Glyphosate, commonly known as Roundup, is the most widely used weed killer in the world—and it’s also the most controversial, especially when it’s found in our food.
It’s a popular product for anyone needing to tend anything from a large farm to a small backyard.
However, its usage and presence in much of the food we eat has caused widespread controversy, including claims that it could cause serious health problems like cancer and have a negative impact on the environment.
Here, we’ll take a look at what glyphosate is, how it differs from Roundup, and what the current science says about its potential health and environmental effects.
Glyphosate is the world’s most popular herbicide used to kill weeds and grasses and manage crops for the food industry.
Its use as an herbicide was discovered in 1970 by a chemist working for the agricultural biotech corporation Monsanto. Four years later the company patented it and began selling it as the active ingredient in their product called Roundup.
In 2000, Monsanto’s patent expired, and companies across the U.S. and Europe began to market their own glyphosate-based products, including Bronco, Rodeo, KleenUp and Weedoff.
It’s important to note that Roundup and similar weed-killing products contain more than just glyphosate.
Roundup contains several other ingredients, called inerts, that help increase the herbicide’s potency—and potentially its toxicity. These ingredients are often not disclosed, and they may just be listed as “other ingredients.”
But these may be harmful to our health, potentially more so than glyphosate.
In fact, researchers with the U.S. National Toxicology Program found that formulations like Roundup significantly decreased human cell viability as compared to glyphosate alone, which didn’t induce oxidative stress (1).
Other studies have also found that major pesticides are more toxic to human cells than their active ingredients alone (2, 3).
This means that studies examining glyphosate in isolation may not reveal the full effects of products like Roundup, which contain several other chemicals.
Glyphosate and GMOs
Glyphosate is a non-selective herbicide, which means it will kill almost all plants.
It does this by inhibiting a metabolic pathway called the shikimate pathway, which prevents microorganisms and plants from making essential proteins (4).
Because of this destructive process on plants, Monsanto began producing seeds for genetically modified plants (GMOs) that can withstand glyphosate.
These are often called “Roundup Ready” crops and dominate American agriculture, including the production of soy, corn, canola, sugar beets, cotton and alfalfa.
According to a 2016 review, genetically engineered herbicide-tolerant crops accounted for about 56% of glyphosate use across the world (5).
Summary: Glyphosate is a widely used herbicide for killing weeds and grasses and managing crops. The most popular product is Monsanto’s Roundup. The company is also known for creating genetically modified crops (GMOs), which can withstand Roundup’s plant-killing ability. Along with the active ingredient of glyphosate, Roundup includes several other inert ingredients that may make it more toxic. This means studies done on glyphosate alone may not reveal the whole story on products like Roundup.
Glyphosate in Food
Glyphosate is used on a wide range of crops around the world, meaning you’ll likely be exposed to it in your food—even if you eat 100% organic.
Any GM crop has been sprayed with a glyphosate product. According to a 2017 study, the U.S. is the world’s largest producer of GM crops (90% of which are corn, soybean and cotton), followed by Brazil, Argentina, India and Canada.
The study also points out that 82% of soybeans, 68% of cotton and 30% of maize (corn) around the world are GM (6).
In other words, the majority of soy- or corn-based food products will be genetically modified, and thus have been exposed to a glyphosate-based herbicide.
Glyphosate in Non-GMO Foods
But even non-GMO foods may contain glyphosate.
Farmers will often spray it on crops like wheat, barley, beans, oats, rye and other grains to speed up harvest. This can lead to higher residues of glyphosate in these foods (7).
If you’re eating any conventionally grown grain or oat-based product, you’re likely being exposed to some amount of glyphosate. Such popular foods as oatmeal, breakfast cereals, granola and snack bars will almost certainly contain it.
This was proven in a 2016 study commissioned by the Environmental Working Group (EWG), which found that 43 of 45 oat-based products contained glyphosate, while almost three-fourths of those samples had glyphosate levels higher than what the EWG consider safe for children (8).
An updated round of tests from 2018 showed even worse results, with glyphosate found in all 28 foods sampled, including Quaker and Cheerios products (9).
Beyond grains and beans, glyphosate may also be found in various fruits, vegetables and nuts like avocados, apples, spinach and pistachios. That said, the edible part of avocados are often protected from pesticides thanks to their thick skin.
In early 2019, a bill was proposed by U.S. congresswoman Rosa DeLauro, called The Keep Food Safe from Glyphosate Act, to ban late-harvest spraying of glyphosate on oats, and require the USDA to annually test commonly consumed foods for glyphosate residues.
Glyphosate in Organic Foods
It’s possible to significantly reduce your exposure to glyphosate by eating organic products.
Glyphosate is banned in organic farming, but traces of it still may show up in organic food. For example, the 2016 oat study mentioned above also detected glyphosate in nearly one-third of products made with organically grown oats, but at levels well below any risk.
However, another study found that GM-soy contained high residues of glyphosate, while organic soybeans contained none (10).
The reason why it may show up in some organic foods is that it can travel through the air or water from nearby farms that may be using it.
This means you’re never 100% protected from glyphosate, even if you only eat organic—or just simply drink water. In fact, glyphosate has even been detected in drinking water (11).
Summary: Glyphosate is used on a wide range of crops around the world, especially genetically modified ones like soybean, corn and cotton. However, non-GMO foods may have also been sprayed with glyphosate, including oats, grains, beans and some fruits and vegetables. It can even be found in trace amounts in organic foods (even though it’s banned in organic farming) due to drift our runoff from nearby farms.
Glyphosate and Cancer
There’s been a lot of controversy over glyphosate’s possible links to cancer, thanks to conflicting results and plenty of conflicting interests as well.
Studies in the early 2000s pointed to a link between glyphosate-based pesticides and non-Hodgkin lymphoma (a cancer of the immune system) (12, 13).
With Roundup in particular, one study found that rats fed on genetically modified maize or Roundup alone developed tumors and died 2-3 times more than controls (14).
In 2015, on the basis of similar evidence, the World Health Organization (WHO)’s International Agency for Research on Cancer classified it as a probable human carcinogen. Since this declaration, numerous other studies have revealed conflicting results.
That same year, a review of 14 studies on rats and mice found no evidence of a carcinogenic effect related to glyphosate. But looking further, this review included authors associated with Monsanto (15).
In 2017, an analysis of data from the Agricultural Health Study—funded by the National Cancer Institute and the U.S. Environmental Protection Agency (EPA)—showed no significant association between glyphosate and cancer risk in more than 57,000 farmworkers in Iowa and North Carolina (16).
However, a more recent analysis concluded that glyphosate increases cancer risk by 41% (17).
These types of findings have led to numerous lawsuits against Monsanto. This includes a few recent landmark cases, one in which the biotech company was ordered to pay $289 million to Dewayne Johnson, a former groundskeeper. A California jury ruled that the use of Roundup and Ranger Pro was the cause of his terminal non-Hodgkin lymphoma.
As of now, more independent research needs to be done on glyphosate (and its various formulations like Roundup) to confirm its possible link to cancer in humans.
Summary: The debate over glyphosate’s possible links to cancer is still going strong. Some evidence points to its potential in causing non-Hodgkin lymphoma, while other researchers have concluded that it has no carcinogenic effect. Still, the World Health Organization (WHO) classified it as a probable human carcinogen in 2015.
Other Potential Glyphosate Health Risks
Exposure to glyphosate may also pose other health risks, mostly for farmers and those who work with glyphosate-based products on a regular basis.
Some scientists believe that its use may be the cause for the drastic increase in chronic kidney disease among agricultural workers in Central America and India (18).
However, studies on the health effects of glyphosate have mostly been done on animals, so it’s hard to say how such effects could translate in humans.
For example, a 13-week pilot study found that glyphosate-based herbicide exposure (at doses considered safe) in male and female rats led to hormonal effects and altered reproductive development (19).
The same researchers found that these herbicides can potentially modify the gut microbiota in early development, particularly before puberty (20).
Another study showed reduced growth or lower survival of gut bacteria on Hawaiian green turtles exposed to glyphosate (21).
Overall, how much is too much for humans is still a large issue up for debate. It doesn’t help that the EWG and EPA have very different standards for safe exposure levels.
The EWG recommends a maximum dose of 0.01 mg per day, while the EPA has set a safe level of 2 mg per kilogram of body weight. So, if you weigh 70 kg, that’s as much as 140 mg.
It would be near impossible to reach the EPA’s limit just in food. And at this point there is no evidence that glyphosate in food can cause any serious health effects.
Summary: Farmers and individuals who work with glyphosate-based products on a regular basis may be at higher risk for certain health effects, including kidney disease. However, it’s not likely that glyphosate in food can cause any serious health issues.
Glyphosate and the Environment
There’s a growing concern around the rise of glyphosate use and how that could affect not only our health but the planet’s as well.
Since it was introduced in 1974, its use has increased 100-fold, and a total of 18.9 billion pounds has been used worldwide. Over 70% of this number was applied in just the 10 years between 2004 and 2014 (22).
This massive increase is largely due to the development of GM crops, as well as glyphosate-resistant weeds (23).
This increase in glyphosate means there’s much more potential for it to run off into nearby ecosystems, causing some environmental damage.
Even the EPA has recognized this, saying that while no human health risks are involved, “there are ecological risks for terrestrial and aquatic plants, birds and mammals, primarily from exposure to spray drift.”
Scientists have also hypothesized that the growing use of glyphosate could lead to shifts in microbiome composition, increases in antibiotic resistance and a rise in animal, human and plant diseases (24).
However, the research available on these theories is still scarce.
Summary: Glyphosate use has increased 100-fold since it was introduced in 1974. This has led to a growing concern over its impact on the environment. With more use comes an increased risk of it running into nearby ecosystems and causing environmental damage.
Should You Be Worried About Glyphosate In Your Food?
Glyphosate is the world’s most used herbicide, with Monsanto’s Roundup being its most popular formulation.
As of now, there are several other glyphosate-based products on the market sold to farmers as well as regular consumers hoping to rid of weeds in their backyards or gardens.
It’s a non-selective herbicide, meaning it will kill almost all plants.
This is one of the main reasons Monsanto created genetically modified crops (GMOs), which can withstand Roundup’s destruction.
This means glyphosate is used heavily in the production of GM crops (most notably soybean, corn on cotton), but it’s also sprayed on other food products before harvest, including oats, grains, beans and some fruits and vegetables.
While it’s possible to significantly reduce your exposure to glyphosate by eating organic products, it’s still likely to show up in trace amounts in these foods—and even in your drinking water, too.
In reality, most of us are never 100% protected from glyphosate exposure.
That said, its potential health risks—including its possible link to cancer—are still up for debate.
While the WHO has deemed it a probable human carcinogen, others (like the EPA) have proclaimed it safe, at least at a daily level of 2 mg per kilogram of body weight.
Farmers and those who work with glyphosate-based products on a regular basis are most at risk.
However, there’s no evidence that glyphosate in food can cause any serious health effects.
As of now, more independent research is needed to confirm its potential health risks on humans.
More importantly, studies also need to be done on products like Roundup, whose inert ingredients may make them more toxic than glyphosate alone.
While glyphosate’s effects on humans is still debatable, we can’t ignore its massive increase in use over the last few decades.
As of now, there’s no clear consensus on how much may be too much for us and our planet.
About Stephanie Garr (Certified Nutrition Consultant)
Stephanie is a certified nutrition consultant. She graduated from the University of Iowa with degrees in journalism and psychology in 2003, and later studied holistic nutrition at Bauman College in Berkeley, California.
