Are teeth-whitening products for personal use safe?

Are teeth-whitening products for personal use safe?

In 2019, the Danish Environmental Protection Agency conducted a marketing screening on the most common teeth-whitening cosmetics available on the market for personal use — trays, pens, and strips. The study did not include toothpaste with whitening properties because they are designed for long-term use, not for time-limited treatment.

The survey considered a total of 25 products supplied by Danish distributors or from other EU or non-EU Countries. In September 2021, the Danish Ministry of Environment published the report of the survey and risk assessment of teeth-whitening products for personal use for a time-limited treatment.

The results raised issues in several respects.

Are teeth-whitening products cosmetics?

According to the Manual of the Working Group on Cosmetic Products on the scope of application of the Cosmetics Regulation (namely, the Cosmetics Borderline Manual), teeth-whitening products can be classified as cosmetics when placed in contact only with the teeth surface.

Conversely, if they are placed inside the tooth, they do not fall under the scope of the EU Cosmetics Regulation.

A teeth-whitening effect can be obtained by chemical or mechanical means or by a combination of both. The physical action consists in the abrasion of the tooth surface to eliminate stains, while the chemical bleaching is achieved using the following substances:

- Hydrogen peroxide and its compounds;

- Chlorite and chlorite-forming compounds

- Sodium bicarbonate;

- Organic and inorganic acids e.g. citric and phosphoric acid.

Out of 25 products analyzed, 14 contained hydrogen peroxide, 8 sodium chlorite, and one sodium perborate, which is prohibited for use in cosmetic formulas (entry 1397 of Annex II to the EU Cosmetics Regulation).

Hydrogen peroxide

The most popular whitening ingredients are Hydrogen peroxide (CAS 7722-84-1) and substances realising hydrogen peroxide: thanks to their oxidizing function, as they generate free radicals making coloured particles smaller thus less visible; hence, teeth appear lighter.

The EU Cosmetics Regulation allows the use of Hydrogen peroxide and other mixtures that release H2O2 in tooth whitening or bleaching products subject to the following restrictions:

- Up to 0,1% in products for personal use;

- Up to 6% in products to be sold only to dental practitioners.

However, in recent years many other substances have been used for their whitening powers; therefore, they require a detailed analysis. This was one of the aims of the study conducted in Denmark.

The risk assessment concluded that whitening ingredients might increase teeth sensitivity, irritate the oral mucous, and damage the enamel. Additionally, dental enamel corrosion can also result from the very high or very low pH of these products.

Sodium chlorite

Sodium chlorite (CAS 7758-19-2) — an inorganic sodium salt — is often used in whitening products for oral hygiene because it dissolves the colored organic pigmentation that has penetrated the tooth. Currently, the EU Cosmetic Regulation does not foresee any limitation on its use.

The Danish survey highlighted that, for products with a concentration of sodium chlorite of 0.09-1%, the calculated MoS values indicate an increased risk of local effects. NaClO2 is corrosive and irritating to mucous membranes and “can cause dissolution of calcium in tooth enamel and change its surface structure and hardness” (Ministry of Environment of Denmark, 2021). Moreover, the risk is higher if sodium chlorite is used in combination with an acid.

Considering the above, the Danish Competent Authority proposed to mandate the Scientific Committee on Consumer Safety to investigate the safety of Sodium chlorite for mouth and teeth products for personal use.

Proof of claims and labeling requirements

According to Article 11 of the EU Cosmetics Regulation, the Responsible Person (RP) must store the Product Information File (PIF) for each cosmetic placed on the EU market. The Competent Authority may access it upon their request. There is proof of the effect claimed among the documents for a complete PIF. The substantiation can be done through:

- Experimental studies;

- Consumer perception tests;

- Scientific literature; or

- A combination of the above.

The Danish Chemical Inspection Service asked the RP of the analyzed cosmetics to provide the documentation proving the claimed whitening effect. The dossier was sent for only 50% of the products and, of these, one-third were evaluated as inadequate.

Moreover, the Danish Competent Authority identified several non-compliances with the labeling requirements – as defined in Article 19 of the EU Cosmetics Regulation and the Statutory Order of the Ministry of the Environment no. 803 of June 21, 2013, on Cosmetic Products. The most common non-conformities were:

- Nominal content, date of minimum durability, precautions for use, and the cosmetic function were not translated into Danish;

- The ingredients were not listed with their Glossary of common ingredient names.

Are you the brand of a teeth-whitening product? Through Obelis, we offer a PIF review service to ensure your Product Information File is compliant with the EU regulatory framework. Contact us today to know more.

References:

- Ministry of Environment of Denmark. (2021). Survey and risk assessment of teeth-whitening products for personal use. Retrieved on 15/12/2021 from https://www2.mst.dk/Udgiv/publications/2021/09/978-87-7038-340-0.pdf

- European Commission. (2020). Borderline products manual on the scope of application of the Cosmetics Regulation (EC) No 1223/2009 (Art. 2(1)(a)). Retrieved on 15/12/2021 from https://ec.europa.eu/growth/sectors/cosmetics/cosmetic-products-specific-topics/borderline-products_nl