318-The True Story Behind the Monsanto Roundup Trials, with Dr. Chadi Nabhan 

| Care, Podcast

Though the International Agency for Research on Cancer concluded that glyphosate, the main ingredient in Roundup, is a probable carcinogen, it remains the most widely used herbicide in the United States. My guest this week, Dr. Chadi Nabhan is here to tell the story behind three court cases that concluded with Roundup maker Monsanto owing large sums to glyphosate users who developed non-Hodgkin lymphoma.

Chadi is a medical oncologist and a hematologist in the greater Chicago area. Over the past several years he has transitioned out of treating cancer patients directly and has become more interested in understanding the healthcare ecosystem at a larger level, he says. “There is nothing more rewarding than being with a patient in the exam room and the patient or the family thanking you for the care you provide, but I really wanted to help patients from a larger platform,” he adds. He has carefully studied glyphosate and served as an expert witness in the three key lawsuits against Monsanto that went to trial. 


Dr. Chadi Nabhan

In front of the courtroom where Johnson won the first case in August 2018
Photo Courtesy of Dr. Chadi Nabhan


Chadi’s new book is “Toxic Exposure: The True Story Behind the Monsanto Trials and the Search for Justice.” If that’s not a compelling subtitle, I don’t know what is. This book is a real page-turner and was a pleasure to read as an organic gardener who is conscious of Roundup’s ubiquity in horticulture and the concerns around it. Whatever your take on glyphosate is, you probably know that Monsanto is like a four-letter word for many gardeners and environmental stewards. 

How Dr. Chadi Nabhan Became an Expert Witness and Author

Chadi, already an M.D., returned to school and earned a Master of Business Administration in healthcare management. Today, he works for a large molecular profiling and data company that helps physicians understand the molecular underpinning of cancer so they can select the proper therapies. 

He says while it was common for lawyers to ask doctors like himself to look at cases for malpractice, he never considered himself an expert witness. There is a lot of uncertainty in medicine, he notes, and malpractice cases don’t always appreciate those nuances. When he receives such requests from attorneys, he typically ignores them. 

The Miller Firm, a national practice that represents patients who have been seriously injured by pharmaceuticals and other products, found Chadi while looking for a lymphoma expert. The firm was representing several cancer patients who were suing Monsanto. A colleague gave the firm a good referral, so he heard the attorneys out.

The encounter was serendipitous, he says. He recalls learning from the firm about the cancer concerns around glyphosate and thinking that he should look into them himself. He decided to conduct his own research.

Chadi points out that information on what Monsanto is, the fact that there were trials, the outcomes of those trials and that Bayer bought Monsanto is all readily available for anyone who wishes to look it up on the internet. He didn’t write his book to reiterate those facts. Rather, he says, he wanted to take readers through the journey from his point of view.

He says he wanted readers to understand the uncertainties he had to think through. He notes that if everyone was already convinced that glyphosate is carcinogenic, there would be no litigation and there would be no clinical trials. The reason for the controversy is that there are two camps: those who are convinced there is a cancer link and those who will defend glyphosate and Roundup “to the bones,” Chadi says.

In addition to what he could learn scientifically, he was also able to learn about the conduct of the company.

“It is being told from through my lens, but it’s really about the patients,” he says of his book. “And it is about what they had to endure, and the lawyers that had defended these patients.” 

He also sought to make the book accessible to all readers. “You do not need to be a physician,” he says. “You do not need to be a lawyer, and you do not need to be an environmentalist or an activist to understand the book.”

From being in a courtroom, he learned the importance of simplifying complexities and giving clear explanations. “The jury really wants to understand things in an easy way to digest, and that really was my goal,” he says.

Case No. 1 – Johnson v. Monsanto

Dewayne “Lee” Johnson was a groundskeeper who started using Ranger Pro, a Monsanto glyphosate product, in 2012. He worked with glyphosate five days a week and had a few incidents when the product spilled.

“I heard about Mr. Johnson through the Miller firm,” Chadi recalls. The firm took Monsanto to a California state court in San Francisco. 

“There was a patient in California, a groundskeeper, who had heavy exposure to Roundup who developed a form of lymphoma that affected his skin, and that he had some recent biopsies that suggested a more aggressive behavior of the lymphoma,” Chadi says. “And because of that, there’s a law in California that you can expedite the trial court date of patients who might have poor prognosis, because they need to have their day in court.” 

Chadi reviewed the medical records and examined Mr. Johnson, who said that about two years after he started spraying glyphosate, he developed a rash on his skin that appeared abnormal. Mr. Johnson had called Monsanto about it but never got a call back.

Mr. Johnson’s case was the first ever brought against Monsanto over Roundup. It started in July 2018, and concluded August 10, 2018, with $289 million awarded to Mr. Johnson — though that figure was later significantly reduced.

A major challenge in winning a court case over non-Hodgkin lymphoma is that it is often unclear how a patient developed the cancer. In the medical field, it’s called “idiopathic” — meaning the cause of a disease is undetermined

“What Monsanto’s argument was, is that all of these cases were idiopathic, which means that we don’t know what caused them,” Chadi says. 

He says that though the majority of non-Hodgkin lymphoma cases are due to unknown causes, some cases, more likely than not, were caused by glyphosate and Roundup.


Beans in suspected killer compost

These bean plants are affected by an herbicide.


Glyphosate’s Dubious Record

Roundup was commercialized in 1974, when the U.S. Environmental Protection Agency was very small, Chadi points out. It was safety tested by Industrial Bio-Test Laboratories, or IBT Labs, which later was found to have participated in scientific misconduct.

“The IBT Lab turned out to be a fraudulent lab,” Chadi says. “They actually made up data.”

When people hear that the EPA, the largest environmental authority in the country, says a product is safe, they believe it must be safe, he says. But he adds that what he has learned is that citizens, advocates and people who care about each other need to look under the hood and never fear asking questions.

“We must ask questions,” he says. “If we don’t ask questions, we are going to rely on others providing answers, and these others may have a different agenda, maybe politicized.”

Because glyphosate is not deemed an unsafe product by the EPA, there is no requirement that it have warning labels or any indicator on the packaging to advise the user to take precautions, Chadi points out. “That is one of the things that is a sore subject to me, because to this day, there is no warning label.”

Unlike cigarettes, which come with warnings of cancer risks and other ill health effects, Roundup is not labeled as risky.

“Monsanto has continued to argue to this day it is very safe, extremely safe, — no issues — has zero health hazards whatsoever,” Chadi says.

Mr. Johnson testified that he was told during a training course that glyphosate is so safe, one can drink it.

The International Association for Research on Cancer, a division of the World Health Organization, reached a different conclusion about glyphosate from the EPA.

“They convene every so often, and they look at whatever we are using in the environment, or whatever humans are using, and look at the carcinogenicity of these compounds,” Chadi says.

In March 2015, IARC convened, looked at the evidence, including animal studies and human studies, and concluded that glyphosate is a probable human carcinogen. The findings were published in The Lancet Oncology

Case No. 2 Hardeman v. Monsanto

Edwin Hardeman developed non-Hodgkin lymphoma after many years of spraying Roundup for residential use. Hardeman, like Johnson, was a California resident, but his case was heard in federal court rather than state court. A jury found that Roundup was a “substantial factor” in Hardeman developing cancer, and he was awarded $80 million in 2019 — an amount that was later reduced.

Chadi says Hardeman v. Monsanto was the first bellwether case, or a case that would have implications on future federal cases.

He decided to write a book on his experience after a Daubert hearing — a hearing in which both sides of the case can question an expert witness in open court, but without the jury present, to evaluate whether the expert’s testimony will be admissible. 

“The judge looks at the methodology of how you reach your conclusion. So they’re not really questioning your conclusion, they’re questioning the methodology. Did you really use sound methodology and sound science to reach your conclusion? And then the judge will decide whether you are allowed to testify in court or not,” Chadi explains.

During the hearing, a Monsanto lawyer pointed out that Chadi had never lectured on Roundup to any of his students or colleagues.

Chadi had thought he was not allowed to lecture on Roundup while he was an expert witness actively involved in Roundup litigation. It wasn’t until that hearing, when the attorney questioned him, that he learned it would not pose a conflict of interest that would disqualify him from testifying. And that’s when he decided that the best way to get the word out would be to write a book that will tell the entire world his opinion and findings.

Monsanto appealed the Hardeman case all the way up to the U.S. Supreme Court, which refused to hear the case, so the ruling stood. 


herbicide application with a pump sprayer

Chemical herbicides that kill plants can also affect the gardeners that work with the chemicals. In the case of glyphosate, three separate court cases concluded that it can cause non-Hodgkin lymphoma.


Case No. 3 – Pilliods v. Monsanto

Alva and Alberta Pilliod are a husband and wife who were both diagnosed with non-Hodgkin lymphoma. Alberta’s cancer was found in her brain and categorized as primary central nervous system lymphoma, while Alva’s cancer was found in organs other than his brain.

Both of the Pilliods had heavy exposure to Roundup after 30 years of residential use. Because they were an older couple, Monsanto argued in court that they had a greater cancer risk due to age, Chadi says. Ultimately, that argument did not help Monsanto in court. The Pilliods won their case and were awarded  $2.1 billion in damages — $1 billion each — though the amount was later reduced to $87 million.

Chadi says that though people over 65 are at greater risk of cancer, that does not mean the Pilliods’ cancer diagnoses were both due to age. In fact, if a couple living together both develop the same cancer, it is more likely that a common environmental factor they were both exposed to is the cause. “It is common sense to ask the question, what is the common denominator that maybe both sides have been exposed to?” Chadi said on the witness stand.

Latency Period

Though Monsanto lost these three cases, it has won others. Chadi explains that one of the challenges in proving cancer was caused by exposure to a certain product is the latency period. That is the time that elapses between the exposure and when cancer manifests, such as the years that go by between using tanning beds frequently and developing skin cancer.

There is no uniform latency period for Roundup exposure and cancer, Chadi points out, adding that Dewayne “Lee” Johnson was exposed to glyphosate for only two years, but he used it five days a week. Someone else could be exposed infrequently for 20 years before developing cancer.

“In non-Hodgkin lymphoma, that duration could be short or could be long,” he says. “It is not one number. 


Applying pesticides

When home gardeners or professional applicators work with pesticides frequently over a short period or occasionally over a long period, they may suffer from ill health effects that will manifest later on.


The Future of Roundup

Bayer-Monsanto has announced that it would stop selling glyphosate products for residential users in 2023, but it’s halfway through 2023 and Roundup with glyphosate is still being sold. 

“There was nothing mandated by court that they have to pull it out,” Chadi says.

He also notes that the surfactant — which increases absorption — that is used in Roundup in the United States is banned in Europe.

Chadi’s wish is that the public can be warned and that Roundup and other products containing glyphosate will be removed from the market and replaced by a safer compound.

He acknowledges how difficult removing Roundup from the market will be because many farmers like how they can spray Roundup Ready crops with Roundup to kill weeds but not their crops. And who sells Roundup Ready seeds? Monsanto.

“If you’re spraying it on corn, on soybean, on alfalfa, on everything, you know, maybe it’s in cereal, it’s in bread, it’s in a lot of things that we actually consume,” Chadi says. “I don’t know what other health effects this might cause beyond cancer. … We should ask these questions. Is it possible that, for example, some of the things that we are observing in terms of gut intolerance, autoimmune disease and other things are related to that? …”

“This is a provocative thought that I think researchers and others should really investigate and look into because it’s certainly plausible.”

The Closing Argument

At the conclusion of the Johnson trial, attorney Brent Wisner delivered a two-hour closing argument. Chadi included excerpts of the argument in his book.

“It’s really history in the making,” Chadi says. “But his ability to articulate and really deliver the information is superb. In my opinion, it was a captivating way of presenting the closing argument, and it’s available on YouTube.” 


Toxic Exposure by Dr. Chadi Nabhan

Dr. Chadi Nabhan shares his experience as an expert witness on glyphosate and lymphoma risk in “Toxic Exposure: The True Story Behind the Monsanto Trials and the Search for Justice.” (Photo Courtesy of Dr. Chadi Nabhan)


If you haven’t already listened to my conversation with Dr. Chadi Nabhan on glyphosate litigation, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.

Do you avoid using Roundup? Let us know in the comments below.

Links & Resources

Some product links in this guide are affiliate links. See full disclosure below.

Episode 007: Organic Weed Control with Jeff Gillman

Episode 155: Managing Weeds Organically: Rodale Institute’s Latest Research, Prevention and Control

Episode 157: How to Prevent Weed Overwhelm: A Practical Organic Approach for Real Results, With Margaret Roach

Episode 281: The Chemical Age: How Tools of War Became Agricultural Chemicals

joegardener Online Gardening Academy™: Popular courses on gardening fundamentals; managing pests, diseases & weeds; seed starting and more.

joegardener Online Gardening Academy Organic Vegetable Gardening: My new premium online course. The course is designed to be a comprehensive guide to starting, growing, nurturing, and harvesting your favorite vegetables: no matter what you love to eat, no matter where you live, no matter your level of gardening experience.

joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out. 

joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.

joegardener Online Gardening Academy Growing Epic Tomatoes: Learn how to grow epic tomatoes with Joe Lamp’l and Craig LeHoullier. 

joegardener Online Gardening Academy Master Pests, Diseases & Weeds: Learn the proactive steps to take to manage pests, diseases and weeds for a more successful garden with a lot less frustration. Just $47 for lifetime access!

joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.

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Growing a Greener World®  


Chadi Nabhan on Twitter: @chadinabhan

Toxic Exposure: The True Story Behind the Monsanto Trials and the Search for Justice” by Chadi Nabhan, M.D., M.B.A.

Bayer Pursued Monsanto Despite Weedkiller Suits and Executive’s Concern”  |  The Wall Street Journal

The Botched Bet to Buy Monsanto” | The Journal Podcast

Roundup Cancer Attorney Brent Wisner Closing Argument | Johnson v. Monsanto”  | YouTube Video

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Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Corona Tools, Milorganite, Soil3, Greenhouse Megastore, Territorial Seed Company, Earth’s Ally, Proven Winners ColorChoice and Dramm. These companies are either Brand Partners of and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.

About Joe Lamp'l

Joe Lamp’l is the creator and “joe” behind joe gardener®. His lifetime passion and devotion to all things horticulture has led him to a long-time career as one of the country’s most recognized and trusted personalities in organic gardening and sustainability. That is most evident in his role as host and creator of Emmy Award-winning Growing a Greener World®, a national green-living lifestyle series on PBS currently broadcasting in its tenth season. When he’s not working in his large, raised bed vegetable garden, he’s likely planting or digging something up, or spending time with his family on their organic farm just north of Atlanta, GA.

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