Scientists have differing opinions when answering why or how is Roundup harmful to humans, but consumer lawsuits argue that cancer is a possible outcome.

How Dangerous is Roundup?

Roundup, a popular herbicide using glyphosate as the active ingredient, is one of the most widely used weed-killing products in the United States. The herbicide is reportedly using in agriculture and forestry industries as well as in domestic applications such as lawn and garden weed management.

The active ingredient glyphosate reportedly works to kill weeds in a non-selective manner – meaning that most plants will be killed by the chemical. In order to kill weeds, glyphosate reportedly disrupts enzymic pathways in the plants which inhibits plant growth and survival.

In addition to being fatal to plants, Roundup and other glyphosate products may be dangerous to humans.

What Happens If I Got Roundup On My Skin?

In the short term, getting Roundup on your skin could cause skin irritation. If you then touch your eyes, you may be faced with eye irritation. Users who breathe in Roundup during application can reportedly suffer from nose and throat irritation while swallowing the products can lead to increased saliva, mouth/throat burns, nausea, vomiting, and diarrhea.

Can Roundup Kill You?

Instances of intentional ingestion of glyphosate have reportedly resulted in deaths, although these are a relatively small number of incidences according to the National Pesticide Information Center.

In the long term, scientists are consistently debating the question: “Is Roundup harmful to humans?”

In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate as a probable human carcinogen. Despite this classification, agencies such as the European Food Safety Authority and the U.S. Environmental Protection Agency have determined that glyphosate is not carcinogenic. In general, scientists agree that there needs to be more research on the issue – including the types of exposure and dosages of glyphosate which lead to cancer.

Part of the issue is being uncertain about how much risk comes from glyphosate and how much is attributed to the other chemicals in formulations such as Roundup.

“So that makes it very difficult for a toxicologist to test the different ingredients to figure out what’s the most toxic, or what’s contributing to it,” Vanessa Fitsanakis, a neurotoxicologist from Northeast Ohio Medical University, told The Scientist. “From a research perspective, I can’t tell which component might need to be changed [to reduce possible toxicity] in those formulations because I don’t know what some of those components are.”

Unfortunately, some evidence suggests that formulated glyphosate is more toxic to cells and animals than glyphosate alone.

“The data are overwhelmingly in agreement that glyphosate by itself is relatively nontoxic,” Fitsanakis notes.

While scientists debate the question of why or how is Roundup harmful to humans, consumers have started taking matters into their own hands.

Roundup manufacturer Monsanto and parent company Bayer have faced repeated lawsuits from consumers claiming that they developed non-Hodgkin’s lymphoma after using the weed killer for years. Lawyers for these consumers argue that Roundup was misrepresented as safe by the manufacturer despite evidence to the contrary.

Have Any Roundup Cases Gone to Trial?

Juries have found Roundup to be harmful and have so far rendered three major verdicts against Bayer in the past two years. The first case to go to trial involved a former school district groundskeeper near San Francisco. Suffering from late stage non-Hodgkin lymphoma (NHL), the jury awarded the plaintiff $289 million in damages. Evidence surfaced in that trial indicating that Monsanto was ghostwriting much of its own research in order to “prove” to regulators that its product was safe. At the same time, the company had plans to discredit the IARC findings. 

In March 2019, a federal jury awarded $5 million in compensatory damages and $75 million in punitive damages to a man who had been diagnosed with non-Hodgkin lymphoma five years earlier. Weeks later, a separate jury found in favor of a Livermore, Calif. couple, both of whom were also diagnosed with non-Hodgkin lymphoma. Jurors in that cases awarded a staggering $2 billion judgment, NPR reported.

Although these awards were significantly reduced in accordance with state and federal tort reform laws limiting punitive damages, Bayer is still appealing all three cases. Currently, Bayer is working with mediator Kenneth Feinberg to come up with a settlement – but it has shown no indication that it is willing to modify the product, add a warning or pull it from the market.