What is it?
A natural thickener made by fermentation. The fungus Sclerotium rolfsii, grown on sugars, releases a gum called scleroglucan, which is recovered and purified. Chemically it is a beta-glucan, a chain of glucose units. In creams, lotions, serums and masks it thickens and stabilizes the formula and gives a smooth, gel-like feel. It is also used in some medicines and in industrial fluids.
Key information
- The CIR Expert Panel concluded in 2012 that sclerotium gum is safe as used in cosmetics, where it was reported in 193 products at up to 2 percent.
- It is a very large sugar-based molecule that is not expected to be absorbed through the skin.
- The CIR found no evidence of skin sensitization across the group of microbial gums it reviewed.
More information
Sclerotium gum is an exopolysaccharide, a sugar polymer that the fungus secretes as it grows. Its backbone is a chain of glucose units, with a single glucose branch on every third unit. The fungus is a plant pathogen, but the gum is recovered from the fermentation and purified, and it is used in the food, pharmaceutical and oil industries as well as in cosmetics. Pharmaceutical uses include tablet coatings and eye solutions.
The Cosmetic Ingredient Review (CIR) Expert Panel assessed it with 33 other gums made by microorganisms, including xanthan gum and beta-glucan, and concluded in 2012 that they are safe in the present practices of use and concentration. Sclerotium gum was reported in 193 cosmetic products at up to 2 percent. The Panel judged these very large molecules unlikely to be absorbed through the skin and found no evidence of skin sensitization in human or animal tests. It also noted that the gums are purified during manufacture, so microbial contamination is not a concern.
Few studies have tested sclerotium gum on its own. The Panel's conclusion relies on data from related gums, which did not cause systemic toxicity when swallowed, were not toxic to reproduction or development, were not genotoxic and were not considered irritants or sensitizers.
On labels it appears as sclerotium gum. Hydrolyzed sclerotium gum, a partly broken-down form, was covered by the same CIR conclusion.
Sources: Cosmetic Ingredient Review: Safety assessment of microbial polysaccharide gums as used in cosmetics (2012); Applied Microbiology and Biotechnology (2011): Scleroglucan, biosynthesis, production and application of a versatile hydrocolloid; Frontiers in Bioengineering and Biotechnology (2021): Efficient production of scleroglucan by Sclerotium rolfsii
