What is it?
Silicon dioxide, the compound that makes up quartz and sand, here in a non-crystalline (amorphous) form. The silica used in cosmetics is mostly made synthetically as a fine, fluffy white powder. It absorbs oil and moisture, adds bulk and opacity to powders and foundations, thickens liquids, keeps powders flowing freely and acts as a mild abrasive in toothpaste. It is also a food additive (E551) and an inactive ingredient in medicines.
Key information
- The CIR Expert Panel concluded in 2019 that synthetically manufactured amorphous silica is safe as used in cosmetics when formulated to be non-irritating.
- The lung disease and cancer linked to silica come from breathing crystalline silica dust at work, a different material from cosmetic silica.
- The European Food Safety Authority found in 2024 that silicon dioxide as a food additive raises no safety concern for any age group at current uses.
- In 2015 EU scientists could not conclude whether nano forms of silica are safe in cosmetics, citing insufficient data.
More information
Synthetic amorphous silica comes in fumed (also called pyrogenic), precipitated, gel and colloidal forms. Its tiny primary particles join into larger aggregates and clumps, and the CIR noted that particles aggregate further once mixed into a product.
The Cosmetic Ingredient Review (CIR) Expert Panel concluded in its 2019 amended report that synthetically manufactured amorphous silica is safe as used when formulated to be non-irritating. It was reported in 8,222 products, at up to 82 percent in face products. It was not a sensitizer in human patch tests, and the Panel found no inhalation risk under cosmetic use, since lung effects in animals appeared at far higher exposures. The International Agency for Research on Cancer considers amorphous silica not classifiable as to its carcinogenicity. In 2024 the European Food Safety Authority concluded that silicon dioxide (E551) raises no safety concern for any age group at current food uses.
Warnings about silica and lung disease refer to crystalline silica. According to OSHA, breathing fine crystalline silica dust at work, for example when cutting stone or concrete, can cause silicosis, lung cancer and kidney disease. The CIR stressed that crystalline silica is not toxicologically similar to synthetic amorphous silica and limited its conclusion to synthetic, not mined, silica.
Reality check: the silica in cosmetics is not the crystalline dust that harms workers. The open question is nano silica: in 2015 the EU's Scientific Committee on Consumer Safety found the data too weak to conclude either way. In the EU, nano ingredients must be labeled with “nano” in brackets after the name. See also our profile for titanium dioxide nanoparticles.
Sources: Cosmetic Ingredient Review: Amended safety assessment of synthetically-manufactured amorphous silica and hydrated silica as used in cosmetics (2019); European Commission SCCS: Revision of the opinion on silica, hydrated silica, and silica surface modified with alkyl silylates (nano form) (2015); EFSA Journal (2024): Re-evaluation of silicon dioxide (E 551) in foods for infants below 16 weeks of age and follow-up for all population groups; OSHA: Silica, crystalline
