Study is published as jurors deliberate in the US Roundup cancer litigation
The noose is tightening on Bayer/Monsanto's glyphosate herbicide (commonly sold as Roundup), as yet another epidemiological study has found a link between exposure to the herbicide and a type of non-Hodgkin's lymphoma called diffuse large B-cell lymphoma (DLBCL). See the abstract and key points below.
This study is published as the jurors in the Roundup cancer litigation in the US are deliberating their verdict.
Pesticide use and risk of non-Hodgkin lymphoid malignancies in agricultural cohorts from France, Norway and the USA: a pooled analysis from the AGRICOH consortium
Maria E Leon, Leah H Schinasi, Pierre Lebailly, Laura E Beane Freeman, Karl-Christian Nordby, Gilles Ferro, Alain Monnereau, Maartje Brouwer, Séverine Tual, Isabelle Baldi, Kristina Kjaerheim, Jonathan N Hofmann, Petter Kristensen, Stella Koutros, Kurt Straif, Hans Kromhout, Joachim Schüz
International Journal of Epidemiology, dyz017, https://doi.org/10.1093/ije/dyz017
Published: 18 March 2019
In this analysis combining data from >300 000 farmers or agricultural workers from France, Norway and the USA, accruing more than 3.5 million person-years under risk, the majority of the hazard ratios observed suggested no association of 14 selected pesticide chemical groups and 33 individual active ingredients with the risk of non-Hodgkin lymphoid malignancies (NHL).
Moderately elevated hazard ratios were seen for NHL overall or certain subtypes with ever use of a few specific pesticides compared with never use of those pesticides: NHL overall and terbufos; chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) and deltamethrin; and diffuse large B-cell lymphoma (DLBCL) and glyphosate; as well as inverse associations of NHL overall with the broader groups of organochlorine insecticides and phenoxy herbicides, after adjusting for exposure to other pesticides. Future work is needed to further investigate these findings.
Pesticides are commonly used in agriculture, and previous studies endorsed the need to further investigate the possible association between their use and risk of lymphoid malignancies in agricultural workers.
We investigated the relationship of ever use of 14 selected pesticide chemical groups and 33 individual active chemical ingredients with non-Hodgkin lymphoid malignancies (NHL) overall or major subtypes, in a pooled analysis of three large agricultural worker cohorts. Pesticide use was derived from self-reported history of crops cultivated combined with crop-exposure matrices (France and Norway) or self-reported lifetime use of active ingredients (USA). Cox regression models were used to estimate cohort-specific hazard ratios (HRs) and 95% confidence intervals (CIs), which were combined using random effects meta-analysis to calculate meta-HRs.
During follow-up, 2430 NHL cases were diagnosed in 316 270 farmers accruing 3 574 815 person-years under risk. 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); chronic lymphocytic leukaemia/small lymphocytic lymphoma and deltamethrin (1.48, 1.06–2.07); and diffuse large B-cell lymphoma and glyphosate (1.36, 1.00–1.85); as well as 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), but not with active ingredients within these groups, after adjusting for exposure to other pesticides.
Associations of pesticides with NHL appear to be subtype- and chemical-specific. Non-differential exposure misclassification was an important limitation, showing the need for refinement of exposure estimates and exposure–response analyses.