The Construction, Forestry, Maritime, Mining and Energy Union says asbestos was first detected in 50 tonnes of landfill supplied by BMI Group to the Brisbane South State Secondary College site at Dutton Park last week.

AAP has sought comment from BMI Group.

Asbestos is a fibrous silicate material, once widely used in construction decades ago, that was banned after being found to be a carcinogen that can cause mesothelioma.

The CFMEU has asked the contactor Broad, a subsidiary of CPB Contractors owned by CIMIC, to audit the site, but say they have refused.

"Broad/CPB have taken a cavalier 'she'll be right' approach - at an operating high school - to managing what is a deadly public health risk," CFMEU assistant secretary Jade Ingham said in a statement.

He has also called for BMI Group's quarries and recycling sites across southeast Queensland to be audited for asbestos.

The company operates sites as Acacia Ridge, Hendra, Larapinta, Mount Gravatt East, Redbank Plains and Stapylton.

"We now know that at least 200 tonnes of material from BMI is contaminated with asbestos, and need to know exactly what other building jobs in SE Queensland this material has been delivered to by Martin Brothers and other subcontractors," Mr Ingham said.

"We have a situation here where potentially dozens of building sites could be contaminated, while workers and the public remain unaware of the risk."

The union has asked workplace health and safety representatives at the landfill sites to check material.

The CFMEU has also called for other builders using BMI Group materials to test them for asbestos.

"Asbestos is a killer, and any building contractor that does not take the danger seriously is putting workers and the general public at very real risk," Mr Ingham said.

Comment has also been sought from Broad Contractors and CIMIC Group.

Australian Associated Press