A new study in the Journal of the American Medical Association reports that pesticide exposure at school caused some children and school employees to become acutely ill. Researchers found that such sickness in kids increased significantly between 1998 and 2002 by about two cases per million kids to a yearly incidence of almost eight cases per million kids. The study also reports that similar sickness in school employees declined during this period, although there were still about 27 cases per million full-time adult employees per year.

"It's encouraging that the overall rate was low," says Geoffrey Calvert, medical officer at the National Institute for Occupational Safety and Health and one of the lead researchers. However, Calvert says these figures might be underestimates of overall illness since people may not seek medical attention for mild symptoms and medical providers may not inquire about possible pesticide exposure.

The pesticide exposure included herbicides, insecticides, fungicides, and disinfectants inside and outside the school building. Pesticides that had drifted from farmland caused about one third of the illness in the study. "Especially within the first one-to-two-day period after pesticides are sprayed, the air can carry pesticides to nearby and somewhat remote places," says Leo Trasande, assistant director of the Center for Children's Health and the Environment at the Mount Sinai School of Medicine.

Researchers analyzed cases reported to three federal and state pesticide surveillance systems and looked at subgroups such as age, sex, pesticide used, symptoms, acuity of sickness, and location of pesticide application. Experts assessed whether the cases represented true exposures by comparing the toxicology of the pesticide applied with symptoms. Nearly 90 percent of the cases in the study were considered mild, with symptoms such as skin and eye irritation, and didn't need medical treatment. No deaths were reported.

The authors recommended that schools minimize pesticide exposure by using nontoxic pest management as often as possible and by providing careful timing and notification of chemical application if such use is necessary.

The pesticide industry is concerned the study may cause parents and schools unwarranted worry. "Our products have significant benefits to society," says Jay Vroom, president and CEO of CropLife America, which represents developers and manufacturers of agricultural chemicals. Vroom emphasizes that pesticides are essential to the production of an "affordable and abundant food supply" in addition to facilitating other public health measures such as disinfection and prevention of mosquito-borne diseases.

While the study examines only acute sickness, some researchers are also concerned about chronic medical and developmental problems that may result following pesticide exposure. Kids' exposure to pesticides is of particular concern because the nervous system develops rapidly during early childhood. "Children eat more, drink more, and breathe more air per pound of body weight than adults," says Trasande. "They run and play closer to the ground where pesticides settle."

A few years ago, the Centers for Disease Control and Prevention began tracking levels of environmental chemicals, including pesticides, in people's bodies. Released last week, the Third National Report on Human Exposure to Environmental Chemicals documented levels of 148 toxic substances, including pesticides, in a sample of 2,400 people from around the country. The study did not address any links between chemical levels and illness or developmental problems.

For more information: The National Institutes of Health has a Web page on pesticides.

The Environmental Protection Agency has a website devoted to integrated pest management at schools.