Victorian WorkSafe CEO Denise Cosgrove and Chairman David Krasnostein have been dismissed by Premier Daniel Andrews over toxic contamination of mains water at the Fiskville Country Fire Authority training centre.

Water storage tanks at the facility were found to contain perfluorooctane sulfonate, a synthetic chemical once used in firefighting foams, which was banned in 2007 over concerns about its toxicity and impact on the environment.

In January a Monash University study confirmed a cancer cluster among the 600 firefighters who worked and trained at Fiskville from 1971-99.

Sixty-nine had suffered cancer and 16 had died. The study found an unusually high incidence of brain, skin and testicular cancers.

Last December, around the time Mr Andrews announced a parliamentary inquiry into health

concerns at Fiskville, the Premier was assured by WorkSafe that water there was safe.

Last week a furious Mr Andrews said he lost confidence in WorkSafe’s management when testing revealed traces of the banned chemical.

“They cannot explain how they got this wrong – in fact they cannot guarantee that they even tested the water,” he said. “I will not be lied to, and I will not accept incompetence, particularly when it comes to the safety of those Victorians who put themselves in harm’s way.”

Ms Cosgrove and Mr Krasnostein submitted their resignations at the Government’s insistence last Tuesday.

The Fiskville facility has been closed since the previous day, when residues of the banned chemical were discovered.

Ms Cosgrove was CEO from November 2012. Before joining WorkSafe she was GM claims management with New Zealand’s Accident Compensation Corporation. She is also a former assistant auditor-general, strategy, in New Zealand.

WorkSafe Executive Director Insurance Clare Amies has been appointed acting CEO. Transport Accident Commission Chairman and WorkSafe board member John Walter is acting Chairman.