Monsanto Science Week marked the first time that the science behind the company’s Roundup weed killer was scrutinized under oath. Expert witnesses from both sides, including epidemiologists, toxicologists and others analyzed relevant research in open court before U.S. District Court Judge Vince Chhabria in what is formally known as a Daubert hearing.
A Daubert hearing is an evaluation to determine the admissibility of testimony from expert witnesses. Legal teams for the plaintiffs and the defendants present their experts to educate the court on the science behind both sides of the Roundup cancer connection.
Judge Chhabria presides over hundreds of Roundup cancer lawsuits in California’s Northern District. California State Court Judge Ioana Petrou, who is presiding over the California state court cases consolidated before her in Alameda County. They will decide whether the experts’ methodologies for analyzing the scientific evidence are valid. Plaintiffs and their experts have concluded that exposure to Monsanto’s Roundup weed killer can cause non-Hodgkin’s lymphoma.
What is Monsanto Science Week and How Does it Affect Roundup Cancer Lawsuits?
Michael L. Baum is managing shareholder of Baum Hedlund Aristei & Goldman, a law firm representing over 600 individuals in state and federal claims against Monsanto. He explained Science Week below:
“We are presenting the experts who are going to be testifying about the general causation issue – whether or not Roundup causes non-Hodgkin’s lymphoma. The experts from both sides are presented to the judges so they can evaluate whether the experts used a valid methodology for arriving at their conclusions. If they determine that the experts used a valid methodology to arrive at their conclusions, then they are permitted to testify in front of juries.”
Experts for the Plaintiffs (in order of appearance):
- Beate Ritz
- Dennis Weisenburger
- Alfred Neugut
- Charles Jameson
- Christopher Portier
- Aaron Blair and Dr. Matthew Ross (videotaped deposition testimony)
- Chadi Nabhan
Experts for Monsanto (in order of appearance):
Transcripts from Monsanto Science Week
Dr. Beate Ritz (pages 9-167)
Dr. Dennis Weisenburger (pages 168-213)
Dr. Dennis Weisenburger (pages 218-286)
Dr. Alfred Neugut (pages 287-370)
Dr. Alfred Neugut (pages 377-401)
Dr. Charles “Bill” Jameson (pages 402-539)
Dr. Christopher Portier (pages 540-595)
Dr. Christopher Portier (pages 603-700)
Dr. Aaron Blair, by deposition (page 702)
Dr. Matthew Ross, by deposition (page 703)
Dr. Thomas Rosol (pages 704-736)
Dr. Christopher Corcoran (pages 737-770)
Dr. Christopher Corcoran (pages 775-793)
Dr. Chadi Nabhan (pages 794-851)
Dr. Lorelei Mucci (pages 852-1011)
Testimony from Dr. Beate Ritz
In her Expert Report, Dr. Ritz concluded that “to a reasonable degree of scientific certainty, glyphosate causes NHL (non-Hodgkin lymphoma). Furthermore, to a reasonable degree of scientific certainty, glyphosate based formulations, including Roundup, cause NHL.”
Dr. Ritz’s testimony began with questions from plaintiffs’ attorney Katherine Forgie. Ritz walked through a series of epidemiological studies that show statistically significant risk factors linking glyphosate to cancer. Based on the literature, Dr. Ritz testified that the risk to individuals considered “routine users” of glyphosate was significant.
Judge Chhabria questioned Dr. Ritz on numerous facets of the literature. He appeared to be concerned about whether the studies were adjusted for exposure to other pesticides.
Dr. Ritz was also asked about a study Monsanto cites as critical evidence that there is no link between glyphosate and NHL. In her testimony, Dr. Ritz explained that the Agricultural Health Study (AHS) had several short-comings.
According to Dr. Ritz, the AHS data on glyphosate relied heavily on memories of individuals who filled out questionnaires to assess usage. “Recall error” is “really the enemy of exposure assessment,” Dr. Ritz said.
“I have to downgrade the importance of the AHS study for time exposure…I can’t take this study seriously if it shows no effect because all the effects are drowned in the noise of exposure misclassification.” – Dr. Beate Ritz
Midway through the day, Dr. Ritz gave a discussion of meta-analyses in which she testified that while there is animal data, “more importantly” human data shows an association between glyphosate and lymphoma. “DNA strand breaks have been shown to occur when individuals are exposed,” she said.
In an interesting exchange, Judge Chhabria asked Dr. Ritz if she believed glyphosate causes NHL or is capable of causing NHL. She answered by saying it depends on the individual’s case.
Dr. Ritz concluded her testimony after about five hours. Before leaving the witness chair, Judge Chhabria asked her one poignant question:
When asked if the studies she evaluated show that glyphosate has caused NHL in people, her reply: “Yes, I think they do.”
Testimony of Dr. Dennis Weisenburger
Dr. Dennis Weisenburger is the Chair of the Pathology Department of the City of Hope Medical Center in Omaha, Nebraska. He specializes in the study of non-Hodgkin’s lymphoma.
In the early part of his testimony, Dr. Weisenburger discussed why he believes that research studies provide strong evidence that exposure to glyphosate and glyphosate-based herbicides like Roundup can cause people to develop NHL. When questioned by Judge Chhabria about whether glyphosate is capable of causing NHL in humans at current exposure levels, Dr. Weisenburger answered, “I believe that, yes.”
“I concluded with a reasonable degree of medical certainty that glyphosate and the formulations including Roundup can cause non-Hodgkin’s lymphoma in humans exposed to these chemicals, both in the workplace and probably in the environment.” – Dr. Dennis Weisenburger
Testimony of Dr. Alfred Neugut
Dr. Alfred Neugut is a practicing medical oncologist, professor of cancer research and professor of medicine and epidemiology at Columbia University.
Dr. Neugut began his testimony by saying research shows a connection between glyphosate and NHL with great specificity. The consistency in study findings is something that cannot be ignored, he said, as scientists have seen repeated evidence linking glyphosate to NHL. “Every time you look what comes up? Glyphosate and NHL,” said Dr. Neugut.
In a discussion about the AHS study, Dr. Neugut called it an “excellent study for many things.” However, when it comes to understanding the link between glyphosate exposure and NHL, he testified that the AHS “fails.”
Among some of the study’s shortcomings, Dr. Neugut said the AHS does not account for the boom in glyphosate use in the 1990s, which dramatically altered the exposure levels for farmers compared to the beginning of the study when baseline exposure levels were established. Another flaw he cited was the loss to follow-up among study participants. AHS researchers attempted to avoid having large amounts of missing exposure data by using imputation—predicting or ‘guestimating’ exposures for participants who did not follow-up.
“You have an error on top of an error on top of an error… the AHS study is basically not so useful,” – Dr. Alfred Neugut
Testimony of Dr. Charles “Bill” Jameson
Dr. Charles W. Jameson (who goes by “Bill”) was the first toxicology expert to take the witness stand. Dr. Jameson has served as program leader for the National Toxicology Program (NTP) at the NIH’s National Institute of Environmental Health Sciences for 12 years. He was also a member of the International Agency for Research on Cancer (IARC) Working Group that concluded glyphosate is a probable human carcinogen in March 2015.
Dr. Jameson detailed the body of research that led him to conclude that glyphosate and Roundup can cause NHL at real-world exposure levels that farmers, farm workers and a host of others face when spraying the herbicide.
His testimony brought objections from Monsanto’s legal team, which Judge Chhabria overruled. Judge Chhabria questioned Dr. Jameson about the conclusions of the IARC Working Group. In particular, he asked why the Working Group arrived at the conclusions for “limited” evidence of carcinogenicity in humans and “sufficient” evidence of carcinogenicity in animals.
In his explanation, Dr. Jameson recalled that some of the scientists in the Working Group felt that the evidence for carcinogenicity in humans was actually stronger than the “limited” conclusion. Others disagreed, however.
In a rare moment of levity in an otherwise tense day of testimony, Dr. Jameson joked, “…if there are three epidemiologists in a room and you ask them their opinions, you’ll get four opinions.”
Like the other expert witnesses for the plaintiffs, Dr. Jameson said the weight of the combined animal and human data is what demonstrates the carcinogenicity of glyphosate and Roundup.
With regard to the animal studies, Dr. Jameson testified that it is “extraordinary” that so many have been conducted to evaluate a chemical, as the cost of such studies can be very expensive. The fact that researchers have so many animal studies for glyphosate adds to the strength of his conclusion that glyphosate causes cancer, he said. He also noted that animal studies demonstrate replication of several tumor sites, including liver tumors and malignant lymphoma.
For example: “…we had a lot of replication for malignant lymphomas in the mouse,” Dr. Jameson said, adding that the same tumors were seen in different studies in different labs at different times, which further underscores the strength of conclusion for carcinogenicity.
During cross examination, Judge Chhabria admonished a Monsanto attorney for repeatedly questioning Dr. Jameson on his deposition rather than questioning the expert on his opinions.
“Why don’t you ask his about his opinion now, Judge Chhabria told Monsanto attorney Joe Hollingsworth. “That’s normally how we do it”
When Hollingsworth asked again about some comments he made in his deposition, Dr. Jameson replied, “I’ve been misquoted and things have been taken out of context so many times… ”
Indeed, context was an area of emphasis for Judge Chhabria, who appeared to grow concerned about the possibility that Monsanto might be taking expert statements out of context. This was underscored when Judge Chhabria ordered Monsanto’s attorney to read aloud into the record two pages of testimony from a deposition that supported the expertise of Dr. Jameson’s analysis before he would allow the attorney to introduce a separate example from a deposition that sought to undercut Jameson’s expertise.
In toxicology, I evaluated all of the available toxicology data I could find, and it showed that glyphosate is an animal carcinogen, and that is the premise that is widely accepted in the toxicology — the scientific community, that if something is shown to be an animal carcinogen, then it is probably also a human carcinogen; and it’s biologically plausible that it is…a human carcinogen. – Dr. Charles Jameson
Testimony from Dr. Christopher Portier
Over the course of a lengthy career, Dr. Portier has held prominent leadership positions with the U.S. government combining the disciplines of toxicology, statistics and epidemiology, including:
• Associate Director of the National Institute of Environmental Health Sciences (NIEHS) National Toxicology Program and thus the nation’s chief toxicologist, among other roles at NIEHS.
• Director of the National Center for Environmental Health, Center for Disease and Prevention.
• Director of the Agency for Toxic Substances and Disease Registry (ATSDR).
In his testimony for Monsanto Science Week Dr. Portier discussed in great detail the animal studies which helped form his conclusion that there is a high probability that exposure to glyphosate causes NHL. “To a reasonable degree of scientific certainty, given the human, animal, and mechanistic evidence, glyphosate probably causes NHL, and the probability that glyphosate causes NHL is high,” he said.
Dr. Portier also talked about the Greim (2015) study that Monsanto has pointed to as proof that glyphosate does not cause cancer (according to documents in The Monsanto Papers, the Greim study was ghostwritten by a Monsanto scientist). According to Dr. Portier, the individual animal pathology data in Greim was “pretty poorly documented.”
In looking at three study reports from three Monsanto studies on glyphosate, Dr. Portier said they did not look like “full” study reports. “I didn’t see the statistical analysis I expected to see, and things like that. So I was a little lost.”
When asked about whether he believed Dr. Christopher Corcoran—an expert witness for Monsanto—has relevant experience evaluating animal bioassays, Dr. Portier said, “no…to evaluate the animal bioassay data to decide whether you’re seeing a positive result or a negative result, you have to be able to not only run a statistical test on it, but you really have to understand the biology. A lot of other things go into deciding whether this is a positive finding or not, and I don’t think he has experience in that area.”
Like other experts for the plaintiffs, Dr. Portier testified that he does not think highly of the AHS study, which he called “fatally flawed.”
After detailing his highly technical methodology and analysis, Dr. Portier told the court that he believes there is a strong causal connection between glyphosate and glyphosate-based herbicide exposure and NHL.
Testimony from Dr. Aaron Blair and Dr. Matthew Ross
Dr. Aaron Blair is a lead investigator of the Agricultural Health Study and the Overall Chair of the IARC 112 Working Group. Dr. Matthew Ross was part of the mechanism section of the IARC 112 Working Group. Both are expert witnesses for the plaintiffs. Their testimony before the court came in the form of videotaped depositions. Transcripts for both depositions are available on the Monsanto Court Papers page.
Testimony from Dr. Thomas Rosol
Dr. Rosol is a veterinary pathologist and professor at Ohio University College of Osteopathic Medicine, and Chairperson of the Department of Biomedical Sciences. He was the first of three experts from Monsanto to testify before the court during Monsanto Science Week.
According to Dr. Rosol, the data set for glyphosate is “enormous.” He added that he has not been involved in a study where he looked at 12 animal bioassays for one chemical. In his analysis, Dr. Rosol concluded that none of the studies demonstrated evidence of carcinogenicity.
He added that it is “important to put this data set into perspective. This is one of the cleanest sets of data I have ever evaluated in terms of carcinogenicity and this is something I routinely do.”
During his cross examination, plaintiffs’ attorneys discussed a key 1983 Monsanto Mouse Study, which Dr. Rosol’s referenced in his Expert Report. According to his testimony, Dr. Rosol never viewed the Mouse Study slides, even though there has been great debate over them. When further pressed, Dr. Rosol said he had not viewed any slides before preparing his Expert Report.
From the transcript:
Q: So have you reviewed any slides in your — in your — the preparation of your Expert Report?
A: No, I haven’t. In this kind of work I rarely look at slides.
Dr. Rosol was also one of very few people to have access to a Reading Room created in Europe in 2016 with the data from 12 animal bioassays. During cross examination, Dr. Rosol stated that he only “reviewed a small percentage of the data” from those studies.
From the court transcript:
Q: And it wasn’t important for you to stay and review more? I mean, you had this data no one else has access to. You didn’t want to review it all?
A: No. I was ready to leave after two days. I had what I needed.
Testimony from Dr. Christopher Corcoran
Dr. Christopher Corcoran is a professor of Mathematics and Statistics and director of Data Management and Statistics Core, Center for Epidemiologic Studies at Utah State University.
Dr. Corcoran spent much of his testimony poking holes in Dr. Portier’s Expert Report. “He hasn’t used a consistent approach. It’s been kind of a moving goal post,” Dr. Corcoran testified.
During his cross examination, plaintiffs’ attorneys discussed Dr. Corcoran’s analysis of tumor data. “Isn’t it true, Dr. Corcoran, that you didn’t run logistic regression with the full dataset in this case?” Dr. Corcoran told the court that his data analysis came from the Greim (2015) study supplement, a study that has become the subject of scrutiny.
Plaintiffs’ attorneys also asked Dr. Corcoran about his experience with rodent carcinogenicity studies to assess the ability of a chemical to cause cancer. He testified that in his career, he has not designed, performed or overseen any rodent carcinogenicity studies to assess the ability of a chemical to cause cancer.
Testimony of Dr. Chadi Nabhan
Dr. Nabhan is a board-certified clinical medical oncologist and past assistant professor of Medicine at the University of Chicago. Dr. Nabhan currently serves as Medical Director of Cardinal Health. His clinical practice and academic research for the past 17 years has focused on lymphomas.
In his testimony, Dr. Nabhan discussed the process by which IARC conducts its Monographs to determine whether chemicals and substances are carcinogens. The agency has a high bar in consideration for what chemicals or substances it will review, he said. Exposures must be high and the animal data must be strong.
Since 1965, IARC has reviewed over 1000 agents and found around 20 percent to be carcinogens; 120 are classified as carcinogens and 81 classified as probably carcinogenic. Glyphosate is listed as a probable human carcinogen.
“In my opinion, the [NHL] risk [of exposure to glyphosate] is clinically significant enough that patients should be aware of it,” said Dr. Nabhan. “The IARC report is very convincing.”
As with other colleagues testifying as expert witnesses for the plaintiffs, Dr. Nabhan testified that he does not have a high opinion of the Agricultural Health Study (AHS), which was discussed at length.
“There are so many flaws in this study that it’s impossible to draw any conclusions,” he said. When asked about the updated analysis released at the end of 2017, he called it “an updated analysis of an already flawed study.”
Testimony of Dr. Lorelei Mucci
Dr. Mucci is an associate professor of epidemiology at Harvard T.H. Chan School of Public Health and an assistant professor of medicine at Harvard Medical School. She focuses her research and teaching on cancer epidemiology.
A significant amount of Dr. Mucci’s testimony during Monsanto Science Week centered on the AHS study, which she characterized as “one of the most important epidemiological studies on this topic [i.e. glyphosate].”
Her review of the AHS drew some questions from the court about the validity of self-reporting in the study’s first and second questionnaires regarding glyphosate exposure levels. Based on her analysis of the AHS and the epidemiological data she reviewed, Dr. Mucci stated that it is her opinion that there is no evidence of positive association between glyphosate exposure and NHL, and there is no evidence of dose response.
During her cross examination, Dr. Mucci told the court that her opinion is based solely on the epidemiological data. She did not look at toxicological studies or animal studies.
Update on Monsanto Science Week
Citing insufficient time during the Daubert hearings, Judge Chhabria has asked Dr. Beate Ritz and Dr. Christopher Portier for additional testimony. Dr. Portier will discuss his opinion as to the epidemiological evidence and Dr. Beate Ritz will be asked some follow-up questions to her testimony during Science Week.