The use of formaldehyde in cosmetics

Formaldehyde is classified as a carcinogen category 1B and as a mutagen category 2 under CLP Regulation (EC) No 1272/2008. This is a reclassification, which was adopted on 17 December 2013 and applied from 1st April 2015.

Formaldehyde and formaldehyde-releasing ingredients

Formaldehyde is a colourless gas with a strong smell. It is quickly broken down in the air, usually within hours, and it is easily dissolved in water. It is commonly used in many industries, including the pharmaceutical and cosmetic industry, as well as for production of building materials, household products etc.

Formaldehyde is used as the active ingredient in nail hardening products. It can cross-link (bind) to keratin, thus hardening the nail plate. According to the industry of nail hardening products, there are no good alternatives to formaldehyde. Many nail hardening products contain formalin, which is formaldehyde dissolved in water.

Formaldehyde-releasing ingredients (eg. Imidazolidinyl Urea, Diazolidinyl Urea, DMDM Hydantoin) are used as preservatives in cosmetic products. Their function is to prevent microbiological growth and spoilage of cosmetics by releasing small amounts of formaldehyde over time.

CMR classification

There are three categories in CMR classification; category 1A, category 1B and category 2. Formaldehyde is classified as a category 1B carcinogen, which means, that it is presumed that this substance has carcinogenic potential for humans. This category classification is mostly based on animal evidence, together with human studies. The classification is based on strength of evidence together with additional considerations of other relevant information.

Formaldehyde is also classified as a mutagen category 2. This category encompasses substances which cause concern for humans as there is a possibility that they may induce heritable mutations in the germ cells of humans. Category 2 classification is based on positive experiments in mammals and/or in vitro experiments, obtained from somatic cell mutagenicity tests in vivo (in mammals) or other in vivo somatic cell genotoxicity tests. The latter must be supported by positive evidence from in vitro mutagenicity assays.

EU Cosmetic legislation strictly regulates the use of substances classified as carcinogenic, mutagenic, or toxic for reproduction (CMR substances). In general, the CMR substances are prohibited for use in cosmetic products, but there are some exceptions to this rule.

Substances classified as CMR substances (category 1A, 1B or 2) may be used in cosmetics if the following conditions are fulfilled:

  • They are compliant with the food safety requirements as defined in Regulation (EC) No 178/2002
  • There are no suitable alternatives available
  • The substance application is made for a product category with a known exposure and for a particular use
  • The Scientific Committee on Consumer Safety (SCCS) has evaluated these substances and found them safe for use in cosmetics, by considering the overall exposure from other sources and by also taking into consideration the vulnerable population groups

There should also be appropriate labelling to avoid misuse of cosmetic products containing these substances, taking into account the possible risks which may arise from the presence of CMR substances.

Exceptions to CMR classification for formaldehyde

If the maximum theoretical concentration of releasable formaldehyde is less than 0.1 %, the classification as a carcinogen does not need to apply. The same goes for classification as a mutagen, but in this case the maximum theoretical concentration must be less than 1 % (according to Regulation No 1272/2008).

Regulatory constraints

Formaldehyde in nail hardening products

According to the EU Cosmetic Regulation No 1223/2009 (EC), the maximum concentration of formaldehyde in nail hardening products is 5 % (as formaldehyde in ready for use preparation). This is for use other than preserving the cosmetic product, which has to be apparent from the product presentation. Mentioned products need to have warnings ‘’contains formaldehyde’’ and ‘’protect cuticles with grease or oil’’ according to Annex III of Regulation No 1223/2009 (EC).

Formaldehyde as a preservative

Annex V of Regulation No 1223/2009 (EC) states, that all finished products which contain formaldehyde or formaldehyde releasing substances must be labelled with the warning ‘’contains formaldehyde’’, if the concentration of formaldehyde exceeds 0.05 %.


Formaldehyde is a known skin sensitizer. Available data has shown that a threshold concentration for sensitization induction for formaldehyde is less than 5 %, but there were some positive responses already at 1 % formaldehyde. On the other hand, concentration, which can cause elicitation in already sensitized individuals, has been estimated to be above 0.006 %.

There is also a potential risk of inhalation of formaldehyde, due to volatilisation from nail hardeners. According to World Health Organisation (WHO), a value of 100 µg/m3 (0.0815 ppm) is considered a safe indoor air level. This guideline should not be exceeded at any 30-min period during a day.

The SCCS has assessed only the safety of the use of formaldehyde in nail hardeners (Opinion on the safety of the use of formaldehyde in nail hardeners, adopted on 7 November 2014). They have concluded that the maximum concentration of 2.2 % can be used safely to harden nails. Due to some concerns raised about sensitisation potential of formaldehyde in nail hardeners, the SCCS has advised careful usage of nail hardeners. They have also advised that in order to reduce inhalation exposure time to formaldehyde, the room in which the nail hardening cosmetic products are being applied, should be ventilated. Risks for professionals, who are frequently exposed to formaldehyde, have not been assessed in the SCCS opinion, thus the safety concern remains.

If you need any help regarding this topic or you have any other regulatory concerns, please contact CE.way Regulatory Consultants. We’re happy to help!