Roundup trial: Monsanto lawyer, expert witness spar over glyphosate-cancer link

Glyphosate x

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.

On [July 12], 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.

Related article:  Glyphosate-cancer lawsuits spur farmers to embrace 'precision farming' to help reduce chemical inputs

Monsanto lawyer Kirby Griffis challenged Portier’s…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.

Read full, original article: Monsanto Lawyer Clashes With Cancer Expert in Roundup Trial

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