To assess the magnitude of the problem, Dr. Alarcon, with the National Institute for Occupational Safety and Health in Cincinnati, Ohio, and his associates analyzed data from three national surveillance systems for the period from 1998 to 2002.

They documented 2593 cases of acute pesticide-related illnesses at schools, with incidence rates of 7.4 cases per million children and 27.3 cases per million employees.

No fatalities were reported, but there were three cases severe illness considered to be life threatening and involving hospitalization, and 275 cases (11 percent) of moderate severity requiring treatment.

Illnesses were caused primarily by insecticides (35 percent), disinfectants (32 percent), repellents (13 percent) or herbicides (11 percent). Exposure was associated with both pesticide applications on school grounds and pesticide drift from applications to neighboring farmland.

The incidence of cases increased over time among children but not among adults. The authors suggest that this trend may be related to increased numbers of schools situated next to farmland.

Alarcon's team notes that their findings probably represent low estimates of the problem because cases may not be reported to surveillance systems or recognized as being related to pesticides.

"To prevent pesticide-related illnesses at schools," they recommend "implementation of integrated pest management programs in schools, practices to reduce pesticide drift, and adoption of pesticide spray buffer zones around schools."