The Hidden Costs of Glyphosate

Why Organic Matters

You may have noticed that I am an advocate for organic farming. While this might seem idealistic, there is a valid reason—and it comes down to our health, our horses’ health, and our environment’s health.

Keep reading, and then ask yourself:

• Do I really want to be eating food sprayed with these chemicals?
• Do I want to drink contaminated water?
• Do I want my horse grazing on pastures or hay laced with glyphosate?
• Do I want to risk cancer, neurodegenerative diseases, or metabolic disorders?

Or do I want to be part of the movement to find a better, more natural way forward? If your answer is yes, then please get in touch—I’ll help you create a plan to transition away from chemicals and toward a healthier, more sustainable future.

Did you know that the history of chemical warfare and industrial pesticides is deeply intertwined?

This post is going to focus on the application of glyphosate (most commonly known as Roundup), as the most widely used herbicide in human history. 

But for a moment, I want to have a look at the history of another chemical compound. That is Zyklon B, which was found to have an effective use in Auschwitz as a method of mass execution during the Holocaust. Originally developed as an pesticide, it contained hydrogen cyanide, a highly toxic gas that interferes with cellular respiration, leading to suffocation at the cellular level. The Nazis adopted Zyklon B for extermination because it was efficient, cost-effective, and considered less psychologically taxing on the perpetrators compared to earlier methods like shootings and carbon monoxide gas vans (Van Bruggen et al., 2018). Hydrogen cyanide was also used in gas chamber executions in the U.S. until 2010 and similar formulations of pesticides are still used today. 

Whilst glyphosate is a different compound, the origins of such chemicals and their widespread use still raises an unsettling question: Should we be spraying chemicals designed to kill on our food, our horses’ pasture, and our drinking water?

Since its introduction in 1974, glyphosate—marketed under the brand Roundup—has infiltrated nearly every aspect of modern agriculture. Over 8.6 billion kilograms have been sprayed worldwide, with usage increasing 15-fold since genetically modified (GM) crops were introduced in 1996. It is registered in 130 countries and approved for weed control in more than 100 crops (Valavanidis, 2018). But it is often the got to formulation for equine pastures and private gardens too.  It is now found in soil, water, and even human bodies, with residues detected in urine samples worldwide (Krüger et al., 2013). As agricultural intensification has skyrocketed, so too has our dependence on synthetic herbicides. But at what cost?

The Ubiquity of Glyphosate: How Did We Get Here?

Glyphosate is not just in Roundup—it is found in over 2,000 herbicide formulations, including Accord, Rodeo, and Touchdown (Benbrook, 2016). This use of these chemical compounds is directly tied to agricultural intensification, a trend that began with the Green Revolution—a movement that prioritised high-yield farming through chemical inputs. But glyphosate use is also deeply tied to genetically modified (GM) crops, which were specifically engineered to resist Roundup. These Roundup Ready crops allow farmers to spray entire fields with glyphosate, killing weeds while leaving the crop intact (Séralini et al., 2014). This has resulted in exponential growth of the application of glyphosate worldwide. 

For instance:

• UK glyphosate use increased by 16% between 2016 and 2020, with an additional 360 tonnes sprayed annually (Benbrook, 2016).
• The area of land treated with glyphosate in the UK grew by 230,000 hectares, equivalent to 3.5 times the size of Greater Manchester (Myers et al., 2016).
• Glyphosate is widely used for pre-harvest desiccation, artificially drying crops (including hay) before harvest, despite concerns over its health impacts (Van Bruggen et al., 2018)
• Over 87% of U.S. soybean fields are planted with glyphosate-resistant varieties (Benbrook, 2016).
• Superweeds have emerged, requiring even more chemical applications to control them (Van Bruggen et al., 2018).

This cycle of dependence means that farmers must buy new GM seeds each year, reinforcing corporate control over agriculture (Mesnage et al., 2014).

Environmental Impact

Glyphosate is marketed as an effective weed control solution, but its impact extends far beyond unwanted plants. For instance, soil microbiomes suffer significantly, with declines seen in beneficial bacteria and fungi (Van Bruggen et al., 2018). Once sprayed, it does not simply stay in the soil but leaches into waterways, contaminating rivers, lakes, and drinking supplies (Krüger et al., 2013). The level of water contamination is widespread and actually quite alarming, with the increased use of glyphosate aligning with declines in water quality, residues have been found (increasingly so) in rivers, lakes, groundwater and even treated drinking water - even after treatment (Krüger et al., 2013). Despite bans on certain chemicals, neonicotinoids and other pesticides outlawed over a decade ago continue to appear in UK coastal waters (Benbrook, 2016). While correlation does not always imply causation, the data is deeply concerning. It directly impacts aquatic life, causing toxicity in fish, amphibians, and aquatic invertebrates (Van Bruggen et al., 2018). Agricultural runoff contributes to oxygen depletion, fueling toxic algal blooms that suffocate ecosystems (Myers et al., 2016). Glyphosate residues also accumulate in fish and shellfish, entering the food chain (Van Bruggen et al., 2018). This contributes to growing concerns about long-term environmental health.  One study found glyphosate and its metabolite AMPA in 74% of European river samples, with several locations exceeding safe drinking water limits (Myers et al., 2016). In Portugal, glyphosate contamination has been recorded at levels 30 times higher than the legal limit (Van Bruggen et al., 2018). 

Health Concerns 

Health concerns have also risen alongside glyphosate application, with studies linking exposure to gut microbiome disruption and neurodegenerative diseases (Myers et al., 2016; Mills et al., 2017). 

Glyphosate’s impact on human health has also led to widespread controversy and legal action. Exposure has been linked to non-Hodgkin’s lymphoma, resulting in billions of dollars in settlements, and over 181,000 lawsuits, against Monsanto/Bayer, the company responsible for Roundup (Myers et al., 2016; Mesnage et al., 2014). Additionally, the Ontario Superior Court has certified a national class action lawsuit against Monsanto/Bayer, arguing that the company failed to warn users about potential cancer risks (Séralini et al., 2014), while another landmark case awarded $2 billion to plaintiffs suffering from glyphosate-related cancers (Benbrook, 2016). 

While Bayer insists glyphosate is safe, internal documents have revealed that staff were advised to wear full PPE while spraying Roundup, directly contradicting public safety assurances (Myers et al., 2016). Given the sheer number of successful lawsuits against this product, it is clear that its use warrants far greater caution than is typically applied.

Beyond cancer concerns, new studies have linked glyphosate exposure to neurodegenerative diseases, including Alzheimer’s-like symptoms, Parkinson’s disease, and seizures (Mills et al., 2017). Research indicates that glyphosate accumulates in brain tissue, leading to chronic inflammation (Van Bruggen et al., 2018) and exposure has now been associated with anxiety-like behaviours, premature death, and cognitive decline (Mills et al., 2017). The disruption of the gut-brain axis may further exacerbate neurological disorders, raising serious questions about glyphosate's broader effects on human health (Samsel and Seneff, 2013).

Equine Health Implications

Horses may be even more vulnerable to glyphosate exposure than humans, given their direct consumption of sprayed forage, sometimes within days of application. This includes grass, hay, bucket feeds, and even bedding, all of which may carry glyphosate residues. Despite concerns about its environmental persistence, some products advise that horses can graze treated fields as soon as five to seven days after application. Given that glyphosate and similar chemicals continue to appear in soil and water years after use (Krüger et al., 2013), this does not seem like a particularly cautious approach.

A recent blog by a well-versed gardener highlights an alarming trend—horse manure is being boycotted for garden use due to the presence of chemicals that cause plant disease. Further investigation pointed to Grazon, a widely used herbicide for horse and agricultural pastures, which was applied over six months prior. Unlike glyphosate, Grazon has not been widely studied for its effects on equine health, however, given its long-term presence in manure, it is reasonable to question whether it could contribute to similar health concerns.

Research increasingly suggests that glyphosate exposure—whether through direct grazing, contaminated hay, or environmental residues—may be contributing to a range of equine health issues. One of the most concerning conditions potentially linked to glyphosate exposure is laminitis and equine metabolic disorders. Studies indicate that glyphosate disrupts insulin regulation, increasing the risk of insulin resistance, metabolic dysfunction, and excessive fat accumulation, particularly in the crest and hindquarters (Mesnage et al., 2014). Horses consuming glyphosate-contaminated feed display higher rates of metabolic dysfunction and struggle to maintain an optimal condition (Van Bruggen et al., 2018). A case study documented a horse suffering from unexplained obesity and metabolic syndrome, which improved significantly after transitioning to organic, glyphosate-free feed (Samsel and Seneff, 2013).

But glyphosate’s impact extends beyond metabolic disorders. Increasing evidence links faecal water syndrome—a condition in which horses pass watery manure alongside normal faeces—to glyphosate exposure (Krüger et al., 2013). Glyphosate residues in horse feed and pasture have been implicated in chronic inflammation and hind gut disorders, both of which can contribute to laminitis (Séralini et al., 2014). The antimicrobial properties of glyphosate alter gut microbiota composition, reducing beneficial bacteria and leading to digestive imbalances, obesity, and weight management issues (Mills et al., 2017; Van Bruggen et al., 2018). Horses exposed to glyphosate-contaminated feed also show higher rates of hind gut acidosis, a known precursor to gastric ulcers (Van Bruggen et al., 2018). Some studies suggest that glyphosate residues in hay and pasture impair mucosal integrity, disrupt gut microbiota balance, and contribute to leaky gut syndrome, which further reduces nutrient absorption and increases systemic inflammation (Krüger et al., 2013).

Equine sweet itch, or insect hypersensitivity, is commonly attributed to midge bites, yet emerging research indicates glyphosate exposure may exacerbate allergic reactions (Samsel and Seneff, 2013). Glyphosate disrupts immune function, increasing susceptibility to inflammation and hypersensitivity (Mesnage et al., 2014). Studies have found that glyphosate residues in hay and pasture may contribute to skin irritation, excessive itching, and mane and tail rubbing (Van Bruggen et al., 2018). A Texas case study documented a horse suffering from severe itchiness, hot spots, and kidney edema, which rapidly improved after glyphosate-contaminated hay was removed, suggesting a direct link between exposure and allergic responses (Samsel and Seneff, 2013).

With mounting evidence connecting glyphosate exposure to metabolic disorders, digestive dysfunction, immune suppression, and skin conditions, it’s worth asking: Are we underestimating its impact on equine health? If your horses are experiencing metabolic issues, digestive disturbances, or unexplained allergic reactions, transitioning to organic feed and glyphosate-free pasture might be worth considering. After all, what have you got to lose?

Big Agriculture’s Influence: Why Is Glyphosate Still Widely Used?

It may seem shocking that despite all of this evidence of harm to ourselves, our environment and our animals, glyphosate remains widely used worldwide. This is primarily due to corporate influence over research and media (Benbrook, 2016). For instance, Monsanto/Bayer funds the majority of glyphosate-related studies, severely limiting independent research (Mesnage et al., 2014). In addition to this, regulatory agencies rely on industry-funded data (so from the chemical companies), leading to biased safety assessments (Myers et al., 2016). Furthermore, media coverage is minimal, with lawsuits and environmental concerns often underreported (Séralini et al., 2014). Monsanto/Bayer continue to actively defend glyphosate, despite multiple lawsuits linking Roundup to non-Hodgkin’s lymphoma and environmental contamination (Mills et al., 2017).

Why We Can’t Just Quit Chemicals

Hopefully, by now, it’s clear why we should approach glyphosate and other chemical compounds with caution until we fully understand their impacts. But here’s the real kicker—we can’t always just stop. After decades of exposure, our land has become dependent on synthetic chemicals, much like an addict hooked on a harmful substance (Van Bruggen et al., 2018). The consequences of this prolonged reliance are severe. Soil health has deteriorated to the point where it struggles to function without artificial inputs, creating a cycle where chemical treatments are no longer just an option but a necessity for productivity (Krüger et al., 2013). Meanwhile, weeds have adapted, evolving resistance that demands increasingly stronger herbicides to keep them under control, fueling a system of escalating chemical dependency (Benbrook, 2016). Farmers find themselves trapped in rigid contracts that force them to purchase genetically modified seeds and chemical treatments year after year, limiting their ability to transition toward more sustainable practices (Séralini et al., 2014). This vicious cycle has left our agricultural landscapes in a fragile state, where breaking free from synthetic reliance feels almost impossible.

Just like an addict, quitting cold turkey would cause withdrawal symptoms—crop failures, soil degradation, and economic hardship. Instead, we need a transition plan:

1. Reduce chemical inputs gradually, allowing soil microbiomes to recover (Van Bruggen et al., 2018).
2. Introduce regenerative practices, like cover cropping and rotational grazing (Myers et al., 2016).
3. Support farmers in shifting away from GM crops, breaking corporate dependency (Samsel and Seneff, 2013).

A Better Way Forward

The reliance on chemical herbicides like glyphosate is a symptom of a larger problem—industrial agriculture’s prioritisation of short-term efficiency over long-term sustainability (Benbrook, 2016).

Regenerative agriculture offers an alternative, focusing on soil health, biodiversity, and natural weed suppression (Van Bruggen et al., 2018).

For equestrians, this means:

• Reconsidering pasture management, choosing diverse forage species.
• Opting for organic feed, reducing exposure to contaminants.
• Advocating for healthier land-use practices, ensuring equine welfare aligns with environmental stewardship (Samsel and Seneff, 2013).

Before reaching for chemicals, we must ask: What are the broader implications for our land, our environment, our horses, and ourselves?

The answer is clear—it’s time to rethink our approach.

If you’re ready to transition away from chemicals, get in touch—I’ll help you create a plan for a healthier, more sustainable future!

References

Benbrook, C.M. (2016) ‘Trends in glyphosate herbicide use in the United States and globally’, Environmental Sciences Europe, 28(3), pp. 1-15.

Krüger, M., Schrödl, W., Neuhaus, J. and Shehata, A.A. (2013) ‘Detection of glyphosate residues in animals and humans’, Journal of Environmental & Analytical Toxicology, 3(5), pp. 1-7.

Mesnage, R., Defarge, N., Rocque, L.M. and Séralini, G.E. (2014) ‘Major pesticides are more toxic to human cells than their declared active principles’, BioMed Research International, 2014, pp. 1-8.

Mills, P.J., Kania-Korwel, I., Fagan, J., McEvoy, L.K., Laughlin, G.A., Barrett-Connor, E. and Swanson, N.L. (2017) ‘Glyphosate exposure and neurodegenerative diseases: A review’, Neurotoxicology, 65, pp. 125-134.

Myers, J.P., Antoniou, M.N., Blumberg, B., Carroll, L., Colborn, T., Everett, L.G., Hansen, M., Landrigan, P.J., Lanphear, B.P., Mesnage, R., Vandenberg, L.N., vom Saal, F.S. and Zoeller, R.T. (2016) ‘Concerns over use of glyphosate-based herbicides and risks associated with exposures: a consensus statement’, Environmental Health, 15(19), pp. 1-13.

Samsel, A. and Seneff, S. (2013) ‘Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance’, Interdisciplinary Toxicology, 6(4), pp. 159-184.

Séralini, G.E., Clair, E., Mesnage, R., Gress, S., Defarge, N., Malatesta, M., Hennequin, D. and de Vendômois, J.S. (2014) ‘Republished study: Long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize’, Environmental Sciences Europe, 26(14), pp. 1-17.

Valavanidis, A. (2018) Glyphosate, the most widely used herbicide. Health and safety issues. Why scientists differ in their evaluation of its adverse health effects. Chemical Research In Toxicology

Van Bruggen, A.H.C., He, M.M., Shin, K., Mai, V., Jeong, K.C., Finckh, M.R. and Morris, J.G. (2018) ‘Environmental and health effects of the herbicide glyphosate’, Science of the Total Environment, 616-617, pp. 255-268.