Pesticide use and incident hyperthyroidism in farmers in the Agricultural Health Study

Occup Environ Med. 2019 May;76(5):332-335. doi: 10.1136/oemed-2018-105518. Epub 2019 Feb 25.


Background: Few studies have evaluated associations between pesticides and hyperthyroidism.

Objective: We evaluated associations between specific pesticides and incident hyperthyroidism in private pesticide applicators in the Agricultural Health Study.

Methods: We used Cox proportional hazards models to estimate HRs and 95% CIs for associations between pesticide use at enrolment and hyperthyroidism (n=271) in 35 150 applicators (mostly men), adjusting for potential confounders.

Results: Ever use of several pesticides (organophosphate insecticide malathion, fungicide maneb/mancozeb, herbicides dicamba, metolachlor, and atrazine in overall sample and chlorimuron ethyl among those ≤62 years) was associated with reduced hyperthyroidism risk, with HRs ranging from 0.50 (95% CI 0.30 to 0.83) for maneb/mancozeb to 0.77 (95% CI 0.59 to 1.00) for atrazine. Hyperthyroidism risk was lowest among those with higher intensity-weighted lifetime days of using carbofuran and chlorpyrifos (ptrend ≤0.05).

Conclusions: Observed associations between pesticides and decreased risk of hyperthyroidism warrant further investigation.

Keywords: Agricultural Health Study; hyperthyroidism; pesticides.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adult
  • Aged
  • Agriculture / instrumentation
  • Agriculture / methods
  • Humans
  • Hyperthyroidism / epidemiology
  • Hyperthyroidism / etiology*
  • Hyperthyroidism / metabolism
  • Male
  • Middle Aged
  • Occupational Exposure / adverse effects
  • Occupational Exposure / statistics & numerical data
  • Pesticides / adverse effects*
  • Pesticides / metabolism
  • Proportional Hazards Models
  • Risk Factors
  • Surveys and Questionnaires


  • Pesticides