An investigation by trading standards has discovered that some home tooth whitening kits can contain illegally high level of hydrogen peroxide.
A report in consumer magazine Which? reveals that the some kits can contain up to 23.8% of hydrogen peroxide. The legal limit is just 0.01%.
But it is not just home kits which come under scrutiny - this figure also applied to dentists.
Mike MacGregor, of Hertfordshire County Council, told Which? "‘We support the limit of 0.1 per cent hydrogen peroxide for products used by anyone who is not a qualified dentist. There may be individual occasions where a fully qualified dentist could decide that a patient could be treated safely with a product containing a higher level of hydrogen peroxide"