Three of the authors of new meta-analysis were members of the EPA's scientific advisory panel on glyphosate
A new scientific meta-analysis of the cancer-causing potential of glyphosate herbicides found that individuals with high exposures to the herbicides have a 41% increased risk of developing non-Hodgkin lymphoma. The findings by five US scientists run counter to an assessment by the US EPA that found no cancer concerns.
The paper is published in the journal Mutation Research/Reviews in Mutation Research, whose editor-in-chief is EPA toxicologist David DeMarini. Three of the study authors were members of the EPA's scientific advisory panel on glyphosate who have stated publicly that the EPA failed to follow proper scientific practices in its glyphosate assessment.
The authors state in their paper, "Together, all of the meta-analyses conducted to date, including our own, consistently report the same key finding: exposure to glyphosate, more precisely to GBHs [glyphosate-based herbicides], is associated with a statistically significant increased risk of NHL."
They conclude, "The overall evidence from human, animal, and mechanistic studies presented here supports glyphosate’s carcinogenic potential in mediating NHL. Given that humans are exposed to adjuvant-containing mixtures known to provoke synergistic toxic effects in vivo and in vitro, future studies of GBHs in experimental animals should be conducted."
The new meta-analysis includes the most recent update of the Agricultural Health Study (AHS) in 2018.
Bayer/Monsanto has heavily relied on the AHS study in the Roundup cancer litigation in the US in claiming there is no link between NHL and glyphosate herbicide exposure. This claim is in line with the conclusion of "no effect" from glyphosate on NHL that was reached by the authors of the previously published AHS study reports.
However, the authors of the new meta-analysis point out that the results of the previous analyses were biased by the inclusion of people with very low exposure, which can dilute the risk estimates. When people with high exposures are considered independently, a link between glyphosate herbicides and NHL is found.
Exposure to glyphosate-based herbicides and risk for Non-Hodgkin Lymphoma: A meta-analysis and supporting evidence
Luoping Zhang, Iemaan Rana, Emanuela Taioli, Rachel M.Shaffer, Lianne Sheppard
Mutation Research/Reviews in Mutation Research
Available online 10 February 2019
Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of glyphosate’s carcinogenic potential by various regional, national and international agencies have engendered controversy. We independently investigate whether there is an association between high cumulative exposures to glyphosate and increased risk of non-Hodgkin lymphoma (NHL) in humans and conduct a new meta-analysis that includes the most recent update of the Agricultural Health Study (AHS) cohort in 2018 along with five case-control studies. For comparison, we also perform an additional meta-analysis with the earlier AHS (2005) report and multiple sensitivity tests to assess the validity of our findings. Using the highest exposure groups when available in our meta-analyses, we report the overall meta-relative risk (meta-RR) of NHL in glyphosate-exposed workers is increased by 41% (meta-RR = 1.41, 95% CI, confidence interval: 1.13–1.75). Our comparison meta-analysis with the earlier AHS shows an increased meta-RR for NHL of 1.45 (95% CI: 1.11–1.91), which is higher than the meta-RRs previously reported. Sensitivity tests did not reveal meaningful differences from our estimated meta-RR. To contextualize our findings of an increased NHL risk in workers with high glyphosate exposure, we also consider available animal and mechanistic studies. We uncover further support in studies of malignant lymphoma incidence in mice treated with glyphosate, and its potential links to immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL. We recommend that future animal studies investigate the glyphosate-based formulations that most humans are exposed to.