Monsanto, part of Bayer, has asked a California court to dismiss a verdict that awarded US$289M in damages to a school groundskeeper who allegedly developed cancer from exposure to Monsanto’s glyphosate herbicides.

In August, a jury in California found that ex-groundskeeper Dewayn Johnson had contracted cancer from years of exposure to Monsanto’s Roundup and Ranger Pro herbicides and that the firm had neglected to warn him and others of the cancer risk, reported Reuters on 19 September.

In its plea, Monsanto argued that the jury’s decision was insufficiently supported by the evidence present at the trial and asked Superior Court Judge Suzanne Bolanos to set aside the verdict, reduce the award or grant a new trial.

“The jury’s decision is wholly at odds with over 40 years of real-world use, an extensive body of scientific data and analysis … which support the conclusion that glyphosate-based herbicides are safe for use and do not cause cancer in humans,” Bayer said in a statement.

The firm added that Johnson had failed to prove glyphosate caused his cancer and that the scientific evidence he presented at the trial “fell well below the causation standard required under California law”.

Bayer’s shares dropped following the August verdict and Reuters said its stock was still trading some 20% below the value preceding the jury’s decision.

Johnson’s case was the first to go trial over allegations of glyphosate causing cancer, but Monsanto was facing roughly 8,000 similar lawsuits in the USA.

The US Environment Protection Agency in 2017 found that that glyphosate was not likely to cause cancer in humans, contradicting a 2015 World Health Organization (WHO) report that classified glyphosate as “probably carcinogenic to humans”.

However, the WHO declaration had been criticised of ignoring scientific studies that did not support its conclusions.

Monsanto’s motion had a set hearing date of 10 October.