Is Roundup Dangerous? Can Weed Killer Cause Cancer?

Weeds in Rocks (is Roundup Safe?)

Update: In August 2018, a California jury awarded a former school groundskeeper $289 million in compensatory and punitive damages. If you or a loved one has been diagnosed with non-Hodgkin’s lymphoma or another form of cancer after using Roundup Weed Killer, talk to a lawyer today for a free case review.

As spring emerges and winter weather gives way to warmer temperatures, ideas about gardening, landscaping, and other types of lawn and flora care start to fill our thoughts. Among those thoughts should not be the word “cancer.”

The sad reality, however, is that there could be a risk of developing cancer if part of your gardening or landscaping activities including using chemicals that contain glyphosate, the active ingredient in Monsanto’s Roundup Weed Killer and other herbicide products.

Talk to a lawyer about Roundup Weed Killer Get a free case review today

Roundup Cancer Risk: Is It Real?

Monsanto and its supporters point to a number of studies that found no evidence of a link between Roundup and any form of cancer. For example, a 2016 study funded by Monsanto “did not find support in the epidemiologic literature for a causal association between glyphosate and [non-Hodgkin lymphoma (NHL)] or [multiple myeloma (MM)],” two types of cancer commonly associated with the substance. Other studies have similarly failed to discover a connection between Roundup and cancer.

Nonetheless, in 2015, the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, classified glyphosate as “probably carcinogenic in humans,” even while noting that there was “limited evidence” of a link between glyphosate and non-Hodgkin lymphoma. There are two primary reasons for why IARC researchers classified the weed killer as a carcinogenic chemical, despite what some have called thin evidence:

  • Animal studies – specifically, studies of mice and rats – demonstrated a possible link between glyphosate and cancerous tumours.
  • Laboratory studies of the damaging effects of glyphosate on DNA showed “mechanistic evidence” that the weed killer can indeed damage DNA in human cells upon exposure.

Other groups have called the IARC’s classification into question, claiming that it ignored various studies. While this is true (scientists at the IARC do not consider studies funded by privately held companies, as well as studies that meet certain other criteria), the IARC has not retracted or changed its classification.

Other agencies have made their own determinations. For example, both the U.S. Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA) found that glyphosate was probably not carcinogenic. However, the California Office of Environmental Health Hazard Assessment lists the chemical as a “known carcinogen,” largely based on the IARC’s classification.

The claim that glyphosate causes cancer has led to the filing of hundreds of Roundup lawsuits in state and federal courts across the United States. Many of these lawsuits are still underway, and given the unclear state of scientific evidence, the amount to which Monsanto could be held liable for causing cancer remains to be seen.

See Why People Are Suing Monsanto Roundup Lawsuits

Non-Cancer Roundup Health Risks

Whether or not Roundup causes cancer, it still could be harmful for other reasons. In fact, there is plenty of evidence that glyphosate has a number of harmful side effects, from mild to severe.

At the most basic level, Roundup can cause a type of skin irritation known as photocontact dermatitis. In most cases this is limited to contact with uncovered hands, arms, or legs while using the weed killer. However, if used in spray form, it could also get into the nose, mouth, or eyes, where the effects could be more severe.

More dangerous is the ingestion of Roundup, especially for those who may swallow it on purpose. The most common damage from swallowing is burns to the mouth, throat and esophagus. However, more severe injury can also occur, including permanent liver damage or even death. Some cases of death have been reported within just a few hours of drinking relatively small amounts of Roundup. Needless to say, this potentially deadly chemical should never be swallowed.

While there are some claims linking Roundup (and glyphosate) to other diseases and conditions – such as diabetes, autism, depression and heart disease – there is very little reliable evidence for those claims. The study these claims primarily rely on was a non-systematic review of the literature, and the editors of the journal that published the study issued a statement of concern, noting that the paper relied largely on opinion and speculation. There is also little evidence that glyphosate exposure by women who are pregnant will lead to birth defects.

Stay Safe While Using Roundup

While the jury may still be out on whether Roundup and other glyphosate-based weed killers can cause cancer, it’s still a good idea to take safety precautions when using it. If you decide to use Roundup, whether you are just doing some work around the house or using it as an industrial herbicide, here are some ways to stay safe:

  • Store it in a safe place, out of reach of children, when not in use.
  • When using it, wear appropriate safety gear, such as long sleeves, pants, gloves, goggles, and a facemask.
  • If you get any on your skin or in your eyes, follow instructions on the bottle to rinse with water for 15–20 minutes.
  • If you swallow any of it, call a poison control center (1-800-222-1222) or your doctor immediately.
  • If you are diagnosed with cancer after having been exposed to glyphosate, talk to a lawyer to understand your legal rights.

Of course, you can also just kill weeds the old-fashioned way – by pulling them up by the roots!

Authored by Curtis WeyantManaging Editor
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Curtis Weyant has more than 20 years as a writer, editor, and communicator, publishing on a wide variety of topics, especially in the financial, legal, and medical fields. At, Curtis oversees the day-to-day publication of all content, ensuring its relevance with the mission of the site.
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