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

Don’t Be Fooled, IARC Does Not Consider “Weight of the Evidence”

In the legal system, judges and juries rely on the “weight of the evidence” to determine whether a defendant should be sent to jail or be set free.


Much like our court system, IARC claims its Monograph Working Groups evaluate the “weight of the evidence” when determining whether substances of behaviors might cause cancer. But if the court systems were to follow IARC’s use of the term, our jails would be filled with many innocent people.

For example, consider how IARC used a “weight of the evidence” approach when it determined the herbicide glyphosate is a “probable human carcinogen.”


IARC boasts that it looked at “about 1,000 studies” and cited 269 references in the glyphosate Monograph. However, IARC refused to use decades of government studies showing glyphosate is not carcinogenic. Additionally, in its press release announcing its findings on glyphosate, IARC referred to only eight studies,   indicating the strongest arguments to support its glyphosate classification originated from just a handful of studies.


Furthermore, each of the eight studies IARC used is hampered by at least one major flaw. For example:


  • IARC took serious liberties with the conclusions of three studies used to support its conclusion that glyphosate is carcinogenic, a fact the U.S. Environmental Protection Agency (EPA) and other scientific experts have documented. In the most glaring instance, IARC flat-out changed the authors’ findings. IARC claimed one study found “strong” mechanistic evidence that glyphosate can cause cancer — a claim that was directly rebuked by study co-author Keith Solomon, who said IARC got the study “totally wrong.”
  • Two of the studies were deemed “low quality” by a recent EPA report that was used by a Science Advisory Panel to evaluate glyphosate.
  • EPA deemed all three case-control studies used by IARC to support its claim “limited evidence” of carcinogenicity in humans as inferior to the large Agricultural Health cohort study that found no evidence linking glyphosate to non-Hodgkin lymphoma.


Bottom line: The studies cited or referenced in IARC’s glyphosate Monograph press release have been flat-out rejected or highly criticized by reputable regulatory and even original authors who came to opposite conclusions from IARC.


IARC clearly cherry-picked the studies it used to make its glyphosate determination, and not one of those studies  even provided definitive evidence to support its claim that glyphosate is “probably carcinogenic to humans.” The case of glyphosate underscores IARC’s failure to consider the weight of scientific evidence when crafting its Monographs.