Glyphosate is a synthetic ingredient in many weed killers. Some research suggests a link between glyphosate exposure and increased risk of certain cancers.

Glyphosate is a synthetic herbicide and pesticide. The Monsanto Company first registered glyphosate as a pesticide in the United States in 1974, and the chemical is widely used throughout the country.

Many weed killing products contain glyphosate, including Roundup-branded weed killers. People may use glyphosate weed killers, such as Roundup, in their garden or in agriculture use.

There is an ongoing debate as to the risks of glyphosate on human health, including whether there is an increased cancer risk from exposure to glyphosate products.

This article looks at the research behind glyphosate and any evidence of cancer risk. We also look at certain cancers which may be a risk type, symptoms to look for, and when to see a doctor.

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A number of scientific studies have found a link between exposure to glyphosate-based herbicides and increased risk of certain cancers, including Non-Hodgkins lymphoma (NHL) and its subtypes.

NHL is a type of cancer that begins in lymphocytes, a type of white blood cell, which are part of the lymphatic system. NHL has many subtypes, including chronic lymphocytic leukemia (CLL).

CLL begins in lymphocytes in the bone marrow, and can then spread to the blood and to other parts of the body.

According to a 2019 meta-analysis, there is a compelling link between glyphosate exposure and increased risk of NHL.

The meta-analysis included six human studies involving almost 65,000 participants. The studies looked at the effects of high exposure to glyphosate-based formulations.

The researchers concluded that the overall evidence from human, animal, and test tube studies shows a compelling link between glyphosate-based herbicides and increased risk of NHL. The researchers found a 41% increase in NHL among individuals with high doses of glyphosate-based herbicides.

Another meta-analysis from 2021 looked at six studies involving participants who have ever had exposure to glyphosate. Results varied across the studies. Two of the four studies found that the highest cancer risk was for CLL.

The researchers concluded there was no link between glyphosate exposure and increased risk of NHL, but there was a potential link between glyphosate and diffuse large B-cell lymphoma, which is a type of non-Hodgkins lymphoma.

A 2018 cohort study from the Journal of the National Cancer Institute looked at the long-term effects of glyphosate on people using the chemical in agriculture.

The study found no link between glyphosate use and solid tumors, abnormalities in lymphoid tissue, or NHL and any subtypes. The study did find a potential link between glyphosate use and acute myeloid leukemia.

There are still mixed opinions on the health effects of glyphosate.

Due to ethical reasons, it is not possible to test the direct effects of glyphosate on humans. Evidence from animal studies may not correlate to effects on humans.

Population studies looking at people with high exposure to glyphosate may find a correlation between glyphosate and health concerns. However, this does not always mean glyphosate is the cause, as many other factors may also be involved.

Studies looking at the effects on people with high exposure to glyphosate, such as people working in agriculture who use large quantities of glyphosate on crops, may not relate to people with low exposure.

It is also important to note any potential bias from research or organizations, either from involvement from Monsanto or review articles that cherry-pick data.

According to an independent evaluation from the federal Environmental Protection Agency (EPA), glyphosate poses no risk to human health if people follow the current usage instructions correctly.

The EPA states that there is no indication that glyphosate affects the reproductive or endocrine system, causes cancer, or that children are at higher risk from exposure.

However, the World Health Organization’s International Agency for Research on Cancer says glyphosate is a potential cause of cancer.

Additionally, the International Federation of Gynecology and Obstetrics, has issued a statement advocating a worldwide end to glyphosate usage, due to the potential cancer risk and adverse health effects.

A number of scientific studies suggest a possible link between glyphosate and a range of health concerns, including:

  • endocrine disruption, which results in the interference of the hormonal system
  • changes to thyroid function
  • adverse effects on the male and female reproductive system
  • non-alcoholic fatty liver disease
  • adverse effects on the gut microbiome

If people are planning to use glyphosate weed killer in their gardening, the National Pesticide Information Centre recommends the following tips for minimizing exposure to chemicals in herbicides or pesticides:

  • Follow all product instructions on the label carefully.
  • Before using, remove any surplus items from the area, such as any pet bowls, toys, or seating.
  • Cover any areas that do not require spraying, such as play areas, vegetable gardens, or sensitive plants.
  • Close any doors and windows in nearby buildings, and turn off any air conditioning.
  • When using, avoid the highest pressure setting, as this can cause small particles to remain in the air.
  • Avoid using when very windy, as the product may blow away from the area of application
  • Make sure nobody else is around except the person applying the product.
  • After using, keep people and pets away from the treated area until it is dry.
  • Wear shoes when walking on any treated areas, and remove shoes before going indoors.

People can check the rules for pesticide use in their state, and place any signs up to notify neighbors of the treated area.

CLL does not always cause symptoms, and people may only discover they have CLL through a routine blood test or checkup.

If people do have symptoms of CLL, they may include:

  • weakness
  • fatigue
  • night sweats
  • unexplained weight loss
  • chills
  • fever
  • swollen lymph nodes, which people may feel as lumps under the skin in the neck, armpits, or groin
  • pain or fullness in the stomach, which may make people feel full after only eating a small amount

According to the American Cancer Society, long-term exposure to certain herbicides and pesticides, including Agent Orange, may have a link to increased risk of CLL. Radon exposure may also increase the risk of CLL.

Other risk factors for CLL include:

  • being over the age of 50
  • having a first-degree relative, such as a parent or sibling, with CLL
  • being male, which increases the risk slightly more than being female, although the reasons for this are unknown
  • race and ethnicity, due to genetics, as CLL occurs more in North America and Europe than Asia, and Asian people living in the United States do not have an increased risk of CLL

If people think they have experienced exposure to glyphosate and have concerns about any health effects, they can speak with a healthcare professional.

People may want to discuss the type, levels, and time frame of glyphosate exposure. This may help a doctor assess their risk factors.

A doctor may perform a physical examination, take a full medical history, and carry out a blood test.

People can also contact a doctor if they have any symptoms of CLL or any type of NHL. Symptoms can overlap with many other conditions, but it is best to get a check-up if people notice any unusual symptoms.

Glyphosate is an ingredient in many common weed killers, such as Roundup. There is a lot of controversy over the health effects of glyphosate, including whether there is an increased risk of cancer from glyphosate exposure.

There is a mix of scientific evidence, although some studies have found a link between glyphosate exposure and increased risk of certain types of cancer.

People can take care to use any glyphosate weed killers as the product instructs, and take precautions to limit exposure. People may want to use an alternative, such as natural methods or non-toxic herbicides.