A US jury has found that Bayer’s widely-used glyphosate weedkiller was a “substantial factor” in causing a man’s cancer, BBC News reported today.

The jury in San Francisco ruled unanimously that Roundup, the weedkiller produced by German pharmaceutical group Bayer, had contributed to causing non-Hodgkin’s lymphoma in California resident Edwin Hardeman.

The next stage of the trial would be to assess Bayer’s liability and damages. During this phase, Hardeman’s lawyers are expected to present evidence allegedly showing Bayer’s efforts to influence scientists, regulators and the public about the safety of its products, according to BBC News.

Bayer – which acquired Roundup as part of its US$63bn takeover of US agrochemicals giant Monsanto last year – said the company was disappointed with the jury’s initial decision.

The trial is the first US “bellwether” or test case aiming to reach a large-scale resolution over Roundup. More than 760 of the 11,200 Roundup cases in the USA had been consolidated in the San Francisco federal court hearing Hardeman’s case.

The San Francisco court heard that Hardeman had “extreme” exposure to Roundup, spraying the chemical more than 300 times over 26 years. He was diagnosed with non-Hodgkin’s lymphoma in February 2015.

However, Brian Stekloff, a lawyer for Bayer, had argued that the cause of Hardeman’s cancer – and non-Hodgkin’s lymphoma generally – was not known, adding that Hardeman had some risk factors, such as old age and a history of hepatitis.

Bayer has argued that decades of studies have shown that glyphosate is not carcinogenic to humans.

The company reported a net loss of US$4.46bn in its fourth quarter, compared with a profit of US$168M a year ago, mostly a result from write-offs for consumer health brands it was selling, a pharmaceuticals plant it was closing and costs linked to buying Monsanto last year, Wall Street Journal (WSJ) said.

Bayer had made a US$695M provision in the fourth quarter, mainly for legal defence costs in the next three years, but had not provisioned for potential plaintiff payouts. Last year, US groundskeeper Dewayne Johnson was awarded US$78.5M after winning a cancer trial against Bayer, which is appealing the verdict.

WSJ said Bayer’s shares were set to remain under pressure until more cases were tried.

BBC News said another trial was due to begin in a California state court in Oakland on 28 March involving a couple claiming Roundup caused their non-Hodgkin’s lymphoma.