The Agricultural Health Study (AHS) is a prospective study of licensed pesticide applicators from North Carolina and Iowa recruited in 1993-1997 at the time of license renewal. The cohort includes 52,395 licensed private pesticide applicators, from both states and 4,916 commercial applicators from Iowa. More than 75% or 32,347 spouses of married private applicators were also enrolled in the cohort. The study is a collaboration of the National Institute of Environmental Health Sciences (NIEHS), the National Cancer Institute (NCI), and the Environmental Protection Agency (EPA). The National Institute for Occupational Safety and Health (NIOSH) previously participated in study leadership.
Applicators completed a short enrollment questionnaire on farming, personal pesticide use and lifestyle factors. Applicators who completed the questionnaire received a set of take-home questionnaires, including two to be completed by the female spouse of farmers and a third to be completed by the applicator that obtained additional details on pesticide exposure and health status. Enrollment questionnaires included demographic factors, self-reported doctors' diagnosed diseases, neurologic and respiratory symptoms, history of smoking and alcohol use, and a lifetime history of pesticide use, including 50 specific compounds.
Details of cohort characteristics and active follow-up, including full questionnaires and response rates, are available on the study website. During 1999-2003 and 2005-2010 follow-up questionnaires updated information on specific pesticide use, and changes in health status. Participants who completed the interview were asked to provide a buccal-cell sample—for DNA and future analyses of gene-environment interactions—and complete a food frequency questionnaire. Subsequent rounds of follow-up surveys to identify new disease diagnoses and update key covariates were completed in 2013-2015 and 2019-2021. Researchers regularly link the cohort to state cancer registries and vital records to monitor cancer incidence and mortality. Health outcomes are also identified through linkage to the U.S. Renal Data system to identify cases of kidney failure, and CMS Medicare administrative claims data.
As an occupational group, farmers are unique in that they often live where they work, and their family members often participate in farming activities and may have inadvertent exposure to potential farm hazards. The AHS is one of the largest and longest studies of farmers and their families in the world, providing Epidemiology Branch investigators and collaborators with an invaluable source of information for research on health in agricultural communities. Topics of specific interest to NIEHS investigators, trainees and collaborators include neurobehavioral function and neurodegenerative diseases, respiratory health, reproductive health, autoimmune disease, diabetes, infections, kidney disease, and thyroid disease. The NCI leads collaborative research on cancer in the cohort. Individuals interested in collaborating with the AHS should contact Christine Parks, Ph.D. to discuss opportunities.
Recent and ongoing add-on studies include:
- Agricultural Lung Health Study
- AHS Study of Memory and Aging
- Biomarkers of Exposure and Effects in Agriculture
- Pesticides and Sense of Smell
Dale Sandler, Ph.D.
Chief, Epidemiology Branch and Senior Investigator