Formaldehyde-Releasing Preservative (FRP)
Definition
A preservative that slowly releases formaldehyde as its antimicrobial active ingredient. The five principal FRPs in cosmetics are quaternium-15, DMDM hydantoin, imidazolidinyl urea, diazolidinyl urea, and bronopol. Permitted in the EU at maximum 0.2% free formaldehyde (Annex V); mandatory label declaration above 0.05% free formaldehyde.
- Class
- Antimicrobial preservative
- EU limit
- Max 0.2% free formaldehyde (Annex V)
- Label trigger
- Mandatory declaration above 0.05% free formaldehyde
- Common examples
- Quaternium-15, DMDM hydantoin, bronopol
- Concern
- Contact dermatitis and formaldehyde sensitisation
Common questions
Why do regulators cap the free formaldehyde level rather than banning FRPs outright?+
FRPs are effective, low-cost antimicrobials, and the release rate can be controlled so free formaldehyde stays below levels that trigger most sensitised reactions. A cap plus mandatory labelling lets allergic consumers avoid the product while allowing everyone else continued access to an effective preservative system.
How is free formaldehyde measured in a finished cosmetic for compliance testing?+
Laboratories commonly use a derivatisation method, reacting released formaldehyde with a reagent such as acetylacetone or 2,4-dinitrophenylhydrazine, then quantifying the coloured or UV-active product by spectrophotometry or HPLC, rather than measuring the intact FRP molecule itself.
Can a product be formaldehyde-free but still contain an FRP?+
No. If an FRP is present, some formaldehyde release is inherent to how it works as a preservative. A genuinely formaldehyde-free product must use a different preservative class entirely, such as an isothiazolinone, organic acid, or phenoxyethanol system.
Related terms
- Ammoniated Mercury
- A mercury-ammonia complex (mercuric chloride-ammonia, HgNH2Cl) historically used as a skin-lightening active ingredient. Inhibits melanogenesis by binding to tyrosinase's active-site cysteine. Causes...
- EU Regulation 1223/2009
- The EU Cosmetics Regulation: the primary legal framework governing cosmetics marketed in the EU. Annex II (prohibited substances) lists lead (Entry 209),...
- Galena (PbS)
- Lead(II) sulfide: the principal ore of lead, a grey-black metallic mineral used as the traditional pigment in kohl eye cosmetics for thousands...
- Kohl (Kajal, Surma, Al-Kohl)
- A dark powder applied to the eyes as a cosmetic in South Asian and Middle Eastern cultural traditions. Traditional mineral kohl is...
- MoCRA 2022
- Modernization of Cosmetics Regulation Act 2022 (US), signed into law December 2022. Requires cosmetic-facility registration with FDA, product listing, safety substantiation, adverse-event...
- Nash Reagent Method
- The EU reference colorimetric method for free formaldehyde in cosmetics: formaldehyde reacts with ammonium acetate and acetylacetone to produce the yellow 3,5-diacetyl-1,4-dihydrolutidine...
- RAPEX / Safety Gate
- The EU rapid alert system for dangerous non-food consumer products, including cosmetics. Analogous to RASFF for food. Member states notify dangerous products;...
- Rhodamine B
- A xanthene dye (C28H31ClN2O3, MW 479.0) with brilliant pink fluorescence, listed on the EU REACH SVHC candidate list as a suspected carcinogen...
- Tyrosinase Inhibition
- The mechanism by which mercury compounds and some other skin-lightening agents achieve depigmentation: mercury binds to the sulphydryl (cysteine) group at the...