A just-released study further buttresses the increasing mass of data that show agricultural pesticides aren't the health hazard the activist groups would have the public believe.

The biomonitoring study, conducted by the University of Minnesota, is the most comprehensive assessment to date of pesticide exposure for farmers' spouses and children — those who would stand to be most affected. The finding: Those who live on farms where pesticides are applied generally do not have appreciable increased exposure to those chemicals.

The $2 million study panel included experts in exposure assessment and epidemiology from U.S. and Canadian universities and the U.S. Environmental Protection Agency.

Unlike other studies, which have relied chiefly on questionnaires, this one monitored 95 farm families in Minnesota and South Carolina. All provided urine samples 24 hours a day for four days after pesticides were applied on their farms, as well as a baseline 24-hour sample the day before the application.

Biomonitoring studies, which scientifically analyze blood, urine, or tissue, are considered the most accurate way to measure the amount of a substance entering the body, notes Jack Mandel, professor of epidemiology at Emory University, who was the chief investigator for the study.

“By determining the pesticide concentration in the urine of the farm families, the scientists were able to estimate the participants' internal exposure,” he says.

“While questionnaire-type studies may determine if someone was present when pesticides were used, the amount of pesticide actually absorbed is the only measure that is important in determining potential health effects. For the types of pesticide scenarios we observed, this study shows it can be erroneous to assume appreciable pesticide exposure based on participants' presence on the farm.”

The study found, Mandel says, that participating children and spouses typically had pesticide exposure levels comparable to levels measured in persons not living on farms.

The analytical techniques used in the study were capable of detecting pesticide traces in urine as low as 1 part per billion of the three pesticides included: glyphosate (the active ingredient in Roundup herbicide), 2,4-D, and chlorpyrifos (the active ingredient in Lorsban). The pesticide applications represented situations that allowed for the highest potential exposure; they had to be made within one mile of the farm house (40 percent of the houses were within 100 yards of treated fields).

Ninety-five percent of the children and spouses in the study had very low or no detectable increase in urine pesticide concentration after applications on their farms. Increases in excess of 10 parts per billion typically were linked to some event, such as children being in the immediate area at the time of application or of teenagers assisting in the pesticide application.

The study found the amount of exposure for farmers applying pesticides depends on the material and activities during handling and application. “In some cases, farmers can apply pesticides and have limited — or even no — detectable exposure,” says Bruce Alexander, assistant professor of environmental and occupational health at the University of Minnesota, and a study co-investigator. “The more appreciable exposures occurred in relation to an event that resulted in direct skin contact, such as spills or repairing equipment.”