Thousands of people are seeking damages over Roundup herbicides in the US, causing concern about what will happen in Australia.

Farm chemical giant Bayer is facing billions of dollars in lawsuits after the weed killer Roundup was found to have caused a school groundsman's cancer.

There are now about 8,700 people seeking damages, and that number is expected to rise.

But farming groups in Australia insist glyphosate, Roundup’s main ingredient, is safe.

Roundup is used extensively nationwide, so there would be significant effects on the local farming industry if the chemical was banned or restricted.

The case followed a 2015 World Health Organisation determination that glyphosate is “probably carcinogenic to humans”.

France has plans to ban the chemical within three years.

“There are thousands of cases pending in the US, and if courts find in favour of the plaintiff that Monsanto [which is owned by Bayer] have breached their duty of care then they will be liable for a significant amount of damages,” Maurice Blackburn personal injury lawyer, Dimi Ioannou, said.

Maurice Blackburn is looking at launching a case after being contacted by several Roundup users who have cancer.

Monsanto says it expects the court decision will be overturned.

“Glyphosate has been a vital tool for farmers and others for more than 40 years,” Monsanto said.

“More than 800 scientific studies and reviews prove glyphosate can be used safely.”

The Australian Pesticides and Veterinary Medicines Authority (APVMA) is not considering banning or restricting the use of glyphosate.

“Regardless of the outcomes of these court cases from other jurisdictions, glyphosate is registered for use in Australia and APVMA approved products containing glyphosate can continue to be used safely according to label directions,” APVMA chief Dr Chris Parker said.