The Lab
Specimen No. 0159
CautionMineralheavy metalmaterial

Antimony Trioxide (Polyester Catalyst)

antimony trioxide · sb2o3 · antimony(iii) oxide

A catalyst used in the manufacturing of polyester fibers. Classified as a possible human carcinogen (IARC Group 2B) in inhaled form. Found in 80–85% of virgin polyester; studies show 0.05–2% can be mobilized into artificial sweat during wear — raising concern for prolonged skin contact with synthetic activewear.

medium confidence
Researched April 18, 2026

Concerns

  • IARC Group 2B possible carcinogen (occupational inhalation)
  • Leaches from polyester fabric under sweat conditions — dermal exposure concern
  • Accumulates in aquatic organisms during textile washing
  • Occupational exposure limits exist for workers in PET manufacturing

Regulatory flags

  • IARC Group 2B possible carcinogen
  • EU restricts in textiles — max 30 mg/kg in fabrics in skin contact

Commonly found in

Polyester clothingActivewearSynthetic underwearFleeceAthletic wear

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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