Introduction Existing epidemiological studies have suggested a positive association between agricultural exposure to carbamates and risks of non-Hodgkin’s lymphomas (NHL); however, the association remains inconclusive with most studies lacking statistical power to examine specific carbamates and subtypes of NHL.

Objectives We estimated the associations between carbamate insecticides and the risks of NHL overall and three major histological subtypes, multiple myeloma (MM), chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL-SLL), and diffuse large B-cell lymphoma (DLBCL) in the French prospective Agriculture and Cancer cohort (AGRICAN).

Methods At enrolment (2005–2007), participants completed a questionnaire on lifetime occupational history of agricultural practices, lifestyle habits, and medical history and were followed up until 2015 through linkage to the cancer registries. Information on pesticide use for different agricultural activities (crops, animals, barns, seeds) was crossed with the French crop-exposure matrix, PESTIMAT, enabling us to assess exposure to 19 specific carbamates (e.g., carbaryl, carbofuran) by type of activity. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs) for NHL overall and its subtypes in relation to activity-specific exposure to carbamates (ever/never, duration) by fitting multivariate Cox proportional hazards models with age as the time scale. Non-users of pesticides were chosen as the reference group.

Results During the follow-up (median=8.9 years), 533 incident cases of NHL (MM=125, CLL-SLL=134, DLBCL=72) were diagnosed. Ever use of carbaryl on animals (HR=1.84, 95% CI=1.05–3.24) or barns (HR=1.86, 95% CI=1.06–3.27) were significantly associated with an increased risk of MM, but not for crops (HR=1.24, 95% CI=0.70–2.19). No significant trend by exposure duration were observed. None of the other carbamate insecticides were significantly associated with the risk of MM, CLL, DLBCL or NHL overall.

Conclusion Use of carbaryl on livestock production may lead to an increased risk of MM. Studies on activity-specific exposure pathways and levels are warranted to better understand the observed association.