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Friday, May 17, 2024 | Back issues
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Monsanto Lawyers Question Cancer Expert in Roundup Trial

Lawyers for Monsanto attempted on Friday to undermine a Chicago oncologist's opinion that its Roundup weed killer caused a Bay Area man's terminal lymphoma, saying he omitted important details in his trial testimony proving the herbicide wasn't the culprit.

SAN FRANCISCO (CN) – Lawyers for Monsanto attempted on Friday to undermine a Chicago oncologist's opinion that its Roundup weed killer caused a Bay Area man's terminal lymphoma, saying he omitted important details in his trial testimony proving the herbicide wasn't the culprit.

Monsanto lawyer George Lombardi with Winston & Strawn flagged three instances in which Cardinal Health oncologist Chadi Nabhan failed to identify references in plaintiff DeWayne Johnson's medical records to the first symptoms of his disease, apparently showing Johnson had been exposed to Roundup for a little over a year before developing symptoms instead of the two years his lawyers claim.

Key to the case is how long it takes cancer symptoms to manifest after exposure to a cancer-causing agent. Monsanto says it takes 20 years, eliminating Roundup as the cause of Johnson's non-Hodgkin lymphoma. But Nabhan said Friday it can take just one month.

"There is no agreed-upon latency period with these types of exposures and these types of cancers," Nabhan, who specializes in lymphomas, testified in San Francisco County Superior Court. "Some patients can develop the disease early on and some patients can develop it in 20 years."

Although U.S. and European regulators have concluded that glyphosate, the active ingredient in Roundup, is safe, the World Health Organization’s International Agency for Research on Cancer (IARC) classified it in 2015 as a probable human carcinogen, prompting a slew of lawsuits against Monsanto in the U.S., including Johnson’s.

Johnson, a retired groundskeeper, sued in 2016 after he was diagnosed with a cutaneous form of non-Hodgkin lymphoma called mycosis fungoides that caused cancerous lesions over most of his body. He says he developed symptoms after he was twice drenched in Roundup while spraying it in schoolyards for his job with the school district in Benicia, 40 miles east of San Francisco.

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 is the most widely used agrichemical in history. Monsanto introduced it in 1974, and its use exploded in 1996 after Monsanto began selling “Roundup-ready” seeds engineered to resist the herbicide. More than 2.6 billion pounds of the chemical was spread on U.S. farmlands and yards between 1992 and 2012, according to the U.S. Geological Survey.

Nabhan, who is not Johnson's doctor but examined him and reviewed his medical records late last year, testified that Johnson's high exposure to Roundup over a two-year period was a "substantial contributing factor" in the development of his disease, noting that Johnson sprayed it four times a week, every week during the summer months and for several hours each day.

But on cross-examination, Lombardi pointed to medical records Nabhan omitted from his earlier testimony indicating Johnson had a rash in September and December 2013, an early symptom of non-Hodgkin lymphoma.

The records also showed Johnson was diagnosed in early 2014 with T-cell lymphoma, though not specifically with mycosis fungoides, Lombardi said. That more-specific diagnosis came later that year.

Johnson's lawyers have said throughout the two-week trial that their client's rash did not appear until May 2014, and that he wasn't diagnosed with any form of cancer until August 2014.

Johnson began using Roundup in June 2012. His timeline would mean he was exposed to Roundup for just shy of two years before contracting cancer. Monsanto's timeline means he was exposed for 15 months.

On redirect, Nabhan explained that although he did see the late 2013 rashes in Johnson's records, he didn't feel they were worth talking about because one record was related to treatment for bee stings, which could have accounted for the rash. The other one seemed inaccurate when reviewed in the context of the thousands of other records, he said.

"It's not unusual to see certain areas in medical records that are not clear or are mistaken," he said. "It happens in every single medical record."

Lombardi, however, went on to imply that Nabhan lied on the stand when he said he would not change his opinion that Roundup caused Johnson's cancer even if he had symptoms in 2013.

When asked in a January 2018 deposition the minimum time he believes it takes to develop non-Hodgkin lymphoma, Nabhan answered he would "have a tough time linking both [glyphosate use and non-Hodgkin lymphoma] together if lag time was less than a year."

Nabhan is the third expert witness Johnson's lawyers have called to the stand. Monsanto has sought to portray each of them as untruthful, or as greedy scientists attempting to profit from consulting contracts with law firms representing cancer plaintiffs against the company.

On Thursday, Lombardi pointed to six instances in which a Columbia University epidemiologist testified differently on the stand than he had in earlier depositions, as well as to his consulting contract with one of the law firms representing Johnson.

And last week, Hollingsworth LLP attorney Kirby Griffis, who also represents Monsanto, presented evidence that a toxicologist who advised IARC on its glyphosate finding lied that he wasn't being compensated for his glyphosate-related work when he had in fact signed a consulting contract with a law firm handling cases similar to Johnson's.

Lombardi ended his cross-examination Friday by noting that although Nabhan had testified favorably about IARC, the lymphoma specialist hadn't looked at the agency's finding about the link between glyphosate and non-Hodgkin lymphoma until he was hired to testify on Johnson's behalf.

"You're correct," Nahban said. "I wasn't aware.”

Johnson testifies Monday.

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