The EPA pesticide office has continued to side with Monsanto by not banning glyphosate-based herbicide products such as Roundup, according to a recent article by the National Resources Defense Council (NRDC).
NRDC recently told the EPA that it had strayed from its mission. The organization believes based upon the combined data of adverse effects, EPA should severely restrict glyphosate use right away. Also, more than 56,000 NRDC members online have emailed EPA to ask for them to protect monarch butterflies from the overuse of herbicides based upon glyphosate.
Since the last ecological risk assessment was done for the chemical in 1993, the use of glyphosate has soared, making it the most commonly used pesticide in the US. Over the years since, evidence has piled up pointing to adverse human health effects and also a decline of the North American monarch butterfly population.
Research in the Journal of the American Medical Association (JAMA) has reported on evidence that glyphosate, which is the key ingredient in Roundup, is leeching into our bodies.
And it has been doing this at higher rates for years, as the use of glyphosate on crops has increased dramatically.
Is EPA Dismissing Cancer Risks?
EPA has currently classified glyphosate as not likely to cause human cancer, even though some studies have reported a higher risk in humans and mice. The NRDC in its comments to the agency continued to push EPA to classify glyphosate as a cancer risk. This would be in concert with the following scientific views:
- The IARC in 2015 concluded in its consensus report that cancer evidence from studies of humans comprised limited evidence for risk of cancer, but which was supported by ‘sufficient’ evidence of carcinogenicity in various animal studies.
- The EPA FIFRA Scientific Advisory Panel (SAP) never reached a consensus, but many of the panelists found there is some evidence that glyphosate is a human carcinogen. EPA Cancer Guidelines provide a definition of ‘suggestive evidence’ as ‘evidence of positive response in studies whose design, power or conduct limits ability to make a confident conclusion.’ Many SAP panelists felt this was proper for glyphosate.
- A Monsanto meta-analysis performed by Chang and Delzell in 2016 reported a marginally statistically significant, positive association between any versus no use of glyphosate and risk of cancer.
Cancer Evidence in Field Studies
Even the EPA has acknowledged that studies are positive for a higher risk of non-hodgkin lymphoma cancer in people who have been exposed to glyphosate. But still, EPA has discarded strong field evidence for a risk of cancer for the following reasons:
- Confused Use of Confounding: EPA has suggested field studies did not adjust properly for occupational exposure to solvents, diesel exhaust fumes, livestock, and other farm animals. Some argue this is a mistaken understanding of a confounder, which has to both cause cancer and happen more often in heavy users of glyphosate. For instance, a study that reviews the link between heavy drinking of alcohol and premature death can be confounded if it does not also account for cigarette smoking. Both cause premature death and are more likely to happen with heavy drinkers.
- Biased Approach to Address Bias: EPA rationalizes dismissal of epidemiologic evidence of cancer from glyphosate by pointing out recall bias and missing data are often limitations of clinical studies. But EPA has not presented evidence to suggest or support recall bias or missing data in enough amounts to change study results. Some believe that EPA should not dismiss harm evidence based on suppositions that are unsupported.
- Overlooking Cancer Red Flags in Agriculture Health Study: Monsanto and EPA have often based their no-cancer argument by citing a long-term epidemiologic study of pesticide applicators in the Midwest known as the Agriculture Health Study or AHS. This study was done by the National Cancer Institute. It does not show a link between exposure to glyphosate and NHL. But an update of the cohort recently did show a potential association between glyphosate and another blood cancer called acute myeloid leukemia. Study authors warned that because use of glyphosate is used so often around the world, strong efforts to replicate the findings are warranted. Increase in this study of AML was two-fold higher in the highest exposed applicators compared with those who were never exposed.
The failure of EPA to initiate and incorporate glyphosate residue testing results in its assessments is a major gap that should be better addressed by using more uncertainty factors. The Food Quality Protection Act requires EPA to prohibit any use for which the registrant did not demonstrate there is a reasonable certainty of no harm to any vulnerable population. It is argued by the NRDC that EPA must ensure it is meeting its responsibilities in evaluating glyphosate exposure and risks to all vulnerable populations as well as to the general population for cancer risks of glyphosate and it has not yet done so.
- Draft of Human Health and Ecological Risk Assessments for Glyphosate. (2016). Retrieved from https://www.epa.gov/ingredients-used-pesticide-products/draft-human-health-and-ecological-risk-assessments-glyphosate
- EPA/SAP Scientific Advisory Panel Meeting. (2016). Retrieved from https://www.epa.gov/sap/meeting-materials-december-13-16-2016-scientific-advisory-panel
- Agriculture Health Study. (n.d.). Retrieved from https://aghealth.nih.gov/