Professor Peter Barham speaks to the media about the effects of liquid nitrogen
8 October 2012
Professor Peter Barham from the University of Bristol’s School of Physics has commented to the media in light of today’s news story about a sixth form pupil who had her stomach removed following an adverse reaction to liquid nitrogen.
Professor Barham said: “Liquid nitrogen is simply the harmless gas nitrogen which has been cooled to such a low temperature that it becomes a liquid. It is intensely cold – (-196°C) and if not used properly can cause frostbite or cryogenic burns. If liquid nitrogen is added to a liquid such as an ice cream mixture, it cools the liquid rapidly while it boils away and produces a cloud of vapour.
“The technique is used by some restaurants to prepare instant ice creams at the table - the rapid freezing produces an ice cream with particularly small ice crystals which has a very smooth texture.
“As with any very hot or very cold liquid proper safety measure must be taken – just as no-one would drink boiling water or oil or pour it over themselves, so no-one should ingest liquid nitrogen.
“Liquid nitrogen can be used safely in the preparation of foods. However, since it is not safe to ingest liquid nitrogen due care must be taken to ensure that the liquid has all evaporated before serving any food or drink that was prepared with liquid nitrogen.
“Nitrogen is not toxic. Liquid nitrogen by being so cold can cause severe cryogenic burns (or frostbite) but once the liquid evaporates back to nitrogen gas it is more or less harmless.”