Objective Pesticide exposure has been associated with certain cancer outcomes among farmers and applicators spraying pesticides. In the AGRICOH consortium of agricultural populations, we have evaluated cancer risk and pesticide exposure in three large cohort studies: The French Agriculture and Cancer Study - AGRICAN (FR), Agricultural Health Study (US), and Cancer in the Norwegian Agricultural Population (NO) studies.

Methods Estimates of lymphohaematologic cancers from the three cohorts (FR, US and NO) were analysed individually and then meta-analysed to yield more robust estimates of associations. Ever-never exposure to 33 chemical active ingredients from 14 chemical groups of agrochemicals was assessed using questionnaire information (US) and Crop Exposure Matrices (FR and NO), in approximately 316 000 persons representing 3.6 million person-years of follow up. ‘

Results Results for Non-Hodgkin lymphomas (NHL) were recently published, based on 2430 cases. Most meta-HRs suggested no association. Moderately elevated meta-HRs were seen for NHL and ever use of terbufos (meta-HR=1.18, 95% CI: 1.00–1.39), based on 300 exposed cases; chronic lymphocytic leukaemia/small lymphocytic lymphoma and deltamethrin (1.48, 1.06–2.07), 148 cases; and diffuse large B-cell lymphoma and glyphosate (1.36, 1.00–1.85), 221 cases; although the latter was driven exclusively by results in the Norwegian cohort. Inverse associations of NHL with the broader groups of organochlorine insecticides (0.86, 0.74–0.99) and phenoxy herbicides (0.81, 0.67–0.98) were observed, but individual active ingredients within these groups were not associated after adjusting for exposure to other pesticides. Preliminary results based on data from the US and NO for myeloid cancers indicate moderate associations with dichlorvos and aldicarb.

Conclusion Individual studies are often underpowered regarding their ability to demonstrate associations of disease, particularly for more rare exposures or for rare cancers or subtypes. Analyses within the AGRICOH consortium provide an opportunity to overcome the low power to detect.