The president of the union representing three Health Canada scientists who were fired after repeatedly criticizing the department's drug-approval policies says their terminations will be appealed.

"There's actually a process under the Public Service Staff Relations Act," Steve Hindle, president of the Professional Institute of the Public Service union, told CTV's Canada AM Thursday.

"They'll file grievances, we'll make our case to the public service staff relations board. And then if we're not successful in convincing the staff relations board to have them reinstated, we'll be taking a look at the reasons they used and determining whether or not we go on to federal court from there."

Shiv Chopra, Margaret Haydon and Gerard Lambert all received letters of termination Wednesday. The reasons for their dismissal have not been revealed, but a Health Canada spokesman denied the terminations have anything to do the scientists' criticism of department policies.

But Hindle believes "there is cause and effect at play here."

"My first reaction was that this is retribution for having been very outspoken over the last two years about Health Canada policies and what's going on in terms of the drug approval process," he said.

Mike McBane of the Canadian Health Coalition agreed the three scientists were being penalized for trying to do their jobs. He calls the firings "an ominous signal from the government," praising the scientists as "Canadian heroes."

The three researchers have spoken out repeatedly in recent years about policy and procedures at Health Canada they were not comfortable with.

They said they were often pressured to approve unsafe veterinary drugs.

In the late 1990s, they publicly opposed rBST, also known as bovine growth hormone, a product that enhances milk production in cows. Their criticism led to a decision not to approve the drug.

The whistleblowers later criticized carbadox, a drug used to promote growth in pigs, and Baytril, used to promote growth in cows and chickens.

The scientists said they felt pressured to approve drugs even if they had reservations. They alleged that Health Canada was pressuring them because they in turn had been pressured by pharmaceutical companies to hustle through approvals.

The health agency has repeatedly denied the allegations.

Chopra said in 2002 that following their public complaints about the Health Canada approval system, he and his colleagues had been suspended without pay, been reprimanded and demoted.

Most recently, the scientists said they were ignored when they warned their supervisors proposed measures to curb mad cow disease were inadequate. They said they were also told not to discuss their views outside the government.