Residential Proximity to Intensive Animal Agriculture and Risk of Lymphohematopoietic Cancers in the Agricultural Health Study

Epidemiology. 2020 Jul;31(4):478-489. doi: 10.1097/EDE.0000000000001186.


Background: Although occupational exposure to animals has been associated with lymphohematopoietic malignancies, to our knowledge no studies have evaluated adult cancer risks associated with living near intensive animal agriculture.

Methods: We linked participants in the prospective Agricultural Health Study to permitted animal feeding operations in Iowa. We created metrics reflecting the intensity of animal exposures within 2 and 5 km of participants' residences, enumerating both total and inverse distance-weighted animal units (AUs), standardized by animal size and manure production. We estimated risk of lymphohematopoietic malignancies and subtypes [hazard ratio (HR), 95% confidence interval (95% CI)], adjusting for demographic and farming-related factors, including occupational pesticide exposure. We stratified associations by animal type and animal-related work activities.

Results: We observed 519 cases (1993-2015) among 32,635 pesticide applicators and 211 cases among 19,743 spouses. Among applicators, no associations were evident within 2 km, but risk of any lymphohematopoietic cancer was elevated across quintiles of weighted AUs within 5 km. Risk of non-Hodgkin lymphoma (NHL) was elevated for the second (HR = 1.5; 95% CI, 1.1, 2.1), third (HR = 1.6; 95% CI, 1.1, 2.2), and fourth (HR = 1.7; 95% CI, 1.3, 2.4) highest quintiles of weighted AUs within 5 km (Ptrend = 0.52) and increased with dairy cattle AUs (Ptrend = 0.04). We found positive trends for leukemia and some NHL subtypes with increasing numbers of both beef and dairy cattle. Risks did not vary by animal-related work (Pinteraction = 0.61). Associations were similar using the total exposure metric and inconsistent among spouses.

Conclusion: Residential proximity to intensive animal agriculture was positively associated with risk of NHL and leukemia, even after consideration of occupational animal and pesticide exposures.

Publication types

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

MeSH terms

  • Adult
  • Agriculture*
  • Female
  • Humans
  • Iowa / epidemiology
  • Leukemia* / epidemiology
  • Lymphoma, Non-Hodgkin* / epidemiology
  • Male
  • Middle Aged
  • Prospective Studies
  • Residence Characteristics* / statistics & numerical data
  • Risk Assessment