The contamination of illegal Ecstasy pills with toxic, psychoactive chemicals has sparked calls for the legalisation of pill testing services.
The lethal chemical PMA, dubbed "Dr Death", has been detected in Green Apple Ecstasy pills sold in Wellington in August and September.
In the past two years PMA has been linked to the deaths of 27 Ecstasy users in Britain and Ireland.
Ecstasy is usually sold to users on the basis that it contains MDMA, a relatively non-toxic, class B substance.
But information obtained under the Official Information Act shows Ecstasy pills intercepted by Police typically contain a range of dangerous substances in place of MDMA.
National Drug Intelligence Bureau coordinator John O'Keefe said intercepted Ecstasy pills most commonly contained mephedrone, methylone, or piperazines – powerful stimulants that can have toxic side effects.
New Zealand Drug Foundation Executive Director Ross Bell said this was a worrying trend, and it meant users very rarely knew what they were taking.
Bell said it was a matter of time before someone died as a result.
"There is a phenomenon of new chemicals being made available on the black market through the internet. We suspect the problem is only going to get worse.
"Chemists are constantly changing up what they are selling."
Bell said the Government routinely tested drugs intercepted on the street to see what they contained, and this information needed to be made available to the public.
"They use this information for criminal proceedings, and send it to hospitals so they know what treatment to provide, but that's where it stops.
"It's not a great leap to make that information more publicly available, to be able to warn people what is out there."
Bell said the Government should also legalise harm-reduction services like pill testing, as had been done in the Netherlands.
"The barrier is the law. If politicians aren't willing to change it, it is because they have a high level of reluctance to embrace harm reduction."
The Misuse of Drugs Act prohibits a person from knowingly allowing drug use on their premises.
This makes it illegal to provide drug-checking services like pill testing, as these services are an acknowledgement that drug use is occurring.
Wellington Hospital clinical toxicologist Dr Paul Quigley said it was extremely difficult to treat someone for an overdose when they did not know what they had taken.
Quigley said pill-testing services would provide a way to support better-informed decisions about drug use.
"For pill testing to happen it would take some legislative change, it would have to be part of the National Drug Policy," he said.
The National Drug Policy released last month sets out the Government's strategy for minimising alcohol and drug related harm until 2020.
Associate Health Minister Peter Dunne said one of the policy's aims was to reduce the harm that was already occurring as a result of drug use.
"The policy also identifies that there is scope to improve the quality and accessibility of public information about particularly harmful drugs, and drug mimics, in the community.
"It includes an action to develop an Early Warning System to respond to this issue.
"This work needs to occur in the context of an unequivocal message that all drug use is potentially harmful."
Dunne said pill testing had not yet been considered under the policy.
"However we would note that the NDP contains an action plan which will be updated over time, so it is always possible for different approaches to be considered."