Plaintiff DeWayne “Lee” Johnson alleges that exposure to certain Monsanto glyphosate-based herbicides, including Roundup, caused him to develop non-Hodgkin lymphoma.

A jury awarded more than $289 million to a former school groundskeeper who claimed he was diagnosed with terminal cancer after using Monsanto Co.'s weed killer.

The jury, in San Francisco Superior Court, found that Monsanto had failed to warn about the dangers of Roundup and Ranger Pro, both herbicides, and awarded $39.2 million in compensatory damages and $250 million in punitive damages to Dewayne “Lee” Johnson.

Johnson was diagnosed with non-Hodgkin's lymphoma in 2014 after two years of spraying Ranger Pro, a Monsanto herbicide similar to Roundup.

The trial, which began July 9, is the first to allege Monsanto's Roundup caused cancer. A San Francisco Superior Court jury started deliberating on Wednesday.

Plaintiff's lawyer R. Brent Wisner had asked jurors to award more than $39 million in compensatory damages and $373 million in punitive damages to his client.

“We were finally able to show the jury the secret, internal Monsanto documents proving that Monsanto has known for decades that glyphosate and specifically Roundup could cause cancer,” Wisner said in a statement. “Despite the Environmental Protection Agency's failure to require labeling, we are proud that an independent jury followed the evidence and used its voice to send a message to Monsanto that its years of deception regarding Roundup is over and that they should put consumer safety first over profits.”

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Monsanto vice president Scott Partridge said in an emailed statement: “We are sympathetic to Mr. Johnson and his family. Today's decision does not change the fact that more than 800 scientific studies and reviews—and conclusions by the U.S. Environmental Protection Agency, the U.S. National Institutes of Health and regulatory authorities around the world—support the fact that glyphosate does not cause cancer, and did not cause Mr. Johnson's cancer. We will appeal this decision and continue to vigorously defend this product, which has a 40-year history of safe use and continues to be a vital, effective and safe tool for farmers and others.”

Monsanto, based in St. Louis, faces about 4,000 lawsuits over Roundup. About 150 suits have been coordinated in San Francisco Superior Court, one of which is Johnson's case, brought in 2016.

Monsanto's attorney, George Lombardi of Winston & Strawn, told jurors that reams of scientific studies and regulatory agencies, like the U.S. Environmental Protection Agency, showed no link between glyphosate, Roundup's key ingredient, and Johnson's cancer, a type of non-Hodgkin's lymphoma called mycosis fungoides.

Wisner relied on a 2015 decision by the International Agency for Research on Cancer classifying glyphosate as a possible carcinogen.