Skip to Content

The Weekly News Source for Wyoming's Ranchers, Farmers and AgriBusiness Community

Cancerous nature of glyphosate boils down to the legal definition, says Vardiman

by Wyoming Livestock Roundup

Riverton – A recent California court decision ruling in favor of a man who claims his cancer was caused by the popular pesticide glyphosate, more commonly known as Roundup®, has stirred the longstanding discussion regarding the safety of pesticides. 

Jeremiah Vardiman, University of Wyoming Extension educator, clarified some of the cloudy waters surrounding this case and other pesticide topics at the Fremont County Farm and Ranch Days held in Riverton on Feb. 6-7.

History and uses 

Vardiman explained the chemical glyphosate was initially researched and tested for use as a common household detergent. After it was thrown into a yard and killed all the grass, it was then developed further as an herbicide. 

“When we think about how the chemical has a foamy consistency, it makes sense it was originally a detergent,” Vardiman said. 

He further explained the chemical is non-selective, systemic and can also be used as desiccant during harvest.

“Glyphosate will kill all types of plants it comes in contact with,” he said. “This is why we call it non-selective.” 

“Systemic chemicals, such as glyphosate, don’t need to be in contact with the entire plant to kill it,” Vardiman said. “It will affect areas outside of where it contacts because it spreads throughout the plant.” 

Farmers also commonly use the chemical as a desiccant. Desiccants are used to dry crops out prior to harvest, according to Vardiman. 

Probable carcinogens 

“The big question is whether or not glyphosate is cancerous,” said Vardiman. “Unfortunately, the answer is maybe.”

The World Health Organization (WHO) lists glyphosate as a probable carcinogen, according to Vardiman. 

In 2015, WHO stated, “Glyphosate is a probable human carcinogen.”

WHO assesses the health of society on a global scale, with a specific branch for cancer research. 

Vardiman explained, for any chemical to be considered non-carcinogenic, the language denotes it must not cause cancer under any circumstances. 

“We have to think about glyphosate beyond normal use,” said Vardiman. “If someone were to bathe in it or drink it, in those circumstances, it might cause cancer and therefore has to be listed as a probable carcinogenic.” 

Other things listed as probable carcinogens include caffeine, red meat, indoor fireplaces and night shifts.   

“We can’t take these things at face value,” he said. “We have to look at it in a larger context.” 

Public concern

Vardiman pointed out there is a lot of public concern surrounding whether or not pesticides are safe to use and safe to put on food. 

“If there was a real public health risk, we would see it first in the people exposed to the chemical the most,” he said. “Farmers and commercial applicators would see a lot more cases of cancer if it were a major issue.” 

He explained multiple studies have shown no probable relation between solid tumors and normal glyphosate use. 

“The largest study ever of its kind found no relation between farmers and commercial applicators who had regular exposure to glyphosate and cancerous tumors including lymphoma,” Vardiman explained. “Interestingly enough, even in Europe, where pesticides are highly regulated, studies also found no relation between the two.”  

He pointed out the court case in California held Monsanto responsible for the health issues suffered by the plaintiff but did not actually rule glyphosate itself to be cancerous.

“This is where the conflict lies,” he said. “The court ruled Monsanto was responsible for this man’s sickness, but science doesn’t support the connection between the two.”

“It boils down to figuring out what is the reasonable likelihood of glyphosate actually causing cancer,” Vardiman stated. “We have to figure out in what dosage and in what scenarios it becomes an issue.”

Callie Hanson is the assistant editor of the Wyoming Livestock Roundup. Send comments on this article to

Back to top