Drug tests would probably not have prevented the suspected overdose deaths of two young festival-goers, a forensic toxicologist says.
Some drug experts have pushed for the tests so users know what they are taking, after two suspected drug deaths at Stereosonic festivals in Adelaide and Sydney.
But Safework Laboratories marketing director Andrew Leibie said the tests provide little more than "best guesses" because they're unable to detect contaminants or other toxic compounds.
"Proper analysis of pills requires highly sophisticated laboratory equipment and can take many hours or days of work by trained technicians," he said on Monday.
"On-site pill testing is impractical and unlikely to have any meaningful impact or prevent the kinds of tragic deaths we have seen in recent weeks."
The tests were also unable to reveal the concentration of substances or to detect a number of new designer drugs, Mr Leibie said.
Health Minister Jack Snelling has ruled out introducing the tests, saying it would send the wrong message about drug safety.
Stefan Woodward, 19, died in hospital on Saturday after taking pills at Adelaide's Stereosonic event.
Police are investigating if he took the same pills as two other revellers who overdosed and were rushed to hospital.
A man, 20, remains in a critical condition and a woman, 21, is in a serious but stable condition.
There was also a death at Stereosonic's Sydney event when pharmacist Sylvia Choi, 25, was struck down, again by a suspected drug overdose.
