IARC declined to comment.
Numerous national and international agencies have reviewed glyphosate. IARC is the only one to have declared the substance a probable carcinogen. Compared with other agencies, IARC has divulged little about its review process. Until now, it has been nearly impossible to see details, such as draft documents, of how IARC arrived at its decision.
The European Food Safety Authority (EFSA) said that in its assessment of the weedkiller, the scientific decision-making process “can be traced from start to finish.” Jose Tarazona, head of EFSA’s pesticides unit, told Reuters: “Anyone can go to EFSA’s website and review how the assessment evolved over time. So you can see clearly how experts…appraised each and every study and also how comments from the public consultation were incorporated into the scientific thinking.”
In the U.S., the EPA published a full 1,261-page transcript of a three-day scientific advisory panel meeting on its ongoing evaluation of the carcinogenic potential of glyphosate in December 2016.
No such record of the deliberations behind IARC’s monographs is published.
In a previous response to questions about the transparency of the IARC process, the agency’s director, Chris Wild, referred Reuters to a letter in which he said his agency’s assessments are “widely respected for their scientific rigor, standardized, and transparent process.” Wild also said IARC’s methods are intended to allow scientists to engage in free scientific debate at its monograph meetings.
Deletions and Additions
IARC says its working group scientists are selected for “their expertise and the absence of real or apparent conflicts of interest.” For the panel that evaluated glyphosate and four other pesticides in what is known as IARC’s Monograph 112, scientists from 11 countries met at the agency’s headquarters in Lyon for a week-long meeting starting on March 3, 2015. The meeting “followed nearly a year of review and preparation” by IARC staff and working group members, “including a comprehensive review of the latest available scientific evidence,” IARC said in a statement at the time.
In June, Reuters reported how the chairman of the IARC working group was aware of new data showing no link between glyphosate and cancer in humans, but the agency did not take it into account because it had not been published.
No drafts of IARC’s glyphosate assessment have surfaced before. However, a draft was obtained by Monsanto as part of the legal proceedings in the U.S. Reuters reviewed chapter 3, the section on animal studies, which is the only section no longer covered by a confidentiality order of the court.
The glyphosate review in IARC’s Monograph 112 runs to 92 pages; the chapter on animal studies consists of just over 10 pages. Reuters has not seen any other sections of the draft and cannot say whether they also underwent significant edits.
In comparing draft and final versions of chapter 3, Reuters found that in several instances comments in the draft were removed; the comments noted that studies had concluded glyphosate was not carcinogenic. They were replaced in the final version with the sentence: “The Working Group was not able to evaluate this study because of the limited experimental data provided in the review article and supplemental information.”
This sentence was inserted six times into the final version. Each time it replaced a contrary conclusion, noted in the draft, by the original investigators on the study being considered, such as: “The authors concluded that glyphosate was not carcinogenic in Sprague Dawley rats;” “The authors concluded that glyphosate technical acid was not carcinogenic in Wistar rats;” and “The authors concluded that glyphosate was not carcinogenic in CD-1 mice in this study.”
Reuters also found changes to the conclusions and statistical significance of two mouse studies. These studies were cited in IARC’s ultimate finding of “sufficient” evidence that glyphosate causes cancer in animals.
Leave a Reply