Mr Lowe said the association was "truly alarmed" by the results.
"We had heard about the extent [of drug use] but never dreamt it was going to be like this."
But he was also concerned at a lack of clarity in the law apparent from a finding that 45 per cent of employers may not be complying with legal requirements in the way they go about testing for drugs in workplaces.
He said employers were prepared to do their best to minimise workplace accidents, but needed support in ensuring drug use did not put staff at extra risk or impair productivity.
Cannabis and methamphetamine were the most common substances picked up by workplace testing.