Does the pesticide glyphosate cause cancer or not? The latest in the controversy surrounding glyphosate (in Roundup), which is the most commonly used herbicide (weed-killer) in the world, is a journal article written by Dr. Charles Benbrook. He looked at why 2 government agencies came out with conflicting views regarding glyphosate - the EPA said glyphosate is “not likely to be carcinogenic to humans”, while the International Agency for Research on Cancer (IARC) considers glyphosate as “probably carcinogenic to humans". Benbrook points out a number of problems with the EPA designation. Uh oh.
It appears that the studies the EPA looked at were not as up to date (they ignored at least 27 recent studies), they relied heavily on the manufacturer's own studies (bias!!! after all, the manufacturer wants to sell the pesticide) rather than studies done by independent researchers, and the EPA ignored work that shows that the product Roundup (with its extra ingredients) is more toxic than glyphosate alone. But guess what - in the real world people are exposed to Roundup, not just to pure glyphosate.
Increasing numbers of studies are finding health effects (cancer, kidney problems, endocrine disruption, etc) from exposure to glyphosate, and it turns out we're exposed to it daily in the foods we eat (here, here). And yes, studies show that most of us have glyphosate residues in us (it can be measured in our urine). What is it doing to us to constantly eat foods with low doses of glyphosate residues? What about pregnant women and their unborn babies?
The investigative journalist Carey Gillam has been extensively following and writing for years about the controversies, the corruption, the unethical behavior of big-business (especially Monsanto, the manufacturer of Roundup), the close ties with Monsanto at the FDA, the refusal of US government agencies to test for glyphosate residues in our food, and the cover-ups surrounding Roundup (glyphosate). In 2017 her incredibly thorough and well-researched book about Roundup was published: Whitewash: The Story of a Weed Killer, Cancer, and the Corruption of Science. Carey Gillum is also the author of the following article from Environmental Health News:
A little more than a month ahead of a first-ever federal trial over the issue of whether or not Monsanto's popular weed killers can cause cancer, a new analysis raises troubling questions about the U.S. Environmental Protection Agency's (EPA) handling of pertinent science on glyphosate safety.
According to the report, which examines the opposing positions taken by the EPA and an international cancer research agency on glyphosate-based herbicides, the EPA has disregarded substantial scientific evidence of genotoxicity associated with weed killing products such as Roundup and other Monsanto brands. Genotoxicity refers to a substance's destructive effect on a cell's genetic material. Genotoxins can cause mutations in cells that can lead to cancer.
The EPA classifies glyphosate as not likely to be carcinogenic while the International Agency for Research on Cancer (IARC), which is part of the World Health Organization, classifies it as "probably carcinogenic."
The paper was authored by Charles Benbrook, a former research professor who served at one time as executive director of the National Academy of Sciences board on agriculture, and was published in the journal Environmental Sciences Europe on Monday. It is based on Benbrook's review of EPA and IARC records regarding the types and numbers of glyphosate studies each organization evaluated. "Clearly, compared to EPA's genotoxicity review, the IARC review is grounded on more recent, more sensitive, and more sophisticated genotoxic studies, and more accurately reflects real-world exposures," Benbrook told EHN.
Benbrook testified as an expert witness in the first lawsuit to go to trial against Monsanto over claims its glyphosate herbicides cause cancer. The plaintiff in that case, Dewayne "Lee" Johnson, won a unanimous jury award of $289 million last year that the judge in the case cut to $78 million. Thousands of additional cancer victims have sued Monsanto and the second trial begins Feb. 25 in federal court in San Francisco. Benbrook is also expected to testify for the plaintiff in that case.
Monsanto is seeking to exclude Benbrook's testimony at trial, saying he has no expertise in any physical science or field of medicine and no training or degree in toxicology and has never worked at the EPA or other regulatory body.
In the new analysis, Benbrook is critical of the EPA's scrutiny of glyphosate herbicides, noting that little weight was given to research regarding the actual formulations sold into the marketplace and used by millions of people around the world. Instead, the EPA and other regulators have mostly pointed to dozens of studies paid for by Monsanto and other companies selling glyphosate herbicides that found no cancer concerns. The EPA has given little attention to several independent research projects that have indicated the formulations can be more toxic than glyphosate alone, according to Benbrook.
Indeed, the EPA only started working in 2016—some 42 years after the first glyphosate herbicides came to market – with the U.S. National Toxicology Program to evaluate the comparative toxicity of the formulations. Early results disclosed in 2018 supported concerns about enhanced toxicity in formulations.
Several scientists, including from within the EPA's Office of Research and Development (ORD), and from a panel of scientific experts convened by the EPA, have cited deficiencies and problems with the EPA's decision to classify glyphosate as not likely to be carcinogenic to humans. But Benbrook's analysis is the first to look deeply at how and why the EPA and IARC drew such divergent conclusions.
Benbrook looked at the citations for genotoxicity tests discussed in the EPA and IARC reports, both those that were published in peer-reviewed journals and the unpublished ones that were presented to the EPA by Monsanto and other companies. Some studies looked at glyphosate alone, and/or glyphosate-based herbicide formulations and some included findings about a substance called aminomethylphosphonic acid (AMPA), which is glyphosate's primary metabolite.
Benbrook's analysis found that within the body of available evidence, the EPA relied on 151 studies, 115 of which showed negative results, meaning no evidence of genotoxicity, and only 36 that had positive results. IARC cited 191 studies, only 45 of which showed negative results and 146 of which showed evidence of genotoxicity. IARC said within these studies it found "strong evidence that exposure to glyphosate or glyphosate-based formulations is genotoxic…"
Benbrook's analysis reports that over the last three years at least 27 additional studies have been published addressing possible mechanisms of genotoxic action for glyphosate and/or formulated glyphosate-based herbicides and all but one of the 27 studies reported one or more positive result. There were 18 positives arising from DNA damage, six associated with oxidative stress, and two with other genotoxicity mechanisms, his paper states.
According to Benbrook, the EPA's failure to focus on formulated glyphosate-based herbicides is dangerous because these formulations "account for all commercial uses and human exposures (no herbicide products contain just glyphosate)." More research is needed on real-world exposures, Benbrook concludes.