It was Scottish farmers in the 1980s who pioneered the practice of spraying glyphosate on their wheat just before harvest. Struggling in the damp glens to get their crop to dry evenly, they came up with the idea of accelerating the process by killing it a week or two before harvesting.

Glyphosate, then a revolutionary herbicide that killed everything plant-based but spared animal life, seemed perfect for the job. Soon the practice spread to wetter, colder agricultural regions around the world.

Four decades on, thousands of tonnes of glyphosate are now applied every year to UK farmland as well as to municipal green spaces and domestic gardens. But the herbicide’s safety record has become deeply contested and – with its licence up for renewal in December – there are calls for it to be banned or severely restricted.

An analysis of government data showed that more than 2,200 tonnes of glyphosate were sprayed by farmers in 2024, more than half on wheat and other cereals.

The figures show a 10-fold rise in the use of the chemical over the past three decades, with its use having remained high even after the World Health Organization classified it as “probably carcinogenic to humans” in 2015. Bayer maintains that its herbicides do not cause cancer.

“The UK’s glyphosate addiction has spiralled out of control,” said Nick Mole of Pesticide Action Network UK, a campaign group which carried out the analysis. “We know that glyphosate has links to a range of cancers and other life-threatening diseases. And that it damages the environment, polluting our waters and harming wildlife.

“The government urgently needs to commit to phase out – and ultimately ban – glyphosate and support farmers and local councils to adopt safe and sustainable alternatives.”

Glyphosate is a full spectrum herbicide, which means it kills all weeds – both grasses and broad leaf varieties. That makes it a powerful tool in a farmer’s arsenal. However, in the UK it is used in a very different way than in the US, where GM crops, resistant to its effects, are liberally sprayed with glyphosate while growing.

“The primary use of glyphosate in the UK is it’s applied before the crop is planted to kill off all the weeds that are growing in the field,” said Helen Metcalfe, an agricultural ecologist at Rothamsted Research in Harpenden, Hertfordshire.

The turn toward less destructive “regenerative” farming is a key reason for the increase in the use of glyphosate, Metcalfe said. The alternative would be to plough the field, destroying the weeds. But that would also damage the soil “and that’s what farmers are trying to protect”, she said. “They’re trying to protect their soil, trying to prevent erosion, trying to build up carbon in the soil and all that good stuff. To be able to do regenerative farming well you need to apply glyphosate.”

But deploying synthetic chemicals has dangers. In the US, Bayer has offered $7.25bn (£5.4bn) to settle thousands of lawsuits alleging the company failed to warn people that Roundup, which contains glyphosate, could cause cancer. In France, the government has acknowledged a link between Parkinson’s and glyphosate and has been compensating farmers.

“As with most things, essentially, the more you’re exposed, the more concern there is,” said Wayne Carter, an associate professor at the University of Nottingham who studies the biological impact of pesticides. “Too much is potentially toxic, so you could be exposed through your diet, you could be exposed to an inhalation route; but also you should be mindful of going out there and slopping it around in your garden, basically.”

In 2023, the EU banned the use of glyphosate in pre-harvest desiccation, reflecting fears about its accumulation in food.

A UK government spokesperson insisted use of glyphosate was subject to strict regulation, adding: “Pesticides are only approved for use if the evidence shows that they won’t harm human or animal health, and won’t have unacceptable effects on the environment.”