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Bemotrizinol
Bis-Ethylhexyloxyphenol Methoxyphenyl TriazineSPF filter
A broad-spectrum sun filter that, in lab tests, stays stable and helps less stable filters last. Now allowed in US sunscreens.
What it does
It’s a chemical filter that covers both UVA and UVB. In lab tests it kept avobenzone and octinoxate from breaking down in UV light, and products with it held up best of those compared. Those tests used instruments, not skin through a day of wear. It’s standard in Europe, Asia and Australia.
The EU’s ingredient database lists it as a UV filter (filters UV rays) and a light stabilizer (protects the product from light).European Commission, CosIng (© European Union, CC BY 4.0) · uses put in plain words by Drop ↗
The evidence, graded
emergingIn a laboratory study, adding bemotrizinol (Tinosorb S) to sunscreen formulas stopped avobenzone from breaking down under an artificial UV source, more so at higher amounts. The formulas kept their SPF and UVA ratio through doses of up to 30 MED, a measure of UV dose. It protected octinoxate too. The test measured formulas with instruments, not skin in sunlight, and the lead author worked for a drug company.Chatelain 2001 · Photochemistry and photobiology ↗ emergingIn a laboratory study, adding bemotrizinol (Tinosorb S) kept avobenzone and octinoxate from breaking down under an artificial UV source, so the formula’s SPF and UVA ratio held up. The summary reports what happened to the other filters, not a figure for bemotrizinol’s own stability. The test measured formulas with instruments, not protection on skin.Chatelain 2001 · Photochemistry and photobiology ↗ emergingA laboratory study exposed sunscreen formulas with five UV filters to UVA light. Avobenzone and octinoxate were significantly degraded, with around 16% less recovered. By one method, HPLC, all the formulas held up similarly; combining three methods, the authors suggest formulas containing bemotrizinol were the most photostable. Adding the antioxidants resveratrol and beta-carotene made avobenzone more stable. Nothing was tested on skin.Freitas 2015 · European journal of pharmaceutical sciences ↗ emergingIn laboratory work by researchers at BASF, avobenzone and octinoxate, two filters that break down under UV light, were steadied by octocrylene or bemotrizinol in the same sunscreen. Two mechanisms can do it: the added filter absorbing more light, or a transfer of energy that quenches the fragile filter. Both may apply; for octinoxate with bemotrizinol, quenching appeared to be the main one.Herzog 2020 · Photochemical & photobiological sciences ↗ Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
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