A California judge on Monday upheld a jury's verdict that found that Monsanto's glyphosate-based weed killer caused a groundskeeper's cancer, but she slashed the amount of money to be paid from US$289 million to US$78 million, NBC News reported.

In denying Monsanto's request for a new trial, San Francisco Superior Court Judge Suzanne Bolanos cut the jury's punitive damage award from US$250 million to US$39 million, the same amount the jury awarded for other damages, for a total of US$78 million.

Johnson's spokeswoman, Diana McKinley, said he and his attorneys were reviewing the decision and hadn't decided the next step.

"Although we believe a reduction in punitive damages was unwarranted and we are weighing the options, we are pleased the court did not disturb the verdict," McKinley was quoted as saying.

Christi Dixon, a spokeswoman for Monsanto, didn't return phone and email inquiries late Monday, according to NBC.

A California jury in early August found that Monsanto was liable was liable for Johnson's cancer in a landmark decision.

Germany-based Bayer, which acquired Monsanto in June for US$66 billion, has dismissed claims that glyphosate is carcinogenic.

As Bayer had not finalized integration of Monsanto during the trial, it was limited in the role it was able to play in defending the company. But with integration now complete, Bayer can provide its full legal backing to its U.S.-based subsidiary.

Johnson’s case was the first lawsuit to go to trial alleging glyphosate – the world’s most common weedkiller – causes cancer. There are more than 5,000 similar plaintiffs across the U.S.