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Polyurethane-34
Polyurethane-34
A polymer that holds a product together.
What it does
It’s a polyurethane, a large plastic-like polymer. It’s there to hold a makeup formula together, not to change your skin.
The evidence, graded
expert consensusUS safety reviewers (2017) judged 66 polyurethanes safe as used, polyurethane-34 among them. These are very large molecules that won’t get through the outer layer of skin, and tests raised no concern that they irritate skin or eyes. Polyurethane-34 is listed as a binder and was used at up to 2.9% in lipsticks. Some are supplied mixed with other ingredients that can include allergy triggers, such as the preservative methylisothiazolinone (MI), so the reviewers told makers to keep those low.Becker 2017 · Cosmetic Ingredient Review ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
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