Does Glyphosate Cause Cancer?

Glyphosate is a common herbicide used to kill certain weeds and grasses primarily in agriculture but also in lawn and garden care. It is found in products by many popular brands like RoundUp. There have been concerns that overexposure to the chemical may lead to an increased risk of developing cancer, but research on this has been mixed, with some showing the association between the two and others revealing none. Exposure to glyphosate has also been linked to other health risks. Studies have found exposure to the chemical may lead to the development of acute or chronic inflammatory syndromes.

What Is Glyphosate?

Glyphosate is classified as a phosphonic acid. It is created when methylphosphonic acid and glycine are coupled together. It comes in a powder and is odorless. The compound is non-selective, which means that it will kill most plants and cannot target specific ones.

It was first developed in 1970. Herbicides made with this chemical usually contains other compounds as well. These products are called glyphosate-based herbicides (GBH). Glyphosate works by blocking an enzyme essential for plant growth.

Uses

Glyphosate is used in agriculture to limit competition for sunlight, water, and soil nutrients that can happen when weeds or other plants grow in crop areas. It works by seeping into the plant through its leaves, where it then infects every cell in the plant from the leaves to the roots. Plants treat glyphosate as an amino acid, and when the chemical gets into the amino acid synthesization cycle, it hinders enzyme production pathways that are absent in animals but critical to plant growth.

Sources of Glyphosate

Trace amounts of pesticides or pesticide chemical residues may remain in or on some crops after they’re harvested. In 2016 and 2017, the U.S. Food and Drug Administration (FDA) batch tested a variety of foods to check for levels of glyphosate. They looked at 879 corn, soybean, milk, and egg samples, and found that chemical residue from GBH could be found on 57% of the corn and soy samples, but none of the milk and egg samples were contaminated. The detected amounts were below the tolerance levels set by the U.S. Environmental Protection Agency (EPA), however.

There have been claims that glyphosate can be found in foods such as cereals and other wheat products, but they lack evidence. Some studies found that the similarities between glyphosate exposure and the effects on the human body are too great to ignore and that the inadequate monitoring of levels of the chemical in food could be partially to blame for a lack of true evidence.

Cancer Risk: What the Research Says

There is no clear answer from research and health authorities on whether glyphosate leads to cancer. A meta-analysis found that there was a direct link between a exposure to GBH and an increased risk for developing non-Hodgkin’s lymphoma, and that association is the strongest among those exposed to high levels of GBH. However, others argued that the evidence is inconsistent and consists of only a few studies and that more research is needed.

A report released by the World Health Organization states that the chemical is “probably carcinogenic to humans” based on findings from the International Agency for Research on Cancer. However, the EPA concluded in its report that glyphosate is not likely to be carcinogenic in humans.

With conflicting evidence and reports, it can be hard to decide what to believe. Much of the research also used animal subjects, so it's unclear if the same effects would be seen in humans overexposed to glyphosate.

Other Health Effects

Although the increased risk of cancer caused by glyphosate is debatable, there are many claims that exposure to glyphosate can cause various health issues in humans, most notably endocrine disruption and fertility issues, increased risk of toxicity in pregnant women and children, the development of liver disease, and microbiome disruption.

Endocrine Disruption and Fertility

A literature review found that some studies have shown glyphosate can have toxic effects on the endocrine system, even in low doses. After exposure to GBH, the development of the female reproductive tract could be negatively affected. Specifically, GBH alters the development and differentiation of ovarian follicles and uterus, affecting fertility when animals are exposed to the chemical before puberty. Studies have also found that exposure to GBHs during gestation could alter the development of the offspring. The caveat is that much of the evidence included in this review is animal studies.

Risks for Pregnant Women and Children

The effect on pregnancy caused by glyphosate exposure is most notably a shortened gestation period. One study found that 90% of the women who participated had detectable glyphosate levels and that these levels correlated significantly with shortened pregnancy lengths.

The EPA states that they found no indication that children are more sensitive to glyphosate from in utero or post-natal exposure, exposure through eating food with glyphosate, or exposure through entering or playing on residential areas treated with glyphosate after reviewing relevant studies. However, a few studies have shown that exposure to GBH may pose developmental risks to an unborn child.

Liver Disease

Another health condition that has been linked to exposure to glyphosate is liver disease. The link had been established in animal studies, but it was recently found in humans as well. One study examined two groups of people: One group had a version of non-alcoholic fatty liver disease known as non-alcoholic steatohepatitis (NASH), while the other group did not have any form of liver disease. The only factor that was the same in those with liver disease was elevated levels of glyphosate residue in their urine. Glyphosate excretion was significantly higher in patients with NASH compared to those without NASH. The authors also found a significant dose-dependent increase of glyphosate exposure with increase in fibrosis stages.

Microbiome Disruption

In humans, the chemical was never considered dangerous to the metabolic system, the system in charge of converting food to energy, because they do not have that pathway that glyphosate affect in plants. Recent research has found that may not be the case. One study found that over half of the gut bacteria living within the microbiome could be sensitive to glyphosate and this could lead to adverse health effects for humans if their gut bacteria are affected by overexposure.

Impact on the Environment

Some studies have shown that glyphosate may have a negative impact on the environment.

Pollinators

Bees and other pollinators like birds are important to the health of the ecosystem. They fertilize plants as they transfer pollen from one flower to the next. This process is needed for the flowers to reproduce. It has been found that glyphosate may hinder the health of pollinators by altering their gut bacteria. Exposing bees to glyphosate alters the bee gut community and their increases susceptibility to infection by opportunistic pathogens, which can lead to colony decline. 

How to Limit Exposure

Even though the evidence to support the claims that glyphosate is carcinogenic is mixed, it may still be a good idea to limit your exposure to the chemical, especially to large amounts of it. There are a few simple ways you can avoid overexposure and ingestion of glyphosate:

• Eating organic foods: Organic foods are less likely to be exposed to glyphosate, and thus will limit your exposure.
• Eat probiotics: Since research has shown that glyphosate has the potential to upset gut bacteria, getting probiotics in your diet can help keep your levels balanced.
• Change your herbicide: By using a herbicide product without glyphosate, you can limit your exposure to the chemical.

Since many cities and other commercial areas use glyphosate, it can be difficult to entirely limit your exposure, but by doing so through your diet and choosing alternate products, you can lower your risk of becoming overexposed to the chemical.  

Using Glyphosate Safely

There are a few steps you can follow to make sure that you limit your exposure to glyphosate while using a GBH, including:

• Reading and following all label instructions
• Limiting the exposure to pets and children by keeping them away from the area you use it in
• Wearing protective clothing while using the product
• Keeping the chemical out of the house by closing windows and doors while spraying it outside
• Using a low-pressure sprayer
• Washing your hands, face, and clothing after using the product

A Word From Verywell

Whether or not glyphosate causes cancer is still up for debate, but it is still a chemical and overexposure to any chemical may lead to adverse health effects. It's still smart to limit your exposure to glyphosate. The easiest way to do that is follow all the manufacturer's instructions for use. If you’re worried about the claims made against the product, you can opt for a herbicide that doesn’t contain glyphosate and avoid eating foods that may have chemical residue on them. Your health is important and limiting exposure to any kind of chemical should be a top priority.