Insecticide use is associated with increased risk of Hodgkin lymphoma: results from the North American Pooled Project (NAPP)

Abstract

INTRODUCTION: The prevalence of haematological cancers is elevated in agricultural populations. It has been hypothesized that exposure to pesticides contributes to this risk. The purpose of this study was to investigate pesticide exposures and risk of Hodgkin lymphoma (HL) using pooled case control data from the North American Pooled Project (NAPP). METHODS: This analysis included 507 HL cases and 1563 controls from three population-based studies conducted in Midwestern USA (1981-1986) and six provinces across Canada (1991-1994). Odds ratios and 95% confidence intervals were estimated for self-reported pesticide use (never/ever) and duration of use (years) using multiple logistic regression adjusted for age, sex, place of residence and respondent status. RESULTS: An increased risk of HL was observed for use of five or more insecticides (OR=1.88, 95% CI=1.08-3.27) relative to unexposed. Use of two or more carbamate insecticides (OR=2.45, 95% CI=1.03-5.84) was associated with more than double the risk of HL. An analysis of individual pesticides showed significant increasing trends of HL with duration of use of terbufos (>4.5 years, OR=3.34, 95% CI=1.27-8.78, p-trend=0.04) and lindane (>4.5 years, OR=2.08, 95% CI=0.95-4.56, p-trend=0.01). Ever use of carbaryl (OR=2.15, 95% CI=1.13-4.07) was associated with an increased risk relative to unexposed and a borderline significant increasing trend for HL was observed for duration of carbaryl use (p-trend=0.06). Several other insecticides were considered in the individual analysis but an exposure-response relationship with duration of use was not found. There was no increased risk of HL with the use of fungicides and herbicides reported. Conclusions: Insecticide use, specifically use of terbufos, lindane, and carbaryl may increase the risk of Hodgkin lymphoma.