There has been a lot of debate around the dangers of Monsanto’s Roundup weed killer. Conflicting studies have been released, and Monsanto representatives argue that most studies have not found a cancer risk from glyphosate exposure.
However, a 2015 assessment of glyphosate released by the International Agency for Research on Cancer (IARC) looked at the safety of five pesticides on the market in an attempt to see if they could be considered carcinogenic. Through their investigation, the IARC labeled glyphosate as “probably carcinogenic to humans” (Group 2A). This category is used for substances that the IARC believes has sufficient enough to indicate a likelihood that the substance can cause cancer, but the evidence is not yet entirely conclusive.
Representatives of the IARC have stood by their evaluation, even speaking out as recently as February 2018 to defend their findings. The agency said the monograph is a crucial first step for further research into glyphosate and other pesticides to better determine carcinogenicity and what levels of exposure specifically can be linked to these various types of cancer.
Separately, the U.S. Environmental Protection Agency (EPA) originally stated back in 1995 that glyphosate should be labeled as a probable human carcinogen. In recent years, however, the agency has changed its mind and argued that glyphosate is not carcinogenic and actually has low toxicity for humans, as long as it is used according to the label directions. In its most recent drafted assessment released in December 2017, the EPA went further to say that the pesticide showed virtually no toxicity to animals, including birds, that encounter glyphosate in the natural environment. The EPA’s final assessment on glyphosate is due in 2019.
Given the disparity in studies, it is still unclear to what degree glyphosate may affect human health or a person’s risk of cancer.