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Thiomersal

CAS 54-64-8
12

Safety score · 0–100

Avoid

Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.

Thiomersal is a cosmetic ingredient. Exercise caution due to limited available safety data.

Thiomersal (CAS 54-64-8, also known as thimerosal) is an organomercury compound that was used as a preservative in cosmetic formulations including eye solutions and vaccines. EU Regulation 1223/2009 Annex II prohibits the use of mercury compounds in cosmetic products. The compound carries extensive hazard statements including H300+H310+H330 (fatal if swallowed, in contact with skin, or if inhaled), H360 (may damage fertility or the unborn child), H372 (causes damage to organs through prolonged or repeated exposure), H400/H410 (very toxic to aquatic life), and H317 (may cause allergic skin reaction). Mercury exposure from cosmetics poses significant neurotoxicity risks, particularly to developing fetuses and children.

Known concerns

  • EU Annex II banned - mercury compound
  • Neurotoxicity risk from mercury exposure
  • Reproductive toxicity (H360)
  • Organ toxicity through repeated exposure (H372)
  • Very toxic to aquatic environment (H400/H410)
  • Allergic contact dermatitis

References

EU

EU CosIng database

European Commission cosmetic ingredient registry: regulatory status, restrictions, authorised functions.

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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve, so always read the physical product label and consult a healthcare professional for personal concerns.