Australia's leading advocate on Parkinson's disease is calling for a ban on a widely-used chemical because of growing evidence about its risk to farmers.

Parkinson's Australia (PA) announced on Wednesday it supports a ban on the herbicide paraquat, citing "scientific evidence linking the chemical to the development of Parkinson's disease".

"It's been banned in 67 countries including in Europe, China, and the UK, and Australia should follow suit," Parkinson's Australia CEO Olivia Nassaris said.

"Parkinson's organisations across the world have been looking at this issue for quite some time and toxins like paraquat can increase your risk of developing Parkinson's."

Ms Nassaris said it was not just farmers who were concerned about the use of the chemical. 

"It's being used on school ovals, on sports grounds, on golf courses, and by council workers," Ms  Nassaris said.

Parkinson's disease is an incurable, progressive, degenerative neurological condition that affects a person's movement and is now the fastest-growing neurodegenerative disease in the world.

More than 150,000 Australians are living with Parkinson's, which causes an "onslaught" of motor and non-motor symptoms.

"We don't know the cause but we can prevent some people from developing Parkinson's by banning paraquat," Ms Nassaris said.

The organisation has also launched a public petition.

The announcement comes after the ABC revealed a leaked email from the National Farmers Federation head office, calling on its members to avoid discussion of an ABC Landline program that investigated the link between paraquat and Parkinson's disease

The story revealed a cluster of Parkinson's disease cases in a Victorian farming community amid a growing number of independent studies linking paraquat to the incurable neurodegenerative condition.

The global agricultural chemical giant Syngenta is the original manufacturer and maintains the chemical does not cause Parkinson's.

Paraquat and the related diquat are fast-acting, non-selective herbicides that will kill most plants on contact.

Farmers' groups say it is an important tool and critical for managing weeds, maintaining soil moisture, and growing food.

Paraquat and diquat have been under review since 1997, and last month the Australian Pesticides and Veterinary Medicines Authority (APVMA) released a draft recommendation.

In its latest draft review, APVMA said:

"Taking into consideration the available database of animal studies, including all studies carried out to OECD guidelines, the overwhelming weight-of-evidence, is that paraquat does not induce neurotoxicity via the oral, dermal or intranasal exposure routes; routes that are of relevance to human exposure to this pesticide."

The Australian Council of Trade Unions (ACTU) has also entered the debate, alleging the APVMA engaged more with industry than workers.

"We see very little evidence of engagement with stakeholders that are concerned with worker health, like unions, particularly ACTU, but also in relation to public health,” Assistant ACTU Secretary Liam O'Brien said.

He said the ACTU "regularly" heard reports of health and safety concerns regarding chemical use among its members, including poisonings. 

"Paraquat is a concerning chemical, both here in Australia but indeed around the world," Mr O’Brien said.

"There are safer alternatives that can be used and are just as effective."

The ACTU is calling on the regulator to work more closely with workers who use chemicals to keep them safe," Mr O’Brien said.

"We want to see it engage broadly with all stakeholders who have an interest in the safe use of chemicals and pesticides in this country, and that's not something that we've seen evidence of in relation to the APVMA."

The ABC has put questions to the APVMA and is waiting for a response.