The cancer-research arm of the World Health Organization recently announced that the world’s most widely-used herbicide is ‘probably carcinogenic to humans.’ Adrienne Gulley wrote in to clarify some of the details of the announcement and the research behind it. 

“Glyphosate is the most commonly used herbicide in the world. It’s found in over 750 different products, including Roundup. And, like most lawn care and agricultural chemicals, it doesn’t stay on the ground. Scientists have found glyphosate in nearby water supplies and food grown in areas where the chemical was sprayed. 

Evidence of a connection between glyphosate and cancer in humans is limited, and past studies are often contradictory. For example, several American and European studies have shown that people who work with the herbicide have an increased risk of non-Hodgkin’s lymphomas. But a U.S. study that began monitoring the health of thousands of farmers and their spouses in 1993 has found no such link. 
The International Agency for Research on Cancer (IARC) noted all of this in their report in March. But other evidence, primarily from animal studies, was seen as enough to warrant the ‘probably carcinogenic’ classification.
It is worth noting that IARC classifies compounds on a multi-point scale: 1 for agents that are definitely carcinogenic to humans and 4 for those that probably aren’t. Glyphosate was categorized as 2A. Also in that category are emissions from high-temperature frying—like the kind a fry cook deals with—and the occupational chemical exposure experienced by barbers. 
But not everyone agrees with IARC’s assessment. In addition to triggering back-lash from the industry, the report has raised some eyebrows in the research community. 
So what happens now? It is up to individual governments to issue public health recommendations or set limits on the use of chemicals reviewed by the IARC. The U.S. EPA does not currently consider glyphosate to be carcinogenic in humans, but they are conducting a formal review of its safety.” 
For more information or to read the IARC study in its entirety, visit
***Photo by of University of Delaware Extension.