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Butylene/Ethylene/Styrene Copolymer
Butylene/Ethylene/Styrene Copolymer
A rubbery thickener for oils that holds sticks and balms together with a smooth, cushioned feel.
What it does
A rubbery synthetic polymer that dissolves in oils and waxes.
The evidence, graded
expert consensusUS safety reviewers (2014) assessed 35 polymers made with styrene, which products use mostly to thicken, make a formula opaque or form a film. Given their large size, the reviewers don’t expect them to pass through skin. Styrene, part of all of them, and butadiene are classed as causing cancer, but they found any left over in products would be well below levels of concern. They judged all 35 safe as used.Johnson 2014 · 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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