A group of Canadian scientists signed another open letter on Thursday, calling on political parties to end to what they see as the "politicization" and "mistreatment" of science.

The letter, signed by 85 scientists in the health, environment and technology fields, focuses particularly on a number of incidents involving the federal Conservative party, including the closure of the office of the National Science Adviser, the firing of the head of the Canadian Nuclear Safety Commission and what it calls "political appointments" to the board of Assisted Human Reproduction Canada.

"While science is not the only factor to be considered in political decision-making, ignoring and subverting science and scientific processes is unacceptable," the scientists write.

"In light of these concerns, we are calling on all political leaders to articulate how they will work to improve Canada's track record with respect to the treatment of science and related due processes."

It's the second open letter from scientists published in the last week that has been critical of the actions of the federal Conservative party.

On Tuesday, 120 of Canada's top climate scientists signed an open letter criticizing the government and urging Canadians to vote "strategically" for the environment in next week's federal election.

Nineteen of those scientists also signed Thursday's letter, including climate change scientists Gordon McBean, John Stone and Andrew Weaver, who all worked as part of the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change.

The remaining 66 scientists who signed Thursday's letter were mostly in the medical community.

Among the medical issues highlighted in the letter were what they saw as the "misrepresentation and suppression" of research related to Vancouver's supervised injection site and the halting of a pilot project that provided prisoners with a safe way to obtain tattoos.

"The policy of claiming uncertainty or doubt with scientific results was successfully used by the tobacco lobby of the past when arguing that no ill side-effects existed through second-hand smoke," said St. Michael's Hospital research scientist Dr. Stephen Hwang in a statement.

"I strongly oppose the distortion of scientific evidence as has been the policy of the current federal government, and we can no longer stand idle while ideology trumps scientific proof," he said.

Queen's University climate change scientist John Smol signed Tuesday's letter on the environment but did not sign Thursday's letter, saying he did not have time to research all of the issues properly before he was comfortable adding his name.

But he said he agrees in principle with the stance of the letter.

Other issues addressed in the letter include cuts to the Canadian Wildlife Service and a number of incidents involving the muzzling of Environment Canada scientists.

That scientists have now taken to protesting in a public forum is a measure of their lack of voice in public policy, said Smol.

"I think scientists tend to be conservative when it comes to voicing their opinions. But as far as the environment is concerned, the problem is so bad and the consequences are so terrible if we do not act," he told CBC News.

"Personally, I cannot sit still any longer."

Smol said the closure of the science adviser office and departure of Arthur Carty, the man who filled that role, took away a potential voice for the scientific community. The lack of a dedicated ministry or minister of science also limits their voice, he said.