The Trouble With Glyphosate: The Cost of Killing Weeds

Glyphosate, the active ingredient in the weedkiller Roundup, is the most widely used herbicide in the world. It works by inhibiting the production of essential plant proteins. Without these proteins, the plant dies. By targeting a specific metabolic pathway – the Shikimate pathway – which is not present in humans and other animals, glyphosate was thought to be safe. 

However, a growing body of evidence is highlighting concerns that the current recommended Acceptable Daily Intake of glyphosate for humans may be far too high, potentially putting farmers, gardeners and anyone living near areas of glyphosate use at risk.

Herbicide on the rise

During a webinar hosted by the Pesticide Action Network (PAN) data were shared on changes in glyphosate use. The amenity sector, which manages public spaces including parks and sports fields, doubled its glyphosate use between 2016-2020. 

Over the last 30 years, the agricultural sector has seen a whopping 676% increase. One of the key issues with such widespread use is the rise in glyphosate-resistant plants. Here in the UK, the first case of a glyphosate-resistant plant was found in a field in Kent in late 2024. Resistance to widely used herbicides poses serious challenges to the farming industry and can lead to increased chemical use over time. 

This hike in herbicide use during food production is finding its way into our food. Analysis from PAN showed that more than 50% of the bread for sale in the UK contains glyphosate residues. 

Is glyphosate a danger to people?

Michael Antoniou, Professor of molecular genetics and toxicology at UCL, has been researching pesticide toxicology for the last decade with a key focus on glyphosate. During PAN’s webinar Professor Antoniou highlighted the threats of glyphosate and shared his dismay that the science has so far been ignored by regulatory bodies. Here are a few things you should know about glyphosate and the risks to people.

 

The Secret Sidekick 

If you were to take a mixture of glyphosate and water and sprayed it directly onto a plant, nothing would happen. This is because the glyphosate needs help penetrating the plant. This help comes in the shape of co-formulants which act as chemical battering rams, punching holes in plant cell walls and opening the door for the glyphosate to slip inside. 

These co-formulants are incredibly toxic in their own right, in some cases up to a thousand times more toxic than the active ingredient. 

But, as Professor Antoniou reveals, the regulation of co-formulants is woeful, with no long-term safety tests required and their presence often hidden on labels under “inert”. 

To fully understand and regulate the effect of herbicides on non-target organisms, regulators must take into account both the active ingredient and the co-formulants. These combinations form the products that people are exposed to.

10% human

In her 2016 book, 10% Human, biologist Alanna Collen highlights the fact that your gut hosts 100 trillion microbes. These miniature hitchhikers are essential to our well-being and can influence our weight, immune system, mental health and even choice of partner. 

Some of them also happen to rely on the Shikimate pathway, the same pathway blocked by glyphosate. Studies have shown that exposure to glyphosate alters bacterial and fungal communities in the gut microbiome.

 

DNA damage, liver fibrosis, birth defects and high-risk pregnancies

The toxicity of glyphosate on human health has been controversial. It would be difficult to underestimate the political power of the chemical industries across the world that have lobbied to keep these products in circulation. 

Yet, the evidence continues to accumulate demonstrating the unintentional impacts of glyphosate use. A study in Argentina found that in areas where glyphosate was sprayed onto soy crops, spontaneous abortion and congenital abnormalities in local communities were three and two times higher than the national average. 

Additional studies have found links between glyphosate exposure and liver fibrosis, a 41% increased risk of non-Hodgkin lymphoma and, in a US study that found glyphosate in the urine of 99% of pregnant women, lower birth weights of infants and a higher risk of being admitted to an intensive care unit. 

Studies have found that DNA damage in the livers of rats increased with glyphosate exposure. During the PAN webinar, Professor Antoniou said: 

“The fact that we showed that glyphosate alone causes DNA damage should have signalled it as a major carcinogenic hazard and it should have been banned by European law. If something is identified at any dose to be DNA damaging, it should be banned.”

So far the research has been largely ignored by regulators.

Glyphosate and the environment

Humans are not alone in finding themselves as unintended collateral damage of glyphosate. Evidence is growing that demonstrates the impact of chemical pollution in the wider ecosystem. Like all herbicides, glyphosate easily enters the soil where it can impact an array of non-target organisms including earthworms, insects and spiders. As it makes its way through the ecosystem it can also damage wildflowers, cause developmental effects on birds and, similar to neonicotinoids, damage honeybee navigation and memory retention. 

A meta-analysis of the effects of glyphosate on the terrestrial environment concluded with the line: 

“Based on the available literature on terrestrial ecotoxicity, and given the drastic decline in biodiversity, we conclude that the continued high use of [glyphosate], resulting in increased exposure and risk, cannot be considered ecologically sustainable.”

Glyphosate and water

Glyphosate is frequently detected in surface waters around the globe and the impacts on aquatic wildlife are widespread. 

Negative impacts include decreased fertility in fish, decreased growth in zooplankton, behavioural changes in crabs, hormonal effects on aquatic snails and changes to the embryonic development of amphibians. 

Worryingly, the information that we have so far about the impact of glyphosate on aquatic wildlife is likely to be a watered=down version of the truth. 

Studies have typically investigated the short-term effects of a single exposure to glyphosate, the reality is that organisms are faced with multiple, long-term exposures while also battling with other pollutants at the same time. 

The cocktail of chemicals in our water systems represents a much larger threat than a single chemical alone. 

A meta-analysis about the impacts of glyphosate in aquatic systems ends with:

"According to the results of aquatic ecotoxicological studies, the current use and pollution of the aquatic environment by [glyphosate] is highly problematic and cannot be considered environmentally sustainable. It is, therefore, necessary to at least tighten the permitted forms of use.”

Glyphosate reapproval 2026

Later this year, the UK approval for glyphosate is due to be reviewed by the Health and Safety Executive (HSE). If glyphosate is reapproved without significant restrictions, it could remain authorised for up to another fifteen years. The review comes at a time of growing public concern around pesticide exposure, biodiversity loss and water pollution, alongside increasing scientific debate about the long-term impacts of glyphosate on both human health and ecosystems.

What we’re calling for

At UK Youth for Nature, we believe communities should have a greater say over pesticide use in the places they live. Through our Your Wild Streets campaign, we are calling for councils across the UK to reduce and phase out pesticide use in streets, parks and public spaces, replacing them with safer, nature-friendly alternatives. You can use our council contact tool to start a direct conversation with your local authority, ask questions about glyphosate spraying in your area and push for pesticide-free public spaces.