H₂O₂ and the law

Sir, I read with interest the article entitled Clinical use of hydrogen peroxide in surgery and dentistry – why is there a safety issue? by Patel, Kelleher and McGurk (BDJ 2010; 208: 61–64). It is clear from the cases presented that dilute hydrogen peroxide solution is of very great value in the surgical management of head and neck oncology where complications can be grave indeed.

However, I did notice an incorrect statement in relation to the UK law in respect of the sale and supply of solutions containing >0.1% hydrogen peroxide. The current version of the Cosmetic Products (Safety) Regulations (CPSR)¹ restricts the concentration of hydrogen peroxide present or released by 'oral hygiene products' to a maximum of 0.1%. Skin-care preparations may contain or release up to 4% and hair-care preparations up to 12% hydrogen peroxide. Unfortunately, following the House of Lords judgement in Optident Limited and Another v. Secretary of State For Trade and Industry and Another,² it is clear that products for tooth whitening are classed as cosmetics within the meaning of the EU Cosmetics Directive³ (and thus the UK conformative legislation), and hence subject to the 0.1% maximum hydrogen peroxide limit.

The definition of 'supply' in the context of in-surgery tooth whitening does not yet appear to have been tested in the UK courts. Whatever arguments may be advanced in this respect, it does seem clear that providing a patient with a tooth whitening product for home use would constitute 'supply', and therefore fall within the ambit of the CPSR.

Consumer safety law is concerned with protection of consumers in the widest possible sense. Although the point is well made in this article that dilute hydrogen peroxide is safe for use on delicate soft tissues, it does not necessarily follow that it is safe for consumers to have unsupervised access to significantly higher concentrations of hydrogen peroxide. Amendment of the current law to differentiate between 'general' supply, and 'professional use' would be of considerable assistance to dentists when the option of bleaching might obviate a destructive alternative such as veneer or crown preparation.

It should be borne in mind, however, that the SCCP 2007 report⁴ which is often quoted as supporting an increase in the permitted concentration of hydrogen peroxide to 6% in cosmetics supplied for tooth whitening purposes does not, in fact, confirm that any concentration greater than 0.1% is safe for use over long periods, highlighting a need for additional research. If in the future it were to be discovered, for instance, that the long-term use of products containing 0.1-6% hydrogen peroxide had a significant mutagenic effect, the existence of doubt as to safety raised by the SCCP report could render many suppliers, including dentists, vulnerable to claims that this should have been recognised.

I do question the inclusion of the 'in brief' practice point inserted at the head of the article stating that 'The dental profession should consider hydrogen peroxide more often in clinical use'. I do not believe the current article states or supports this point, or even that it set out to do so.