OAKLAND, Calif. (CN) – In the trial of claims by an elderly couple who say the world’s most popular weed killer gave them cancer, jurors heard of a new study linking Roundup’s active ingredient glyphosate to non-Hodgkins lymphoma.

The study, a meta-analysis conducted by University of California, Berkeley, toxicologist Luoping Zhang and two colleagues found a “compelling link between exposure to glyphosate-based herbicides and an increased risk of non-Hodgkin lymphoma.”

Zhang and her team did a comprehensive review of the existing literature on glyphosate, focusing on the mostly highly exposed groups in those studies.

The analysis even accounted for the Agricultural Health Study, a large, long-term study on the effects of pesticides on farmers in the United States that began in 1993. That study found no cancer link between Monsanto’s weed killer Roundup and non-Hodgkins Lymphoma.

Zhang and two of her co-authors had been board members for the U.S. Environmental Protection Agency’s 2016 scientific advisory panel on glyphosate.

At trial Monday, UCLA epidemiologist Dr. Beate Ritz testified she trusted the analysis, saying “they really used the best exposure estimate.”

Ritz spent much of her testimony condemning the Agricultural Health Study as rife with problems, particularly because it misclassified some of the participants. Farmers who reported no glyphosate use in 1993, for example, could have been considered a non-user throughout the study, even if they began using Roundup a year later. The researchers also failed to adequately follow up with the participants, Ritz said.

This kind of misclassification, Ritz said, favors a finding of no carcinogenicity. Monsanto has cited the Agricultural Health Study as proof of no connection between glyphosate and non-Hodgkins lymphoma.

During cross-examination, Monsanto attorney Kelly Evans hit hard on Ritz’s position as a member of the Agricultural Health Study advisory board in 2001. He asked her why she didn’t speak up about her concerns with the study earlier, before the plaintiffs’ attorneys retained her as an expert witness in 2016.

“So you did not tell anybody the criticisms you told the jury today,” Evans asked. “You didn’t bother to pick up the phone or send an email?”

Ritz said there was nothing she could do at that point. The study had been going on for years and she didn’t realize what the Agricultural Health Study researchers were really doing until 2002.

“What would have been changed by that? They had already done all of their data collection,” she said. “What do you tell people who put their blood and tears into something that didn’t work? Do you hit them over the head with it? No, you don’t.”

She added that if the researchers had gotten 98% of the original participants to follow up, “they could have done a bang-up job.”

The case of Alva and Alberta Pilliod is the third to go to trial alleging Roundup – specifically the active ingredient glyphosate – causes non-Hodgkins lymphoma. A jury awarded Sonoma County resident Ed Hardeman $75 million in punitive damages last month, and a state court jury in August 2018 awarded San Francisco Bay Area groundskeeper Dewayne Johnson $289 million in damages – later reduced by a judge to $78 million – after finding Roundup caused his terminal non-Hodgkins lymphoma.

Toward the end of the day Monday, the Pilliods’ lawyers played a taped deposition of former Monsanto toxicologist Mark Martens who in the Johnson trial acknowledged the agrochemical giant declined to publish research by genetic toxicologist Jim Parry of Swansea University in Wales. Parry concluded that both glyphosate and an Italian formulation of Roundup may cause genetic damage.

Monsanto had hoped Parry would be an ally against several studies released in the 1990s that the company deemed “problematic.”

Roundup came on the market in the 1970s and exploded in use in the mid-1990s.