Mercury compounds, including Thiomersal (INCI: Thiomersal, CAS No. 54-64-8) and Phenylmercuric salts (including borate) (CAS No. 62-38-4 / 94-43-9), are listed in Annex V of the EU Cosmetics Regulation (EC) No. 1223/2009 as restricted preservatives. They are regulated under entries 16 and 17, and may only be used in eye-area cosmetics, with a maximum allowed concentration of 0.007% (expressed as mercury). Products containing these substances must also carry the required warning statements.
Given the inherent toxicity of mercury and its compounds, their potential risks to human health remain significant. Although the use of Thiomersal and Phenylmercuric salts (including borate) is strictly limited, ongoing safety assessments are necessary to ensure consumer protection. In this context, the European Commission has requested the SCCS (Scientific Committee on Consumer Safety) to conduct a new safety evaluation on the use of these substances as preservatives in cosmetic products.
On 19 November 2025, the SCCS released the draft Scientific Opinion SCCS/1686/25 on the safety of Thiomersal and Phenylmercuric salts used as cosmetic preservatives. The draft concludes that, taking into account the most sensitive toxicological endpoint—kidney toxicity—the calculated Margin of Safety (MoS) is below 100, and genotoxicity concerns remain unresolved. Therefore, under the current permitted limits, the use of Thiomersal and Phenylmercuric salts (including borate) in eye cosmetics cannot be considered safe. The SCCS also notes that human health risks from non-cosmetic sources of mercury exposure are increasing, which further heightens overall concern.
The draft opinion is currently open for public consultation, with the feedback deadline set for 21 January 2026.
from SGS China
