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2-chloro-4-[(1E)-(1-methyl-1H-pyrazol-5-yl)diazenyl]-phenol

CAS 1184721-10-5 · 70/100 · High conf.

Concern score

70/100High concern based on regulatory listings.
High confidence

2-chloro-4-[(1E)-(1-methyl-1H-pyrazol-5-yl)diazenyl]-phenol in plain language

What it is

On cosmetic ingredient lists it appears as “Hc yellow no. 16”.

Also known as Hc yellow no. 16 · HC Yellow No 16

What it does

Used in cosmetics as a hair dye.

  • Hair dyeing
  • Colourant
Is it a concern?
High concern: no hazard classifications on record. It is restricted in EU cosmetics.

Why it's flagged

2-chloro-4-[(1E)-(1-methyl-1H-pyrazol-5-yl)diazenyl]-phenol is restricted in cosmetic products under Annex III of the EU Cosmetics Regulation (EC) 1223/2009.

RestrictedEU EC — restricted

The score describes this ingredient's chemical identity — its hazard profile from published classifications and regulatory status — not the safety of any product it appears in.

Regulation

Restrictions first, then routine listings from published regulatory sources.

  • EU Annex III — restricted
  • EU restricted in cosmetics

Recorded in these product areas

  • Found in consumer products
  • Industrial
  • EUEC

    Annex III of EU Cosmetics Regulation (EC) 1223/2009: substances which cosmetic products must not contain except subject to the restrictions laid down. Product types: (a) Hair dye substance in oxidative hair dye products (b) Hair dye substance in non-oxidative hair dye products Maximum concentration: (b) 1,5 % Other conditions: For (a): After mixing under oxidative conditions the maximum concentration applied to hair must not exceed 1 %. Conditions of use and warnings: For (a): To be printed on the label: The mixing ratio. “Hair colourants can cause severe allergic reactions. Read and follow instructions. This product is not intended for use on persons under the age of 16. Temporary ‘black henna’ tattoos may increase your risk of allergy. Do not colour your hair if: — you have a rash on your face or sensitive, irritated and damaged scalp, — you have…

    restricted
    View source →
  • EUCosIngActive2 entries
    • Cosmetics Regulation annex III / ref 385.Source →
    • Listed in CosIng inventory for cosmetic use.Source →
  • USEPAcommercial use observedEPA CPDat observed this chemical in 0 composition records across product categories including unclassified products. EPA CPDat classifies this chemical for functional uses including Dye.
    • EPA CPDat observed this chemical in 0 composition records across product categories including unclassified products. EPA CPDat classifies this chemical for functional uses including Dye.Source →

Expert safety opinions

No expert opinion on file for 2-chloro-4-[(1E)-(1-methyl-1H-pyrazol-5-yl)diazenyl]-phenol. These are the independent scientific bodies that assess ingredients like this one; we show an opinion only when a record we hold cites it.

  • SCCS

    EU Scientific Committee on Consumer Safety

    No SCCS opinion on file.

  • CIR

    Cosmetic Ingredient Review (US expert panel)

    No CIR safety assessment on file.

Evidence & sources

No graded research studies for 2-chloro-4-[(1E)-(1-methyl-1H-pyrazol-5-yl)diazenyl]-phenol yet. This record is compiled from the published data sources below — registries and regulatory listings, not study findings.

4 data sources

Where this comes from

  • CosIng

    regulatory · updated 2026-09-23

    Open →
  • EU CosIng Cosmetics Regulation Annexes

    regulatory · updated 2026-05-06

    Open →
  • EPA Chemical and Products Database

    exposure · updated 2019-12-20

    Open →
  • EPA DSSTox Identifiers

    chemistry · updated 2025-12-29

    Open →

Suitability

Context-specific fit derived from published classifications and the current ingredient evidence profile.

Fragrance avoidance

No fragrance-linked caution surfaced in the current profile.

Good fit

This ingredient does not currently read as a fragrance-linked driver in the published evidence and hazard profile.