Agricultural workers who perform thinningremoving young buds from orchard trees to increase the size of the remaining fruitface a greater likelihood of pesticide exposure than other farm workers, according to new findings from Fred Hutchinson Cancer Research Center, in Seattle.


The study findings appear in the February issue of a publication called Environmental Health Perspectives.


The researchers found that workers who thinned orchards were more likely to have detectable levels of pesticides in their house and vehicle dust than agricultural workers who didnt perform such thinning. The study also found that children of thinners were more likely to have detectable levels of pesticide metabolites in their urine than children of non-thinners. These findings support the theory that agricultural workers may track home pesticides on their clothing and shoes.


Most previous pesticide-exposure research on farm workers has focused on pesticide handlers, such as pesticide mixers, loaders, and sprayers, but this study suggests that more research is needed regarding exposure patterns among other types of farm workers as well, says Gloria Coronado, lead author and staff scientist in Fred Hutchinsons cancer prevention program.


The study revealed that about 20 percent more thinners than non-thinners had pesticide residue in their home and vehicle dust. The researchers also found that a urinary pesticide metabolite called DMTP was present in children of thinners 10 percent more than in children of non-thinners.


Orchard thinners are thought to be at higher risk for pesticide exposure because thinning usually takes place in the spring, when crops are being sprayed to prevent pests. Such workers also have substantial physical contact with fruits, leaves, twigs, and branches that may contain pesticide residues. In addition, unlike pesticide handlers, thinners arent required by the U.S. Environmental Protection Agency to use protective equipment or undergo safety training.


Unfortunately, we do not know the extent to which ongoing, low-level exposure to pesticides leads to adverse health consequences, says project leader Beti Thompson, a member of Fred Hutchinsons public health sciences division. However, knowing exposure pathways helps us plan interventions to reduce exposure risk, which is particularly important for young children.


Children are uniquely susceptible to home-pesticide exposure because they spend greater amounts of time on carpets and floors, and often wear minimal clothing during the summer spray season, increasing their likelihood of skin exposure. They also engage in hand-to-mouth behavior, increasing their likelihood of ingesting pesticides.


Children are not small adults, Thompson says. With less-developed immune systems, children may be less able to clear pesticides from their bodies.


The project, conducted in Eastern Washingtons Lower Yakima Valley, involved nearly 600 farm workers in 24 communities and labor camps who were interviewed about their pesticide-exposure patterns. Dust samples from households and vehicles of 213 randomly selected study participants were checked for the presence of six pesticides. Urine samples from those workers and family members were analyzed.


Thinning was the second-most common farm task reported among those surveyed, accounting for about 64 percent of the workers.


The five-year study was funded by the EPA and the National Institute of Environmental Health Sciences. Its part of the University of Washington-based Center for Child Environmental Health Risks Research, led by Elaine Faustman, a professor of environmental and occupational health sciences.


It is the first study of its kind to search for evidence of a possible take-home pathway of pesticides, whereby children are exposed to pesticide residues from their agricultural worker parents.


Previous reports from this project showed a significant association between urinary pesticide-metabolite levels in farm workers and children living in the same home.


A local community-advisory board has worked with the researchers. That involvement has ranged from identifying questions for surveys and helping to develop strategies for reducing pesticide exposure to communicating information about the project to agricultural workers throughout Eastern Washington.


The Fred Hutchinson Cancer Research Center, located in Seattle, is an independent, nonprofit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. The institution receives more funding from the National Institutes of Health than any other independent U.S. research center.