The Football Association has said it has taken action over claims that the nitrous oxide inhalation products sold at football matches are contaminated with dangerous levels of the powerful anaesthetic.
The products are marketed under the brand name Nitrofit.
They have been banned in England, Wales and Northern Ireland for two years after being linked to deaths in fans.
The FA said the products were sold in stores and online as a supplement, but the regulator’s investigation has found they are contaminated by nitrous oxides.
The use of nitrous is banned in European Union rules but there are no similar restrictions in England.
In an email, the FA said: “The product NitroFit contains the nitrosamines nitric oxide and hydroxyl radical which are dangerous when inhaled or ingested.
Nitrous oxide is a potent anaesthetic which is known to be highly toxic to humans, animals and other wildlife.””
It is important to recognise that, in the current environment, these products are unlikely to pose any significant risk to people in the UK.”
Nitrous oxide is a potent anaesthetic which is known to be highly toxic to humans, animals and other wildlife.
“However, this is not the case with the nitrofit supplement which contains nitric acid which is a substance which is less likely to be absorbed or to cause any harmful effects in humans.”
The FSA is also investigating a claim made by a member of the public in a letter published on the Football Association’s website.
It said it would not take action unless there was clear evidence the product was not safe for people to consume.
Nitrofit is available in bottles for £2.99 and the inhaler comes in a packet.
It says it is “a gentle, mild and fast-acting product that is intended to be used with a trained practitioner”.