Phorate Exposure and Incidence of Cancer in the Agricultural Health Study

Abstract

BackgroundWe recently reported a link between use of the organophosphate pesticide phorate and risk of prostate cancer among applicators with a family history of prostate cancer in the Agricultural Health Study (AHS).ObjectiveThis finding, together with findings of associations between other organophosphate pesticides and cancer more broadly, prompted us to examine phorate exposure and overall cancer incidence in the AHS. Adding 3 years of follow-up and using more detailed exposure information allowed us to see whether the prostate cancer finding held.MethodsThe AHS is a prospective study of licensed restricted-use pesticide applicators from North Carolina and Iowa. To our knowledge, this is the largest examination of workers occupationally exposed to phorate. Pesticide exposure and other information was collected using two self-administered questionnaires completed from 1993 to 1997. Poisson regression was used to calculate rate ratios (RR) and 95% confidence intervals (CI), adjusting for potential confounders.ResultsPhorate use was not related to the incidence of all cancers combined or to any individual cancer, although we had insufficient numbers to study non-Hodgkin lymphoma or leukemia, which have been linked to organophosphates in other studies. Although prostate cancer risk was not significantly related to phorate use overall or among those without a family history, the risk tended to increase among applicators with a family history of prostate cancer. The interaction RR was 1.53 (95% CI, 0.99–2.37).ConclusionThe observed statistical interaction suggests a gene–environment interaction between family history and phorate exposure in the incidence of prostate cancer, but other explanations are also possible.

Circulating estradiol in men is inversely related to urinary metabolites of nonpersistent insecticides

“…There have been consistent reports of increased risk of prostate cancer among farmers (39,40), and among male pesticide applicators an increased risk of cancers potentially associated with endocrine disruption (testicular, prostate) has been reported (41)(42)(43). In the US Agricultural Health Study, where data on the application of specific pesticides was collected by questionnaire, there was evidence for an increase in the risk for prostate cancer through an interaction between exposure to chlorpyrifos or other organophosphate insecticides (fonofos, phorate) and having a family history of prostate cancer (44)(45)(46). Exogenous estrogen/estradiol is used in the treatment of certain prostate cancers (47) and a decreased risk of prostate cancer has been reported among men with higher circulating estradiol levels, suggesting a potential protective role (48)(49)(50)(51).…”

A review of pesticide exposure and cancer incidence in the agricultural health study cohort

“…examined were associated with a significant increase in overall cancer incidence (alachlor, atrazine, captan, carbaryl, carbofuran, chlorothalonil, cyanazine, dicamba, dichlorvos, fonofos, glyphosate, heptachlor, imazethapyr, malathion, metolachlor, pendimethalin, permethrin, phorate, and tri-fluralin) (Bonner et al , 2007De Roos et al 2005a;Greenburg et al 2008;Hou et al 2006;Kang et al 2008;Koutros et al 2008Koutros et al , 2009Lee et al 2004b;Lynch et al 2006;Mahajan et al 2006aMahajan et al , 2006bMahajan et al , 2007Mozzachio et al 2008;Rusiecki et al 2004Rusiecki et al , 2006Rusiecki et al , 2009Samanic et al 2006). Lung cancer.…”

“…However, the most recent study of pendimethalin exposure did not observe a significant exposure-response trend for lung cancer . Fourteen other pesticides were examined but were not associated with increased lung cancer incidence in pesticide applicators (atrazine, captan, carbaryl, chlorothalonil, cyanazine, dichlorvos, EPTC, fonofos, glyphosate, imazethapyr, malathion, permethrin, phorate, and trifluralin) (Alavanja et al 2004;Bonner et al 2007;De Roos et al 2005a;Kang et al 2008;Greenburg et al 2008;Mahajan et al 2006aMahajan et al , 2006bMahajan et al , 2007Mozzachio et al 2008;Lynch et al 2006;Rusiecki et al 2004Rusiecki et al , 2009Samanic et al 2006;van Bemmel et al 2008).…”

Endocrine disruptors and prostate cancer risk

“…Furthermore, 6 pesticides out of 45 common agricultural pesticides showed correlation with exposure and increased prostate cancer in men with a familial history, suggesting gene-environment interactions. These six agents were chlorpyrifos, fonofos, coumaphos, phorate, permethrin, and butylate (Alavanja et al 2003, Mahajan et al 2006. The first four of these compounds are thiophosphates and share a common chemical structure.…”