When scientists study chemicals to determine whether or not they may cause disease, they generally perform one of three different types of testing:
All three types of studies have been conducted by researchers investigating the toxic and carcinogenic (cancer-causing) properties of Roundup weed killer and its active ingredient, glyphosate.
In addition to the three types of studies listed above, scientists also write summary reviews and meta-analysis papers that tie together the knowledge gained from dozens and even hundreds of previously conducted studies in order to draw conclusions about the risk of disease associated with particular toxins. A meta-analysis examines several independent studies on the same subject, using the increased number of combined participants to help detect significant elevated risks of adverse events linked to exposure to a chemical as opposed to chance or other factors.
The 2015 monograph written by the International Agency for Research on Cancer, which found glyphosate to be “probably carcinogenic to humans,” is a summary review of studies and included a meta-analysis showing a significantly increased risk of NHL for individuals exposed to Roundup.
In animal studies, scientists expose mice, rats, or other animals to Roundup or glyphosate over weeks or months, then examine organs and tissues for tumors, genetic changes, or other signs of toxicity that suggest cancer risk. These tests may reveal effects that short-term studies often miss, such as dose-dependent increases in cancer and lymphomas.
The studies below summarize key findings from animal research on Roundup’s toxicity.
Title: Glyphosate induces benign monoclonal gammopathy and promotes multiple myeloma in mice
Journal: Journal of Hematology and Oncology (2019)
Lead Author: Lei Wang
Scientists at the Lerner Research Institute in Cleveland, Ohio, have uncovered a biological mechanism through which glyphosate activates an enzyme known to play a key role in genetic mutations that lead to multiple myeloma (MM) and non-Hodgkin lymphoma (NHL). This mouse study produced data that “support glyphosate as an environmental risk factor for MM and potentially NHL.”
“Our data disclose, for the first time, that glyphosate elicits a B cell-specific mutational mechanism of action in promoting carcinogenesis, as well as offering experimental evidence to support the epidemiologic finding regarding its tissue specificity in carcinogenesis (i.e., only increasing the risk for MM and NHL).”
Title: Long-term toxicity of a Roundup herbicide and a Roundup tolerant genetically modified maize
Journal: Food and Chemical Toxicology (2014)
Lead Author: Gilles-Eric Séralini
The link between Roundup, genetically modified corn, and cancer was revealed by this French study that investigated the long-term consequences of exposure to Roundup. Though this study is actually a long-term toxicity study, not a cancer study, the results demonstrate that chronic exposure to Roundup and GM corn can produce evidence of carcinogenesis that may not appear in short term (90-day) studies.
Title: Studies on glyphosate-induced carcinogenicity in mouse skin: A proteomic approach
Journal: Journal of Proteomics (2010)
Lead Author: Jasmine George
In this 2010 mouse study, scientists found that glyphosate is a cancer promoter. In other words, if cancer cells are already present, glyphosate promotes the growth of those cells and causes tumors to grow faster.
Title: A chronic feeding study of glyphosate in mice
Journal: Unpublished report prepared for Monsanto by BioDynamic Inc. (1983)
Lead author: A. L. Knezevich
In this unpublished 1983 mouse study, which was submitted by Monsanto to the U.S. Environmental Protection Agency (EPA), scientists found that exposure to glyphosate was associated with a dose dependent increase in renal carcinomas (kidney cancer). Monsanto went to great lengths to try to reverse the findings of the study and refused EPA requests to conduct a second study that might have confirmed the association.
In mechanistic studies, scientists look at how a chemical affects humans or animals on a cellular level. They seek evidence that glyphosate is disrupting the complex operation of cells in ways that could lead to cancer or other disease. Often, this disruption includes damage to the cell’s genetic material – DNA.
In some studies, known as “in vivo” studies, the cells of humans or animals who have been exposed to Roundup or glyphosate are examined for genetic damage or damage to other essential cellular mechanisms. In other studies, known as “in vitro” studies, human or animal cells are exposed to glyphosate or Roundup in a laboratory setting (in a Petri dish) and then examined for damage to cellular mechanisms.
The studies below represent various types of mechanistic studies.
Title: Screening of Pesticides with the Potential of Inducing DSB and Successive Recombinational Repair
Journal: Journal of Toxicology (2017)
Authors: K. Suárez-Larios, A.-M. Salazar-Martínez, R. Montero-Montoya, National Autonomous University of Mexico
Mexican researchers found glyphosate, the active ingredient in Roundup, causes double-strand DNA breaks (DSBs) in human lymphocytes, the white blood cells targeted by non-Hodgkin lymphoma. Testing eight pesticides, they identified glyphosate as one of only two chemicals that significantly activated the error-prone DNA repair protein p-Ku80 in a dose-dependent manner, with higher doses producing severe damage (over 10 foci per cell). These DSBs trigger error-prone repair leading to chromosomal changes characteristic of lymphoma and other cancers, even at low concentrations over short exposures.
Title: Toxicity of formulants and heavy metals in glyphosate-based herbicides and other pesticides
Journal: Toxicology Reports, Vol. 5 (2018), pp. 156–163
Authors: N. Defarge, J. Spiroux de Vendômois, G.E. Séralini, University of Caen Normandy, France
University of Caen Normandy researchers demonstrated that glyphosate-based herbicides (GBHs) like Roundup are far more toxic than glyphosate alone due to formulants like POEA surfactants. In plant tests at agricultural dilutions, GBHs killed plants rapidly while glyphosate alone showed minimal effects. Human kidney cells died within 90 minutes from formulations but not glyphosate alone, with toxicity thousands of times higher. Even low doses caused endocrine disruption, and 11 GBHs contained toxic heavy metals (arsenic, lead, nickel) that are known endocrine disruptors. The researchers concluded that regulatory approvals based solely on testing glyphosate in isolation do not account for the greater toxicity of full commercial GBH formulations.
Title: Glyphosate Induces Human Breast Cancer Cells Growth Via Estrogen Receptors
Journal: Food and Chemical Toxicology (2013)
Lead Author: Siriporn Thongprakaisang
This study, published in the June 2013 edition of Food and Chemical Toxicology, found that glyphosate drives breast cancer proliferation. Researchers in Thailand compared glyphosate’s effect on both hormone-dependent and hormone-independent breast cancer cell lines, finding that the herbicide stimulates hormone-dependent cancer cell lines in “low and environmentally relevant concentrations.”
There are two main types of epidemiological studies – the case-control study and the cohort study. In a case-control study, individuals with the disease being studied, the cases, are compared with individuals who do not have the disease, the controls. Using questionnaires, scientists try to determine whether those with the disease were exposed to the chemical being studied much more frequently than the controls. They can use this information to determine whether that chemical is contributing to an increased risk of the disease.
In a cohort study, researchers start with one group of individuals who are exposed to a factor, such as a chemical, that is thought to increase the risk of a particular disease and another group of people who are similar but are not exposed to the risk factor. Then they follow both groups over a defined period of time to see if the incidence of the disease is significantly greater in the exposed group compared to the non-exposed group.
The epidemiology studies below are among the many that have linked glyphosate to non-Hodgkin lymphoma.
Title: Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence
Journal: Mutation Research-Reviews in Mutation Research, Vol. 781 (2019), pp. 186–206
Authors: L. Zhang, I. Rana, R.M. Shaffer, E. Taioli, L. Sheppard, UC Berkeley, University of Washington, Icahn School of Medicine at Mount Sinai
In 2019, UC Berkeley-led researchers reviewing human epidemiological studies reported a “compelling link” between glyphosate-based herbicides like Roundup and a 41% increased risk of non-Hodgkin lymphoma (meta-RR = 1.41, 95% CI: 1.13–1.75), particularly among the most highly exposed individuals. In contrast to earlier meta-analyses that combined all exposure levels, this study focused specifically on the highest-exposure groups from six epidemiological datasets, including the updated 2018 Agricultural Health Study cohort. The researchers also documented supporting evidence from animal studies showing malignant lymphoma in glyphosate-treated mice, as well as mechanistic evidence of immune suppression, DNA damage, and oxidative stress associated with glyphosate exposure.
Title: Non-Hodgkin Lymphoma and Occupational Exposure to Agricultural Pesticide Chemical Groups and Active Ingredients: A Systematic Review and Meta-Analysis
Journal: International Journal of Environmental Research and Public Health (2014)
Lead Author: Leah Schinasi
In this 2014 study, two researchers published the results of their analysis of nearly thirty years of epidemiological research, finding significant associations between glyphosate and non-Hodgkin lymphoma. The authors called for more research to determine which subtypes of NHL are most strongly associated with exposure to pesticides.
Title: Pesticide Exposure as Risk Factor for Non-Hodgkin Lymphoma Including Histopathological Subgroup Analysis
Journal: International Journal of Cancer (2008)
Lead Author: Mikael Eriksson
This pesticide study, the fourth in a decade-long series of Swedish studies examining the link between several different pesticides and non-Hodgkin lymphoma (NHL), provided additional support to previous research that had linked glyphosate pesticide and herbicide exposure to non-Hodgkin lymphoma. Individuals that were exposed to Roundup for more than 10 days had a significant 2.36 times greater rate of NHL than individuals not exposed to Roundup.
Title: Integrative assessment of multiple pesticides as risk factors for non-Hodgkin’s lymphoma among men
Journal: Occupational and Environmental Medicine (2003)
Lead Author: A. J. De Roos
In this study, scientists working in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute studied several dangerous pesticides and glyphosate to determine if exposure to any of them was tied to non-Hodgkin lymphoma. DeRoos et al found a statistically significant doubling of the risk for NHL among individuals exposed to Roundup, a risk that remained significant even when adjusted for other pesticide use. These findings support the NHL risk being induced by Roundup, not by chance.
Title: Exposure to Pesticides as Risk Factor for Non-Hodgkin’s Lymphoma and Hairy Cell Leukemia: Pooled Analysis of Two Swedish Case-control Studies
Journal: Leukemia and Lymphoma (2002)
Lead Author: Lennart Hardell
In this 2002 study, three experienced Swedish cancer researchers, Dr. Marie Norström, Dr. Lennart Hardell, and Dr. Mikael Eriksson, combined data from their two previous studies to assess whether there is a link between glyphosate, the active ingredient in Roundup weed killer, and non-Hodgkin lymphoma (NHL).
In addition to the above studies, scientists often write papers summarizing the scientific literature related to a particular toxic substance. Studies have been written about Roundup weed killer and its active ingredient, glyphosate.
Title: Some Organophosphate Insecticides and Herbicides: Diazinon, Glyphosate, Malathion, Parathion, and Tetrachlorvinphos, Monograph on Glyphosate
Journal: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 112
Authors: International Agency for Research on Cancer (IARC), IARC Working Group, Lyon France
In 2015, the International Agency for Research on Cancer (IARC) published the results of a year-long investigation into the link between several different insecticides and herbicides, including glyphosate, and cancer. The group concluded that glyphosate is “probably carcinogenic to humans.”
"Wisner Baum gave exceptional attention to all aspects of the case, detailed inquiry, and tenacious overview of all the information submitted. The paralegals are efficient and diligent. I was completely surprised to find an empathic personal message to take care of my own health during the challenging time of being a full-time caretaker.*"
In May of 2019, the jury in the case of Pilliod et al. v, Monsanto Company ordered the agrochemical giant to pay $2.055 billion in damages to the plaintiffs, Alva and Alberta Pilliod, a Bay Area couple in their 70s. R. Brent Wisner served as co-lead trial attorney for the Pilliods, delivering the opening and closing statements and cross-examining several of Monsanto’s experts. Wisner Baum managing shareholder, Michael Baum and attorney Pedram Esfandiary also served on the trial team in the Pilliod case.
The judge later reduced their award to $87M. Monsanto appealed the Pilliod’s verdict which the California Court of Appeal for the First Appellate District denied on August 9, 2021. Monsanto then requested the California Supreme Court review the appeal’s court decision, which the court denied on Nov. 17, 2021. Monsanto (Bayer) then submitted a petition for a writ of certiorari with the U.S. Supreme Court which SCOTUS denied on June 27, 2022, allowing the final judgment of $87M to remain intact.
$289.2 million jury verdict in Monsanto Roundup trial
Wisner Baum co-represented Dewayne “Lee” Johnson in the first Roundup cancer lawsuit to proceed to trial. On Aug. 10, 2018, a San Francisco jury ordered Monsanto to pay $39.25 million in compensatory damages and $250 million in punitive damages to Mr. Johnson, a former groundskeeper who alleged exposure to Monsanto’s herbicides caused him to develop terminal non-Hodgkin lymphoma.
Months after the jury verdict, the judge overseeing the trial reduced the punitive damages to $39.25 million. Mr. Johnson decided to accept the remittitur, bringing the adjusted amount awarded to Mr. Johnson $78.5 million.
Monsanto (Bayer) appealed the verdict and Johnson cross appealed. On July 20, 2020, the First Circuit Court of Appeals upheld the verdict against Monsanto but reduced Mr. Johnson’s award to $20.5 million. The company chose not to take the case to the U.S. Supreme Court, ending the litigation.
In 2016, Wisner Baum attorney Timothy A. Loranger and six other attorneys in the Plaintiffs’ Management Committee were able to secure a $265 million settlement for victims of the 2015 Amtrak 188 derailment in Philadelphia, one of the largest in the U.S. for 2016.
