What you may have heard
Glyphosate, the main ingredient in the herbicide Roundup, has been called a potential cancer-causing chemical. Some lawsuits and media coverage have claimed that people exposed to glyphosate developed cancer, especially non-Hodgkin lymphoma. This has led to confusion and concern about whether glyphosate causes cancer in humans.
What science tells us
Glyphosate is one of the most commonly used herbicides worldwide. It’s used on major crops like corn and soybeans and can be found in trace amounts in food, air, and water (EPA). Because of how widely it is used, researchers have studied glyphosate for decades to understand its possible effects on cancer risk. Although some studies have found a potential link between glyphosate and non-Hodgkin lymphoma, especially in high-exposure populations, others have not. Government agencies and international research groups have reached different conclusions about whether glyphosate causes cancer, which has made this issue difficult to settle.
Epidemiological Evidence
- The U.S.-based Agricultural Health Study, which followed over 50,000 licensed pesticide applicators for more than two decades, found no association between glyphosate use and overall cancer risk or non-Hodgkin lymphoma (JNCI).
- A 2019 meta-analysis found that individuals with the highest cumulative glyphosate exposure had a 41% increased risk of non-Hodgkin lymphoma compared to those with the lowest exposure (PMID: 31292884). However, the authors noted that some of the studies had limitations, such as relying on people to remember past exposures, which can be inaccurate, and including too few participants to draw strong conclusions.
- These mixed results have made it difficult for scientists to reach a consensus on whether glyphosate increases cancer risk in humans.
Laboratory Evidence / Supporting Evidence
- The International Agency for Research on Cancer (IARC) cited animal studies showing that glyphosate exposure caused tumors in mice and rats. These included increases in rare tumors, such as kidney and skin tumors, at high doses (IARC).
- Laboratory studies also found that glyphosate can cause cell and DNA damages in human cells at high concentrations (ESE).
- However, the U.S. EPA concluded that glyphosate is “not likely to be carcinogenic to humans” at expected exposure levels, pointing out that the doses used in many animal studies are much higher than what most people would experience (EPA).
IARC Carcinogen Classification:
Group 2A – Probably carcinogenic to humans
This classification comes from a mix of findings, such as only limited evidence in people, clear evidence in animals, and lab studies showing cell and DNA damage.
How to reduce your risk
If you’re concerned about glyphosate exposure, consider avoiding glyphosate-based products in your garden or yard. Instead, pull weeds by hand every couple of weeks before they establish deep roots (NC State). Flame weeders, which briefly heat plants to kill them, are a chemical-free option for cracks and gravel areas, while steam or hot-foam methods are safer in flammable settings, though they require caution to prevent burns (NC State). If you work in agriculture or landscaping, use protective gear like gloves, long sleeves, and eye protection when handling herbicides (EPA).
Bottom line
Some studies suggest that high glyphosate exposure may be linked to non-Hodgkin lymphoma, but large long-term studies have not consistently supported this. Animal and lab studies suggest it’s possible that glyphosate could affect cancer risk, but those results don’t always apply to people.