Subject: Insolubility of Silica and its Classification as Nanomaterial
Silica (CAS 7631-86-9) is a ubiquitous cosmetic ingredient found in all kind of products and more particularly in make-up. More than 1,500 cosmetics notified on the CPNP by BIORIUS contain Silica.
The size distribution of Silica particles can vary quite a lot from a raw material to another. Until now this aspect was not controlled since the Silica industry (and for instance, ASASP, the Association of Synthetic Amorphous Silica Producers) unanimously considers that Silica is water-soluble. This position was important because a ‘Nanomaterial’ is defined by the European Cosmetics Regulation (EC No 1223/2009) as “an insoluble or biopersistant and intentionally manufactured material with one or more external dimensions, or an internal structure, on the scale from 1 to 100 nm”.
Unfortunately, in a Scientific Opinion published during summer, the SCCS strongly contradicts the position of the industry on the basis of a different definition of what “soluble” means. According to the SCCS, Silica is insoluble and therefore may qualify as ‘nanomaterial’ if more than 50 % of its particles has a size below 100 nanometers. Although ASASP expressed its disagreement with such an interpretation, the Competent Authorities consider that the position of the SCCS is the official one and must be followed. This view was communicated to BIORIUS by the Belgian Ministry of Health.
In practice, this means that particle size distribution should be required to suppliers of Silica and the preferred analytical method should be electronic microscopy or a method providing a distribution curve by number. Alternatively the classification by Volume Specific Surface Area (VSSA) is appropriate.
In case a quality of Silica qualifies as a nanomaterial on the basis of its particle size, two regulatory consequences apply:
- As required by Article 19 of the European Cosmetics Regulation, the “nano” status of this Silica should be highlighted in the list of ingredients to be labeled on the cosmetic product. The traditional way to do it is to label “SILICA [NANO]”.
- As required by Article 16 of the European Cosmetics Regulation, cosmetic products containing this nano-form of Silica will be subject to a specific notification to the European Commission by the Responsible Person 6 months prior to being placed on the market. This specific notification is a complicated exercise that will come with additional expenses for the cosmetic brand.
For these two reasons (and more specifically for the second one), BIORIUS strongly recommends that only non-nano qualities of Silica be used in the future. Cosmetic brands should contact their Silica suppliers and investigate with them if an action needs to be taken.
We hope that this letter will be of help and stay at your disposal for any questions related to this topic. Should you have any question, please, feel free to contact your dedicated Account Manager.
Dr. Fred Lebreux
 A VSSA below 6 m²/cm³ is characteristic of normal materials and a VSSA above 60 m²/cm³ is always considered to be a nanomaterial (intermediate values need to be analyzed on a case-by-case basis).