UK cosmetics 2026: the substances prohibited by SI 2026/23
The Cosmetic Products Regulation (EC) No 1223/2009 (Restriction of Chemical Substances) (Amendment and Transitional Provisions) Regulations 2026, SI 2026/23, prohibit a UV filter and a set of CMR substances on the Great Britain market and tighten the formaldehyde-releaser warning. This is a working reference to what the instrument does, the dates, and the full list.
What the instrument does
SI 2026/23 was made on 12 January 2026 and laid before Parliament on 15 January 2026, under Articles 31(1)(b), 31(1)(f) and 32(1) of the assimilated UK Cosmetic Regulation. It extends to England, Wales and Scotland. It makes four operative changes:
- Prohibits 4-MBC. 3-(4'-methylbenzylidene)-camphor is added to Annex 2 (prohibited substances) as entry 1744 and removed from Annex 6 (permitted UV filters), following a Scientific Advisory Group on Chemical Safety assessment that could not conclude it was safe.
- Prohibits 16 CMR substances. The substances in the Schedule, entries 1745 to 1760, classified as carcinogenic, mutagenic or toxic for reproduction (category 1B or 2) under the GB CLP Regulation, are added to Annex 2.
- Tightens the formaldehyde-releaser warning. In the preamble to Annex 5 (permitted preservatives), the word "contains" is replaced by "releases" and the threshold "0,05" by "0.001", so the warning "releases formaldehyde" is now triggered at 0.001 per cent (10 ppm) of free formaldehyde rather than 0.05 per cent.
- Removes 4-MBC from the UV filter list. The Annex 6 entry at reference number 18 is omitted.
Dates and transitional provisions
The instrument commences in two stages, and each carries a sell-through period for stock already on the market:
- 15 July 2026: the 4-MBC prohibition and the formaldehyde labelling change take effect. A product placed on the GB market before that date may continue to be made available until the end of 14 January 2027, provided it was labelled to the previous Annex 5 wording.
- 15 August 2026: regulation 2(3) takes effect, the date from which the 16 CMR substances are prohibited. A product placed on the market before that date may continue to be made available until the end of 14 February 2027.
Which of these matter for a cosmetic
Most of the Schedule substances are industrial chemicals or agrochemicals (insecticides, herbicides, fungicides, organotin stabilisers, flame retardants) that would not normally be formulated into a cosmetic. They are prohibited here as a direct consequence of their CMR classification under GB CLP, and the prohibition is absolute, extending to their presence as impurities, so the practical task for most brands is to confirm with suppliers that none appears as a contaminant. The two entries that warrant direct attention are 4-MBC, a UV filter that has been in genuine cosmetic use, and TPO (entry 1745), a photoinitiator used in UV-cured gel nail products. Brands in sun care and professional nail categories should treat these as reformulation items.
The full list of prohibited substances
Entry numbers, names, CAS and EC numbers are as set out in SI 2026/23. The "context" column is our note on what each substance is, not part of the instrument.
| Annex 2 entry | Substance | CAS | EC | Context |
|---|---|---|---|---|
| 1744 | 3-(4'-Methylbenzylidene)-camphor (4-MBC, enzacamene) | 38102-62-4 / 36861-47-9 | 253-242-6 | UV filter, moved from Annex 6. The substance here most likely to be in a cosmetic. |
| 1745 | Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) | 75980-60-8 | 278-355-8 | Photoinitiator used in UV-cured gel nail products. Reproductive 1B. |
| 1746 | Clothianidin (ISO) | 210880-92-5 | 433-460-1 | Neonicotinoid insecticide |
| 1747 | Dimethyl propylphosphonate | 18755-43-6 | 242-555-3 | Industrial flame-retardant intermediate |
| 1748 | Dibutyltin maleate | 78-04-6 | 201-077-5 | Organotin stabiliser |
| 1749 | Dibutyltin oxide | 818-08-6 | 212-449-1 | Organotin compound |
| 1750 | Tetrabromobisphenol-A | 79-94-7 | 201-236-9 | Brominated flame retardant |
| 1751 | 1,4-Benzenediamine, N,N'-mixed phenyl and tolyl derivatives | 68953-84-4 | 273-227-8 | Rubber antioxidant (PPD family) |
| 1752 | 4-Methylimidazole | 822-36-6 | 212-497-3 | Industrial intermediate |
| 1753 | Acetone oxime | 127-06-0 | 204-820-1 | Anti-skinning agent |
| 1754 | Benthiavalicarb-isopropyl (ISO) | 177406-68-7 | not listed | Fungicide |
| 1755 | 2,3-Epoxypropyl neodecanoate | 26761-45-5 | 247-979-2 | Epoxy ester intermediate |
| 1756 | Multi-walled carbon tubes (defined geometry, including MWCNT) | not listed | not listed | Carbon nanotubes |
| 1757 | 7-Oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptan-3-carboxylate | 2386-87-0 | 219-207-4 | Cycloaliphatic diepoxide |
| 1758 | 2-(Dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(morpholin-4-yl)phenyl]butan-1-one | 119344-86-4 | 438-340-0 | Photoinitiator |
| 1759 | S-Metolachlor (ISO) | 87392-12-9 | not listed | Herbicide |
| 1760 | Trimethyl borate | 121-43-7 | 204-468-9 | Boron ester |
Position as at June 2026. SI 2026/23 is made law, with the application dates above. A separate follow-on instrument, the (No. 2) Regulations 2026, adds further prohibited substances and an Annex 3 restriction on hexyl salicylate on its own timeline. As with any live framework, confirm the current OPSS position before relying on these dates.
How this fits the wider picture
These are Great Britain obligations under the assimilated UK Regulation, set independently of the EU, and they are one half of a market that is now diverging in both directions: the EU has expanded its fragrance allergen labelling under Regulation (EU) 2023/1545, which GB has not adopted, while GB has moved first on this set of substance prohibitions. For a brand selling into both, the formulation has to be checked against each set of annexes separately. We carry out that check as part of a UK CPSR and the Responsible Person service, and the labelling consequences, including the formaldehyde warning, are covered in our labelling requirements guide. For the EU allergen position, see the EU fragrance allergen reference.