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Ag Health Study Update

September 26, 2007

It is estimated that 1.8 billion people worldwide use pesticides in their occupation. Research also indicates that everyone in the United States is exposed at least indirectly to pesticides. Of the pesticides and their components, only arsenic and dioxin are listed as known human carcinogens. The National Agricultural Health Study was initiated in 1993 to determine the incidence of cancer and other health problems associated with pesticides, other agrichemicals, and agricultural practices in the United States.

The National Agricultural Health Study is a federally funded, long-term study focusing primarily on cancer rates among farmers. However, a large portion of the participants from Iowa are professional agricultural pesticide applicators; and many of the results are applicable to landscape applicators. The 89,658 participants in the study are all agricultural workers, their spouses, and their children—from North Carolina and Iowa.

Many studies of the effects of agricultural chemicals and other practices rely primarily on the long-term memory of the participant or surviving family members to determine exposures. As a result, these backward-looking studies have some inherent problems in the data that they collect, causing some concerns about the conclusions that are drawn from that data. The Agricultural Health Study relies on memory for the practices of participants prior to 1993, but since then has been tracking agricultural practices and health effects as they occur. Included in some of the studies has been the collection of genetic, urine, and blood samples, as well as on-site observations of the agricultural activities of the participants. The study is expected to continue at least through 2013. All of the participants are interviewed every 5 years. Their third interviews have just been completed and provide some interesting information.

It was determined that 14% of pesticide applicators have had an acute exposure to pesticides in their lifetime. Concerning chronic exposure to pesticides, it was determined that there is a 66 to 75% reduction in pesticide exposure to applicators who wear chemical resistant gloves. There is a 33 to 51% reduction in pesticide exposure when using a broadcast boom sprayer, compared to using a hand sprayer. This survey exposure information was verified through measurements of pesticides in urine samples, exposure patches on the skin, and air measurement during application.

Personal practices were also surveyed. After using pesticides, 37% take a shower or bath, whereas 63% do not. Of those surveyed, 5% wear the same clothing that they wore on the previous day when they applied pesticides without it being washed; 95% wear clean clothing the next day.

Other studies have shown that a major source of contamination indoors is due to tracking in pesticide residues on shoes. In this study, 78% take off their work boots before entering their home; 21% do not. Clothes worn during pesticide application are washed separately by 74%; 26% do not wash pesticide contaminated clothes as a separate laundry load. Agricultural or commercial pesticides were stored in the home by 13% of the applicators; 87% do not.

Studies in the past have shown that exposure to pesticides during application is greatly reduced if the applicator is in a tractor cab or is similarly protected. In this study, 64% of the applicators were in an enclosed cab during pesticide application; 36% did not use an enclosed cab. Almost all, 93%, of the applicators repaired their own pesticide application equipment; 7% did not repair their own equipment.