Roundup is agriculture’s most commonly used herbicide. The herbicide’s active ingredient is glyphosate. It also contains formulants.
Glyphosate kills most plants, as it is a non-selective herbicide. It stops plants from making proteins they need for growth. It does this by stopping the pathway for an enzyme known as shikimic acid.
However, there are safety concerns and controversy surrounding Roundup. Cancer is once of those human health concerns. Glyphosate exposure has been linked with non-Hodgkin lymphoma.
The History of Roundup and Its Widespread Use
A chemist who worked for Cilag, a Swiss pharmaceutical company, first synthesized glyphosate in 1950. The company didn’t manage to find a medical use for glyphosate, though. So, the company sold glyphosate to Stauffer chemicals, who patented it in 1964 for use in mining.
At the time glyphosate was patented for use in mining, Monsanto Company had been synthesizing agents for softening water. When Dr. Phil Hamm tested these compounds as herbicides, he discovered that organophosphonates could kill perennial weeds.
With the assistance of Dr. John Franz, Monsanto began exploring organophosphonate derivatives’ herbicidal properties. They synthesized glyphosate in 1970, tested it in a greenhouse that year, and patented it as an herbicide in the year 1971.
In 1974, glyphosate was introduced to the herbicide market under the name Roundup.
Upon being introduced, the chemical quickly became the primary herbicide on the market.
In 1996, Monsanto developed crops which are resistant to glyphosate herbicides, including soybeans, cotton, corn, alfalfa and canola. Eventually, the company developed glyphosate-resistant varieties of almost all agricultural plants.
As a result, the United States saw a dramatic increase in the usage of glyphosate products: two-thirds of the Roundup sprayed since 1974 was sprayed between 2004 and 2014. About 59 percent of soy and corn samples tested positive for glyphosate residue or glufosinate residue, according to the FDA. The herbicide has been found in over 80 percent of adults tested by the United States Centers for Disease Control and Prevention, according to Environmental Working Group.
Potential Health Risks for Humans
According to the Agency for Toxic Substances and Disease Registry, glyphosate can cause vomiting and nausea if swallowed. It can also irritate the eyes and skin.
Glyphosate is associated with effects on the nose and lungs, like nose irritation or asthma.
Animal studies have found that glyphosate can lead to developmental effects such as problems with organ and bone growth, as well as lower body weight.
Does Roundup Cause Cancer?
The International Agency for Research on Cancer, in 2015, classified glyphosate as being a probable human carcinogen. This classification was based upon “limited” evidence of human cancer and “sufficient” evidence of a link between the herbicide and cancer in animals. The agency, part of the World Health Organization, also stated that “strong” evidence exists that glyphosate is genotoxic.
Several scientific studies, meta-analyses and reviews have linked glyphosate with a higher risk of developing non-Hodgkin lymphoma (NHL), a deadly form of cancer:
- A 2014 review discovered an association between B-cell lymphoma, which is a type of NHL, and exposure to glyphosate.
- A 2019 meta-analysis came to the conclusion that a higher risk of humans developing NHL is associated with exposure to Roundup. The meta-analysis, which analyzed six different studies, associated glyphosate exposure with a 41 percent higher chance of developing NHL.
- A 2021 review concluded that there is a compelling, coherent pattern of evidence supporting the link between NHL and glyphosate exposure.
There have been conflicting findings from other regulatory agencies, though. For example, in 2020, the Environmental Protection Agency found that glyphosate poses no health risk to humans exposed to it, including exposure on farms, roadsides or yards, or as dietary exposure to glyphosate residues on food.
In 2023, the European Food Safety Authority (EFSA) concluded that their assessment of glyphosate found no critical areas of concern regarding the impact of the herbicide on the health of humans. The EFSA noted that a 2022 European Chemicals Agency hazard assessment of the herbicide concluded that glyphosate doesn’t meet the scientific criteria necessary to be considered carcinogenic.
Despite these conflicting findings, courts have often ruled in favor of cancer patients suing Monsanto and Bayer who claim that Roundup caused them to develop NHL.
Occupational Exposure Risks
Farm workers, pesticide applicators and home gardeners who use glyphosate have a risk of inhalation, ocular and dermal exposure to glyphosate. The primary route of glyphosate exposure in those involved in the application of the herbicide appears to be dermal contact.
A 2022 study found that it is “unequivocal” that glyphosate exposure can lead to “important alterations” in the function and structure of the human nervous system.
However, the greatest concern regarding the human health risks of occupational glyphosate exposure is NHL. Since a growing body of scientific evidence links glyphosate exposure with NHL, no amount of exposure to Roundup is safe.
Is Roundup Safe for People & Pets?
Dogs can spend time outside, coming into close contact with plants and grass. So, they can be at risk of being exposed to Roundup which has recently been applied. Cats which go outside may have similarly high levels of exposure. When pets like cats and dogs lick their fur, they may ingest glyphosate.
Some veterinarians advise that pet owners should not use chemical pesticides. Pet owners who use Roundup should keep their pets off of grass for a period of 48 hours following application. Pet owners should also try to avoid walking their pets on weedless, uniform grass, since this grass is likely to have seen pesticide exposure.
A 2020 study found that some ingredients of Roundup, both inert and active, appear to be reproductive toxicants. The ingredients can have many effects on female and male reproductive systems of animals, including dysfunction of gametogenesis, tissue damage and endocrine disruption.
A 2012 study found that pesticides professionally applied to lawns was associated with a 70 percent higher chance of dogs developing lymphoma.
Exposure to lawns treated with herbicides has been linked with a higher risk of bladder cancer in dogs.
Environmental Concerns
There are significant environmental concerns associated with Roundup.
Roundup may cause serious disruption to soil health by harming earthworms and the soil microbiome:
- Roundup can change the abundance and composition of fungi and bacteria in soil, potentially decreasing beneficial organisms and increasing pathogenic organisms.
- Roundup can reduce root mycorrhization, mutually beneficial relationships between plant roots and fungi, impacting the growth and health of plants.
- Roundup can change the nutrient composition of xylem sap, grape juice, leaves and roots.
- Roundup can have severe impacts on the behavior, microbiome, body mass and survival of earthworms. This, in turn, can lead to declines in farmland birds who feed on earthworms.
Roundup can have negative impacts on water systems and aquatic life. A 2024 review came to the conclusion that pollution of aquatic environments by Roundup is “highly problematic.” A 2022 review found that Roundup presents a “serious” threat to water organisms, finding that the herbicide damages the gills, brains, livers and kidneys of fish, and has toxic effects on fish reproduction.
There are also concerns about glyphosate residue being found on foods, since the herbicide has been linked with cancer.
Legal Cases and Settlements
Thousands of lawsuits have been filed alleging that Roundup has caused people to develop NHL.
So far, as of September 2024, almost 100,000 Roundup lawsuits have been settled by Monsanto, who has paid out about $11 billion, and Monsanto estimates that there are still 54,000 active Roundup lawsuits. People continue to file Roundup lawsuits every month, especially those living in agricultural regions.
In addition, there have been numerous significant court verdicts in favor of plaintiffs in Roundup litigation, including:
- In 2024, a Pennsylvania jury awarded a plaintiff $2.25 billion, finding that his NHL was caused by Roundup. This verdict was later reduced to $400 million by an appeals court.
- In 2023, a Missouri jury awarded four plaintiffs $1.56 billion over claims that Roundup caused NHL. This verdict was later reduced to $611 million by an appeals court.
- In 2023, a California jury awarded a plaintiff $332 million over his claim that he developed NHL due to exposure to Roundup. An appeals court later reduced this verdict to $28 million.
- In 2023, a Philadelphia jury awarded a plaintiff $175 million over his claim that he developed NHL due to using Roundup in his garden.
- In 2019, a federal jury awarded a plaintiff $80.2 million over his claim that Roundup caused him to develop NHL. An appeals court later reduced this verdict to $25 million.
- In 2019, a California jury awarded a married couple $2.05 billion over their claim that Roundup caused them both to develop NHL. This verdict was later reduced by an appeals court to $86.2 million.
- In 2018, a California jury awarded $289 million to a plaintiff who claimed that Roundup caused him to develop NHL. This verdict was later reduced to $20.5 million by an appeals court.
Implications for Consumers and Homeowners
As a result of litigation over the link between Roundup and NHL, Bayer, in 2021, announced they would stop selling Roundup containing glyphosate to residential consumers starting in 2023. Because of this, the Roundup that residential consumers can now buy for their lawns no longer contains glyphosate.
Roundup containing glyphosate continues to be sold in the United States for agricultural and commercial use.
Since Roundup containing glyphosate is still sold for commercial use in the United States, property owners who spray Roundup on their property may be at potential risk for liability concerning Roundup exposure and NHL.
Alternatives to Roundup
Alternatives to Roundup include:
Acid-Based Herbicides
A safe Roundup alternative is vinegar. It damages weeds by leading to leaf cell leakage. Vinegar can dry out the area surrounding a plant, shutting off the plant’s moisture absorption and killing it.
While vinegar is typically found at a concentration of four to eight percent acetic acid, some herbicides are sold which contain 20 percent or more acetic acid.
Corn Gluten
Corn gluten is capable of eliminating germinating seeds. Numerous herbicide products contain corn gluten.
Essential Oils
Essential oils can inhibit plant growth and damage plant tissue. They can kill weeds by altering hormone and enzyme regulation, reducing energy intake and causing cell death.
Red thyme, clove and cinnamon are examples of ingredients found in herbicides based on essential oils. Numerous herbicide products contain essential oils.
Iron
Some herbicides are based on iron. These herbicides dry broadleaf weeds.
Mulch
Mulch such as wood, grass clippings, pine needles or leaves can block sunlight, suffocating weeds.
Manual Removal
While time-consuming, pulling weeds out of the ground, roots and all, is an effective method of weed control. Weeds can also be killed with steam or boiling water.
Soap Salts
Soap salts, or potassium salts of fatty acids, are found in numerous herbicides. Salt can kill weeds by dehydrating plants. Numerous herbicide products contain soap salts.
Chemical Alternatives
There are chemical alternatives to Roundup. However, they can be dangerous.
A 2020 study tested 14 different chemical alternatives to Roundup. The researchers found that all 14 herbicides contained dangerous chemicals which were not listed on their labels. These chemicals included toxic heavy metals like arsenic and mercury as well as known carcinogens.
Making Informed Decisions About Roundup Use
It is important to weigh the risks and benefits of Roundup use. While some organizations such as the EPA don’t consider Roundup to be carcinogenic, other organizations do, and multiple scientific studies, meta-analyses and reviews have linked Roundup with NHL.
It’s important to stay informed about ongoing research and legal developments regarding Roundup and exposure to other dangerous chemicals.
By keeping informed about the science surrounding Roundup, you can make an informed decision as to whether the benefits of using the herbicide outweigh the risks for you.
Jeffrey Nadrich
Jeffrey Nadrich is a nationally-recognized California plaintiff’s personal injury attorney. He is a graduate of UC Berkeley and UC Hastings College of the Law. He has successfully represented thousands of injury clients over the last 40 years.
