Shining a Light on Glyphosate-Based Herbicide Hazard, Exposures and Risk: Role of Non-Hodgkin Lymphoma Litigation in the USA

Abstract

Roundup, and other glyphosate-based herbicides, are the most heavily used pesticides in the history of the USA and globally. In March 2015, the International Agency for Research on Cancer (IARC) classified glyphosate as a “probable human carcinogen”. A portion of the 695,000 Americans then living in 2015 with non-Hodgkin lymphoma (NHL) became aware of IARC’s decision. Several thousand Roundup–NHL lawsuits had been filed by the end of 2017, rising to 18,400 by July 2019 and 42,000 by November 2019. Three cases have gone to trial, each won by the plaintiffs. The author has served as an expert witness for the plaintiffs in this litigation and has been compensated for his time spent. The impact of the litigation on the independent assessment of the science useful in determining whether glyphosate and glyphosate-based herbicide exposures are linked to NHL is reviewed, as is why the US Environmental Protection Agency (EPA) and IARC reached such different judgements regarding glyphosate human cancer hazard and risk. Two important “lessons learned” regarding the EPA versus IARC assessment of glyphosate cancer hazard and risk are highlighted. The first arises from differences in the magnitude of applicator risks from mostly dermal exposures to formulated glyphosate-based herbicides compared to just dietary exposures to technical glyphosate. The second relates to missed opportunities to markedly lower applicator exposures and risks with little or no impact on sales via reformulation, added warnings and worker safety provisions, company-driven stewardship programmes and greater determination by the EPA in the 1980s to compel Monsanto to add common-sense worker protection provisions onto Roundup labels (eg “wear gloves when applying this product”). Policy reforms designed to alleviate systemic problems with how pesticide hazards, exposures and risks are analysed, regulated and mitigated are described.