Scientific Collaboration

Questionnaires & Study Data

The AHS cohort includes 89655 private pesticide applicators (mostly farmers), spouses of private applicators, and commercial pesticide applicators recruited in Iowa and North Carolina (Table 1). Participants were recruited from 1993 to 1997. Active follow-up efforts were conducted in 1999-2003 (Phase 2), 2005-2010 (Phase 3) and 2013-2015 (Phase 4). 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. Active follow-up in Phases 3 and 4 was limited to private applicators and spouses who had done at least one prior cohort activity besides completing the enrollment questionnaire (participants with more extensive exposure data, mostly in agricultural settings), and questionnaires updated information on farming practices, lifestyle, and health. Phase 3 was completed by 46% of enrolled private applicators and 61% of enrolled spouses. Phase 4 was completed by follow up 47% of the enrolled private applicators and 61% of enrolled spouses. All enrolled applicators (private and commercial) and spouses are passively followed for cancer and mortality through registry linkages.

Questionnaires Used in the AHS

Phase 1

Phase 2

Phase 3

Phase 4

Phase 1 (1993-1997) Questionnaires
Self-administered questionnaires obtained information on lifetime pesticide use, and demographic and medical history information.

Applicators were asked to complete two questionnaires—one that was filled out at a pesticide training/licensing location and one to be filled out at home and mailed back. While over 80% of licensed applicators enrolled in the study by completing the on-site form, only 44% returned the second questionnaire. Although the content was similar with respect to exposures, the second questionnaire obtained more detailed information one some pesticides, as well as some details of medical history and information on some covariates (e.g., BMI).

Private applicators were also given questionnaires to be filled out by their spouse, and 75% of married spouses completed them to enroll. Women who enrolled (both spouses and female applicators) were asked to complete a Female and Family Health questionnaire that obtained reproductive histories and information about children; 60% of female participants completed it.

Phase 2 (1999-2003) and Phase 3 (2005-2010) Follow-up Questionnaires
These phases involved computer-assisted telephone interviews to obtain information on current pesticide use, potential confounders, and medical history.

In Phase 2, exposure questions were similar for applicators and spouses, and the health questionnaires varied slightly by gender and age. A total of 67% of the total cohort completed questionnaires. In addition, participants who completed the follow-up survey were asked to complete a self-completed food frequency questionnaire (the NCI Diet History Questionnaire, with added items on cooking practices). About 39% of the cohort completed the diet questionnaire. Buccal cell samples (for DNA) were also collected from 39% of the total cohort.

In Phase 3, a common instrument was used for better integration of data for applicators and spouses. Eligibility for Phase 3 was limited to private applicators (mostly farmers) and spouses who had done at least one prior cohort activity besides completing the enrollment questionnaire. Approximately 60% of eligible applicators and 66% of spouses completed Phase 3 (about 49% of the total cohort).

Phase 4 (2013-2015) Follow-Up Questionnaire
This follow-up focuses on updating important covariates such as farming status, smoking and family history of disease and non-cancer chronic diseases, including diseases of aging.

Approximately 70,000 Phase 3 eligible private applicators and spouses were invited to participate regardless of whether they participated in the Phase 3 interview. For the first time, data were also collected from next-of-kin for participants who were incapacitated or deceased. The data collection was done primarily by self-administered mailed questionnaires and computer assisted telephone interviews. Approximately 61% of eligible participants or their proxies completed the Phase 4 survey (about 46% of the total cohort).

Table 1: AHS Cohort-wide Data Collection

  Phase 1
1993-7
Phase 2
1999-2003
Phase 3
2005-2010
Phase 4
2013-2015
  Enrolled Main Questionnaire Buccal cells* Diet History Questionnaire* Main Questionnaire Main Questionnaire
  N N (%) N (%) N (%) N (%) N (%)
Private Applicators 52394 33456 64 18599 36 17869 34 24170 46 24145 46
Spouses 32345 23796 74 14391 44 15385 48 19959 62 18186 56
Commercial Applicators 4916 2885 59 1837 38 1757 36 NA NA NA NA
Total 89655 60137 67 34827 39 35011 39 44129 49 42331 47