United Kingdom – It is legal for people to use a teeth whitening kit at home.

Untrained salon staff are carrying out teeth whitening on clients, according to consumer magazine Which?{{more}}

The General Dental Council (GDC) said it was illegal for non-dentists to carry out the procedure.

The dental regulatory body has launched investigations into six London clinics offering the service and visited by Which? magazine.

Habia, the body which helps salons understand legislation, said some may have been confused by regulations.

James Goonik, of the British Academy of Cosmetic Dentistry, said the use of a substance by three of the clinics – chlorine dioxide – was particularly worrying.

“This chemical is a bleaching agent used to purify water and is very acidic,” he said. “It can wreck tooth enamel”.

The other three clinics reportedly used a hydrogen peroxide formula at a strength above the legal limit.

Concerns were also raised about the failure of some of the clinics to check for gum disease.