"My main concern is people are consuming products containing a range of untested chemical ingredients," Mr Hurley said.
"There is a very high likelihood that people will become very ill."
The wider concern was also expressed last night by Hawke's Bay social activist and drug-use reduction movement leader Denis O'Reilly who said synthetics are "rampant" in the community again, with increased danger about what might be in the drugs Mr Hurley called "toxic".
"There are varieties which contain anything from acetones to flyspray," he said. "No one knows what's in it.
"Whatever it is," he said, "it seems to be having a profound soporific effect. It is a significant problem. We do not know what the substance is, therefore the difficulty is knowing how to give help."
While police are seeking any information about manufacture and supply, Mr O'Reilly said anyone using synthetics and wanting to get out, or anyone concerned about use by friends and loved ones, should seek help from services that are available.
Sources have told Hawke's Bay Today that there has been talk of "synnie" houses, indicating the availability of synthetic products, amid questions about the sources of the products, and how they might be produced or altered locally.
Underground production and supply was indicated in the South Island this week when police raised about 10 properties in Christchurch, seizing several hundred thousand dollars worth of synthetic psychoactive substances and ingredients used in manufacture, much of it in several "large boxes" in a storage lock-up.
Five people, at least three of them immigrant or foreign nationals and including one listed as a "chef" and another a "real estate agent", were arrested. The dangers of synthetic use are highlighted by former users urging potential users not to start, on the hard-hitting online forum Spice Addiction Support.
One says it's "a chemical poison ... it gets into patients blood then spreads to brain and all organs".
Another wrote: "I've been hospitalised more times than I can remember, and had seizures from this stuff."
"My cousin tried it, and now he says he can't see correctly," another wrote. "He is freaking out that he will not be able to see correctly again."
A warning from one post of a month ago says: "As hard as it is you can get through this, but please remember how bad you feel right now and don't ever put yourself in that position again."