Former employees of Tasmanian-owned utility company TasNetworks are calling for compensation after it emerged they were exposed to dangerous weed-killing chemicals.

Key points: 78 current and former TasNetworks workers have come to the company with concerns over exposure

78 current and former TasNetworks workers have come to the company with concerns over exposure Government documentation from the 1970s reveals staff wearing no protection while applying chemicals

Government documentation from the 1970s reveals staff wearing no protection while applying chemicals Former workers are worried they will die before they get answers about compensation

Many of those workers are worried they will die before they see compensation.

A document obtained by the ABC has revealed high concentrations of the chemicals, including 245T, a component of the Vietnam War-era defoliant Agent Orange, were used with no protective equipment.

245T was banned across Australia in the 1980s and 1990s because it contained dioxin, an impurity linked to cancers.

Seventy-eight Tasmanian workers have now come to the company with concerns they may have been exposed.

The health of workers today

Geoffrey Pratt struggles for breath these days.

The retiree says long days applying herbicides to clear the path for power lines in the Tasmanian bush have taken a terrible toll.

Geoffrey Pratt worked for TasNetworks as far back as the 1960s. ( ABC News: Henry Zwartz )

"If I sat still and didn't move or talk, you wouldn't know that I was ill, but if I started talking or moving it would be like if I had run for a kilometre, couldn't get my breath, breathing real hard, probably for five or six minutes," he said.

"I couldn't drive my car at one stage because of how ill I was."

Mr Pratt says his breathing problems started soon after he took up a job as a weed-sprayer for the Tasmanian Hydro Electric Commission, now known as TasNetworks.

"I'd go fishing, I used to go duck shooting, I used to go kangaroo shooting, I'd played football and cricket. [I] was never much good at a lot of it, but I still played it," he said.

"I just wasn't one to sit around — I was pretty active until I got ill."

Mr Pratt and dozens of former workers like him say their health has deteriorated after working as weed-sprayers.

What happened in the 1970s

Their calls for compensation have sparked a TasNetworks investigation into the scale of worker exposure.

But the company will not be drawn on whether it will make any payouts.

Former Greens MP Paul O'Halloran, who raised the issue of compensation in Tasmanian Parliament six years ago, says Tasmania's Liberal Government and the company have "ducked and weaved" on the issue.

"These men were not given any protective equipment, they were not educated in the dangers of using these chemicals," he said.

"It seemed to me at the time the dangers of these chemicals were clearly known and I don't think it's been good enough either from the authority or the Government.

"Governments of the day have ducked and weaved on this and I guess that's because of the possible cost of compensation."

Government documentation from the 1970s reveals the 245T chemical concentrations used by the sprayers were "high", to achieve "effective" weed-killing results.

The documents show workers during the era were not equipped with protective gear. ( Supplied )

The document shows images of workers without masks and wearing shorts.

Leafing through that document brought back memories for Mr Pratt.

"You were saturated in them, they mixed it all up in the water in a half of a 200-litre drum, and then you dished it out in a bucket and put it in the misting machines and put them on your back," he said.

"The stuff used to spill out of them and run down your back.

"Your clothes would have it all over you, when you eat your meals you just had a bit of water to wash your hands in. So you were breathing it in and swallowing it all day."

Dioxin linked to horrific health issues in Vietnam

Associate Professor Darren Roberts, a clinical toxicologist at the University of New South Wales, says 245T has been associated with exposure to dangerous dioxins, a family of about 400 chemical compounds.

Mr Pratt said he was not given protective gear when handling chemicals. ( ABC News: Henry Zwartz )

"A lot of the early research noted that people who had been exposed to 245T developed some toxicity," Professor Roberts said.

"It was actually thought that the main issue with the 245T exposures wasn't actually the 245T itself, it was actually a compound called dioxin, or dioxins, which are a range of different chemicals."

Tetrachlorodibenzo-p-dioxin (TCDD) is one of the most dangerous, and has been linked to horrific health issues in Vietnam.

It is also the dioxin Tasmanian workers may have been exposed to.

The World Health Organisation classifies dioxins as part of the so-called "dirty dozen" of dangerous chemicals, also known as persistent organic pollutants.

"The toxicity related to Agent Orange could or could not have been caused by the dioxins. Dioxins have been associated with certain sorts of conditions, for example affecting the skin and liver," Professor Roberts said.

"There's ongoing debate about whether they do or do not cause more severe problems, for example cancer."

A 2015 inquiry in Victoria found Government weed-sprayers there were exposed to cancer-causing dioxins through the use of 245T.

Similar inquiries in Western Australia saw a small number of workers compensated.

TasNetworks have called on any concerned current or former workers to come forward, but the prospect of redress is uncertain and is expected to be drawn out.

"Our primary focus at the moment is the wellbeing of all our employees and former employees," a company spokesperson said.

"We are working through this process thoroughly and rigorously, which will take some time, but we are determined to get it right."

But that is little comfort to those former employees like Mr Pratt who are now aged in their 70s and running out of time.

"They've just treated us like we weren't there. I reckon the Government is waiting for us all to die so it will all fade away," Mr Pratt said.

Anyone who is concerned they may have been exposed is being asked to contact WorkSafe Tasmania.