One in ten drug samples tested for impurities by CanTEST were discarded, new data reveals.
Canberra-based CanTEST is Australia's first fixed site health and drug checking service.
The service has tested over 3000 samples since its launch in July 2022.
Drugs were discarded 12 per cent of time in the first year of operation, and ten per cent in the second.
The expected drugs Canberrans were most likely to sample in 2023-24 were MDMA (35.4 per cent), cocaine (19.7 per cent), ketamine (11.8 per cent), meth (7 per cent) and heroin (4.5 per cent).
There were more samples of what people thought was cocaine and meth tested in 2023-24; but fewer samples of ketamine and performance and image enhancing drugs such as steroids (PIED).
In 2023-24, one in four (23 per cent) of expected ketamine samples were a completely different substance.
Samples of expected heroine were only pure in six per cent; while expected cocaine samples contained another substance half the time.
LSD (90 per cent), methampethatime (86 per cent) and MDMA (80 per cent) were more likely to be pure.
Drugs were found to be more pure in the second year of CanTEST's operation.
This includes cocaine, heroin, ketamine, MDMA and meth.
This might reflect changes to the drug market in the ACT or abroad, ANU Research School of Chemistry Professor Malcom McCloud said.
"The data shows noteworthy changes in the samples presented to the service over the past two years, including an increase in the median purity of cocaine and heroin," he said.
CanTEST is open for three hours each Thursday and Friday evening.
Since opening, it has also issued 20 community notices to alert the public about unexpected or concerning substances.
This includes three instances of nitazenes detection, extremely potent synthetic opioids that carry a high risk of overdose.
CanTEST identified four entirely novel substances previously undetected by other drug checking services globally.
They also provided nasal naloxone for free 225 times.
This reverses the effects of opioid overdoses.
The service is being funded until June 2027.
Canberra's drug market is unpredictable, executive director of Canberra Alliance Harm Minimisation and Advocacy Chris Gough said.
"It has been surprising just how unpredictable the illicit drug market is in Canberra, with some very dangerous substances found over our first two year period," he said.
"The information that CanTEST provides through testing and community alerts is therefore crucial to let people know the dangers involved and make informed choices about their drug use."
