More than 40 former Hydro Electric Commission employees are claiming compensation after being exposed to dangerous chemicals at work.
Communications, Electrical and Plumbing Union of Australia (CEPU) organiser Lee Archer said the men, some employed by TasNetworks and some retired, were meeting with the utility company's toxicologist next week.
Ms Archer said the employees had used a number of chemicals in their work for Hydro Electric Commission between the 1950s and late 1990s.
These chemicals included T5D, Tordon, Grazon, Garlon and Ustalin herbicides, as well as Ferrodor lead-based paint, she said.
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TasNetworks confirmed Shell, Hortico, Yates, Weedone, Vallo and Hart's herbicides were also used during the 1960s and 1970s.
The men worked in crews of four - two on chainsaws and two spraying - to cut down and poison trees underneath transmission lines and property right of ways during eight-hour shifts.
"The mist would saturate them every day," Ms Archer said.
Their uniform was overalls and Blundstone boots and they were not advised about what was contained in the chemicals, she said.
Chief executive Lance Balcombe confirmed TasNetworks was investigating the former Hydro Electric Commission's use of herbicide for vegetation spraying between the 1960s and the 1980s.
TasNetworks is looking into how the herbicide was applied, he said.
Mr Balcombe conceded "work safety practices during the 1960s and 1970s was not of a standard that would be accepted today".
Former Braddon Greens MHA Paul O'Halloran brought this issue up in parliament in 2013, sharing stories about how former Hydro Electric Commission employees were exposed to chemicals while working on the state's West Coast.
"They were spraying herbicides under high wires. They were dripping in chemicals. It was direct exposure without any safety clothing on," Mr O'Halloran said.
"It impacted on their lives - personal, financial and their health."
TasNetworks is speaking with 12 employees and seven former Hydro Electric Commission employees about the chemical exposure, but Mr Balcombe said "because this is a historical matter and some records are still being located or reviewed, we don't know how many people may be affected".
"We are in direct contact with all of the people that we currently know of that may have come into contact with this herbicide at the time," he said.
"As a business and with the support of our board, we will be doing everything we can to ensure that any current or former employees who may have applied the herbicide are provided with the appropriate support and information."
WorkSafe Tasmania chief executive Mark Cocker confirmed it was working with TasNetworks and the state government in examining "former Hydro Electric Commission and Tasmanian State Service employees' application and use of [2,3,7,8 - Tetrachlorodibenzo-p-dioxin (TCDD), a contaminant used in the herbicide 2,4,5-T] for vegetation spraying from the 1960s through to the 1980s".
"It is understood that a number of scientific studies have recognised possible links between high exposure to TCDD and an increased risk of certain cancers, skin conditions and possibly other health effects," Mr Cocker said.
Current or former employees who think they may be affected can visit worksafe.tas.gov.au or phone 1300 366 322.