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"By denying scientific principles, one may maintain any paradox." – Galileo Galilei


IARC’s Unsupported Evaluation of Glyphosate

The International Agency for Research on Cancer’s (IARC) classification of glyphosate as a carcinogen goes against the conclusions of numerous government agencies, and is undermined by issues of bias and failure to consider the weight of the scientific evidence.


  • From April 18-19, 2014, IARC convened an advisory group that recommended a common herbicide, glyphosate, be studied by the agency’s Monograph Program – charged with identifying and evaluating environmental causes of cancer in humans – identifying the substance as “Medium priority.”
    • Forty other substances were classified by the advisory group as “high priority.” However, glyphosate was selected and evaluated, and a Monograph was published before any of the “high priority” substances. Twelve of these substances are currently “in preparation,” while work on the others has not been initiated.
  • From March 3-10, 2015, IARC met to discuss the hazards associated with glyphosate.
    • The Monograph 112 Working Group concluded on March 20, 2015, that glyphosate was “probably carcinogenic to humans,” making it a Group 2A carcinogen.
  • On April 29, 2016, the U.S. Environmental Protection Agency (EPA) published on its website a risk assessment report by its Cancer Assessment Review Committee (CARC). This report, marked final and signed by its authors, concluded that glyphosate is not likely to be carcinogenic to humans. In its report, CARC is critical of IARC’s Monograph on glyphosate. Days after the report was posted, it was suddenly taken down from the website because, EPA claimed, it was not final.
  • On September 12, 2016, the EPA released an issue paper, once again finding that “glyphosate is not likely to be carcinogenic to humans at doses relevant for human health risk assessment.” On September 16, 2016, EPA announced a Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) would meet in October to review EPA’s evaluation.
  • On October 14, 2016, the EPA reversed course and the FIFRA SAP meeting, scheduled for October 18-21, 2016, “due to recent changes in the availability of experts for the peer review panel.”The postponement came after it was announced that Kenneth Portier, vice president of the Statistics & Evaluation Center at the American Cancer Society, is on the panel. Portier’s brother, Christopher Portier, former director of the U.S. National Center for Environmental Health at the Centers for Disease Control and Prevention, served as an “invited specialist” on the IARC panel that determined glyphosate is “probably carcinogenic to humans.”

What IARC Said

“For the herbicide glyphosate, there was limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma. The evidence in humans is from studies of exposures, mostly agricultural, in the USA, Canada, and Sweden published since 2001.” – IARC press release (March 20, 2015

Criticism of the IARC Glyphosate Monograph

  • “The overwhelming majority of agencies that have examined glyphosate have determined it is not a cancer risk.” – U.S. District Judge William B. Shubb (June 13, 2018)
  • “We are here to ensure that we protect citizens, and I think all of us have that in mind. But we also need to make sure that we are taking a responsible attitude, maintaining a sense of proportion, and not causing alarm. My concern is that there is a desire amongst some people to base assessments of possible carcinogens … on hazard instead of risk. If we decided that we were going to ban all potentially [carcinogenic] substances, we would be banning coffee, we’d be banning champagne, we’d ban goulash and prosciutto and Belgian beer and frites, we wouldn’t allow people to go outside in the sunshine, and many products and activities would be banned. This is where we need to maintain a sense of proportion and actually understand that basing our decisions on a risk assessment is far more sensible and responsible than to take an attitude of anything that is potentially [carcinogenic] should be banned.” – British MEP Anthea McIntyre (June 7, 2018)
  • “At the end of the day, the totality of the evidence, especially in light of the extensive testing that glyphosate has received, as judged by the Expert Working Group, does not support the conclusion that glyphosate is a ‘probable human carcinogen’. Indeed, the data, inclusive of GLP-compliant unpublished studies, point to classification of ‘non-carcinogenic to humans’.” – Intertek Panel: A review of the carcinogenic potential of glyphosate by four independent expert panels and comparison to the IARC assessment (September 28, 2016)
  • “This is a compound with no toxicological effects on humans and no biological pathway with which to cause harm that a panel using selected epidemiology papers nonetheless declared a cancer-causing agent[…]. They took papers that had people with various cancers and correlated that to the existence of glyphosate and then declared causation.” – Hank Campbell, President of the American Council on Science and Health (June 23, 2016)
  • “Once again, an impartial peer review has found that IARC’s classification of glyphosate, diazinon and malathion was, at best, questionable. And frankly, CLA views IARC’s findings as an unnecessary threat to farmers and the global supply of food[…]. In the U.S., we are eagerly awaiting the U.S. Environmental Protection Agency’s (EPA) new risk assessment for glyphosate. We urge EPA to consider the real risk of products and to use broad data sets, rather than responding to outside political pressure from activist groups.” – Jay Vroom, President and CEO of CropLife America (May 25, 2015)

What Regulatory Agencies Have Said about the Safety of Glyphosate

  • “It is important to note that a hazard classification is not a health risk assessment. The level of human exposure, which determines the actual risk, was not taken into account by WHO (IARC). Pesticides are registered for use in Canada only if the level of exposure to Canadians does not cause any harmful effects, including cancer.” – Canadian Pest Management Regulatory Agency, (April 13, 2015)
  • “In accordance with the 2005 Guidelines for Carcinogen Risk Assessment, based on the weight-of evidence, glyphosate is classified as ‘Not Likely to be Carcinogenic to Humans.'” – EPA’s Cancer Assessment Review Committee (October 1, 2015)
  • “[EPA’s glyphosate issue paper includes] the Agency’s proposed classification that glyphosate is not likely to be carcinogenic to humans at doses relevant for human health risk assessment.” – EPA press release (September 16, 2016)
  • “EFSA concluded that glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential….” – European Food Safety Authority (November 12, 2015)
  • “In view of the absence of carcinogenic potential in rodents at human-relevant doses and the absence of genotoxicity by the oral route in mammals, and considering the epidemiological evidence from occupational exposures, the Meeting concluded that glyphosate is unlikely to pose a carcinogenic risk to humans from exposure through the diet.” – United Nations/World Health Organization (May 9-13, 2016)
  • “Based on the epidemiological data as well as on data from long-term studies in rats and mice, taking a weight of evidence approach, no hazard classification for carcinogenicity is warranted for glyphosate according to the “[Classification, Labelling and Packaging]” – German Federal Institute for Occupational Safety and Health to the European Chemicals Agency, (May 2016)
  • “Based on the inconsistency in the results of the studies on glyphosate exposure and [non-Hodgkin lymphoma], and the lack of any association in the largest, most robust study, it was concluded that there is no convincing evidence of an association between glyphosate exposure and the development of cancer in humans.” – New Zealand Environmental Protection Authority, (August 2016)

Additional Links and Resources

  • IARC Monographs Volume 112: evaluation of five organophosphate insecticides and herbicides (IARC, March 20, 2015)
  • Glyphosate Monograph 112 (IARC, 2015)
  • Errors, bias and conflicts of interest make UN agency contender for worst regulator ever (Forbes, May 18, 2016)
  • Is your weed killer carcinogenic? (Reuters, April 18, 2016)
  • ‘The Facebook Age of Science’ at the World Health Organization (National Review, May 3, 2016)
  • U.N. committee finds weed killer glyphosate unlikely to cause cancer (Reuters, May 16, 2016)
  • EPA report favorable to glyphosate herbicide mysteriously disappears (Washington Times, June 8, 2016)
  • EPA takes offline report that says glyphosate not likely carcinogenic (Reuters, May 2, 2016)
  • EPA Glyphosate Issue Paper (EPA, September 16, 2016)