The Deceptive Art of Confirmation-Biased 'Science': Condemning Glyphosate

With a little conflict of interest thrown in


Mike Mozart/CC BY 2.0

Anti-biotech activists hate the herbicide glyphosate, sold by Monsanto under the brand name Roundup. Those activists won a victory in 2015, when the World Health Organization's International Agency for Research on Cancer (IARC) issued a report classifying glyphosate as a "probable human carcinogen." That conclusion stood in stark contrast to the findings of every regulatory agency that has evaluated glyphosate over the past two decades, all of which have found the herbicide safe for people and the environment.

How did the World Health Organization diverge so sharply from the scientific consensus? By suppressing extensive evidence of glyphosate's safety. This month Reuters acquired a draft copy the IARC's glyphosate report. In the chapter on animal testing, references to numerous studies that found no link between glyphosate and cancer had been systematically deleted. The IARC refused to explain how that happened other than to refer to its consensus review process.

Meanwhile, a subsequent analysis of how the IARC evaluated the animal testing studies found that "the classification of glyphosate as a probable human carcinogen was the result of a flawed and incomplete summary of the experimental evidence." Many ongoing lawsuits against Monsanto allege that the plaintiffs contracted either non-Hodgkin's lymphoma (NHL) or multiple myeloma (MM) as a result of exposures to glyphosate. Researchers in a new review of human epidemiological studies reported that they "did not find support in the epidemiologic literature for a causal association between glyphosate and NHL or MM."

I should note that one Christopher Portier chaired the Advisory Group to Recommend Priorities for IARC Monographs and later served as an invited specialist to the group that evaluated studies related to glyphosate and the risk of cancer.* After he retired from National Center for Environmental Health, Portier began working in 2013 as a senior scientist with the Environmental Defense Fund (EDF), an activist group that has long opposed many aspects of crop biotechnology and the use of glyphosate. In a 2014 letter to the journal Environmental Health Perspectives defending a scientifically discredited study on biotech corn, Portier listed only his affiliation with the IARC. The IARC did later disclose Portier's affiliation with EDF, but the agency apparently failed to consider the possibility that his work with anti-pesticide activist group might amount to a conflict of interest.

Nor is that Portier's only potential conflict of interest. Earlier this month, the European statistician David Zaruk reported that "during the same week that IARC had published its opinion on glyphosate's carcinogenicity, Christopher Portier signed a lucrative contract to be a litigation consultant for two law firms preparing to sue Monsanto on behalf of glyphosate cancer victims." Portier also agreed not to disclose publically his consulting arrangements with the law firms.

Over at Forbes, Albert Einstein College of Medicine cancer epidemiologist Geoffrey Kabat concludes, "All of this points to a trusted agency redacting the evidence to suit its predetermined and preferred story-line." That sounds entirely correct. The IARC's evaluation methodologies need to be dramatically overhauled and its leadership changed.

*[CORRECTION] Portier chaired the group that recommended IARC priorities for substances (including glyphosate) to be evaluated for carcinogencity through 2019, but served as an invited specialist with the group that concluded that glyphosate was a probable human carcinogen.

Disclosure: About three years ago I bought 100 shares of Monsanto with my own money for $109 per share. They were going yesterday at $121.30 per share.