Exposures to multiple pesticides and the risk of Hodgkin lymphoma in Canadian men

PurposeTo determine the risk of Hodgkin lymphoma (HL) associated with exposures to multiple pesticides grouped by various classes, including carcinogenic classifications.MethodsData collected in the Cross-Canada Study of Pesticides and Health, a population-based incident case–control study in six provinces conducted between 1991 and 1994, were analyzed using unconditional logistic regression. Cases (n = 316) were identified through provincial cancer registries and hospital records. Controls (n = 1,506) were frequency-matched to cases by age (±2 years) within each province and were identified through provincial health records, telephone listings, or voter lists. The Cochran–Armitage test was used to check for trends within pesticide classes.ResultsOverall, there was an increase in the risk of HL among all subjects who reported use of five or more insecticides (OR 1.88, 95 % CI 0.92–3.87) and among subjects younger than 40 who reported use of two acetylcholinesterase inhibitors (OR 3.16, 95 % CI 1.02–9.29). There was an elevated odds ratio associated with reported use of three or more probably carcinogenic pesticides (OR 2.47, 95 % CI 1.06–5.75), but no increase in risk for use of possibly carcinogenic pesticides. The risk of HL from reported use of fungicides or any pesticides was greater for cases diagnosed before age 40 than for cases diagnosed at or after age 40. When analyses excluded proxy respondents, OR estimates strengthened in some circumstances.ConclusionsThis study found associations between HL and fungicides, insecticides, specifically acetylcholinesterase inhibitors, and pesticides previously identified as probable human carcinogens. These associations should be further evaluated, specifically in relation to age at diagnosis.