A new study of Victorian firefighters shows high levels of psychological distress could make them more prone to suicide, alcohol abuse and depression.

The University of Newcastle research, commissioned by the firefighters' union, reveals fresh concerns about the stress of being the first to respond to medical emergencies.

The national secretary of the United Firefighters Union, Peter Marshall, has told ABC News Breakfast that it is not the first study of its kind.

He says a survey in 2001 found 68 per cent of Victorian firefighters showed symptoms of post-traumatic stress disorder.

"Since then, firefighters have taken on a role of emergency medical response," he said.

"We are really sitting on tip of iceberg of seeing a large percentage of firefighters who are going untreated because of the type of roles that they're expected to do."

He said at one station alone, there were three firefighters on different shifts who did not know they had post traumatic stress disorder.

He is calling for a reworking of the support mechanisms for the fire services.

"What we need here is an injection of resources to be able to support the firefighters," he said.

"We need a change of culture to not just expect firefighters to front up every day and confront this trauma and then go home without adequate support mechanisms."