Pharmaceutical giant Bayer has dismissed claims that an ingredient used in weed killers causes cancer.
The German company, which owns controversial agricultural company Monsanto, says herbicides containing glyphosate are safe.
Monsanto was recently ordered to pay $289 million damages to Dewayne Johnson who claimed the products caused his cancer.
A Californian jury said Monsanto should have warned users about the dangers of its Roundup and RangerPro weedkillers.
The jury found that Monsanto had acted with “malice” and that its weed killers contributed “substantially” to Johnson’s terminal illness.
Bayer said in a statement: “Bayer is confident, based on the strength of the science, the conclusions of regulators around the world and decades of experience, that glyphosate is safe for use and does not cause cancer when used according to the label.”
Johnson’s landmark lawsuit was the first to go to trial alleging that glyphosate causes cancer.
He was diagnosed with non-Hodgkin’s lymphoma in 2014. His lawyers said he regularly used a form of RangerPro at a school in Benicia, California where he was working as a groundsman.
There are more than 5 000 similar plaintiffs across the US. Glyphosate is the world’s most common weedkiller. The California court ruling could lead to hundreds of other claims against Monsanto.
Monsanto intends to appeal against the verdict.
Carcinogenic or safe?
In 2015, the International Agency for Research on Cancer, the World Health Organisation’s cancer agency, concluded that glyphosate was “probably carcinogenic to humans”.
In contrast the US Environmental Protection Agency (EPA) says it is safe when used carefully and the European Food Safety Authority (EFSA) says glyphosate is unlikely to cause cancer in humans.
Monsanto’s reaction to the court ruling
Monsanto’s reaction in a statement was that the company was “sympathetic to Mr Johnson and his family” but it would “continue to vigorously defend this product, which has a 40-year history of safe use”.
“Today’s decision does not change the fact that more than 800 scientific studies and reviews – and conclusions by the US Environmental Protection Agency, the US National Institutes of Health and regulatory authorities around the world – support the fact that glyphosate does not cause cancer, and did not cause Mr Johnson’s cancer.”