Monsanto is far from happy. The main ingredient of its highly profitable weedkiller, Roundup, often used in conjunction with GM crops, has been declared a “probable carcinogenic”.

As well as being profitable for Monsanto, glyphosate is one of the most widely adopted weedkillers in the world by gardeners and farmers alike. Use of it by UK farmers, for example, has soared by 400% in the last 20 years.

In response to the cancer warning, the US biotech company has been quick to accuse the body behind the new classification of bias. It says the International Agency for Research on Cancer (IARC), an arm of the World Health Organisation (WHO), lacks transparency and has made an irresponsible decision – one likely to cause confusion among farmers and the wider public.

Monsanto’s strategy of confusion and controversy is an obvious one, suggests Professor Andreas Kortenkamp, a toxicologist at Brunel University London. In reality, he says, the process by which IARC comes to its decisions is “very rigorous and scientific, and not controversial or subjective as has been suggested sometimes.”

Risk to growers

Although Monsanto as the major producer of glyphosate is outraged, the warning on its own makes little difference to its availability or use.



That’s because decisions on the risk assessment and whether to ban or restrict sale of a chemical is the responsibility of national and EU regulators, not the WHO. The EU is due to decide whether to reapprove use of glyphosate before the end of the year and, so far at least, the indications are that they won’t act, despite growing public pressure.

In Germany, for example, retailers have started removing glyphosate herbicides from their shelves, with one state protection minister calling for a ban on the use of the chemical by the general public. “This pesticide should not be found in gardens, parks or on children’s playgrounds. I also do not think use in private gardens is appropriate,” explained Lower Saxony’s consumer protection minister Christian Meyer.

However, German government safety officials recently declared it safe. A report from the German Federal Institute for Risk Assessments (BfR), seen by the Guardian, found “very limited evidence of carcinogenicity” in mice exposed to glyphosate and recommended its reapproval.

European officials are far from unanimous, however, with the French environment minister Ségolène Royal announcing plans in June for new restrictions on the sale of glyphosate at garden centres in the country.

Among the gardening community the debate rumbles on. After a number of garden centres in London pulled glyphosate products from their shelves, the chemical industry, acting under the pseudonym Common Sense Gardening Group, issued a fact sheet in an attempt to allay the concerns of retailers and gardeners. It said “glyphosate does not cause cancer ... [and] does not pose any unacceptable risk to human health.”

How to reduce risk

Although campaigners in the UK have tried to focus attention on possible risks to human health from glyphosate residues found in bread, toxicologists suggest gardeners and farm workers are the ones most at risk.

“It is difficult to work out the magnitude of cancer risks of glyphosate, but based on the quantities people come into contact with, it can be expected that agricultural workers applying the pesticide are at much greater risk than consumers in Britain, who are exposed via residues in food,” says Kortenkamp.

While not yet in favour of a ban, Kortenkamp says home gardeners should cut down on their use of glyphosate. “Neither panic nor a cavalier attitude is a reliable guide to working out what a sensible response should be. Home gardeners should minimise their exposure by asking themselves: do I really need to use Roundup? Can I not hand-weed?”

For those worried about their health, one organisation now allows you to pay $120 (£75) to have your urine, breast milk or tap water tested for glyphosate contamination. Far from scaremonging, toxicologist Dr Robin Mesnage from Kings College London says such testing could help.

“If the sample collection and analysis is performed properly under the supervision of experienced academics, the results could be used by the scientific community. Indeed, there is no biomonitoring and nobody really knows the glyphosate burden in the general population. I will not call that scaremonging, even if it is an NGO tactic to open public awareness to environmental health issues,” he says.