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4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products

CAS 2050-34-2 · 100/100 · High conf.

Concern score

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

4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products in plain language

What it is

On cosmetic ingredient lists it appears as “Acid orange 6”.

Also known as Acid orange 6 · CI 14270 · Acid orange 6 free acid · C.I. Acid Orange 6 parent · 2,4-DIHYDROXYAZOBENZENE-4'-SULFONIC acid · Benzenesulfonic acid, 4-((2,4-DIHYDROXYPHENYL)AZO)-

Show all 13 names

Benzenesulfonic acid, P-((2,4-DIHYDROXYPHENYL)AZO)- · Benzenesulfonic acid, p-((dihydroxyphenyl)azo)- · C.I. acid orange 6 (free acid) · 2,4-Dihydroxyazobenzene-4′-sulfonic acid · 4-((2,4-DIHYDROXYPHENYL)AZO)BENZENESULPHONIC acid · 4-(2,4-Dihydroxyphenylazo)benzenesulfonic acid · 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid

What it does

We don't have a plain-language description for 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products yet.

Is it a concern?
Critical concern: no hazard classifications on record. It is banned in EU cosmetics.

Why it's flagged

4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products is prohibited in cosmetic products under Annex II of the EU Cosmetics Regulation (EC) 1223/2009.

RestrictedEU EC — banned

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 II — prohibited
  • EU prohibited in cosmetics

Recorded in these product areas

  • Found in consumer products
  • Industrial

  • EUEC

    Annex II of EU Cosmetics Regulation (EC) 1223/2009: substances prohibited in cosmetic products.

    banned
    View source →
  • EUCosIngActiveCosmetics Regulation annex II / ref 1330.
    • Cosmetics Regulation annex II / ref 1330.Source →
  • USEPAcommercial use observedEPA CPDat observed this chemical in 0 composition records across product categories including unclassified products.
    • EPA CPDat observed this chemical in 0 composition records across product categories including unclassified products.Source →
  • USFDAlisted in openFDA substanceopenFDA substance registry classifies this ingredient as chemical.
    • openFDA substance registry classifies this ingredient as chemical.Source →

Expert safety opinions

No expert opinion on file for 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products. 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 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products yet. This record is compiled from the published data sources below — registries and regulatory listings, not study findings.

6 data sources

Where this comes from

  • CosIng

    regulatory · updated 2026-09-23

    Open →

  • EU CosIng Cosmetics Regulation Annexes

    regulatory · updated 2020-08-13

    Open →

  • EPA Chemical and Products Database

    exposure · updated 2020-02-13

    Open →

  • EPA DSSTox Identifiers

    chemistry · updated 2025-12-29

    Open →

  • FDA GSRS UNII

    registry · updated 2026-02-26

    Open →

  • openFDA Substance

    registry · updated 2026-05-24

    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.

Where it has been recorded

How often EPA CPDat has listed 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products in a product composition. These are source records, not Greenveil catalog products.

Named organisations

1

See products using 4-(2,4-Dihydroxyphenylazo)benzensulphonic acid (CAS 2050-34-2; EINECS 218-087-0) and its sodium salt (Acid Orange 6; CI 14270) (CAS 547-57-9; EINECS 208-924-8) when used as substance in hair dye products →