Dr. Beate Ritz and Dr. Christopher Portier, two experts testifying on behalf of the plaintiffs in the Monsanto Roundup litigation, were called back to court this week to defend their assessments that Roundup causes non-Hodgkin lymphoma (NHL).
U.S. District Court Judge Vince Chhabria asked both scientists to return to San Francisco to provide further testimony weeks after they and other scientists testified on the alleged link between Roundup and NHL in what is formally known as a Daubert hearing, an evaluation to determine the admissibility of testimony from expert witnesses.
During the week of March 5, 2018, the legal teams for the plaintiffs and for Monsanto presented their experts to educate the court on the science behind both sides of the Roundup cancer connection, in what was dubbed ‘Science Week’.
Judge Chhabria, who oversees hundreds of Roundup cancer lawsuits in a consolidated federal multidistrict litigation (MDL), is not himself charged with deciding whether or not exposure to Roundup, or its main ingredient, glyphosate, causes NHL. Rather, he is to decide whether the methodology used by the experts is valid.
Judge Chhabria Invites Dr. Beate Ritz Back for Additional Testimony on Roundup Cancer Link
In a causation hearing following testimony from experts, Judge Chhabria was critical of Dr. Ritz’ analysis of the glyphosate data. In particular, Judge Chhabria expressed some doubt on whether Dr. Ritz considered exposure to other pesticides in her analysis of the data.
Dr. Ritz disagreed with Judge Chhabria’s characterization of her testimony from Science Week. “If it came across like I didn’t look at those, then that’s not right,” said Dr. Ritz on Wednesday.
In her testimony on the Roundup cancer link, she told Judge Chhabria that “over-adjusting” the data can bias the results. “Even though we have a knee-jerk reaction of put everything in the model, that’s the wrong approach,” she said.
To illustrate her point, Dr. Ritz cited the 1999 Hardell and Eriksson study, presenting a chart showing that adjusting for exposure to pesticides actually strengthened the link between glyphosate and cancer more than not adjusting. According to Dr. Ritz, adjusting for other pesticides “exploded the model,” resulting in what is known as “sparse data bias.”
“You can’t just throw everything in the model and expect to know the truth,” she said.
Judge Chhabria challenged Dr. Ritz with a hypothetical question—if she focused solely on the data that adjusted for exposure to other pesticides, would she reach the same conclusion that exposure to glyphosate causes cancer?
“I did put a plot together with all the adjusted numbers,” Dr. Ritz said, “and still believe what I said is correct.”
Dr. Christopher Portier Discusses NHL Latency and the Scientific Community’s Backing of IARC Conclusion on Glyphosate
Dr. Portier’s testimony focused on the subject of latency, the “failures” of a 2018 glyphosate study known as the Andreotti study, and perhaps most importantly, on the significance of nearly 100 world-renowned scientists agreeing with IARC’s conclusion that glyphosate is a probable human carcinogen.
Following Dr. Portier’s testimony on the Roundup cancer link during Science Week, Judge Chhabria wanted to know more about the subject of latency, the time between initial exposure to a carcinogen, and the cancer diagnosis.
Judge Chhabria’s concern with regard to the glyphosate data is that case-control studies looking at the link between glyphosate exposure and NHL utilized data from patients with latency periods of seven years.
Dr. Portier’s response was that numerous cohorts in the case-control studies had exposures between 10 and 12 years. Furthermore, these studies represent up to four million people.
“[W]hen you look at the size of the base population that these case-controlled studies represent, all of them as a conglomerate — I don’t know what it is, but it’s going to be in excess of 2 or 3 or 4 million people. And from such a large draw, you can get the people who have really short latencies and you can actually see the effects…it’s clear to me that even if somebody comes in and says the latency should be six years on average for glyphosate, that’s — for NHL, that’s still average. 50 percent of the people were less, 50 percent of the people were more, if it’s a bell curve. And so when you get that big population, you can see those short latency people.”
– Dr. Christopher Portier
According to Dr. Portier, one study found a link between glyphosate and non-Hodgkin lymphoma had actually adjusted for 48 pesticides, which made latency less of an issue. “Unless there’s a phantom pesticide out there causing the NHL, then seeing the NHL should worry you,” Dr. Portier testified. “If you hadn’t seen it, you might say it wasn’t long enough. But having adjusted for everything, I would have to conclude that is a real NHL pesticide.”
Another topic Judge Chhabria questioned Dr. Portier about was the 2018 Andreotti study, named after lead author Gabriella Andreotti of the National Cancer Institute. Dr. Portier said his meta-analysis of the glyphosate data would not include the Andreotti study because of some “failures” and because it is different than other epidemiological studies on glyphosate.
“After looking at the Andreotti study,” Dr. Portier testified, “I believe the strength of the observed association [between glyphosate and non-Hodgkin lymphoma] is high enough to warrant a strong opinion there…We have epidemiological studies—or evidence in the real world—in real people at current exposures.”
Lastly, Baum Hedlund Aristei & Goldman attorney Brent Wisner asked Dr. Portier during re-direct about a letter he sent to the European Food Safety Authority (EFSA) after it disagreed with IARC’s conclusions on glyphosate.
Wisner: I just kind of want to point out something that I think came out just now, this idea of IARC being a respected organization. You actually — this came up in cross-examination. There was about this publication that you were looking to have published relating to the glyphosate analysis and comparing it to what EFSA did, is that right?
Portier: The email referred to a letter that we were writing that eventually got published as a publication. But it referred to the letter criticizing EFSA on the way they did their evaluation.
Wisner: How many people signed that letter with you?
Portier: I think it was 96.
Wisner: We’ve heard a lot of testimony that when you have four epidemiologists you’ll have 25 opinions or something. Is there any significance to you, Dr. Portier, that 95 other world-renowned scientists would join you in your statement?
Portier: They all agreed with the statement. They very carefully looked at it. I don’t know what more to say about that. It was — we all feel the same way. We spend a lot of time and effort developing methods and evaluating literature. We want our governments to do the same — we want them to do it right. And so, yeah, they were all very much into this.