Roundup: Controversies, Health Risks & Industry Failures

Roundup is a widely used herbicide containing glyphosate as its active ingredient. First registered in the United States in 1974, it is commonly applied to crops, lawns and gardens.

Its use has increased with “Roundup Ready” crops. These crops are genetically modified plants resistant to glyphosate’s effects, making them easier to treat. The broader use of Roundup has led to greater exposure risk.

National and international organizations have differing opinions about whether Roundup increases cancer risks. However, some studies suggest a link between glyphosate and non-Hodgkin lymphoma (NHL). Glyphosate can also leave residues in food and water, raising concerns about long-term health effects.

The controversy regarding Roundup revolves around the herbicide’s possible connection to cancer, especially a type of lymph system cancer called non-Hodgkin lymphoma. There is evidence that Monsanto — the company that initially made Roundup — was aware of potential dangers many years ago.

The Link Between Roundup & Cancer

Evidence from the U.S. Environmental Protection Agency’s archives indicates that Monsanto — Roundup’s original manufacturer — knew as far back as 1981 that Roundup’s active ingredient, glyphosate, could potentially cause cancer in mammals.

In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic to humans.” However, the IARC noted its decision was based on “limited” evidence. The EPA continues to state that glyphosate is not likely to be carcinogenic to humans based on its evaluation of available data.

Research into the link between Roundup and cancer has returned mixed findings.

How Glyphosate Exposure Harms Human Health

Scientists have identified several ways glyphosate — the main ingredient in Roundup — may contribute to cancer, especially non-Hodgkin lymphoma. These mechanisms damage DNA, alter gene activity and disrupt normal cell functions.

While scientists continue to discuss the potential risks, these findings indicate several links glyphosate may have to cancer, particularly non-Hodgkin lymphoma.

What Monsanto & Bayer Knew About Glyphosate Risks

Internal documents and court cases show that for decades, Monsanto, now owned by Bayer, knew about the health risks linked to glyphosate, the main ingredient in Roundup.

In 2019, former Monsanto CEO Hugh Grant testified in a Roundup lawsuit trial. He acknowledged during his testimony that the company had never performed cancer-related studies on the herbicide. Still, he claimed the company relied on “sound science” for its practices.

In a 2003 company email, Monsanto toxicologist Donna Farmer told colleagues, “You cannot say that Roundup is not a carcinogen… we have not done the necessary testing on the formulation to make that statement.”

A year earlier, another Monsanto toxicologist, Dr. William Heydens, communicated with a consultant. Heyden said, “What I’ve been hearing from you is that this continues to be the case with these studies — Glyphosate is OK but the formulated product (and thus the surfactant) does the damage.”

Scientists continue looking into how Roundup and its active ingredient, glyphosate, affect human health, especially at low exposure levels. In addition to research examining a Roundup cancer link, they have documented high doses causing immediate harm, while the long-term effects of low amounts are still unclear.

Glyphosate is found in food, drinking water and air, raising safety concerns. Opinions on its safety vary among regulators and researchers. Based on starkly different scientific approaches, the IARC and EPA have arrived at different conclusions about a Roundup cancer link.

Is Roundup Harmful Even at Low Exposure Levels?

It’s unclear how significant low-level exposure to Roundup may be. However, according to the U.S. Centers for Disease Control and Prevention (CDC), swallowing a large amount of glyphosate can cause nausea and vomiting. Exposure to the chemical can also irritate the skin and eyes. If you frequently work with glyphosate, you may experience breathing issues like nasal irritation or asthma.

In the United States, glyphosate is prevalent in the environment. It was detected in 81% of the U.S. population aged six and older, according to a 2022 research article in Environment International.

Glyphosate is found in the water supply across the United States. A 2020 study by the U.S. Geological Survey found the chemical at least once in 66 out of 70 rivers and streams across various land-use areas.

Why Did Regulatory Agencies Disagree on Glyphosate’s Safety?

While the IARC has reported that glyphosate is likely to cause cancer, the EPA has stated that when used as directed, glyphosate does not pose a risk to human health. The EPA also found that glyphosate is unlikely to cause cancer in humans.

The big difference in conclusions from the two organizations can be attributed to various reasons. These include their research and evaluation methods.

The IARC and EPA evaluate glyphosate differently. The IARC focuses on whether glyphosate can potentially cause cancer. The EPA, however, assesses the actual risk based on exposure levels and usage.

Their information sources also vary. The EPA examined a broader range of data — including industry reports and public studies — while the IARC relied solely on a handful of carcinogenicity studies. For instance, the EPA reviewed 15 animal studies on cancer, while the IARC analyzed only eight studies.

Monsanto played a key role in the controversy surrounding Roundup and glyphosate. Internal documents and government reports suggest the company used questionable tactics to shape scientific research, influence regulations and control public perception.

The actions have fueled tens of thousands of Roundup lawsuits. Consequently, Bayer has inherited billions of dollars in liability since it acquired Monsanto.

How Monsanto Influenced Glyphosate Research & Regulations

Monsanto employed various tactics to influence research and regulations regarding glyphosate. The tactics raised significant concerns about the integrity of scientific research and regulatory processes surrounding glyphosate and other agricultural chemicals.

The consumer advocacy group U.S. PIRG Education Fund has reported that the Monsanto emails suggest the company collaborated with other chemical firms — like Dow and the paraquat manufacturer Syngenta — to create and publish scientific studies that would help promote their products.

In 2020, Bayer agreed to pay up to $10.9 billion in Roundup settlement payments to resolve thousands of lawsuits claiming Roundup causes non-Hodgkin lymphoma. Despite the payout, Bayer continues to deny that Roundup is unsafe. The company also settled lawsuits over other chemicals, including polychlorinated biphenyls (PCBs) — man-made organic chemicals banned by the EPA in 1979 — and the herbicide dicamba.

Over 200,000 lawsuits have claimed Roundup caused non-Hodgkin lymphoma. According to Bayer’s 2024 Annual Report, as of January 31, 2025, it had settled or was close to settling many of the 181,000 remaining Roundup lawsuits, with about 114,000 resolved or ineligible.

The Annual Report also states that courts have tried Roundup cases in federal and state courts in at least seven states.

Plaintiffs often received both compensatory and punitive damages when they won. Appeals and post-trial motions continue, including a key federal preemption ruling that may reach the U.S. Supreme Court.

Judges later decreased the monetary awards, and Bayer challenged the verdicts. However, the financial setbacks unsettled investors, causing Bayer’s stock price to drop significantly.

Bayer’s 2024 Annual Report said the company has set aside $5.9 billion for ongoing litigation.

Bayer’s Response to Roundup Lawsuits

Bayer outlines a four-point strategy on its website to resolve lawsuits and keep Roundup on the market.

Some cities and states have restricted glyphosate use, but future federal or state regulations may threaten these restrictions.

What Are the Best Alternatives to Roundup?

There are several Roundup alternatives, including organic and chemical weedkillers, and different techniques to prevent weed growth. These techniques include removing weeds with tools and using insects to control weeds.

Other chemical herbicides are available but may not be as effective for large-scale applications as Roundup.

How Some Cities and States Are Restricting Glyphosate Use

According to the Environmental Working Group, states and cities have enacted over 40 local laws to limit glyphosate use to protect children, farmworkers and nearby residents. Some states set pesticide-free zones around schools, require warning signs or limit spraying times.

States like California and Oregon have stricter restrictions due to health risks. However, these state and local pesticide laws could be overturned if the EPA approves a petition from attorneys general in 11 states. Their petition seeks to block local bans on glyphosate and other pesticides, removing protections for schools, parks and farmworkers. This could weaken regulations meant to reduce health risks.

If you’ve been exposed to Roundup, wash your skin with soap and water immediately and rinse your eyes for at least 15 minutes if they are affected. If you inhale or ingest it and feel sick, seek medical attention. Monitor for symptoms like skin irritation, nausea or breathing issues. If you have long-term exposure concerns, talk to your doctor about potential health risks and testing options.

If you believe you have developed non-Hodgkin lymphoma because of Roundup exposure, seek medical diagnosis and treatment immediately. You may also want to talk to an experienced environmental attorney about filing a Roundup lawsuit.

How to Tell if Your Health Has Been Affected by Glyphosate

Glyphosate exposure may cause immediate or short-term health effects. Symptoms can vary based on the level and type of contact.

Non-Hodgkin lymphoma affects the body’s lymphatic system. Some symptoms may be mild at first but worsen over time.

Long-term exposure to glyphosate has links to various health concerns beyond immediate symptoms. A 2021 review of previous studies found references to possible risks of “obesity, diabetes, liver and kidney dysfunction, autism, dementia, Parkinson’s and Alzheimer’s disease, leukemia, various forms of cancer and inflammatory diseases.”

What to Do if You’re Concerned About Roundup Exposure

If you work around Roundup, here are a few steps to minimize your exposure to glyphosate.

Glyphosate is prevalent in our environment, making it hard to avoid, even if you never handle it. To reduce exposure, filter drinking and bathing water, choose organic foods, or grow your own produce. Drinking herbal teas like dandelion, burdock or barberry can also help your body eliminate toxins.

Where to Find More Information on Roundup’s Safety

There are several reliable sources about handling Roundup safely and mitigating the health risks of glyphosate.

When reviewing this information, it’s essential to note conflicting views on glyphosate’s safety, such as the differences between the EPA and IARC classifications of glyphosate risks. Always consult multiple reliable sources to fully understand the current state of research on Roundup’s safety.

Editor Lindsay Donaldson contributed to this article.