A Roundup on Roundup

Firm News | March 20, 2024

Several large verdicts have been reported recently concerning Monsanto’s signature herbicide, Roundup, which Monsanto has repeatedly represented to the world is “safer than table salt.”  In August 2018, a jury returned a $289 million verdict against Monsanto (later reduced to $78 million) to Dewayne Johnson, a school groundskeeper; a different jury awarded $80 million in March 2019 to Edwin Hardeman, who had sprayed Roundup on his 30 acre property; and in May 2019, a jury awarded more than $2 billion to Alva and Alberta Pilliod, who alleged that spraying Roundup around their house and other properties had caused their non-Hodgkins lymphoma.  There are more trials to come in various jurisdictions, including several pending cases in Missouri, and my firm’s case, captioned Cazier v. Monsanto et. al., which will be tried in April of next year in Bozeman. While certainly not comprehensive, this article provides background on the science establishing the link between Roundup and cancer and  explains why Roundup was allowed into the market without warnings.

a.    Studies Demonstrating the Carcinogenic Nature of Roundup

Roundup is a broad-spectrum herbicide that kills any growing plant, tree, vine, or shrub, whether regarded as a weed or a crop. The active (plant killing) ingredient in Roundup is glyphosate. To make the different formulations of Roundup, glyphosate is combined with other ingredients, such as surfactants (which help the glyphosate penetrate the protective outer layer of a plant) and even other herbicides.

Around the turn of this century, evidence began to mount in the medical literature demonstrating that glyphosate is a carcinogen. For example, in 1997, Chris Clements published “Genotoxicity of select herbicides in Rana catesbeiana tadpoles using the alkaline single-cell gel DNA electrophoresis (comet) assay.” The study found that tadpoles exposed to Roundup showed significant DNA damage when compared with unexposed control animals.

In 2003, Lennart Hardell and Mikael Eriksson published the results of two case controlled studies on pesticides as a risk factor for non-Hodgkins lymphoma (NHL) and hairy cell leukemia. The study concluded that glyphosate had the most significant relationship to NHL among all herbicide studies with an increased odds ratio of 3:11.

Also in 2003, AJ De Roos published a study examining the pooled data of mid-western farmers, examining pesticides and herbicides as risk factors for NHL. The study found a relationship between increased NHL incidence and glyphosate.

In 2006, César Paz-y-Miño published a study examining DNA damage in human subjects exposed to glyphosate. The study produced evidence of chromosomal damage in blood cells showing significantly greater damage after exposure to glyphosate than before in the same individuals, suggesting that the glyphosate formulation used during aerial spraying had a genotoxic effect on exposed individuals. In 2008, Mikael Eriksson published a population-based case-control study of exposure to various pesticides as a risk factor for NHL. This strengthened previous associations between glyphosate and NHL.

Most recently, an important meta-analysis demonstrating the link between Roundup and NHL was published. See Zhang L, Rana I, Shaffer RM, Taioli E, Sheppard L, Exposure to Glyphosate-Based Herbicides and Risk for Non-Hodgkin Lymphoma: A Meta- Analysis and Supporting Evidence, Mutation Research-Reviews in Mutation Research (2019). This meta-analysis was important in no small part because it included the most recent Agricultural Health Study (AHS) cohort study, which Monsanto has relied heavily upon in its defense in these lawsuits. The Zhang paper found that the overall meta-relative risk of NHL in individuals exposed to high amounts of glyphosate-based-herbicides was increased by 41%.

b.    The IARC Monogram

The International Agency for Research on Cancer (IARC) is the specialized intergovernmental agency that the World Health Organization (WHO) of the United Nations tasked with conducting and coordinating research into the causes of cancer. IARC reviewed numerous studies, many of which had been in Monsanto’s possession since as early as 1985.

IARC’s working group published its conclusion that the glyphosate contained in Monsanto’s Roundup herbicide is a Class 2A “probable carcinogen” as demonstrated by the mechanistic evidence (genotoxicity and oxidative stress) of carcinogenicity in humans and sufficient evidence of carcinogenicity in animals. IARC also found that glyphosate caused DNA and chromosomal damage in human cells.

In its monogram, IARC concluded that there is “strong evidence” that Roundup is a carcinogen, prompting many individuals who had been diagnosed with NHL and who had been exposed to Roundup to file suit against Monsanto.

c.    The Flawed Science Supporting Roundup’s Entry into the Market

If Roundup causes cancer, how has Monsanto been allowed to sell its product without a warning for so many years? Answering that question has been, in part, the subject of the three Roundup trials, each of which has taken weeks to try. For the purposes of this article, I’ll focus on two of the issues related to the science that supported EPA’s approval of Roundup.

1.    Confusion Over the Mouse Oncogenicity Trial and Other Early Discredited Studies

Glyphosate was first approved by EPA in 1974. Most of the initial toxicological database supporting the early tolerance petitions and registrations of glyphosate were done by a lab called Industrial Bio-Test      Laboratories (IBT). In 1976, a routine FDA audit of an IBT test facility uncovered problems with the conduct of some studies and led to a thorough assessment of all studies done by IBT that supported regulatory actions by the Office of Pesticide Programs (OPP).  Four IBT executives were indicted in federal court on various counts, including scientific misconduct and fraud, and were convicted in 1983.

A decade later, it was finally determined that most of the toxicological data submitted by Monsanto in the mid-1970s, and used by EPA to support all early registration actions, was invalid. Via an agreement with the OPP within the EPA, Monsanto was allowed to repeat the invalid studies. In the interim, EPA allowed existing registrations and tolerances to remain in place.

One of the most important, and now hotly-contested, studies that was required to be repeated was the long-term glyphosate cancer (oncogenicity) study in rats conducted by IBT. The importance of OPP’s evaluation of the oncogenicity study on glyphosate was widely recognized inside EPA and Monsanto, and also in the pesticide regulatory community. The original IBT study formed the basis of the classification of glyphosate as “not oncogenic.” If the EPA had determined that the study was positive, it would have significantly altered the outcome of a number of tolerance petitions and registration applications in the U.S.

When the study was repeated in 1983, however, the results were different than those results achieved by IBT. This resulted in EPA’s brief consideration of glyphosate as a category C possible oncogene in 1985.

Monsanto took swift and concerted action to change EPA’s view before such a classification could adversely affect labelling or sale of Roundup. First, Monsanto argued that rather than use the incidence of tumors actually observed in the control group in the study at issue, EPA should instead rely on the highest incidence of kidney tumors ever observed in any control group.

Next, Monsanto hired numerous pathologists to scrutinize the results of the mouse study. The pathologists hired by Monsanto argued that the original study group missed a tumor in the control group, therefore the results were not statistically significant. All of the EPA pathologists who had reviewed the kidney slides could not see – and did not agree that there was – a tumor in the kidney of control mouse #1028. However, each of the pathologists paid by Monsanto to assess the kidney slides believed that there was a tumor in control mouse #1028.

Eventually, EPA succumbed and changed its interpretation of the 1983 Bio/dynamics mouse oncogenicity study to Monsanto’s satisfaction, thus effecting no change with respect to EPA’s classification of glyphosate as an oncogene. However, despite multiple EPA requests, Monsanto still has not conducted a new mouse oncogenicity study. Monsanto has also failed to carry out a follow-up study that EPA and Monsanto scientists designed collaboratively, in the hope of resolving lingering issues over the presence of renal tubular adenomas in the 1983 Bio/dynamics study.

2.    EPA’s reliance on Monsanto-Submitted Glyphosate-Only Studies, Rather Than Studies of Roundup

A second flaw in the studies of Roundup relied upon by EPA is that the studies were conducted on pure, or “technical” glyphosate, rather than Roundup itself. Roundup contains numerous ingredients other than glyphosate, which change the toxicological profile of the chemical. For example, Roundup contains surfactants which interfere with the membrane of the plan so that glyphosate can enter the plant and kill it.

The primary surfactants used in Roundup formulations fall within the family of polyoxyethylene-alkylamine (POEA) surfactants. A POEA surfactant was generally present in a 3:1 ratio of glyphosate to POEA in the early years of commercial use, with the concentration of POEA falling to ratios around 7:1 in Roundup brands since about 2000.

Almost all of the testing submitted to the EPA has been on technical glyphosate, including all of the long-term animal oncogenicity tests. Hence, most EPA and Monsanto claims relative to the oncogenicity of Roundup are based on tests conducted with pure glyphosate, which no one applies in real life.

This is important because Roundup is more toxic than glyphosate itself. The surfactants added to Roundup function on human skin in similar ways that they function on a plant. The surfactants increase the amount of glyphosate reaching and penetrating cell walls in people and animals by disrupting our cells’ protective membranes. Therefore, testing pure glyphosate does not fully or accurately capture the toxicity of Roundup.

d.    Reaction to the Verdicts

The recent verdicts have brought to light the safety concerns with Roundup, and have put Bayer, the German firm that acquired Monsanto in June of 2018, in a defensive posture. France recently passed a bill banning Roundup sales at garden centers and plans to ban the use of all pesticides for home gardeners by 2022. Costco has also made plans to remove Roundup from its shelves and pressure is mounting on other retailers to do the same. Having seen how damning the science on glyphosate is and the devastating effects Roundup exposure had had on my firm’s client (who sprayed about 100,000 gallons of Roundup as a commercial farmer), it is good to see that the jury verdicts and surrounding publicity have brought the effects of exposure to Roundup into the light of day.