A federal judge on Monday slashed a damages award that Bayer AG owed a California man who blamed Roundup weed killer for his cancer to $25.27 million from $80.27 million, saying the punitive damages component was too high.

U.S. District Judge Vince Chhabria in San Francisco agreed that the evidence sufficiently supported the $5.27 million compensatory damages award for the plaintiff Edwin Hardeman, and said the jury acted reasonably in awarding punitive damages.

He nonetheless reduced punitive damages to $20 million from $75 million, saying it was "constitutionally impermissible" to award the higher amount, which was roughly 15 times the size of the compensatory damages award.

"Monsanto's conduct, while reprehensible, does not warrant a ratio of that magnitude, particularly in the absence of evidence showing intentional concealment of a known or obvious safety risk," Chhabria wrote.

In a statement, Bayer called Chhabria's ruling "a step in the right direction," but said it still plans to appeal the verdict and damages award to the federal appeals court in San Francisco.

Roundup was long manufactured by Monsanto Co, which Bayer now owns. The companies have long maintained that glyphosate, the active ingredient in Roundup, is safe.