glyphosate health

The Glyphosate Problem

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Glyphosate is the active ingredient in Roundup® – the world’s most popular broad spectrum herbicide used by gardeners and farmers to increase crop yields and kill weeds. It is used widely in agriculture, but also in urban settings and to control weeds as part of conservation efforts.

Glyphosate is an analogue of the amino acid glycine. It works by interfering with the shikimate pathway – a seven-step process used by plants, bacteria (including our gut bacteria), archaea, fungi and some protozoa to synthesise folates and amino acids. Specifically, glyphosate inhibits an enzyme called EPSP synthase (5-enolpyruvylshikimate-3-phosphate synthase) which is required to produce the amino acids tryptophan, tyrosine and phenylalanine – all of which are needed for plants to grow.

Humans depend on the shikimate pathway working in our gut bacteria as well as in plants to supply us with essential amino acids. Glyphosate is absorbed by the foliage of plants and to a lesser extent the roots, so it cannot be used to prevent germination of a plant, only once the plant has started growing. Once the EPSP enzyme is inhibited, shikimate builds up in the plant, diverting resources from where it is needed and causing the plant to turn yellow and die.

Glyphosate was first discovered by a Swiss chemist in 1950. It was developed and brought to market in the 1970s by multinational agrochemical and biotech giant Monsanto (recently acquired by pharmaceutical company Bayer), under the name of Roundup®. Monsanto’s marketing tagline for Roundup was “a herbicide that gets to the root of the problem.”

Since the seventies, its use has grown by over 100-fold, making it the world’s most used herbicide, in part due to the rise in glyphosate-resistance amongst plants. There are now several hundred different glyphosate products on the market.

Monsanto has developed a number of genetically modified crops that are resistant to glyphosate, so that farmers can broadly apply the herbicide to their crops. As we will discuss later, this affects far more than just the crop. Glyphosate resistant crops include soy, cotton, canola, beets, sugar cane, alfalfa and maize. Currently, over 90 percent of U.S. corn, upland cotton, and soybeans are produced using genetically engineered varieties.

Ignoring Gut Bacteria: The Great Shikimate Debate

The human health impacts of glyphosate exposure is a heated topic. This is unsurprising considering Roundup delivered a whopping $4.8 billion in revenue to Monsanto in 2015. There are significant financial interests in suppressing comprehensive research into this topic. Companies like Monsanto argue that Roundup® cannot be toxic to humans because we do not have a shikimate pathway. However the bacteria in our guts do.

Glyphosate also disrupts methionine, an essential sulfur-containing amino acid, and glycine. Numerous other vital molecules including serotonin, melatonin, melanin, epinephrine, dopamine, thyroid hormone, folate, coenzyme Q10, vitamin K, and vitamin E, depend on the shikimate pathway metabolites as precursors. As such, glyphosate’s disruption of the shikimate pathway very likely affects our health, contrary to Monsanto’s assertions.

Glyphosate and Cancer

In 2015, the World Health Organization’s International Association for Research on Cancer identified glyphosate as a “probable carcinogen” whilst in the same year the European Food Safety Authority stated that glyphosate is unlikely to cause cancer, words that were echoed by the US Environmental Protection Agency (EPA) in 2018.

Although glyphosate is regularly found in human urine (both from those experiencing direct exposure and via food), there is no consensus on what a safe tolerable daily intake is. The US EPA sets a limit of 1.75mg per kilogram of body weight whilst the EU’s limit is much lower at 0.3mg per kilogram of body weight. Glyphosate residues in food are found up to a year after the herbicide’s application.

Despite this disagreement, there are a number of studies indicating glyphosate exposure is toxic to humans and animals. To this end, Bayer has been forced to payout almost $11 billion in the settlement of 95,000 non-Hodgkin lymphoma and cancer claims from sufferers linking their illness to RoundUp exposure.

In 2015, after reviewing approximately one thousand published studies on glyphosate, a working group of 17 World Health Organization experts from 11 countries deemed glyphosate a category 2a carcinogen. That means it is likely to cause cancer in humans and that there is sufficient evidence of its carcinogenic effects in animals. The WHO scientists also concluded there was strong evidence that glyphosate damages genes, causing mutations.

In 2019, the Agency for Toxic Substances and Disease Registry (part of the US Department of Health) released its draft toxicology report on glyphosate concurring and even strengthening the WHO’s findings. This was despite efforts from Monsanto, working in collaboration with the US EPA’s Pesticide Office, to suppress the report. In fact, US EPA’s Pesticide Official Jess Rowland was caught telling Monsanto’s Dan Jenkins, “If I can kill this I should get a medal”.

Glyphosate Linked to Neurodevelopmental and Neurodegenerative Disorders

In addition to demonstrating statistically significant links between glyphosate and cancer in humans, the ATSDR report also links glyphosate with developmental delays, gastrointestinal effects including nausea and vomiting, kidney and liver toxicity, and eye irritation in rodent and some human studies.

The ATSDR highlighted a link[1] between parental use of glyphosate among farm families and an increased risk of neural tube defects, miscarriage, preterm delivery, and small for gestational age (ATSDR Table 2-5, p. 40-41). Animal studies of early life exposure to glyphosate indicate an increased incidence of testicular lesions, elevated abnormal sperm, decreased testosterone, decreased sperm production, and skeletal malformations (ATSDR, p. 14). Long term studies by the US National Cancer Institute link glyphosate exposure to chronic bronchitis, wheezing and asthma (ATSDR, Table 2-5, p. 36; Ag Health Study).

Recent research has suggested a link between glyphosate and neurodegenerative disease, such as Parkinson’s, and prion diseases. This is thought to be due to glyphosate’s disruption of bile acid homeostasis, which causes a toxic buildup of manganese in the brain.

Laboratory studies have found evidence that glyphosate may contribute to endocrine disruption in animals and human cell lines, even when used at concentrations below those applied in agriculture. Ironically, chemicals that act as endocrine disruptors often have an inverted-dose effect, whereby low doses can cause more acute effects than high doses. Considering many of the published studies on glyphosate look at high dose effects, one might infer that they have missed the full picture.

Interestingly, the adjuvants in pesticides inflate the toxicity of the active ingredient. A 2014 study showed that Roundup® was 150 times more toxic than glyphosate on its own, stating:

Despite its relatively benign reputation, Roundup® was among the most toxic herbicides and insecticides tested.

Systemic Effects of Glyphosate

Whilst glyphosate is used to control weeds, its effects on our environment are clearly far more systemic than that. Other plants, animals, insects and surrounding ecosystems are exposed to its application in the soil, water and from run-off and precipitation. The full impact of these effects is poorly understood as toxicity studies have tended to be laboratory based, high dose and include a limited number of species – very different conditions to what is found in nature.

Once in the soil, glyphosate is rapidly degraded by microbes into aminomethylphosphonic acid (AMPA). When applied to hard surfaces (e.g. sidewalks) rather than soils, up to a quarter makes its way into the waterways through run-off. It is commonly found in soils and waterways, particularly those downstream from agricultural sites, and to a lesser extent in wetlands and groundwater.

So widespread is its use that it is found in rain (the US Geological Survey found glyphosate in 86% of rainwater samples). It persists longer in soil than in water, with a half life in soil of over 12 months in some cases, depending on the soil composition (soils with higher clay contents hold onto glyphosate for longer whereas it is washed out of sandy soils faster).

Once in the soil, glyphosate can form complexes with metal ions, which may affect the availability of soil nutrients. In fact, it has been shown to interfere with the uptake of key minerals in agricultural crops and to alter the composition of soil microorganisms, the full effects of which are poorly understood. For example, glyphosate reduces populations of fungi-suppressing microorganisms whilst reducing the growth of symbiotic fungi. Researchers find that earthworms, critical to soil health, are also adversely affected by glyphosate.

According to McGill University researchers, glyphosate can trigger biodiversity loss, which in turn affects all of us. We are already in the midst of unprecedented biodiversity loss, with over a million species at risk of extinction, according to the United Nations. The last thing we need is more damaging chemicals accelerating this process.

Non-target plants are impacted by glyphosate application. Studying the impact of glyphosate on 23 native non-target species, Argentinian researchers found that all species showed lethal or sub-lethal effects after just 25% of the recommended field application rate of glyphosate, with 50% of species exhibiting phytotoxicity or death.

The decline of the Monarch butterfly in North America has been linked to glyphosate use. Glyphosate obliterates milkweed – the plant on which Monarchs exclusively lay their eggs. By some estimates, over 850 million milkweeds have been lost since 1999 – over 70% of the plants relied upon by the Monarch butterfly. In 2019/20 alone, monarch caterpillars in Mexico plummeted by 53%. Butterflies are key indicators of ecosystem health and biodiversity, with their fragility making them quick to react to changes in the environment.

But the impacts aren’t limited to insects. Research indicates that glyphosate impacts upon the cardiovascular systems of mammals, with a 2015 French study linking abnormal heart patterns to glyphosate exposure. It has also been found to be toxic to amphibians, for example shortening the bodies of frog embryos and interfering with enzymes required for normal nervous system development in tadpoles. Toxic impacts have also been found among mussels, carp and eels, among other species.

Protecting Ourselves and the Environment

According to the United Nations Food and Agricultural Organization, we are on-track to reach over 9 billion people by 2050. How on earth do we feed a population like this? This is one of the arguments used by industrial agriculture – that we simply cannot feed the world without it and its arsenal of chemicals like Roundup®. In fact, this argument couldn’t be further from the truth.

We certainly need ways to grow more food, but we need to do it in ways that do not harm the natural resources that enable us to grow that food – which is exactly what industrial agriculture does.

Modern industrial agriculture is pumping our environment with harmful chemicals, creating monocultures and toxic waste products that are altering the natural ecosystems we depend upon. For example, food production (including post-farm processing) accounts for one quarter of all greenhouse gas emissions. Pollution from conventional agriculture (specifically the loss of nitrogen from farming in the Mississippi River Basin) is also a large contributor to the 9,000-square-mile dead zone in the Gulf of Mexico.

Organic agriculture, by comparison, can generate fewer greenhouse gas emissions, and uses less energy whilst protecting soils and sequestering carbon. Organic methods are also capable of producing competitive yields during stable weather conditions and out-producing conventional agriculture during times of drought and flooding, the latter of which we can expect a lot more of in a warming world. This is because organic soils retain more moisture, thereby producing higher yields during periods of drought.

According to a team of American scientists, organic farming could provide sufficient food for the entire human population, whilst causing less pollution and fewer health problems than conventional agriculture. Organic food has a higher nutrient content than conventionally farmed food, protecting us against illness.

When it comes to glyphosate, switching to an organic diet reduces glyphosate levels in the body significantly and rapidly. In a 2020 US study, researchers found that switching to an organic diet reduced urinary glyphosate levels by an average of 70% in just 6 days for both children and adults. But there are powerful lobbies and interests working hard to maintain the status quo, which is why organic and regenerative forms of agriculture currently make up such a small percentage of the global food supply.

To shift these numbers, all of us need to play a part. That includes lobbying our politicians to regulate companies that produce products which harm our health and environment, boycotting companies that pollute the environment and buying safer alternatives, including switching to chemical-free, organic products wherever possible. Many great schemes exist now where you can buy direct from producers to support local sustainable agriculture, cutting out the middle-man and accessing good, clean, healthy food at an affordable price.

Continuing business as usual and relying on harmful chemicals like glyphosate is not worth the loss of our health or that of our planet. Especially when there are already viable alternatives that can feed us and our world sustainably.

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This article was published originally on January 18, 2021. 


[1] 90% confidence interval rather than the 95% required threshold, though still sufficient to prompt tighter regulation to avoid the risk of harm.

The Choices We Make: Glyphosate

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The story of glyphosate and glyphosate-based-herbicides is emblematic of the perspective we hold towards chemical safety and the tactics employed by the chemical industry to maintain that perspective. Here was a chemical that was initially used industrially and recognized as toxic but through the magic of marketing and intense lobbying, became ‘safe’ for human consumption. What is particularly interesting about the glyphosate story is that each of the mechanisms by which the chemical produced its desired results in industry were compartmentalized by the manufacturers as being somehow distinct from how the chemical would behave in humans or animals. It was a brilliant sleight of hand, one we all bought hook, line, and sinker because we wanted to believe it. Glyphosate based herbicides, at least initially, and if we did not think too much about the chemistry, worked. The herbicides made life easier, or so we thought. If we look at the history of this chemical and the mechanisms by which it acts, however, we should have known better.

From Industrial Descaling Agent to Herbicide and Antibiotic

Glyphosate was first patented in 1961 as an industrial descaling agent. It was used to remove minerals like calcium, magnesium, iron, manganese from piping. Glyphosate chelates or grabs and binds these minerals so that they can be flushed out. It does the same thing in plants and in humans that consume glyphosate-doused products, maybe not as quickly as when used as a descaling agent because the dosage is markedly different, but over time the small and continuous exposure to a chelating agent, will chelate minerals and create deficiencies. Why should we think otherwise; well, because we were told that it would not harm us and we wanted to believe that the inherent properties of these chemicals would somehow change relative to the organism into or onto which the chemical was used. They do not.

Ten years later, glyphosate along with undisclosed and untested chemical adjuvants (helper chemicals that maximize absorption, enhance metabolism and other critical functions) was patented as a weedkiller and brought to market as Roundup in 1974 by Monsanto. Glyphosate-based herbicides kill plants via disruption of an enzyme (enolpyruvylshikimate-3-phosphate synthase –EPSPS) in what is called the shikimate pathway. In plants and microbial organisms like bacteria, fungi, algae and some protozoa, the shikimate pathway synthesizes folates and amino acids (phenylalanine, tyrosine, and tryptophan). Of note, folates (vitamin B9) are important for red blood cell development and oxygenation, iron homeostasis, and DNA synthesis and repair, and methylation among other functions and amino acids are critical for protein synthesis, a requisite for health and survival. The amino acids that glyphosate blocks comprise about 30% of plant dry mass and contribute largely to the dietary needs of the larger animals and humans. This is one of the many reasons conventionally grown produce contains fewer nutrients and higher sugar content than their organic counterparts.

The EPSPS enzyme is present in all plants, fungi and bacteria. Since this pathway only occurs in plants and lower organisms like bacteria, it was argued that ingested glyphosate would have no effect on the health of animals or humans. This has proven not to be true for a number of reasons, not the least of which is that these bacteria are commensal with humans. That is, bacteria with this pathway are naturally present on human skin, in the lungs, the gut and the reproductive tract. In that regard, glyphosate is a potent antibiotic and antifungal. The company filed patents for its antibiotic properties in 2002, while simultaneously and vociferously denying glyphosate’s antimicrobial tendencies, using of course, the standard trope that the formulation only affects plants. It most certainly does not. The human gut, in particular, is comprised of incredibly complex and tightly balanced ecosystem of billions of microorganisms that perform all sorts of critical functions from nutrient absorption and synthesis to immune regulation. Alterations in gut bacteria are proving to be key contributors to disease; a fact that was purportedly missed by the manufacturers.

So, we have a chemical formulation that kills plants and microbes; one that is toxic to all plant life, not just weeds, but all plant life. This necessitated the development of genetically modified (GM) crops to withstand the poison. GM crops contain either two copies of the EPSPS enzyme or a strain of the enzyme resistant to the chemicals. That is the genetic modification used in conventional agriculture. It is not the simple crossbreeding of yesteryear to produce bigger, prettier, or tastier produce. The modifications are to withstand a poison. It should be noted that although the plants are modified to withstand the poison, they cannot to metabolize it. That means that glyphosate residues remain in and on the plant that is destined to become food or, and in the cotton that is used in all sorts of applications from clothing to medical and feminine hygiene products. Yes, glyphosate has been found in 85% of tampons tested. Might this be a problem in women’s health? Likely, but again, it is not something that is considered by conventional medicine. Glyphosate remains in the soil indefinitely and leaches into the surface and ground water changing the nutrient and microbial composition ever so slightly as to be considered insignificant, unless of course, one understands the ramifications of small changes, compounded over time. Finally, and as mentioned previously, while glyphosate alone carries certain toxicities, glyphosate with its adjuvants becomes exponentially more dangerous, a 1000 times more potent according to some studies. Researchers in France have demonstrated this repeatedly (see work by Giles Seralini Lab ). The adjuvants, however, are presumed inert, and thus, never tested pre-release and not recognized for their toxicity post-release.

Manufacturing Approval

Looking at the history of this product, we see where the manufacturer actively collides with contrary regulatory indices and research findings. Work on genetically modified (GM) strains of crops began in the eighties and reached culmination in the nineties. In 1985, however, glyphosate was recognized as a class C carcinogen by the Environmental Protection Agency (EPA). Monsanto, fought against this classification and in 1991, just as the first GM products were to reach market, successfully bid the EPA to change its classification from Class C “Suggestive evidence of carcinogenic potential” to Class E which suggests “evidence of non-carcinogenicity for humans”. Nearly thirty years later, and hundreds of studies, the International Agency for Research on Cancer’s (IARC), a semi-autonomous branch of the World Health Organization, declared glyphosate as a probable carcinogen in 2015 with ‘strong evidence of genotoxicity, and just as it did in decades earlier, the manufacturers fought the classification and are largely succeeding. In 2018, however, a US court, said wait a minute; glyphosate based herbicides are indeed carcinogenic and found in favor of the plaintiff who developed non-Hodgkin’s lymphoma. Subsequently, additional cases have been brought against the manufacturers and any many more will likely follow. Whether and how this will ultimately affect the chemical industry remains to be seen.

We know that according to industry, glyphosate based herbicides are completely safe and effective and pose no cause for concern. None. They argue that the glyphosate based herbicides, much like every other chemical toxicant mass marketed, would not be allowed on the market unless they were safe. Failing to mention, of course, that through a series of regulatory loopholes, many components of these products are never tested, including the adjuvants, or that the regulatory agencies rely on data provided by industry; data that is edited heavily to present the compound in its most favorable light. Emblematic of the industry’s cavalier attitude towards chemical safety:

Monsanto should not have to vouchsafe the safety of biotech food,” he said. ”Our interest is in selling as much of it as possible. Assuring its safety is the F.D.A.’s job.” – Phil Angell, Monsanto’s Corporate Communications Director, 1999

Speak to the farmers, however, and a different story emerges. Animals fed GM foods develop all sorts of health issues from birth defects in offspring, to tumors in the animals themselves. Perhaps even more damning, at least economically, is that farmers who originally embraced glyphosate based herbicides now face invasive super-weeds for which there are no easy solutions.

Glyphosate Mechanisms of Ill-health

Here are just a few of the findings regarding the impact of glyphosate based herbicides on health. We know that glyphosate based herbicides:

  • Destroy gut bacteria. Research shows that glyphosate destroys gut bacteria. It is an antibacterial by design, after all (blocking the EPSPS enzyme in all microorganisms). The disruption of gut bacteria significantly influences the synthesis and absorption of nutrients and is linked to a wide variety of disease processes from autoimmune to neurological and everything in between.
  • Chelate minerals. Because glyphosate also binds to the minerals that do absorb, it acts as a chelator, effectively inactivating remaining minerals. The chelated metals (iron, zinc, magnesium, manganese, cobalt) contribute to mineral deficiencies but also vitamin deficiencies inasmuch as minerals are required for the enzyme activity that regulates vitamin synthesis.
  • Damage mitochondria. Roundup® with glyphosate damages complex I and III of the electron transport cycles, reducing ATP production by some 40%. Early evidence of this was demonstrated over 30 years ago.
  • Block liver detoxification pathways. The glyphosate-based herbicides block the Cytochrome P 450 (CYP450) enzymes in the liver responsible for detoxifying substances we ingest and impair metabolic transport mechanisms that underlie critical biochemical pathways in our bodies, thus magnifying the effects both food born toxicants and other ingested toxicants like pharmaceuticals. The net results include the array disease processes associated with the modern diet, everything from gastrointestinal disorders to depression and neurological conditions.
  • Initiate antibiotic resistance. Glyphosate based herbicides, are essentially antibiotics. When applied regularly, as they have been for decades, the bacterial community adapts by inducing what are called epigenetic changes; changes that increase their likelihood of survival. The regular consumption of these products, changes the bacterial landscape of the gut, skewing toward the hardier bacteria, which are typically of the pathogenomic strains like coli.
  • Induce fibrinous tumors in animals. This one should be particularly interesting for women who suffer from fibroids. Glyphosate induced alterations in the vitamin A pathway are linked with fibrinous tumor growth in rodents. Alterations in vitamin A metabolism can be mechanistically linked to the development of fibroid tumors. Similarly, a diet of GM (glyphosate tolerant) soy and maize has been shown to increase the size of the uterus in female pigs by 25%. Remember, glyphosate is sprayed on the cotton used for tampons and other feminine hygiene products providing a direct route of exposure for millions women every month, year in and year out.
  • Accumulate in humans, animals, ground soil and waterways. Glyphosate is present in significantly higher concentrations of individuals who eat genetically modified foods compared to those who eat predominantly organic foods and also in in chronically ill versus healthy individuals.

Many of the damages invoked by glyphosate based herbicides are linked to its structure as a synthetic glycine analog. Glycine is an essential amino required for protein synthesis and repair. It is also an excitatory neurotransmitter in the brain. When glyphosate displaces glycine at random points in the protein synthesis and repair processes or by constituitively activating excitatory receptors in the brain, the consequences are vast and complicated. Research suggests that glyphosate’s role as a glycine analog underpins the explosion of chronic disease over the last few decades.

Glyphosate substitution for conserved glycines can easily explain a link with diabetes, obesity, asthma, chronic obstructive pulmonary disease (COPD), pulmonary edema, adrenal insufficiency, hypothyroidism, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), Parkinson’s disease, prion diseases, lupus, mitochondrial disease, non-Hodgkin’s lymphoma, neural tube defects, infertility, hypertension, glaucoma, osteoporosis, fatty liver disease and kidney failure.”

The notion that substituting an important amino acid with a synthetic analog would be safe, particularly over time, is laughable, but that is exactly what the industry argues and what we, as a population, chose to believe. We believed not just because we did not understand the chemistry, but because we wanted to believe. We wanted to believe in the supremacy of our man-made inventions and in the compartmentalization of effects. We never bothered to question whether there might be ill-effects from this or any of the thousands of other chemicals currently in use. We never asked whether the chemistry is indeed compartmentalized. We did not ask because to do so would require a fundamental change in the economic fabric of modern living; to ask would mean that we would have to act. If we are truthful with ourselves, with glyphosate, as with so many other modern chemicals that we now know are dangerous, we chose to ignore what we did not want to know. We chose convenience and the purported economic gain this convenience would bring us.

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More people than ever are reading Hormones Matter, a testament to the need for independent voices in health and medicine. We are not funded and accept limited advertising. Unlike many health sites, we don’t force you to purchase a subscription. We believe health information should be open to all. If you read Hormones Matter, like it, please help support it. Contribute now.

Yes, I would like to support Hormones Matter.

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