The Lab
Specimen No. 0162
AvoidSyntheticdyecolorant

Azo Dyes (Carcinogenic Class)

carcinogenic azo dyes · 4-aminoazobenzene · benzidine-based azo dye

Azo dyes constitute 70–80% of textile dyes and can break down into carcinogenic aromatic amines — including benzidine — under conditions mimicked by skin bacteria and perspiration. These amines penetrate the skin and are metabolized by the liver. Carcinogenic azo dyes are banned in the EU; however, over 5% of tested imported products exceed safe limits.

high confidence
Researched April 18, 2026

Concerns

  • Break down into carcinogenic aromatic amines (benzidine, 4-aminoazobenzene) via skin bacteria
  • Amines penetrate the skin and are liver-metabolized — systemic exposure confirmed
  • Banned in EU cosmetics and textiles; non-compliant imports are common
  • Mutagenic in in vitro testing

Regulatory flags

  • EU banned carcinogenic azo dyes in textiles (REACH Annex XVII)
  • Breakdown aromatic amines include IARC Group 1 carcinogens

Commonly found in

Dyed textilesFast fashionColored synthetic clothingLeather goods

Research disclaimer: This rating is based on available peer-reviewed research and regulatory assessments at the time of publication. It is not medical advice. Consult a qualified professional for personal health or skin concerns.

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LabelCleared verdict badge: Azo Dyes (Carcinogenic Class) — Avoid
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