Chlorpyrifos use and human cancer risk: An Agricultural Health Study update

Authors

• S Cotsmire
• A Medina Farias
• K Derr
• P Derr
• YC Chen
• M Ferrer
• E Lee

Abstract

Chlorpyrifos is an organophosphate insecticide recently banned in the US for use on food and animal feed crops due to associations with neurodevelopmental effects in children. Its relationship with cancer risk is unclear. Here we incorporate more than 13 additional years of follow-up, updated exposure information, and >6700 additional cancer cases in the AHS to more comprehensively evaluate cancer risk associated with chlorpyrifos.

We included 52,848 AHS applicators with follow-up from enrollment (1993-1997) through 2014 (North Carolina) or 2017 (Iowa). We determined cumulative intensity-weighted lifetime days of chlorpyrifos use using self-reported data at enrollment and follow-up (1999-2005). Poisson regression was used to calculate rate ratios (RR) and 95% confidence intervals (CI) for combined cancers and specific sites/subsites, adjusting for potential confounders.

A total of 22,080 AHS applicators (41.8%) reported applying chlorpyrifos. We observed an increased risk of brain cancer (RRQ4 vs. no chlorpyrifos use=1.74, CI: 1.00-3.02; p-trend=0.38). Our findings also suggested an elevated risk of leukemia (RR Q4=1.64, CI: 0.96-2.78; p-trend=0.13), which appeared to be driven by acute myeloid leukemia (AML) (RR Q4=2.71, CI: 1.46-5.05; p-trend=0.005). We did not observe an association for non-Hodgkin lymphoma overall but found a positive association for follicular lymphoma (RR Q4=1.95, CI: 1.07-3.56; p-trend=0.38).

Our results provide evidence of positive associations with brain cancer, AML, and follicular lymphoma. These findings are important in understanding cancer risk among individuals historically exposed to chlorpyrifos in the US and in regions of the world where chlorpyrifos remains widely used.

Scientific Focus Area: Epidemiology

This page was last updated on Monday, September 25, 2023