THE union representing construction workers at the Sunshine Coast Public University Hospital says random drug tests won't eradicate illicit substance use in the workplace.
Construction, Forestry, Mining and Energy Union divisional branch secretary Michael Ravbar said mandatory blanket testing - from managers to labourers - was a better deterrent.
"Blanket testing of the whole workplace puts everyone on notice not to be impaired while at work," he said.
Police conducted a drug-driving blitz outside the hospital building site at Kawana on Friday. Three male drivers aged 20, 28 and 43 were charged after they tested positive. Another driver was nabbed for possessing cannabis.
Mr Ravbar said although drugs and alcohol were a major community problem, there were better ways to address the issue than just a drug blitz.
"The CFMEU does not take offence to police stating 'in the construction industry there is a propensity for some people to utilise illicit substances'," he said.
"However, it is important to remember the percentage of people using drugs in the construction industry is no more or less than the general community."
TechniTest conducts workplace drug and alcohol testing for Sunshine Coast and Queensland businesses.
Its spokeswoman Kerry-Anne de Jager said unfortunately there was a dangerous perception that "recreational drugs" were safe.
"The Sunshine Coast and south-east Queensland's general attitude is that cannabis is a happy high drug," she said.
"They claim it to be non-addictive and a social thing.
"Same with ice or speed (methamphetamines) and prescription or self-medicated drugs.
"There is no such thing as a safe drug."
Ms de Jager said employees under the influence can make decisions and take risks that a sober person would never take.
"Sometimes these risks result in serious injury or death," she said.
"At this time, not only is the employee or department scrutinised but also the supervisor, manager, director and the company as fines and penalties may apply."
Ms de Jager said workplace drug testing was increasing. "Our clients are a mix of corporations, local government, state government and small businesses."
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