The preparation of synthetic drugs in this country is out of control, with doses of a dangerous chemical far greater than used overseas, a New Zealand scientist says.
Police have stepped up public warnings in the wake of the recent deaths possibly linked to synthetic drugs with about 20 being investigated by the coroner.
Testing of the drugs by the Environmental Science and Research Crown Institute (ESR) has found the chemical AMB-fubinaca which has been linked to a "zombie-like" drug outbreak in New York.
ESR forensic chemistry manager Kevan Walsh told Nine To Noon it was the concentration of the chemical that seemed to be causing issues.
"I think one of the big factors that may be making a particular effect in this particular time is actually the dosage of the chemical on the plant material.
"In New Zealand we're seeing between 10 and 25 or 30 times greater concentration on the plant material than was reported in Brooklyn and that's got to have a serious impact on people's health."
He said while it was not something they could teach, he said the drug's preparation was "out of control" and needed to "be reigned in."
"Quite clearly people aren't mixing it right. There does seem to be a complete ignorance in terms of what the dosage should be, and that's not surprising because there really is no information given out. This is not a product that we can recall ... this is something prepared in people's backyards in terms of putting out plant material and adding the chemical to it."
But Mr Walsh said ESR was finding other synthetic drugs being used from other parts of the country and it was clear others were likely to pop up.
"AMB- fubinaca, for example, in our laboratory, we weren't seeing this 12 to 18 months ago. It was something that was novel to New Zealand over a year ago and it's quickly changing, so we've seen that ramp up in terms of its prevalence but we have no notion that that's going to stay the same.
"Once people do get the message and stop using it almost certainly they're going to try something else."
Police reinforced their public warning yesterday after two deaths in the past week in West Auckland.
"What this exercise we're doing here right now is trying to address that demand issue. We've got to get the message out to people, and that has been done over the last four weeks, for people to stop using the stuff because it's just not good."