Carbon monoxide
Carbon monoxide is listed in Annex II as a prohibited substance for cosmetic products placed on the EU market.
Chemical identity and properties

Carbon Monoxide
Carbon monoxide is a one-carbon compound in which the carbon is joined only to a single oxygen. It is a colourless, odourless, tasteless, toxic gas. It has a role as a metabolite, a mitochondrial respiratory-chain inhibitor, a neurotransmitter, a vasodilator agent, an EC 1.9.3.1 (cytochrome c oxidase) inhibitor, a P450 inhibitor, a probe, a neurotoxin, a ligand, a biomarker, a signalling molecule, a mouse metabolite and a human metabolite. It is a gas molecular entity, a carbon oxide and a one-carbon compound. It is a conjugate base of a carbon monoxide(1+). — ChEBI
- IUPAC name
- carbon monoxide
- Molecular formula
- CO
- Molecular weight
- 28.010 g/mol
- Exact mass
- 27.994914619 Da
- XLogP3
- 0.7
- Topological polar surface area
- 1.0 Ų
- Hydrogen-bond donors
- 0
- Hydrogen-bond acceptors
- 1
- Covalent units
- 1
- Defined stereocentres
- 0
Also known as
16 more reported names
External database identifiers
- ChEBI:CHEBI:17245
- ChEMBL:CHEMBL1231840
- EPA DTXSID:DTXSID5027273
- PubMed:41205789
- PubMed:39504919
- PubMed:37860845
- PubMed:37141245
- PubMed:36481359
- PubMed:36272593
- PubMed:35999615
- PubMed:35287715
- PubMed:34774656
- PubMed:34533065
- PubMed:34032369
- PubMed:33603036
Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.
Record details
Chemical name
Carbon monoxide
Regulatory information
SCCS opinions
- Opinion concerning Chemical Ingredients in Cosmetic Products classified as Carcinogenic, Mutagenic or Toxic to Reproduction according to the Chemicals Directive 67/548/EECC
- Opinion concerning Chemical Ingredients in Cosmetic Products classified as Carcinogenic, Mutagenic or Toxic to Reproduction according to the Chemicals Directive 67/548/EEC
CMR
| Category | Carcinogenic | Mutagenic | Reprotoxic |
|---|---|---|---|
| Cat. 1A | — | — | ✓ |
Key data
Related records for Carbon monoxide
Direct matches are limited for this record, so nearby entries from Annex II are shown as well.
Buta-1,3-diene, see also entries 464-611
Nickel (II) sulfide [1]; nickel sulfide [2]; millerite[3]
Isobutane, if it contains = >0,1% w/w Butadiene
Butane, if it contains = >0,1 % w/w Butadiene
Trinickel disulfide; nickel subsulfied [1]; heazlewoodite [2]
Gases (petroleum), C3-4, if they contain > 0.1% w/w Butadiene
Tail gas (petroleum), catalytic cracked distillate and catalytic cracked naphtha fractionation abso…
Tail gas (petroleum), catalytic polymn. naphtha fractionation stabilizer, if it contains > 0.1 % w/…
What Annex II means for Carbon monoxide
Carbon monoxide is listed as a prohibited substance under Annex II of EU Cosmetics Regulation 1223/2009 and must not be intentionally added. Article 17 separately addresses unintended small quantities that are technically unavoidable under good manufacturing practice and compatible with the Article 3 safety requirement.
Formulators must screen their ingredients and raw materials to ensure none contain this substance. Suppliers should provide documentation confirming absence when requested.
The page also surfaces 12 related annex records with overlapping identifiers, annex logic or naming patterns.
Compliance checklist
- Verify this substance is absent from all raw materials and finished formulations.
- Request absence confirmation or CoA from raw material suppliers.
- Document the screening result in the Product Information File (PIF).
- This substance has CMR classification. Review the CMR table above and verify current Annex II/III status before use.
Frequently asked questions
Source note for Annex II record Carbon monoxide
This page summarizes one Annex II record for Carbon monoxide from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.
Use this record page to review Annex II conditions for Carbon monoxide, but confirm any final regulatory decision against the current official annex wording and source files.
Tools & next steps
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