater than the sum of the two," Perera says.

Two recent studies show possible links between air quality and childhood leukemia, but the cause of this still needs to be studied. Children in northern Italy who lived near roads with high traffic emissions had significantly more cases of leukemia, the February 10, 2004, International Journal of Cancer reported. A California study published in the April 2003 EHP found an association between a rise in childhood leukemia and high levels of outside air pollutants.

Connections between outdoor air quality and asthma are becoming well established. "There is little doubt that children with asthma are especially vulnerable to high levels of air pollution," say Yale researchers in the October 8, 2003, Journal of the American Medical Association. But by looking at daily respiratory symptoms among children in southern New England during the spring and summer of 2001, they found that children using daily asthma medication were also susceptible to ozone at levels below EPA standards.

Asthma symptoms also worsened for children living within five miles of the World Trade Center in the year after the September 11 attacks, investigators reported in the March 2004 Journal of Allergy and Clinical Immunology. They looked at 205 asthma patients at a Chinatown clinic, and will explore whether the WTC attacks will have continuing consequences for asthmatic children.

Lori Bongiorno is a freelance writer living in Brooklyn, New York.