(Reuters) - A California jury on Friday found Monsanto liable in a lawsuit filed by a man who alleged the companys glyphosate-based weedkillers, including Roundup, caused his cancer and ordered the company to pay $289 million in damages.

The case of school groundskeeper Dewayne Johnson was the first lawsuit to go to trial alleging glyphosate causes cancer. Monsanto, a unit of Bayer AG following a $62.5 billion acquisition by the German conglomerate, faces more than 5,000 similar lawsuits across the United States.

The jury at San Franciscos Superior Court of California deliberated for three days before finding that Monsanto had failed to warn Johnson and other consumers of the cancer risks posed by its weedkillers.

It awarded $39 million in compensatory and $250 million in punitive damages.

Monsanto in a statement said it would appeal the verdict. Todays decision does not change the fact that more than 800 scientific studies and reviews...support the fact that glyphosate does not cause cancer, and did not cause Mr. Johnsons cancer, the company said.

Monsanto denies that glyphosate, the worlds most widely used herbicide, causes cancer and says decades of scientific studies have shown the chemical to be safe for human use.

Johnsons case, filed in 2016, was fast-tracked for trial due to the severity of his non-Hodgkins lymphoma, a cancer of the lymph system that he alleges was caused by Roundup and Ranger Pro, another Monsanto glyphosate herbicide. Johnsons doctors said he is unlikely to live past 2020.

A former pest control manager for a California county school system, Johnson, 46, applied the weedkiller up to 30 times per year.

Brent Wisner, a lawyer for Johnson, in a statement said jurors for the first time had seen internal company documents proving that Monsanto has known for decades that glyphosate and specifically Roundup could cause cancer. He called on Monsanto to put consumer safety first over profits.

Over the course of the four-week trial, jurors heard testimony by statisticians, doctors, public health researchers and epidemiologists who disagreed on whether glyphosate can cause cancer.

The U.S. Environmental Protection Agency in September 2017 concluded a decades-long assessment of glyphosate risks and found the chemical not likely carcinogenic to humans. But the World Health Organizations cancer arm in 2015 classified glyphosate as probably carcinogenic to humans.

(Reporting by Tina Bellon; Editing by Cynthia Osterman)