Last year a United States court ruled Monsanto’s Roundup Weed Killer caused or at least contributed to a former school groundskeepers terminal cancer (non-Hodgkin lymphoma). The court awarded him $289M and 9,000+ other lawsuits are in the works throughout the country. Multiple studies categorize the active ingredient in Roundup, glyphosate (an herbicide) as “probably carcinogenic to humans”. This was the study used by the plaintiff and the jury voted unanimously in his favor. This sets the precedent for the thousands of other lawsuits coming into courtrooms within the next couple years.
Most studies show that short term exposure to glyphosate poses minimal risk. The lawsuits are tasked with deciding if long term exposure causes cancer. Most investigations and studies examine if the chemical causes damage to DNA or mutations in bacteria. Most of these studies came back negative with respect to glyphosates short term ability to cause these outcomes.
A lot of the evidence against Monsanto came from plaintiffs who asserted that the company attempted to influence regulators and manipulate public opinion. The shady practices of Monsanto were used to show them as corrupt overall and therefore capable of putting out a product that causes cancer.