The International Agency of Research on Cancer (IARC) classified glyphosate as a probable human carcinogen (class 2A) in March 2015 after thorough, independent, and rigorous investigation by independent researchers and investigators in the field.
IARC is a division of the World Health Organization (WHO) (https://www.iarc.fr/), established in 1965 as an independent body to assess potential human hazards that can cause cancer. For IARC to evaluate the potential carcinogenicity of a substance, it must have ubiquitous human exposure and there must be some preliminary data to suggest a potential harm and carcinogenicity. IARC reviews peer-reviewed published literature including epidemiologic studies, animal data, and genotoxicity studies. In addition, IARC assesses plausible mechanisms of action for possible carcinogenicity of the studied compound. As of the last update on 11/09/2018, IARC had evaluated 1,013 substances since its inception. This shows the high selectivity of IARC in deciding which substances to evaluate. Of these, only 20% were classified as either group 1 (human carcinogens) or 2A (probable human carcinogens). In the above-referenced review of both the epidemiologic, animal, and mechanistic studies, 217 expert scientists evaluated the carcinogenic hazard for four insecticides and the herbicide glyphosate. The Working Group (WG) concluded that the data for glyphosate met the criteria for classification as a probable human carcinogen. and classified glyphosate as “probably carcinogenic to humans” (Group 2A). This conclusion was reached after thorough, independent, and rigorous investigation by independent researchers and investigators and was published in Lancet. In 2019, after reviewing newly published studies, IARC reaffirmed its finding that glyphosate should be classified as probably carcinogenic to humans. As of February 2021, IARC has classified only 20% of substances reviewed as either group 1 (human carcinogens) or 2A (probable human carcinogens).