Agricultural Health Study/Pesticide Exposure Study

2003 Research Abstracts - Table of Contents

National Exposure Research Laboratory - FY03 Research Abstract

Scientific Problem and Policy Issues

Despite low mortality and cancer incidence rates overall, farmers may experience excess risk of specific cancers, as observed in some retrospective epidemiological studies of agricultural workers. Farmers, their families, and other pesticide applicators may have contact with pesticides and a variety of other potentially hazardous substances (e.g., solvents, fuels, oils, exhaust, dust, agriculturally-specific microbes). Previous epidemiologic studies of farmers, other agricultural workers, and agricultural pesticide applicators have been limited by inadequate or retrospective exposure information.

Limitations of these previous studies are being addressed through the Agricultural Health Study (AHS), a prospective epidemiological study to quantify the cancer and non-cancer risks in the agricultural community and to study the relationships between agricultural pesticide exposures and disease. The AHS is a collaborative effort between the National Cancer Institute (NCI), the National Institute of Environmental Health Sciences (NIEHS), and the U.S. Environmental Protection Agency (U.S. EPA). The study uses questionnaires to provide information regarding pesticide use, work practices, and other agricultural exposures, as well as information on other activities that may affect either exposure or risk for a large (more than 89,000) cohort of licensed agricultural pesticide applicators and their spouses in Iowa and North Carolina.

Information derived from the study questionnaires is used to develop exposure-classification procedures for subsequent investigation of associations between pesticide exposure and specific diseases. Exposure measurement data are needed to assess these questionnaire-based exposure-classification procedures.

Research Approach

The U.S. EPA is conducting the Pesticide Exposure Study (PES) to assess the exposure classification procedures developed from the AHS questionnaire data and to better understand factors leading to pesticide exposures for agricultural pesticide applicators and their families. The PES is an exposure measurement field study for a small subset of agricultural pesticide applicators and participating family members in the AHS cohort.

On-farm field measurements during pesticide applications on a single day were conducted in North Carolina and Iowa over a three-year period during the 2000 to 2002 growing seasons. A total of 84 licensed agricultural pesticide applicators in the AHS cohort were enrolled into the study and completed 108 monitoring days. Potential dermal exposures were measured using patch and hand wipe samples. Personal air samples were collected to measure inhalation exposure. Urinary biomarker concentrations were measured in samples collected before and at several times after monitored pesticide applications. Pesticide handling activities were used and questionnaires were administered at two times following the observed chemical use. Urinary biomarker concentrations were also measured for 49 participating spouses and 12 children to determine whether applicator family members may be exposed to applied pesticides.

Results and Impacts

The AHS Pesticide Exposure Study provides real-world exposure data for improving exposure and risk assessments for agricultural pesticide applicators and their families. This research will contribute towards improving health risk assessments in the AHS epidemiological study. Information from the study will be used to assess and refine exposure classification procedures and to aid development of the exposure component of the AHS cohort-wide questionnaire to be administered beginning in 2005. The results may also provide information on how pesticides can be handled more safely to reduce the exposure risks to farm-workers and their families. Study findings may be used by pesticide safety educators to improve training programs for agricultural pesticide applicators and other pesticide handlers.

Research Collabortation and Research Products

The AHS is a collaborative study being conducted by the National Cancer Institute, the National Institute of Environmental Health Sciences, and the U.S. Environmental Protection Agency. The Office of Research and Development's National Exposure Research Laboratory (NERL) and the Office of Pesticide Programs are the primary EPA collaborators for the study.

The AHS Pesticide Exposure Study field monitoring and sample analysis was supported by task orders under contracts with Battelle Memorial Institute and RTI International. Battelle subcontractors include the University of Iowa and Southwest Research Institute. Support for participant selection and screening was made through an interagency agreement with the National Cancer Institute and their field stations in Iowa (University of Iowa) and North Carolina (Battelle Centers for Public Health Research and Evaluation) as well as their data coordinating center (Westat).

Preliminary results from the AHS Pesticide Exposure Study have been presented at recent scientific conferences and symposia. Examples of these presentations include the following:

Thomas, K., Sheldon, L., Gordon, S., Jones, M., Reynolds, S., Raymer, J., Akland, G., Dosemeci, M. and Alavanja, A. " Interim Results from the Agricultural Health Study/pesticide Exposure Study." International Society for Exposure Analysis12th Annual Conference, Vancouver, BC, Canada, August 11 - 15, 2002.

Thomas, K.W., Sheldon, L.S., Sandler, D.P., Dosemeci,M., and Alavanja, M.C.R. "Agricultural Health Study/Pesticide Exposure Study: Study Design and Preliminary Biomarker Results." International Symposium on Agricultural Exposures and Cancer, Oxford, U.K., November 17 - 22, 2002.

The U.S. EPA/NERL is supporting exposure and health-outcome analyses and publications for the larger AHS epidemiological study. The following is an example of a recent publication led by NCI researchers:

Alavanja, M., Samanic, C., Dosemeci, M., Lubin, J., Tarone, R., Lynch, C., Knott, C., Thomas, K., Hoppin, J., Barker, J., Coble, J., Sandler, D., and Blair, A. "Use of Agricultural Pesticides and Prostate Cancer Risk in the Agricultural Health Study Cohort." J. of American Epidemiology 157:800-814, 2003.

Future Research

Data analysis and reporting will continue on the AHS Pesticide Exposure Study through 2004. No additional exposure measurement studies are planned by the U.S. EPA/NERL in support of the AHS. NERL scientists will continue to collaborate with researchers from other agencies in support of exposure assessment for the AHS cohort.

Contacts for Additional Information

Questions and inquiries can be directed to the principal investigator:
Mr. Kent Thomas
U.S. EPA, Office of Research and Development
National Exposure Research Laboratory
MD E205-04
Research Triangle Park, NC, 27711
Phone: 919-541-7939
E-mail: thomas.kent@epa.gov

Federal funding for this research was administered under EPA Contracts 68-D99-011 and 68-D99-012, and through Interagency Agreement DW-75-93912801-0.

2003 Research Abstracts - Table of Contents

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