A prospective study of cancer risk associated with use of organochlorine insecticides among Agricultural Health Study farm spouses

Authors

• LM Louis
• CC Lerro
• MC Friesen
• G Andreotti
• S Koutros
• D Sandler
• A Blair
• MG Robson
• LE Beane Freeman

Abstract

Organochlorine (OC) insecticides were once the most commonly used pesticides in the US, comprising 72% of pesticides used in agricultural and residential settings.Although banned in western countries, they are widely persistent in the environment and are still used in developing countries.Previous epidemiologic studies have linked OC use to cancer risk among male agricultural workers, but have lacked statistical power to examine risks in women.We evaluated the personal use of specific OCs and cancer incidence among the female spouses of pesticide applicators in the prospective Agricultural Health Study cohort. At study enrollment (1993-1997) women provided information on their lifetime use of specific pesticides, including 7 OCs (aldrin, chlordane, dieldrin, DDT, heptachlor, lindane, and toxaphene), as well as farming and pesticide application practices, demographic information, health histories, and other potential confounders.Incident cancer cases were obtained from the North Carolina and Iowa state registries through 2011 and 2012, respectively.We used Poisson regression to calculate relative risks (RRs) and 95% confidence intervals (CIs) for 15 cancer types and the use of any OC and individual OCs.We included 28,909 female spouses in our analysis, of whom 2,191 reported use of at least one OC, and 287 were diagnosed with incident cancer during the study period.Chlordane was associated with an elevated risk of multiple myeloma (RR=2.71,95%CI:1.12-6.55).Lindane was associated with an increased risk of glioma (RR=4.45,95%CI:1.36-14.55) and pancreatic cancer (RR=3.7,95%CI:1.15-12.0).Dieldrin was associated with an increased risk for endocrine receptor-negative breast cancer (RR=3.55,95%CI:1.12-11.18).We report significantly increased risks of multiple myeloma, glioma, pancreatic cancer, and endocrine receptor-negative breast cancer, with personal use of specific OCs among women.This study represents the first prospective evaluation of individual OC use and risk of multiple cancer sites in a population of women, and the first examination of associations between OC use and risk of glioma and pancreatic cancer.This unique cohort allowed us to examine female-specific cancers, which are understudied with respect to pesticide exposure.Our results suggest that relatively modest OC exposure is associated with elevated risks of multiple cancers.Future epidemiologic research should attempt to replicate these findings with a greater number of exposed cancer cases.

Scientific Focus Area: Epidemiology

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