Introduction Farming occupations have been reported at risk of developing non Hodgkin lymphoma. Within the EPILYMPH multicentre European case-control study on the aetiology of lymphoma, we explored the association of risk of the major lymphoma subtypes with exposure to specific classes of pesticides, contact with livestock, and exposure to organic dust.

Methods In 1998–2003, 2348 cases of lymphoma (all subtypes), and 2462 controls participated in the EPILYMPH case-control study in several centres six European countries. A detailed occupational history was collected in cases and controls. Information on contact with breeding animals, exposure to five organic dusts, and to specific classes of pesticides was obtained through personal interviews. Local agronomists and occupational experts assessed likelihood, frequency and intensity of specific exposures based on the questionnaire information. Risk of the major lymphoma subtypes associated with contact with the most frequently represented species of livestock, organic dusts, and classes of pesticides was calculated with unconditional logistic regression analysis adjusting by age, gender, education, and centre.

Result Exposure to organophosphate insecticides was significantly associated with an increase in risk of chronic lymphocytic leukaemia; risk of DLBCL, was significantly lower amongst subjects who started occupational contact with any species of livestock before or at age 12 (OR=0.5, 95% CI: 0.2 to 0.9), but not at older ages. A significant heterogeneity in risk of B cell lymphoma by age at first contact was detected for contact with cattle, poultry and swine. We did not find an association with exposure to any of the organic dust exposures.

Discussion Agricultural exposures are numerous, and difficult to disentangle; also, the use of agrochemicals varies with time, type of crop, and location. Some exposures might be etiologically relevant, others might protect against lymphomas depending on age at first exposure, possibly in relation to the different type of immune response elicited.