New Zealanders are being warned over the potentially dangerous use of liquid nitrogen in cocktails after a near-fatal incident in England.
New Zealand's National Poisons Centre director says he has only just become aware liquid nitrogen was being used in food and drinks here.
This week British teen Gabby Scanlan had her stomach removed after unwittingly drinking a cocktail containing the substance.
Several New Zealand bars and restaurants use nitrogen, typically in cocktails and sorbets, as a cooling agent and to add a dramatic vapour. Nitrogen gas must be cooled to -196C before it becomes liquid and turns back into gas as it warms.
The National Poisons Centre criticised the practice because of the potential risks.
"I really do think it's a bit irresponsible to say the least because of the potential danger. Cocktails and things are nice, but do you really need to put liquid nitrogen or carbon dioxide into them just to jazz it up? It's pretty much a no-no," said director Wayne Temple. Bar owners in New Zealand said if used correctly, there was no risk to customers.
Karai Wall, owner of Hamilton's Nitro Cocktail Bar, was appalled by the British case. "They've created a cocktail and just poured liquid nitrogen on top. This girl's drunk straight liquid nitrogen.
"It's absolutely horrific and the thing is that the people that did it haven't been trained."
Mr Wall had dedicated his business to using liquid nitrogen to create cocktails and sorbets.
Once the vapour had gone, the drink was safe, he said.
Auckland's Suite bar used liquid nitrogen in cocktails to give them the "wow factor", said owner David Hawk. The bar followed strict safety procedures to make sure the chemical dissipated before it was served.
It was permitted as a food additive here at the minimum level required to achieve the desired technical effect, a Ministry for Primary Industries spokesman said.
Q&A: Liquid nitrogen
Q: What is liquid nitrogen?
"It is used as a freezing agent, as a coolant, and for medical uses such as freezing off warts."
Q: Have there been any similar cases in NZ of someone being injured from drinking a cocktail containing liquid nitrogen?
"No, I'm not aware of any in New Zealand, but there have been some reported in medical literature from overseas."
Q: What are the effects if it is consumed incorrectly?
"As it touches surfaces it rapidly warms up and you get a massive volume of expansion of nitrogen gas. The liquid expands to thousands of times its volume, so it's just going to perforate everything that it comes in contact with. Also, because it's very cold any surfaces it touches on the way down will freeze immediately."
Q: What injuries would it cause if ingested?
"It can perforate the stomach. It is just going to find the weakest link in your stomach and push right through it."
Q: Can anything be done to lessen the effects once consumed?
"No, not really. You've done the damage."
Q: Should liquid nitrogen be used in food and drinks?
"I don't think so, no. I really do think it's a bit irresponsible to say the least because of the potential danger. Cocktails and things are nice, do you really need to put liquid nitrogen or carbon dioxide into them just to jazz it up? It's pretty much a no-no."
Answers given by Wayne Temple, director of the National Poisons Centre.