At festivals, a volunteer-based service runs quality-control on illegal drugs.

The Detail goes inside a drug-checking tent at a music festival, where drug testers say 10 percent of drugs could be dodgy.

Every weekend 80,000 doses of the illegal party drug MDMA are taken around New Zealand.

That's the number Casey Spearin, manager of the drug-checking programme KnowYourStuff, quotes from police wastewater testing data.

"That's just MDMA, that's not including all the other things that people take," she says.

It is her response to critics of drug-testing, who say that it normalises and even encourages illicit drug use.

"It's already normalised. What's not normalised is talking about it out in the open. And that's really what we're doing, we check drugs but we sit people down, we have a conversation with them: 'this is what you've got, what are you doing to keep yourself safe, how do you look after your friends'," she says.

"And we're just consistently hearing from people this is the first time I've had an honest conversation with someone about drugs."

Those conversations have been going on all summer at music festivals and orientation weeks at universities, and they are all out in the open because in 2020 New Zealand became the first country in the world to legalise checking of illicit substances by licensed organisations such as KnowYourStuff.

The drug checking hasn't stopped new, potentially dangerous synthetics popping up on the market - in recent weeks university students celebrating orientation week or O week are being warned of a potentially dangerous synthetic that is being sold as MDMA.

"We have been seeing a number of harmful things this summer," says Spearin. "Synthetic cathinones are often sold as MDMA and we're seeing those pop up, there's been a lot coming up in Dunedin this week over O week. Up to half of MDMA that we got through our drug checking clinics was not, it was cathinones," says Spearin.

Cathinones, sometimes called bath salts, are a group of laboratory-made stimulants that mimic the effects of the khat plant but the effects of one dose are much stronger than MDMA.

"We've detected one or two brand new types of cathinones in the last few days in Dunedin and that really shows that we're just going to continue to play whack a mole with all of these chemicals that can hit the market with zero quality control," she says…

Go to this episode on rnz.co.nz for more details