Carrageenan

What it is

Carrageenan is extracted from red seaweeds such as Irish moss and comes in kappa, iota and lambda types that gel to different degrees. It is a long-established food and cosmetic thickener that also forms soft films, so it turns up in jelly masks, sheet-mask essences and sleeping packs. In cosmetics its role is purely textural.

What it does well

• Gives a cushioned, slippery texture and helps a mask stay in place

  Its gelling and suspending behaviour is thoroughly characterised. It also forms a light film that slows water evaporation during wear, which is part of why a jelly mask feels hydrating.

  Strong evidence

Worth knowing

• The carrageenan cancer scare does not apply to cosmetic use

  The concern people have read about relates to degraded carrageenan (poligeenan), a deliberately broken-down form that IARC classified Group 2B based on rat feeding studies. Native food- and cosmetic-grade carrageenan was classified Group 3, not classifiable as to carcinogenicity to humans, and the studies in question involved eating it, not applying it to intact skin.

  Matters most toAnyone who has seen carrageenan flagged on ingredient-scoring apps and is worried about it in a face mask.

Where the EU stands

Sources (1)

Every link goes to the original: a journal, a PubMed record or an EU document.

1. [1]
   Carrageenan (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 31; Supplement 7)

   IARC Monographs (WHO / IPCS INCHEM) · 1983

   IARC classified degraded carrageenan as Group 2B (possibly carcinogenic to humans) on the basis of rat feeding studies, while native undegraded carrageenan - the form used in food and cosmetics - was placed in Group 3, not classifiable.