The union representing 20,000 federal scientists is releasing a survey today in Ottawa that details what they say is the extent and impact of political interference and "muzzling" of research work. 

Starting at 11 a.m.ET Monday, the Professional Institute of the Public Service of Canada (PIPSC) is announcing the results of the survey it commissioned from Environics Research "to gauge the scale and impact of 'muzzling'" and political interference among federal scientists." The news conference is being streamed live on CBCNews.ca.

The union sent invitations to 15,398 federal scientists in June, asking them to participate in the survey. More than 4,000 took part.

PIPSC represents 60,000 public servants across the country in federal departments and agencies, including scientists involved in food and consumer product safety and environmental monitoring.

In recent years, there have been numerous complaints from scientists and the media about federal scientists being restricted from publicly talking about their research. Some complaints are being investigated by Canada's information and privacy commissioner.