A New Zealand drug intelligence report obtained by Newshub says criminal groups are producing synthetic cannabis laced with weed killer and fly spray.
Drug experts, and even Black Power, say the black market trade of homemade dope is well entrenched, but the Government insists it isn't too much of a problem.
Since the ban on psychoactive drugs, backyard dealers have emerged, spraying all sorts of potions on plant material to cash in.
"Acetone, tranquiliser - any substance that can get someone out of it," says Black Power life member Denis O'Reilly.
But there are even cruder methods of manufacture. According to a 2015 drug intelligence report, "groups are producing 'synthetic cannabis', which does not even contain cannabinoids, but is made by spraying plant material with substances such as fly spray or weed killer. Such mixtures...deprive the user's brain of oxygen".
"It's frankly selling poison, and anyone who buys that sort of a product is exposing themselves to massive risk," says Associate Health Minister Peter Dunne.
The report also states organised criminal groups are selling synthetic cannabis concoctions in "several regions".
Trading on Facebook is also prevalent. But Mr Dunne says the black market isn't much of a problem.
"It's not particularly widespread as far as I understand. But it is there from time to time. It's reasonably localised and sporadic."
Last year, TV3's 3D programme revealed how easy it was to acquire synthetics on the street in Tauranga.
Mr O'Reilly says there are plenty of houses selling homemade brews of synthetic cannabis in Hawke's Bay and the effects are serious.
"People just nod off to sleep, are unintelligible in speech, can hardly walk," he says.
Fewer people are being admitted to hospitals suffering side effects from synthetics since the ban, but there are still problems. An emergency physician from Middlemore Hospital told Newshub three people recently turned up at the ED after having seizures. All of them had been smoking synthetic drugs.