Roundup and Non-Hodgkin Lymphoma: The Link Between Glyphosate and Cancer

What Is Non-Hodgkin Lymphoma?

Non-Hodgkin Lymphoma (NHL) is a broad category of blood cancers that originate in the lymphatic system, the network of tissues and organs that help rid the body of toxins and waste. NHL includes more than 60 different subtypes, ranging from slow-growing (indolent) to aggressive forms that require immediate treatment. In the United States, approximately 80,000 people are diagnosed with NHL each year, making it one of the more common cancers.

The most common subtypes of NHL linked to Roundup litigation include diffuse large B-cell lymphoma (DLBCL), follicular lymphoma, mantle cell lymphoma, and marginal zone lymphoma. Symptoms of NHL may include painless swollen lymph nodes in the neck, armpits, or groin; fatigue; fever; night sweats; unexplained weight loss; and abdominal pain or swelling.

Survival rates for NHL vary significantly by subtype and stage at diagnosis. Some indolent forms of NHL are managed for years without aggressive treatment, while aggressive subtypes may require immediate chemotherapy, radiation, or stem cell transplantation.

IARC's 2015 Classification of Glyphosate

The most significant scientific event in the Roundup litigation was the March 2015 decision by the International Agency for Research on Cancer (IARC) — the cancer research arm of the World Health Organization — to classify glyphosate as 'probably carcinogenic to humans' (Group 2A). This classification placed glyphosate in the same category as red meat and working as a hairdresser.

The IARC classification was based on a review of peer-reviewed scientific studies, including epidemiological studies showing elevated NHL rates among agricultural workers who used glyphosate-based herbicides, animal studies demonstrating tumor formation at high doses, and mechanistic evidence that glyphosate can damage DNA and disrupt hormones.

Importantly, IARC evaluates hazard — whether a substance is capable of causing cancer under any exposure circumstances — not risk, which accounts for the likelihood of harm at typical real-world exposures. Critics of the IARC classification argue that the agency used a more selective review of the science than other regulatory bodies.

Key Scientific Studies Linking Glyphosate to NHL

Several major epidemiological studies have examined the relationship between glyphosate exposure and NHL risk. While results have been mixed, several key studies have found elevated risk among agricultural workers:

Courts have allowed plaintiff experts to testify on the basis of these studies, and multiple juries have found the evidence sufficient to hold Bayer/Monsanto liable for plaintiffs' NHL diagnoses.

The Monsanto Papers: What Internal Documents Revealed

One of the most damaging aspects of the Roundup litigation for Bayer has been the release of internal Monsanto documents through the discovery process. Collectively known as the 'Monsanto Papers,' these communications revealed discussions among company scientists, executives, and consultants that raised serious questions about the company's handling of safety data.

Key revelations from these documents include: Monsanto scientists expressing private doubts about glyphosate's safety while publicly defending it; alleged efforts to influence the EPA's review process; drafts of scientific articles that critics argue Monsanto ghostwrote and then recruited independent scientists to publish under their own names; and internal discussions about research that contradicted the company's public positions on glyphosate.

These documents have been presented to juries in multiple trials and have significantly influenced verdicts. Judges in several high-profile cases allowed evidence of Monsanto's alleged corporate misconduct to support punitive damages awards, which are designed to punish particularly egregious behavior.

The EPA vs. IARC: The Scientific Divide

A key point of confusion for many potential claimants is the apparent conflict between the IARC's carcinogenicity classification and the U.S. EPA's position that glyphosate is 'not likely to be carcinogenic to humans.' Both agencies reviewed extensive scientific literature but reached opposite conclusions.

The difference comes down partly to methodology. IARC focuses on hazard identification — can the substance cause cancer at any dose? The EPA's risk assessment framework considers exposure levels and dose-response relationships relevant to typical consumer use. The EPA has also been criticized by some scientists for potentially excluding certain studies from its review.

Courts have navigated this divide by allowing both sides to present expert testimony. Plaintiff experts rely heavily on the IARC classification and meta-analyses, while defense experts cite EPA conclusions. Juries have repeatedly found in favor of plaintiffs, suggesting that the IARC-based evidence has been persuasive in litigation even when regulatory agencies have not restricted glyphosate use.

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