An expert on weapons police have says using a stronger type of pepper spray is problematic and there is not enough research to identify the long term side-effects.
The Sabre Red spray (left) recently trialled is six times more concentrated than the Sabre Defence spray. Photo: NZ POLICE
Officers in Bay of Plenty have been trialling a spray called Sabre Red which is described as having six times the amount of the key ingredient - capsicum - than the spray used now.
Police say the current spray is not always as effective as they would like, and a stronger version would help protect officers and the public.
However, John Buttle, a senior criminology lecturer at Auckland University of Technology, says the stronger product could cause problems for officers if they become cross-contaminated.
Mr Buttle says the long-term effects of the chemicals are not known.
"The long-term effects we actually don't know about, but I would assume it would most likely to affect the lungs. There are also situations short-term where if you spray someone too close to their face and the jet stream of liquid goes into their eyes, they can actually turn round and blind them."
Police say there are always risks involved, but they take steps to provide enough aftercare and first aid to minimise any medical risks as a result of contact with the spray.
The results of the trial are expected to be evaluated before the end of this year.