Is the Roundup Weed Killer (Glyphosate) Bad for You?
Roundup is one of the most popular weed killers in the world.
It is used by farmers and homeowners alike, in fields, lawns and gardens.
Many studies claim that Roundup is safe and environmentally friendly.
However, other studies have linked it to serious health issues like cancer.
This article takes a detailed look at Roundup and its health effects.
Roundup is a very popular herbicide, or weed killer. It is produced by biotech giant Monsanto, and was first introduced by them in 1974.
This weed killer is most commonly used in agriculture. It is also used by the forestry industry, cities and private homeowners.
The key ingredient in Roundup is glyphosate, a compound with a molecular structure similar to the amino acid glycine. Glyphosate is also used in many other herbicides.
Roundup is a non-selective herbicide, meaning that it will kill most plants it comes in contact with.
Its use increased massively after genetically modified, glyphosate-resistant ("Roundup ready") crops were developed, such as soybeans, corn and canola ().
Glyphosate kills plants by inhibiting a metabolic pathway called the shikimate pathway. This pathway is crucial for plants and some microorganisms, but does not exist in humans (, ).
However, the human digestive system does contain microorganisms that make use of this pathway.
Bottom Line: Roundup is a popular weed killer. The active ingredient, glyphosate, is also found in many other herbicides. It kills plants by interfering with a specific metabolic pathway.
Roundup is a highly debated topic these days. Some studies claim that the active ingredient, glyphosate, may be increasing the risk of many diseases (, ).
On the other hand, Roundup has long been considered one of the safest herbicides available on the market ().
However, Roundup contains more than just glyphosate. It also contains a lot of other ingredients, which help make it a potent weed killer. Some of these ingredients may even be kept secret by the manufacturer and called inerts ().
Several studies have actually found that Roundup is significantly more toxic to human cells than just glyphosate (, , , , ).
Therefore, studies showing safety of isolated glyphosate may not apply to the entire Roundup mixture, which is a blend of many chemicals.
Bottom Line: Roundup has been linked to many diseases, but is still considered a safe herbicide by many organizations. It contains a lot of other ingredients that may be more toxic than glyphosate alone.
In 2015, the World Health Organization (WHO) declared glyphosate as "probably carcinogenic to humans" ().
Put simply, this means glyphosate has the potential to cause cancer. The agency based their conclusion on observational studies, animal studies and test tube studies.
While mice and rat studies link glyphosate to tumors, there is limited human evidence available (, ).
The studies that are available mainly include farmers and people who work with the herbicide.
A few of these link glyphosate to non-Hodgkin lymphoma, a cancer that originates in white blood cells called lymphocytes, which are part of the body's immune system (, , ).
However, several other studies have found no connection. One huge study of more than 57,000 farmers found no link between glyphosate use and lymphoma ().
Two recent reviews also found no association between glyphosate and cancer, although it should be mentioned that some of the authors have financial ties to Monsanto (, ).
The most recent update on the matter comes from the European Union Food Safety Authority (EFSA), who concluded that glyphosate is not likely to cause DNA damage or cancer ().
However, the EFSA looked at studies of only glyphosate, while the WHO looked at studies on both isolated glyphosate and products containing glyphosate as an ingredient, such as Roundup.
Bottom Line: Some studies have linked glyphosate to certain cancers, while others have found no connection. The effects of isolated glyphosate may differ from products that contain glyphosate as one of many ingredients.
There are hundreds of different types of microorganisms in your gut, most of which are bacteria ().
Some of them are friendly bacteria, and are incredibly important for your health ().
Roundup may negatively affect these bacteria. It blocks the shikimate pathway, which is important for both plants and microorganisms ().
In animal studies, glyphosate has also been found to disrupt beneficial gut bacteria. What's more, harmful bacteria seemed to be highly resistant to glyphosate (, ).
One article that received a lot of attention on the internet even hypothesized that the glyphosate in Roundup is to blame for the increase in gluten sensitivity and celiac disease worldwide ().
However, this needs to studied a lot more before any conclusions can be reached.
Bottom Line: Glyphosate disrupts a pathway that is important for the friendly bacteria in the digestive system.
Many reviews exist about the health effects of Roundup and other products that contain glyphosate.
However, they report conflicting findings.
Some of them claim that glyphosate may have negative effects on health and play a role in many diseases (, , ).
Others report that glyphosate is not linked to any serious health conditions (, , ).
This may differ depending on population. For example, farmers and people who work closely with these products seem to be at the highest risk of adverse effects.
Glyphosate residues have been found in the blood and urine of farm workers, especially those who do not use gloves ().
One study of agricultural workers using glyphosate products even reported problems with pregnancy ().
Another study has hypothesized that glyphosate may at least be partly responsible for a chronic kidney disease in farm workers in Sri Lanka ().
These effects need to be studied further. Also keep in mind that studies on farmers who work closely with the herbicide may not apply to people who are getting it in trace amounts from foods.
Bottom Line: Studies report conflicting findings about the health effects of Roundup. Farmers who work closely with the weed killer seem to be at the highest risk.
The main foods that contain glyphosate are genetically modified (GM), glyphosate-resistant crops, such as corn, soybeans, canola, alfalfa and sugar beets ().
One recent study found that all 10 genetically modified soy samples examined contained high levels of glyphosate residues ().
On the other hand, samples from conventional and organically grown soybeans did not contain any residues.
What's more, many weed species are now resistant to glyphosate, which is causing more and more Roundup to be sprayed on crops ().
Bottom Line: Roundup and glyphosate residues are mainly found in genetically modified crops, including corn, soy, canola, alfalfa and sugar beets.
You are most likely to come into contact with Roundup if you live or work near a farm.
Studies show that direct contact with Roundup may cause health issues, including a greater risk of developing a cancer called non-Hodgkin lymphoma.
If you do work with Roundup or similar products, then make sure to wear gloves and take other steps to minimize your exposure.
However, the glyphosate in food is another matter. The health effects of these trace amounts is still a matter of debate.
It is possible that it can cause harm, but it hasn't been shown conclusively in a study.