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On May 21, 2025, the UK's Scientific Advisory Group on Chemical Safety of Non-Food and Non-Medicinal Consumer Products (SAG-CS) issued safety opinions on formaldehyde releasing substances, homosalate, and 4-methylbenzylidene camphor, offering updated guidance grounded in recent scientific evidence to protect consumers.1-3
Opinion on Formaldehyde Releasing Substances
Under UK Regulation (EC) No 1223/2009 (the Cosmetics Regulation), formaldehyde (CAS No. 50-00-0) is prohibited for use in cosmetics, while it may still be present through the use of permitted preservatives that release formaldehyde, such as DMDM hydantoin, imidazolidinyl urea, and methenamine. To thoroughly protect consumers, point 2 of the preamble to the List of Permitted Preservatives requires that cosmetics containing such substances shall bear the warning "contains formaldehyde" when the released formaldehyde exceeds 0.05%. However, emerging evidence suggests that allergic reactions may occur even below this threshold, prompting SAG-CS to review the adequacy of current labelling requirements.
Following two rounds of review in 2022 and 2024, SAG-CS concludes in its current opinion that the existing 0.05% labelling threshold for formaldehyde releasing preservatives is insufficient to ensure consumer safety. Based on the available scientific evidence, the group recommends lowering the threshold to 0.001% (10 ppm) to better safeguard users of both leave-on and rinse-off products.
Opinion on Homosalate
Homosalate (CAS No. 118-56-9) is currently listed in the List of Permitted UV Filters of the Cosmetics Regulation, with a concentration limit of 10%. Due to concerns over its endocrine disrupting potential, the Office for Product Safety and Standards (OPSS) launched a call for data on this substance in April 2022, and requested SAG-CS to evaluate its safety based on dossiers submitted by industry stakeholders.
Based on its assessment, SAG-CS confirms in its latest opinion that homosalate remains safe for use in sunscreen products at concentrations up to 10%.
Opinion on 4-Methylbenzylidene Camphor
At present, 4-methylbenzylidene camphor (4-MBC, CAS No. 38102-62-4 / 36861-47-9) is regulated as a permitted UV filter under the Cosmetics Regulation, subject to a 4% concentration limit. Following its classification by the EU in 2021 as a substance of very high concern due to endocrine disrupting and reproductive effects, OPSS requested further data from the industry and mandated SAG-CS to assess the safety of this substance.
In the absence of industry-submitted data, SAG-CS based its assessment of 4-MBC on publicly available studies and reviews. During the review, the group identified the substance's endocrine disrupting properties, and noted concerns raised regarding its potential genotoxicity. In light of these factors and limited data available, SAG-CS concluded that it could not determine the safety of 4-MBC for use in sunscreens or other cosmetic products.
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