SCCS Opinion on “Silica, Hydrated Silica, and Silica Surface Modified with Alkyl Silylates (nano form)”

Silica, Hydrated Silica, and Silica Surface Modified with Alkyl Silylates (nano form)

Silica, Hydrated Silica, Silica Silylate and Silica Dimethyl Silylate nano forms are used in many leave-on and rinse-off cosmetic products, including skin, hair and nail products. However, these ingredients are not regulated in the Cosmetic Regulation (EC) No 1223/2009, although they are reported in the CosIng Database with several cosmetics functions.

Silica in nano forms raises concerns because of its high skin penetration potential and its potentially high exposure in many types of products. However, generally, synthetic amorphous silica (SAS) has a long history of safe use as cosmetic ingredient. Additionally, SAS is widely used in pharmaceuticals and foods.

Safety evaluation

The Commission received 172 notifications for Silica, Hydrated Silica, Silica Silylate and Silica Dimethyl silylate in nano form in cosmetic products. SCCS was requested to provide a safety assessment of the four types of nano silica. 28 SAS materials were categorized in four categories: hydrophilic precipitated silica, hydrophilic pyrogenic silica, hydrophobic pyrogenic silica, and colloidal silica materials, were assessed. In the toxicological evaluation the following were taken under consideration: acute toxicity, local toxicity, dermal absorption, mutagenicity, carcinogenicity, reproductive toxicity, toxicokinetics, and repeated dose toxicity.

SCCS used a case-by-case approach to assess each material safety. The evaluation has shown large differences in the experimental values for some of the physicochemical properties, even within one SAS category.

Conclusion

The SCCS did not draw any firm decision either for or against the safety of any of the individual SAS materials – as well as any of the SAS categories that are intended for use in cosmetic products – due to the inadequate and insufficient evidence provided in the submission and the available scientific literature.

To enable future evaluations of the SAS materials, the Committee drew attention to the importance of receiving more detailed analysis, including:

  • adequate dermal absorption data;
  • adequate physicochemical characterisation for neat (i.e. not surface treated) SAS materials;
  • clear identification of the surface particles for surface modified (hydrophobic) SAS materials;
  • the penetration potential of the nanoparticles assessed in ethanolic media for the SAS materials intended for use in ethanolic formulation;
  • additional data on secondary particle size for the SAS materials produced by a non-pyrogenic route (e.g., precipitation);
  • data on particle size distribution based on a method other than DLS;

 

What to do?

As no conclusion regarding the safety of the SAS could has been made SCCS advises to follow the SCCS Notes of Guidance (SCCS/1501/12), the SCCS Guidance on Risk Assessment of Nanomaterials (SCCS/1484/12), and the SCCS Memorandum on Data Quality (SCCS/1524/13) for any future evaluation of the SAS materials.

For the manufacturers to be certain that the ingredients are considered safe/ allowed to be used in the cosmetic products placed on the European Union territory it is advised to contact the Responsible Person and to ask for advice on the formulations before deciding launching the sales in Europe.

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