Health Canada says it has taken no action against four of its leading researchers for speaking out against the agency.

In a CTV News exclusive on Wednesday, the four scientists accused the department of exerting undue pressure on them to approve potentially harmful veterinary drugs, medicine that could eventually make it up the food chain to humans.

Health Canada flatly denied the allegations Wednesday.

One of the drugs is used to fight bacterial infections in chickens. It was recently approved by Health Canada despite warnings from at least one of its scientists that the drug could be dangerous to humans.

"People find different views about the same thing. So one of the good things about the process is that you try to make collective decisions, not individual decisions about how this will move forward," says Health Canada chief scientist Dr. Kevin Keough.

The four Health Canada scientists told CTV News they feel pressured to approve drugs even if they have reservations. Health Canada, they say, is feeling pressure itself from pharmaceutical companies. That's raising questions about job security for employees who speak out.

Health Canada insists its scientists are encouraged to debate -- among themselves.
"I think there is an adequate measure of dissent, and beyond that there is the possibility of going to the public service integrity officer," explains Health Canada's J. Robert Joubert.

But the scientists argue the public service integrity officer cannot enforce recommendations, and say the office moves too slowly.

Medical ethicists say the government is forced into a difficult debate between the needs of industry and safety of the public.

"Both want to act commercially, and ethically-commercially," says McGill University medical ethicist Margaret Somerville. "But what is ethical commercially may not be ethical if you're the guardian of the public."

So far, Health Canada says no action has been taken against the four scientists who went public. The scientists say they're not backing down and have called for a full Senate investigation into the matter.