Writing that "a reasonable jury could conclude" that the herbicide in Monsanto's Roundup can cause a form of cancer, a federal judge says liability lawsuits against the company should proceed, siding with plaintiffs against an effort to quash the litigation. But the judge also said some of the expert opinions presented so far in the case are "shaky."

The lawsuits allege that glyphosate, the herbicide in the widely used Roundup, can cause non-Hodgkin's lymphoma — and that Monsanto didn't warn consumers or regulators about that alleged risk.

Claims against Monsanto received a boost in 2015, when the International Agency for Research on Cancer – part of the World Health Organization — announced that two pesticides, including glyphosate, are "probably carcinogenic to humans."

Monsanto is now facing hundreds of lawsuits, many of which were filed after that 2015 announcement. Dozens of the suits were joined to be heard in the court of U.S. District Judge Vince Chhabria – who, even as he allowed the case to proceed, said the plaintiffs "appear to face a daunting challenge" in supporting their claims at the next phase of the case.

Citing expert testimony from three doctors who spoke on plaintiffs' behalf, Chhabria wrote in his ruling, "the opinions of these experts, while shaky, are admissible."

It wasn't the time, Chhabria said, for a judge to exclude those opinions – even if he believes potential jurors in the case might question the experts' findings or credibility. He allowed their testimony to stand, even as he excluded all or part of other opinions from the plaintiffs' experts.

The judge wrote, "Therefore, the plaintiffs have presented evidence from which a reasonable jury could conclude that glyphosate can cause NHL at human-relevant doses. Monsanto's motion for summary judgment is denied."

Up next, Chhabria said, individual plaintiffs will need to present "enough evidence to warrant a jury trial on whether glyphosate caused the NHL [cause non-Hodgkin's lymphoma] they developed."

In response to the ruling, Monsanto Vice President Scott Partridge said, "More than 800 scientific studies and reviews, the U.S. EPA, the National Institutes of Health and regulatory agencies around the world have concluded glyphosate-based herbicides do not cause cancer."

Partridge added in his statement to NPR, "We have sympathy for anyone suffering from cancer, but the science clearly shows that glyphosate was not the cause."

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