A former Big Island coffee farmer is among 300 people suing agribusiness giant Monsanto.

A federal judge in San Francisco started reviewing claims Monday that the company's widely used weed killer - Roundup - can cause cancer. 

The judge is hearing from experts this week to decide whether there is scientific evidence showing the chemical can cause Non-Hodgkin's lymphoma. 

68 year old Christine Sheppard was diagnosed with the disease in 2003 and given six months to live. She says she sprayed Roundup for years to control weeds on her Hawaii coffee farm.

Now, she's in remission but still has severe pain in her hands and legs from her cancer treatment. 

Monsanto's has denied the claims.

"Glyphosate, the active ingredient in our product, Roundup, we know that it is not a carcinogen. It is completely safe. There is over 40 years of safe use around the world. It's the most popular and widely used herbicide in history. It also happens to be the most widely studied agricultural compound in history," Scott Partridge, Monsanto said.

Monsanto claims workers at the International Agency for Research on Cancer, those who claim Roundup is dangerous, were being paid off by plaintiffs lawyers to help create lawsuits.