Non-Hodgkin's lymphoma and specific pesticide exposures inmen: Cross-Canada study of pesticides and health

Abstract

Our objective in the study was to investigate the putative associations of specific pesticides with non-Hodgkin's Lymphoma [NHL; International Classification of Diseases, version 9 (ICD-9) 200, 202]. We conducted a Canadian multicenter population-based incident, case (n = 517)-control (n = 1506) study among men in a diversity of occupations using an initial postal questionnaire followed by a telephone interview for those reporting pesticide exposure of 10 h/year or more, and a 15% random sample of the remainder. Adjusted odds ratios (ORs) were computed usingconditional logistic regression stratified by the matchingvariables of age and province of residence, and subsequentlyadjusted for statistically significant medical variables (historyof measles, mumps, cancer, allergy desensitization treatment, anda positive history of cancer in first-degree relatives). We found that among major chemical classes of herbicides, the risk of NHLwas statistically significantly increased by exposure tophenoxyherbicides [OR, 1.38; 95% confidence interval (CI),1.06-1.81] and to dicamba (OR, 1.88; 95% CI, 1.32-2.68). Exposureto carbamate (OR, 1.92; 95% CI, 1.22-3.04) and to organophosphorus insecticides (OR, 1.73; 95% CI, 1.27-2.36), amide fungicides, andthe fumigant carbon tetrachloride (OR, 2.42; 95% CI, 1.19-5.14)statistically significantly increased risk. Among individualcompounds, in multivariate analyses, the risk of NHL wasstatistically significantly increased by exposure to the herbicides2,4-dichlorophenoxyacetic acid (2,4-D; OR, 1.32; 95% CI,1.01-1.73), mecoprop (OR, 2.33; 95% CI, 1.58-3.44), and dicamba(OR, 1.68; 95% CI, 1.00-2.81); to the insecticides malathion (OR,1.83; 95% CI, 1.31-2.55), 1,1,1-trichloro-2,2-bis (4-chlorophenyl)ethane (DDT), carbaryl (OR, 2.11; 95% CI, 1.21-3.69), aldrin, andlindane; and to the fungicides captan and sulfur compounds. Inadditional multivariate models, which included exposure to other major chemical classes or individual pesticides, personal antecedent cancer, a history of cancer among first-degreerelatives, and exposure to mixtures containing dicamba (OR, 1.96;95% CI, 1.40-2.75) or to mecoprop (OR, 2.22; 95% CI, 1.49-3.29) andto aldrin (OR, 3.42; 95% CI, 1.18-9.95) were significantindependent predictors of an increased risk for NHL, whereas apersonal history of measles and of allergy desensitizationtreatments lowered the risk. We concluded that NHL was associated with specific pesticides after adjustment for other independent predictors.