Did weed killer Roundup cause cancer in Sonoma County resident Edwin Hardeman?

It was Christmas morning in 2014 when Sonoma County resident Edwin Hardeman looked in the mirror and saw a big lump on the side of his neck.

Within two months, he’d been diagnosed with a cancer of the blood called non-Hodgkin lymphoma and began chemotherapy treatment.

Today, Hardeman is at the center of a closely watched trial in U.S. District Court in San Francisco where he is up against the company that makes Roundup, the weed killer he routinely used for about three decades that he believes gave him cancer.

Hardeman’s case is the first of three bellwether trials that, if the juries decide in favor of the plaintiffs, could establish settlement standards for thousands of pending lawsuits across the country against Roundup manufacturer Monsanto, a branch of the Germany-based conglomerate Bayer, alleging a key ingredient is making people sick.

“You have this one man right there in Sonoma, and by luck of the draw his case has the potential to move the needle,” said UC Hastings professor David Levine, a close watcher of the case. Federal jurors Tuesday will hear closing arguments in a first phase of Hardeman’s trial.

They will decide whether testimony from doctors, Hardeman and other evidence presented by his team of lawyers supported his claims that the glyphosate-based product is carcinogenic and that using it contributed to his illness.

If the jury verdict goes in his favor, Hardeman will then be able to present evidence toward his allegations that Monsanto presented its popular weed killer as a safe product while concealing research that may have provided the public with information about its potential health risks.

He is asking for unspecified compensatory and punitive damages.

The herbicide maker is facing an avalanche of lawsuits from people claiming Roundup has caused cancer and other health problems. A Bayer spokesman said there are about 11,200 cases in both state and federal courts, and noted that “is not indicative of the merits of the litigation.”

In what’s been described as the first Roundup case to go to trial, a San Francisco jury awarded $289 million in damages last year to a former school groundskeeper with non-Hodgkin lymphoma after finding Monsanto failed to warn him about the potential health hazards from using Roundup, which he did over years as part of his job.

A judge reduced the damages to $78 million, and Monsanto has appealed the decision.

In response to questions from The Press Democrat, a Bayer spokesman said the company contends “none of the science presented at trial - epidemiological, animal or mechanistic - supports the conclusion that glyphosate or the Roundup formulation was a substantial cause” of the plaintiff’s cancer.

The company defended its herbicide as safe to use based on “extensive science over four decades.”

“While we have great sympathy for Mr. Hardeman, Bayer stands strongly behind these products and will vigorously defend them,” company spokesman Daniel Childs said.

Hardeman couldn’t be reached, and his attorneys didn’t respond to repeated requests for comment made over the last week. A representative for the law firm said they are not speaking to the media during the trial.

When Hardeman testified at the federal courthouse in San Francisco last week, he described using Roundup regularly for nearly three decades, first at a Gualala property and then a 56-acre parcel in Forestville he and his wife called home from 1988 until about five years ago.

“During these 26, 28 years that you used Roundup at your two properties, Mr. Hardeman, did you ever get Roundup on your skin?” his attorney Jennifer Moore said while questioning him on the stand last week.

“Oh, yes, quite a few times. I described the sense that I breathed something in. Also a couple of times when it was foaming out the top when you are mixing it, it could get on your hands,” Hardeman said.

The Forestville property, 56 acres of mostly steep terrain on Westside Road near the Russian River, was in disrepair when Hardeman and his wife Mary Hardeman bought it from a seller who had an exotic animal preserve.

Hardeman said he used Roundup at least once a month from May through November every year to control poison oak and weeds like scotch broom that provided a safe harbor for ticks.

Early on, he developed a severe poison oak rash all over his body from clearing brush.

“I just started off on this mission to go after it,” Hardeman said from the stand.

Using a pump sprayer, Hardeman would spray the herbicide in the driveway, parking areas, near water tanks and on trails along the property to reduce the amount of poison oak and other problem weeds on his land. He described spraying it in the wind.

“Sometimes you could ... be spraying it and an afternoon wind would come up. You get winds there. And you get a little blow back, and it would blow back up on you,” Hardeman said.

The more a person is exposed to Roundup, the greater the risk the person has of developing non-Hodgkin lymphoma, according to the testimony from Dennis Weisenburger, a pathologist specializing in disease of the blood. Weisenburger was part of a team of scientists originally convened to study a rapid increase in the incidents of non-Hodgkin lymphoma in the 1980s, and which still meets today.

Weisenburger discussed research and studies that showed “that glyphosate is both genotoxic and carcinogenic.”

Attorneys representing Monsanto didn’t cross-examine Hardeman. But lawyers for the company have suggested during the trial that Hardeman’s previous diagnosis for hepatitis C was a risk factor for cancer. Hardeman testified during trial that he was cured of hepatitis C in 2006 after receiving treatment, and has been free of the disease since.