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Why Glyphosate is Dangerous, and How to Avoid Eating it

Article at a Glance
  • Glyphosate is the most widely used herbicide worldwide and is the main active ingredient in Bayer-Monsanto’s Roundup®, which was first sold in 1974.
  • Glyphosate is classed as a probable carcinogen by the World Health Organization’s International Agency for Research on Cancer, and is thought to be an endocrine (hormone) disruptor and to have adverse effects on the microbiome.
  • In a landmark court case in 2018, a school groundskeeper was awarded $289 million in damages from Bayer’s Monsanto by a jury who determined that his non-Hodgkin’s lymphoma was caused by repeated exposure to Roundup®.
  • This court case opened the way for a purported 9,500 plaintiffs in the U.S., mostly farmers, to bring suits against Bayer-Monsanto for similar cause.
  • Glyphosate appears to have adverse effects on the health of earthworms, bees (and may contribute to Colony Collapse Disorder), and biodiversity in general.
  • Glyphosate is not exclusively used on GMO crops. Its use is forbidden in USDA Organic Certified crops, but it is often used as a pre-harvest desiccant on non-GMO crops to speed up harvest.
  • Several companies are looking to ban or phase out glyphosate use and market pressures are increasing for growers to adopt alternative agricultural practices.
  • The use of glysophate may affect food quality, including levels of nutrients such as cholesterol-lowering beta-glucans in oats.
  • Glyphosate-free certification is in its infancy, so the best way to minimize exposure is to buy organic and/or to buy local, so you can talk to the farmer about their growing practices and potential for glyphosate contamination.
Glyphosate found in most oat products

Glyphosate is the main ingredient in the weed-killer Roundup® and is the most widely used chemical herbicide in history. Chances are, this chemical is in at least some of the food you’ll eat today, even if that food is organic, non-GMO, and ‘natural’. Why should that concern you and what can you do to avoid glyphosate exposure?

Glyphosate is a broad spectrum herbicide

Glyphosate is a broad-spectrum herbicide sold under the common trade name Roundup®. It was first sold to farmers in 1974 by Monsanto, the company recently acquired by Bayer. Since the late 1970s the use of glyphosate-based herbicides (GBHs) has increased approximately 100-fold (by volume), although some estimates put it at a 300-fold increase. Why has glyphosate usage spiked like this?

The reason for this dramatic increase in glyphosate use is likely two-pronged.

Why do farmers use Roundup® and glyphosate-based herbicides?

After the introduction of Roundup® in 1974, farmers began using more and more of the weed-killer to make life on the farm a little bit easier, by killing off invasive species of weeds that could threaten crop yields. Then, in the 1990s, Monsanto launched their genetically modified Roundup Ready® soybeans and carried out a very active and aggressive campaign to get more farmers to use these seeds. The purpose of these seeds is to allow everything else around them to be sprayed with pesticides without killing the cash crop. Roundup® could then be used liberally on fields without the GMO crops dying. Over time, the emergence of glyphosate-resistant weeds has become widespread, and this has led to farmers using greater volumes of Roundup® to try to maintain crop yields.

The introduction of Roundup® resistant crops led to vastly increased use of glyphosate. Indeed, usage increased to 36 million kg in 2000 and by 2014 annual usage was estimated at 113.4 million kg. Between 1974 and 2004, an estimated 1.6 billion kilograms of glyphosate have been applied to fields in the United States, (Benbrook, 2016).

Farmers have also started using glyphosate in an ‘off-label’ fashion, as a pre-harvest desiccant on non-GMO food crops. While most farmers spray the crops after they reach maturity, which kills the weeds and makes for easier harvesting, some farmers use glyphosate to force their crops to ripen early. This is increasingly common for crops such as wheat, barley, oats, and beans, and allows farmers to get a better harvest even in areas with a short growing season.

The glyphosate cancer link

Ok, so glyphosate makes life easier on farmers, that sounds like a good thing, what’s so bad about spraying crops?

Unfortunately, lots.

Glyphosate has been labelled as a probable carcinogen by the World Health Organization’s International Agency for Research on Cancer. In fact, this chemical is now the subject of several lawsuits brought by people who have developed cancer after years of using Roundup®. One such suit concluded in August this year, with a jury awarding the plaintiff, Dewayne Johnson, a school groundskeeper, $289 million in damages from Bayer’s Monsanto. The jury concluded that it was Johnson’s repeated exposure to Roundup® that led to him developing non-Hodgkin’s lymphoma (a type of cancer).

Another hearing is set for October 9th in Alameda County to determine if Roundup® is to blame for two further cases of non-Hodgkin’s lymphoma, this time in an elderly couple, Alva and Alberta Pilliod, who used Roundup® for years. And, according to Bloomberg, “Bayer is currently facing litigation by more than 9,500 plaintiffs in the U.S., mostly farmers, who blame exposure to glyphosate for non-Hodgkin lymphoma.”

How is glyphosate linked to cancer? Well, there is some suggestion that the chemical is an endocrine disruptor in humans, meaning that it adversely affects hormone balance. (R) At very high levels (not representative of normal exposure through food consumption) glyphosate has been found to induce breast cancer in human cells in vitro via estrogenic activity. (R) Again, at very high levels, glyphosate and its metabolites also cause hemolysis and hemoglobin oxidation in human blood cells in the lab. (R) Even at low levels, glyphosate may increase the risk of oxidative damage to DNA, raising the likelihood of cellular mutations.

Glyphosate works by inactivating the enzyme 5-enolpyruvylshikimate-3-phosphate synthase. This enzyme is used in the shikimate pathway of plants to form aromatic amino acids. By inhibiting the enzyme, glyphosate causes the death of the plant.

The shikimate pathway is not present in animals, which is why glyphosate has long been considered non-toxic. (R) The EPA places glyphosate in the “least toxic” category, category IV. Questions have arisen in recent years over both the direct and indirect impact of glyphosate on human health.

Changing use patterns of glyphosate and advances in understanding of potential risks have led many researchers to reassess early claims of safety for the herbicide. In one Statement of Concern, published in the journal Environmental Toxicology in 2016, the authors noted that:

  1. Products containing glyphosate often contaminate drinking water sources, precipitation, and air, especially in agricultural regions
  2. The half-life of glyphosate in water and soil is longer than previously recognized.
  3. Glyphosate and its metabolites are widely present in the global soybean supply
  4. Human exposures to GBHs are rising
  5. Glyphosate is now authoritatively classified as a probable human carcinogen
  6. Regulatory estimates of tolerable daily intakes for glyphosate in the United States and European Union are based on outdated science.

The half-life of glyphosate is thought to be up to 151 days. This varies greatly, however, based on soil type.

Evaluating the safety of glyphosate

Increasingly, scientists are highlighting the major gaps in the evaluation of glyphosate safety. This includes the glaring oversight whereby glyphosate has never been tested alone at the daily intake considered acceptable, nor at doses relevant for human exposures. (R) Only recently have studies in rats been performed to assess the effects of chronic ingestion of an ultra-low, environmentally relevant dose of Roundup®, and those studies revealed damage to the rats’ kidneys and liver structure and function. (R) (R) The rats appeared to develop non-alcoholic fatty liver disease, which is a leading cause of liver dysfunction in humans.

There may also be indirect health effects of glyphosate use. For example, the shikimate pathway is present in many of the beneficial bacteria in the human gut and the gut of other animals and insects. Consuming food which contains glyphosate may, therefore, kill off beneficial bacteria populations, which can have significant adverse effects on health.

Evidence of this has been seen in bees, where glyphosate is now thought by many to be a key contributor to colony collapse disorder. Changes in the bee microbiome appear to increase their susceptibility to infection, causing huge numbers of bees to die off. (R) As well as affecting bees, glyphosate applied to coffee crops has been shown to have detrimental effects on earthworms and biodiversity overall. (R)

If you’re not already upset at the idea of undesirable chemicals in your food, this might tip you over the edge: the ongoing litigation around Roundup® has cast light on the dark machinations of its creator, Monsanto, as well as the U.S. Environmental Protection Agency (EPA), to hide the evidence of this chemical’s potentially devastating effects on human and environmental health. Indeed, authors of papers published in respected journals have recently been forced to admit that they received ‘assistance’ from Monsanto while writing the papers, although they stress that the data remains unbiased.

Governments and glyphosate disclosures

The concerns about Roundup® and glyphosate in general led California legislators to introduce a regulation requiring glyphosate to come with a warning label saying it causes cancer. Several countries are also considering banning the chemical altogether or are actively phasing out the use of glyphosate. The European Union came close to banning glyphosate use last fall, while French President Emmanuel Macron has publicly committed to phasing it out over the next three years (although, he is being hobnailed by the rest of government). Market pressure may lead other countries to phase out glyphosate. Online Canadian agricultural industry journal, the Western Producer, notes that ‘Italy is refusing to buy Canadian durum wheat, partly over concerns that glyphosate is used on the durum prior to harvest.’

Glyphosate use impacts crop quality

As if all of the things I’ve already mentioned aren’t bad enough, there is evidence that glyphosate treatment can adversely affect crop growth and quality.

Seedlings planted after treatment with glyphosate have been found to have lower germination rates and decreased root growth. And wheat treated with glyphosate before harvesting was found in one study to have elevated levels of shikimic acid, which makes dough made from this wheat weaker and less suitable for breadmaking. (R)

Another problem with the off-label use of glyphosate as a pre-harvest desiccant is that crops are harvested shortly after spray and long before the chemical can be broken down. That means that glyphosate is present at high levels in many common food crops, and these crops are often labelled as ‘natural’ and non-GMO, which can, understandably, cause confusion for consumers.

There are other potential issues with this practice too. Some researchers have raised concerns, for example, that the nutritional quality of food crops might be reduced by the use of glyphosate. Organic soybeans, for instance, have been found to have higher nutritional value than GM soybeans. There is also speculation that the cholesterol-lowering beta-glucans in oats, which only emerge shortly before the plant ripens naturally, may be lower in crops that are forced to ripen early.

Some companies worried about nutrient levels, such as Grain Millers Inc. (one of the largest oat buyers in Western Canada), have even gone as far as to state that they will no longer purchase oats treated with pre-harvest glyphosate (Cross, 2016). In one interview, Terry Tyson, a procurement manager with the company, said “In order to meet those (Heart Healthy) claims, beta glucan levels in the raw oats (has) to be in excess of four percent.  Other factors can also adversely affect beta glucan levels, but our research demonstrates that premature application of glyphosate can have that effect.”

Others in the industry have said that they don’t think this is as big an issue as Tyson and co. are making it out to be. The problem, though, is that there’s no published data on the potential problem. To undertake such research would be tricky using commercially available oats, given that treated crops often contaminate untreated crops because they are processed alongside each other or mixed together. What’s more, crops grown near fields sprayed with glyphosate may also be contaminated as the chemical can drift or end up in water supplies. Maintaining a 100 percent glyphosate-free food-chain is nigh on impossible, an issue that was highlighted recently by a report from the Environmental Working Group (EWG).

Glyphosate contaminated foods vs. safer foods – how to choose

The EWG published a report on August 15th, 2018, that sent health food consumers into something of a spin. And quite rightly! This report revealed that glyphosate was present in 43 of 45 samples of products made with conventionally grown oats. Indeed, almost 75 percent of the samples had glyphosate levels higher than 160 parts per billion, the daily level of exposure which EWG scientists consider protective of children’s health.

Shockingly, around a third of the 16 samples of products made with organically grown oats also had glyphosate, although these levels were well below EWG’s health benchmark.

So, which products came out best in the EWG report? The five samples, tested by Eurofin Analytical Laboratories, with no detectable levels of glyphosate were as follows:

  • Nature’s Path Organic Honey Almond granola
  • Simple Truth Organic Instant Oatmeal, Original
  • Kashi Heart to Heart Organic Honey Toasted cereal
  • Cascadian Farm Organic Harvest Berry, granola bar
  • 365 Organic Old-Fashioned Rolled Oats.

Of four samples of Bob’s Red Mill Organic Old Fashioned Rolled Oats, one had no detectable levels, one had 10 ppb, and two others had 20 ppb. The presence of any glyphosate in Bob’s Red Mill products led to uproar in long-time fans of the company, many of whom felt betrayed by the marketing used by BRM. For their part, BRM stated in 2015 that they would begin asking the farmers producing their ingredients to avoid using glyphosate. In response to the recent EWG report, company representatives issued statements such as:

“Our farmers of organic oats are 100% committed to growing their crops by the rules of the National Organic Program. The use of glyphosate as a pre-harvest desiccant isn’t allowed in the growing of organic oats. Unfortunately, even with the rules, it’s still possible for glyphosate to blow over from other non-organic farms. Even still, choosing organic is the best way to avoid pesticides and other chemicals in foods.”

Some consumers are not happy with that answer, however, and a federal class action against Bob’s Red Mill was filed in August in San Francisco in response to the EWG report. The complaint states that “Consumers have a reasonable expectation that material product information, such as the presence of a probable carcinogen like glyphosate, will be provided by a product manufacturer, especially when the manufacturer affirmatively identifies the health-related attributes of its products”. The complainants say that BRM’s labels and marketing are misleading, given that they promote their products as “wholesome” and healthy.

It should be noted that many companies use the same type of marketing and are not facing lawsuits. What’s more, companies producing Lucky Charms and Cheerios (found to very high in glyphosate, and generally not considered healthy) have issued simple statements to the effect that levels of the chemical remain below the EPA’s limits. (While I understood the anger of the complainants in the BRM case, I’m inclined to continue to support a company that produces largely healthy food products and is at least attempting to address the issue of food contamination.)

The EWG’s 2018 report follows a report from 2016, courtesy of Food Democracy Now! and The Detox Project, a research and certification platform that uses an FDA-registered food-testing lab to test for toxic chemicals. These organizations commissioned tests that found high glyphosate levels in many foods sold in America, including some certified organic and non-GMO products.

In a 2017 report, the Canadian Food Inspection Agency said it detected traces of herbicide in nearly 29.7 percent of the 3,188 food products it tested. In all food products, 1.3 percent contained residue levels above Health Canada’s Maximum Residue Limits (MRLs) – the level at which they aren’t a concern for human health. For the grain products tested, 3.9 percent had residue levels above MRLs. None of the products were deemed to pose a risk to human health and safety, however, and, as such, Health Canada did not publish the brand or product names of those foods tested.

So, what can you do to avoid glyphosate?

Well, first, you can look for products that feature the Detox Project’s “Glyphosate Residue Free” label. This label offers extra assurance that a product does not contain glyphosate.

The first product to be verified “Glyphosate Residue Free” was Leaf & Love Organic Lemonade. A full listing of certified products can be found here. Unfortunately, the roll-out of this label is slow-going, although the Detox Project is working with food manufacturers and grocery chains to get this label on more products.

In the meantime, your next best option is to buy organic wherever possible. Organic crops are not allowed to be treated with glyphosate, so any presence of the chemical is incidental and likely to be much lower than in crops treated intentionally. Buying non-GMO does not guarantee that the crops haven’t been treated pre-harvest with glyphosate.

By buying organic, you reduce the likelihood of glyphosate contamination and you also support decreased use of these agricultural chemicals overall. This helps lower the general risk of contamination of the food supply. Think of it like vaccines and herd immunity, if you will.

Which crops are the worst for glyphosate?

If your budget for organics is limited, you’ll want to know which food crops are the worst offenders when it comes to glyphosate. Unfortunately, the EPA has largely given up carrying out the ‘protection’ part of its mandate in recent years and no longer seems to test crops. This is despite evidence tat unofficial testing revealed high levels of glyphosate in many household foods.

Thankfully, the FDA has begun to test foods for glyphosate, albeit 40 years after the chemical was introduced. A report was just released showing 2016 levels of pesticides in food crops.

Over half of all samples of soy (67.4%), wheat (47.8%), rice (80%), and corn (58.6%) contained pesticide residues. These were not the worst offenders, however. A staggering 95.9% of cherry fruit/juice and 90.8% of apple fruit/juice tested positive for pesticides. As for grape fruit/juice and raisins, 92.8% of samples were found to be contaminated, while 92.5% of strawberries were also tainted. As a group, almost four out of five samples (79%) of fruit or fruit products tested positive for pesticides.

Vegetables fared a little better, with just over half (52.3%) testing positive for pesticides. The worst offenders here were celery (77.3% contaminated), sweet peppers (79.6%), spinach (88.6%), and tomatoes (80%).

This report also lists imported foods, many of which also tested positive for pesticides.

The FDA report does not separate out pesticides, however, although it does reveal that 63.1% and 67% of corn and soybean samples tested positive for glyphosate. So, for now, one of the best resources in terms of likely glyphosate food contamination is a list from 2015, included in a memorandum from the EPA for “updated Screening Level Usage Analysis”.

This list includes seventy crops, some of which might surprise you. The list details the percentage of each type of food crop treated with glyphosate, and the annual average use for the decade 2004-2013. Since glyphosate use has increased every year since its introduction, chances are that the situation is now even worse for many of these crops in the US.

The following could be considered a list of the worst glyphosate culprits, where you’re best to buy organic or choose a different food altogether. These are crops where treatment levels are higher than 50%, i.e. at least half of the non-organically grown foods on this list have been treated with glyphosate. I have also included several crops where the maximum found to be treated was higher than 50 percent.

CropAnnual average (Lbs. Glyphosate)Percent crop treated  
AverageMaximum
Almonds2,100,0008595
Apples400,0005570
Apricots10,0005580
Asparagus30,0005570
Canola500,0006580
Cherries200,0006585
Corn63,500,0006585
Cotton18,400,0008595
Dates8,0006525 [?]
Fallow8,800,0005570
Figs10,00085100
Grapefruit400,00085100
Grapes1,500,0007080
Hazelnuts30,0006590
Kiwifruit5,0007095
Lemons200,0007590
Olives40,0006075
Oranges3,200,0009095
Peaches100,0005570
Pears100,0006590
Pistachios500,0008595
Plums/Prunes200,0007085
Pluots1,0006590
Pomegranates40,0007090
Soybeans101,200,000105100
Sugar beets1,300,00060100
Sunflowers1,100,0006075
Tangelos9,0005580
Tangerines60,0006580
Walnuts600,0007590
Avocados80,0004565
Nectarines20,0004570
Rice800,0003050
Sorghum3,000,0004060
Sugarcane300,0004560
Wheat8,600,0002570

If the price tag that comes with organic products is an obstacle, your next best option may be to seek out local growers with whom you can have a real conversation about their growing practices. Many farmers that use organic growing practices cannot afford to obtain organic certification (which means their prices may be lower). Farmers are also likely to know if neighboring fields are treated with glyphosate or other chemicals, and how their crops are processed. Some wholesale companies, such as Healthy Traditions, enlist third-party laboratories to test the products they’re considering selling, and offer a guarantee that everything they sell is glyphosate-free.

By demanding accountability and transparency from our food manufacturers, we can all do our bit to help improve food security, safety, and quality. And, while you’re taking steps to minimize glyphosate exposure, you might also want to consider offsetting some of the potential negative effects of the chemical. That might mean ensuring a good intake of antioxidants, taking probiotics and/or eating probiotic foods regularly, and using herbs and lifestyle changes to support liver health so your body’s natural detoxification processes can help get glyphosate out of your system.

Leigh Matthews

Leigh Matthews, BA Hons, H.Dip. NT, is a health and wellness writer specializing in plant-based nutrition. A long-time vegan, Leigh is interested in nutriepigenetics, diet as preventative medicine, and the politics of food justice.

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