Letter: A Roundup response


In his defense of glyphosate as non-carcinogenic in last week’s Indy, Mr. Reed offers very sweeping conclusions but no evidence in his column.

He asserts without evidence, as just one example, that the World Health Organization (WHO) engages in “fearmongering” and is “notorious for listing chemicals as potential carcinogens after a single suggestive scientific study is published.” As a physician who has evaluated countless claims of chemical exposures in the state’s workers’ compensation system dating to 1981, that has never been my experience.

The International Association for Research on Cancer (IARC), a creation of the WHO, is an authoritative resource on the issue of substance carcinogenicity. IARC monographs are quite lengthy, with extensive data analysis and discussion and numerous study and review-article citations. The IARC conclusion in 2015 was that glyphosate is “probably a human carcinogen” (Group 2A).

Mr. Reed mentions the USDA Forest Service profile on glyphosate as “a good source.” A word search of the current U.S. Forest Service website for “glyphosate” concludes with “no results found.” A word search for “herbicide” offers 19 results, none addressing health effects. The only USDA Forest Service information sheet I could locate was from 1997, which is outdated. Perhaps there is a more recent one I am not aware of.

A review article to update the IARC assessment published on Jan. 7, 2019, in Environmental Health concluded that the IARC’s categorization was appropriate.

Also, in 2019, a review article by Benbrook in Environmental Sciences Europe addressed the discrepancy between the conclusion about glyphosate from the IARC (probably carcinogenic) versus that of the EPA (likely not carcinogenic). There were three primary reasons: 

1) the EPA relied primarily on unpublished studies, whereas the IARC relied upon peer-reviewed studies; 

2) the IARC relied on studies of formulated glyphosate-based herbicides (GBHs) and assays of glyphosate’s primary breakdown product in the body (AMPA), whereas the EPA looked primarily at technical glyphosate alone.

3) the IARC took into account occupational and elevated exposure scenarios, which the EPA did not.

Based on my knowledge and experience, the IARC assessment methods are superior. Clearly, more research is ongoing. I invite the reader to contrast Mr. Reed’s multiple broad, unsupported assertions with what I have presented here. This might help explain why juries are reaching the verdicts they are.

Gary Stewart, Laguna Beach

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  1. IARC ignored a major study that evaluated a large number of applicators of Roundup that found no link to NHL. IARC finds everything carcinogenic including working at night, ethanol, red meat and many others. They do not take into account risk and only the most absurd level of hazard.


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