What’s new?
On the 30th of October 2025, the SCCS has published a preliminary scientific advice evaluating the safety of two mercury-based preservatives: Thiomersal (INCI Thimerosal) and Phenylmercuric salts (INCI Phenyl Mercuric Acetate and Phenyl Mercuric Benzoate). This assessment responds to the European Commission’s request to re-evaluate the safety of these preservatives in cosmetic eye products, based on concerns about the health risks associated with mercury.
Mercury and its compounds have been prohibited from use in cosmetics products. However, the Cosmetics Regulation 1223/2009 allows the use of ‘Thiomersal’ and ‘Phenylmercuric salts (including Borate)’ (entries 16 and 17 of Annex V), as preservatives under specific conditions. These mercury compounds are allowed in eye products and with a maximum concentration that does not exceed 0.007% (of mercury), when used alone or in combination.
Thiomersal is an organomercury compound that has historically been used as a preservative in various products, including some cosmetics and pharmaceutical preparations. Phenylmercuric salts represent another class of mercury-containing preservatives.
The SCCS review examined available toxicological data, including dermal absorption, sensitization potential, reproductive toxicity, and systemic effects of these ingredients.
Key findings:
The SCCS concluded that Thiomersal and Phenylmercuric salts are not safe for use as preservatives at concentration levels currently permitted in cosmetic eye products.
The potential risk for human health is also aggravated by exposure to mercuric compounds from sources other than cosmetics.
What now?
The preliminary scientific advice is open for comments until 21 January 2026.
- SCCS will review submitted comments during working group meetings.
- Final Advice is expected following comment evaluation and potential revisions.
