A trial is underway this week in California as witnesses will begin to testify in the first case alleging that Monsanto’s Roundup weed killer causes cancer. Politico says Lee Johnson, a groundskeeper for a California school district, alleges that years of spraying hundreds of gallons of the product caused him to develop non-Hodgkin’s lymphoma, a form of cancer. Opening statements took place on Monday. This case is a separate one from a class-action suit that involves more than 300 plaintiffs who argue that their exposure to Monsanto’s weed killer caused them to also develop non-Hodgkin’s lymphoma. That case is waiting on a judge’s evidentiary decision that could determine if the case will proceed. The Johnson case is taking place on its own because attorneys feared he would die before the proceedings could begin. While the jury’s decision won’t have any effect on the class-action suit, it will likely be a bellwether for other future proceedings. Monsanto says in court filings that glyphosate has been deemed safe by “every major regulatory agency.” The company notes that cancers “take many years to form,” and says Johnson wasn’t exposed to Roundup long enough to make a connection between the product and his diagnosis.