By Jessica Domel
Multimedia Reporter

Despite doubts regarding evidence, a U.S. District Court judge in California will allow lawsuits alleging popular weedkiller Roundup causes cancer to move forward.

“The court concludes that the opinions of these experts, while shaky, are admissible,” Judge Vince Chhabria said.

The plaintiffs’ claims rely heavily upon a controversial report from the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) that has been the subject of several Congressional committee hearings doubting its veracity.

IARC classified glyphosate, the main ingredient in Roundup, as “probably carcinogenic to humans.”

“This classification is not as helpful to the plaintiffs as it might initially seem,” Chhabria wrote. “To render a verdict for a plaintiff in a civil trial, a jury must conclude, applying the ‘preponderance of the evidence’ standard, that the plaintiff’s NHL (non-Hodgkin’s lymphoma) was more likely than not caused by exposure to glyphosate.”

The judge noted the IARC report is a public health assessment that identifies hazards. It does not evaluate the risk the hazard poses at particular hazard levels.

“Moreover, even with its hazard assessment, IARC makes clear that although it uses the word ‘probably,’ it does not intend for that word to have any quantitative significance,” Chhabria wrote. “Therefore, the public health inquiry does not map nicely onto the inquiry required by civil litigation. And the hazard assessment IARC undertakes is too limited and too abstract to fully serve the plaintiffs’ purposes here.”

The plaintiffs’ evidence of a causal link between NHL and Roundup exposure is also weak, according to the judge’s summary.

“The evidence, viewed in its totality, seems too equivocal to support any firm conclusion that glyphosate causes NHL. This calls into question the credibility of some of the plaintiffs’ experts, who have confidently identified a causal link,” Chhabria wrote.

Regardless of that assessment, case law emphasizes a trial judge should not exclude an expert opinion because he/she believes the evidence is shaky.

“So long as an opinion is premised on reliable scientific principles, it should not be excluded by the trial judge. Instead, the weaknesses in an unpersuasive expert opinion can be exposed at trial, through cross-examination or testimony by opposing experts,” Chhabria wrote.

He said the jury may reject what former IARC director Dr. Christopher Portier, Dr. Beate Ritz and Dr. Dennis Weisenberger say about glyphosate because the opinions are too results-driven or the evidence behind the opinions is too weak.

“But applying the standard set forth in the case law for admission of expert testimony, the court cannot go so far as to say these experts have served up the kind of junk science that requires exclusion from trial,” Chhabria wrote. “And the testimony of these three experts is directly on topic, because they (in contrast to some other experts) went beyond the inquiry conducted by IARC, offering independent and relatively comprehensive opinions that the epidemiological and other evidence demonstrates glyphosate causes NHL in some people who are exposed to it.”

In addition to the witnesses, the plaintiffs provided the court with information from case studies they claim links Roundup to NHL.

The Environmental Protection Agency (EPA) released a new assessment of glyphosate in December, finding it is not likely to cause cancer in humans.

“The agency’s assessment found no other meaningful risks to human health when the product is used according to the pesticide label,” a release from EPA said.

The review evaluated dietary, residential/non-occupational, aggregate and occupational exposures to glyphosate.

In its study of human breastmilk, the EPA reported it found no glyphosate residue.

In a 2015 report, the European Food Safety Authority revealed its evidence reveals glyphosate is unlikely to cause cancer in humans.

The Associated Press reports the judge’s decision could open the door to hundreds of lawsuits claiming Roundup exposure contributed to NHL.