Occupational exposure to pesticides and multiple myeloma in the AGRICAN cohort

Abstract

Purpose: Epidemiological studies have found an increased risk of multiple myeloma (MM) in farmers. Few studies have investigated the detailed circumstances of occupational pesticide exposure which could explain these increased risks (pesticide use on crops, seeds or on animals, contact with treated crops) and the role of other exposures. In the Agriculture and Cancer cohort (AGRICAN), we assessed the associations between MM and crop- or animal-related activities, with specific attention to pesticide exposure via use on animals and crops or contact with treated crops and to disinfectant exposure.

Methods: Analyses concerned 155,192 participants, including 269 incident MM identified by cancer registries from enrolment (2005-2007) to 2013. Cox models using attained age as time scale were run to calculate hazard ratios (HR) and 95% confidence intervals (CI).

Results: MM risk was increased in farmers (i) who started using pesticides on crops in the 1960s, especially among those applying pesticides on corn (≥ 20 years: HR 1.73, 95% CI 1.08, 2.78, p for trend < 0.01) and (ii) using insecticides on animals (HR 1.48, 95% CI 1.11, 1.98), especially among horse farmers (≥ 10 years: HR 2.77, 95% CI 1.22-6.27, p for trend = 0.01). We also observed significant elevated risks with disinfectant use in animal barns.

Conclusions: Findings support the role of pesticide use on crops and animals in the occurrence of MM risk in farmers.

Keywords: Cohort; Corn; Farming; Insecticides; Multiple myeloma; Occupational exposure; Pesticides.