About the Study

The Agricultural Health Study (AHS) is a prospective study of cancer and other health outcomes in a cohort of licensed pesticide applicators and their spouses from Iowa and North Carolina. The AHS began in 1993 with the goal of answering important questions about how agricultural, lifestyle and genetic factors affect the health of farming populations. The Agricultural Health Study is funded by the National Cancer Institute and the National Institute of Environmental Health Sciences in collaboration with the United States Environmental Protection Agency. The National Institute for Occupational Safety and Health has previously played an important role in the study.

More than 89,000 farmers and their spouses in Iowa and North Carolina have participated in the study. Their participation has provided, and continues to provide, the data that researchers need to help the current and future generations of farmers and their families live healthier lives.

Study Participants

Between 1993 and 1997, 52,394 licensed private pesticide applicators (mostly farmers) from Iowa and North Carolina enrolled, as did 32,345 of their spouses. The study also included 4,916 commercial pesticide applicators in Iowa in its first two phases. The average ages at enrollment were 47 years, 38 years, and 47 years for private applicators, commercial applicators and spouses.

	Private Applicators (%)	Commercial Applicators (%)	Spouses (%)
Gender
Male	97	96	1
Female	3	4	99
Race
White	97	99	98
Other	3	1	2
State
Iowa	61	100	67
North Carolina	39	0	33
Education
≤ High School	59	46	46
> High School	41	54	54
Smoking Status
Never Smoked	53	48	72
Past Smoker	31	26	17
Current Smoker	16	26	10
Pesticides
Mix or Apply Pesticides	99	92	56

Phases of the Study

The study began by collecting baseline information from participants when they enrolled (1993-1997). Follow-up telephone interviews were conducted in the second (1999-2003) and third phases (2005-2010) of the study. The Phase 2 interview was completed by 64% of private applicators, 59% of commercial applicators, and 74% of spouses. Participants provided updated information on farming practices, lifestyle, and health and were asked to complete a dietary questionnaire and provide a sample of cheek cells as a source of DNA. The Phase 3 interview also updated information on farming practices, lifestyle, and health. It was completed by 46% of enrolled private applicators and 62% of enrolled spouses. All participants who were eligible to participate at Phase 3 were asked to provide information updating health and farming status in Phase 4. Participants completed the questionnaires either by mail, telephone or through the Internet; for the first time, next-of-kin were able to provide health update information for those who could not complete the questionnaires themselves. Data collection began in 2013 and ended 2015; 61% of eligible cohort members (applicators and spouses) participated. Following the same eligibility as the Phase 4 follow-up sample, Phase 5 data collection began in 2019 and was completed in 2021; 50% of eligible participants (or next of kin) completed questionnaires updating farming status and health outcomes through a web survey, mail survey or phone interview.

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The cohort is also followed for mortality, cancer incidence, end stage renal disease incidence, and other incidence diseases through periodic linkage with state cancer registries*, the National Death Index (NDI)*, and the United States Renal Data System (USRDS)** and Medicare claims data**.

Study Findings

Findings from the AHS are shared in the scientific literature, through newsletters, and other publications.

Special Studies

In addition to the main study, the AHS encourages researchers to conduct add-on studies that focus on specific related health issues. These studies are designed to leverage the data collected from participants to ask important questions about the health of farm families. Examples of current and past studies can be found on the Add-on Studies page.