Bisoctrizole on your skin: a safety profile

What is bisoctrizole?

The IUPAC name is 2,4-bis(1,1-dimethylethyl)-6-(5-chloro-2H-benzotriazol-2-yl)phenol.

Also known as: 2,4-bis(1,1-dimethylethyl)-6-(5-chloro-2H-benzotriazol-2-yl)phenol, Tinosorb M, MBBT, 2,4-bis(tert-butyl)-6-(5-chloro-2H-benzotriazol-2-yl)phenol.

IUPAC name

2,4-bis(1,1-dimethylethyl)-6-(5-chloro-2H-benzotriazol-2-yl)phenol

CAS number

103597-45-1

Molecular formula

C31H33N3O3

Molecular weight

495.61 g/mol

SMILES

C(C(C(=O)O)N)SC(=CCl)Cl

PubChem CID

6433207

Regulatory consensus

2 regulatory and scientific bodies have classified Bisoctrizole. The classifications differ — that's the data.

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter bisoctrizole

• premium_sunscreen
• water_resistant_sunscreen
• facial_sunscreen
• sports_sunscreen

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Bisoctrizole:

• Mineral UV filters (zinc oxide, titanium dioxide) — no systemic absorption
  Trade-offs: Alternative approach; specific tradeoffs depend on application context, scale, and regulatory requirements. Full hazard assessment of alternative recommended before adoption to avoid regrettable substitution.
  Relative cost: 1.2-2×
• UPF-rated clothing and physical sun protection
  Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.
  Relative cost: 1.2-2×

Frequently asked questions