Incidence of Solid Tumors Among Pesticide Applicators Exposed to the Organophosphate Insecticide Diazinon in the Agricultural Health Study: An Updated Analysis

Abstract

Objective:

Diazinon, a common organophosphate insecticide with genotoxic properties, was previously associated with lung cancer in the Agricultural Health Study (AHS) cohort, but few other epidemiologic studies have examined diazinon-associated cancer risk. We used updated diazinon exposure and cancer incidence information to evaluate solid tumor risk in the AHS.

Methods:

Male pesticide applicators in Iowa (IA) and North Carolina (NC) reported lifetime diazinon use at enrollment (1993–1997) and follow-up (1998–2005); cancer incidence was assessed through 2010(NC)/2011(IA). Among applicators with usage information sufficient to evaluate exposure-response patterns, we used Poisson regression to estimate adjusted rate ratios (RRs) and 95% confidence intervals (95% CI) for cancer sites with ≥10 exposed cases for both lifetime (LT) exposure days and intensity-weighted (IW) lifetime exposure days (accounting for factors impacting exposure).

Results:

We observed elevated lung cancer risks (N=283) among applicators with the greatest number of LT (RR=1.60; 95%CI:1.11,2.31; P _trend=0.02) and IW days of diazinon use (RR=1.41; 95%CI:0.98,2.04; P _trend=0.08). Kidney cancer (N=94) risks were non-significantly elevated (RR _{LT days}=1.77; 95%CI:0.90,3.51; P _trend=0.09; RR _{IW days}=1.37; 95%CI:0.64,2.92; P _trend=0.50), as were risks for aggressive prostate cancer (N=656) .

Conclusions:

Our updated evaluation of diazinon provides additional evidence of an association with lung cancer risk. Newly identified links to kidney cancer and associations with aggressive prostate cancer require further evaluation.