Tooth Whiteners & Oral Hygiene Products containing hydrogen peroxide

6. How safe are products containing hydrogen peroxide?

• 6.1 How are hydrogen peroxide solutions classified and labelled?
• 6.2 How safe are oral hygiene products and toothwhiteners?

6.1 How are hydrogen peroxide solutions classified and labelled?

Solutions containing more than 5% hydrogen peroxide are labelled “harmful”.

In addition solutions containing:

• 5 – 8% hydrogen peroxide are labelled “Irritating to eyes”,
• more than 8% are labelled "Harmful if swallowed" and “Risk of serious damage to eyes”,
• more than 35% have an additional label “Irritating to respiratory system and skin”,
• higher concentrations are in addition labelled “Causes burn”.

No labelling is required in EU for hydrogen peroxide solutions of less than 5%.

The International Agency for Research on Cancer (IARC) has concluded that there is only “limited” evidence of carcinogenicity of hydrogen peroxide in experimental animals.

It has therefore classified hydrogen peroxide as “unclassifiable as to carcinogenicity in humans”. More...

6.2 How safe are oral hygiene products and toothwhiteners?

The risk of effects of oral hygiene products and toothwhiteners containing hydrogen peroxide on the body as a whole is low, because the substance is rapidly broken down. However, in animals repeatedly exposed to higher doses adverse effects have been observed. In addition, there are concerns about direct, more localised, effects like irritation in the mouth and in the gastrointestinal system after swallowing.

In the European Union, oral hygiene products are regulated by the Cosmetics Directive and they may only be sold freely to consumers if they contain no more than 0.1% hydrogen peroxide.

In the case of toothpastes and mouth rinses the exposure times are short and risks to humans can be assessed by comparing human exposures to the highest exposure at which no harmful effects were observed in any animal studies: 20 mg/kg body weight per day (NOAEL). The ratio between the two is the margin of safety for general effects on the body.

• For toothpastes and mouthrinses containing 0.1% of hydrogen peroxide, the calculated margin of safety of repeated dose toxicity (2500 and 400 respectively) is considered to give sufficient protection. A margin of safety of 2500 means that the calculated exposure of humans using the product is 2500 times lower than the exposure level at which no harmful effects were observed in any animal study.

In the case of tooth whitening products the exposure times are longer. The assessment of the safety of tooth whitening products is based both on calculations of a margin of safety as well as consideration of possible immediate and long-term effects.

• For tooth whitening products containing 6% of hydrogen peroxide, the calculated margin of safety for repeated dose toxicity (100) is on the borderline of that considered to give sufficient protection.
• For tooth whitening products containing more than 6% of hydrogen peroxide, the margin of safety will be below 100, and they are thus not considered safe.

In order to carry out a robust risk assessment there is a need for long-term and independent clinical data and long-term epidemiological studies in order to evaluate possible adverse effects in the mouth linked to the use of tooth whitening products.

Although the majority of the products contain hydrogen peroxide or carbamide peroxide, other chemicals such as sodium percarbonate, sodium perborate, and potassium peroxymonosulphate may be used. The later chemicals are should be assessed and regulated in a similar way as hydrogen peroxide on the basis of hydrogen peroxide or reactive oxygen products released.

SCCP’s  "Guidance document on Epidemiological and clinical studies on Tooth Whitening Products" More...