SAN FRANCISCO (CN) – On the fourth day of a jury trial over whether Monsanto’s Roundup weed killer caused a Bay Area man’s deadly lymphoma, a cancer-risk expert and a lawyer for the agrichemical company sparred over the evaluation of scientific research on the herbicide’s potential carcinogenicity, with neither side emerging a clear winner.
The expert, Christopher Portier, testified for more than five hours in San Francisco County Superior Court about the ways he believed the research should have been evaluated by U.S. and European regulators to make conclusions about glyphosate’s carcinogenicity, and slammed them over their methods of analysis.
The methods have prompted regulators to conclude that glyphosate is not a likely human carcinogen. But Portier says it is, and that it can cause non-Hodgkin lymphoma, the cancer from which plaintiff DeWayne Johnson is dying.
“My entire career been about using scientific evidence to make decisions, primarily about the carcinogenicity of compounds, and we’ve worked for years and years to do that appropriately,” Portier testified during cross-examination. “This was just so amazingly wrong in the way they were doing it.”
Johnson, a retired school groundskeeper, sued Monsanto in 2016 after he developed cancerous lesions over most of his body. He alleges that Roundup caused his lymphoma after he was twice drenched in the herbicide while spraying it in schoolyards for his job. He also claims Monsanto has known for decades that Roundup is carcinogenic but didn’t disclose it for fear of disrupting its $6.6 billion global business.
Glyphosate, the active ingredient in Roundup, is the most widely used agrichemical in history. Monsanto introduced it in 1974, and its use exploded after Monsanto began selling “Roundup-ready” seeds – engineered to resist glyphosate – in 1996. More than 2.6 billion pounds of glyphosate was spread on U.S. farmlands and yards between 1992 and 2012, according to the U.S. Geological Survey.
Monsanto earns $1.9 billion a year from Roundup and $10.2 billion from “seeds and genomics,” most of that category being Roundup-ready seeds.
In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate as a “probable” human carcinogen, touching off a heated debate over evaluation methods.
On Friday, Portier testified that the European Food Safety Authority (EFSA) missed 15 tumors in a group of rodent studies done on glyphosate because it used the wrong method of analysis.
The agency called the tumors irrelevant and declined to change its finding of non-carcinogenicity for glyphosate.
Portier accused EFSA of failing to follow its own guidelines for evaluating herbicides, which he said state that if two positive animal tests are observed, the chemical in question must be classified as a possible carcinogen.
“There is much more than two positive findings in these data,” he said.
Portier also assailed the twin decisions by EFSA and the U.S. Environmental Protection Agency that glyphosate isn’t carcinogenic despite finding an association between glyphosate and cancer that he said could have been causal.
“That is an astonishing finding,” he said of the decisions. “It’s completely illogical.”
Monsanto lawyer Kirby Griffis challenged Portier’s tumor assessment on cross-examination.
“It’s almost certain that the number of mouse and rat tumors you told the jury about are false-positives,” he said, referring to the 15 additional tumors.
Griffis, who is with Hollingsworth LLP, explained that animal carcinogenicity studies involve dosing large numbers of animals. The large number of resulting tests creates a number of false-positives by chance alone, he said.
Portier said that was true, but that he had based his conclusions on the strongest trends in the data.
Griffis then questioned IARC’s glyphosate review, on which Portier acted as an adviser. A mouse review used by IARC found an increase in benign and malignant kidney tumors, Griffis said. But the review, as well as a second mouse review IARC used, also found statistically significant negative trends for hemangiosarcomas, a rare cancer of the lining of the blood vessels.
“Each of these studies would provide evidence against a consistent tumor finding, right?” Griffis said. “That sort of evidence would tend to demonstrate inconsistency between the two.”
Portier disagreed. A negative response in hemangiosarcomas is “not that surprising because they’re rare,” he said.
Earlier in the day, Portier testified that the totality of scientific evidence shows that glyphosate and glyphosate-based formulations like Roundup can cause cancer in humans.
Formulations are slightly more carcinogenic than pure glyphosate, he added.
“Glyphosate is a carcinogen causing NHL [non-Hodgkin lymphoma] in humans,” he said. “Roundup has glyphosate in it, so by that argument you would say immediately that Roundup is also a human carcinogen.”
In arriving at his conclusion, Portier in part reviewed three human studies conducted in Central America of people who lived near areas sprayed with glyphosate.
A statistically significant increase in DNA damage was found in their cells five days after spraying that hadn’t been present before spraying, Portier said.
Most of that damage disappeared within four months, and no glyphosate was sprayed in the interim. That led him to conclude that the glyphosate damaged the participants’ DNA because “blood cells don’t stay around forever.”
However, chronic DNA damage from repeated sprayings can lead to cancer, he warned.
Griffis pushed back on cross-examination, revealing that EFSA had called the Central America results “equivocal” and “insufficient” to conclude that glyphosate was behind the damage.
“Is that astonishingly incorrect and so amazingly wrong,” Griffis asked, echoing the language Portier had earlier used to describe the agency’s glyphosate findings.
“I disagree with what they did to the data,” Portier replied, “which should have put it [glyphosate] into a different category.”
Testimony continues Monday.