Figure 2. Differences among the EU recomendation for a definition of nanomaterials and the EU definition for nanomaterials in cosmetics.

In the European Union, if a product contains a material which falls under the definition depicted in Figure 2, further provisions need to be provided regarding notifications, safety assessment and labelling.

Besides the EU recommendation and the Cosmetic product definition, different EU countries have their own definitions (Table 1).

Table 1. Comparative overview of how selected European countries define 'nanomaterial' in national legislation or regulatory practice. While many definitions stem from the European Commission Recommendation (2011 or 2022), differences remain in interpretation and implementation.

The European Union’s Cosmetic Products Regulation (CPR) is currently undergoing a comprehensive evaluation what is called a “fitness check” of the CPR to assess whether the Regulation is still fit for purpose in the current European changing environment. Nanomaterials remain a significant area of attention in these ongoing updates.

The revision is not emerging in a vacuum. Over the past few years, the legislative landscape has been increasingly shaped by initiatives such as the European Green Deal (7), the Chemicals Strategy for Sustainability (8), and broader political goals like decarbonisation and digital transformation.

However, updating the definition alone is not sufficient. Industry stakeholders stress the need for a clear transition mechanism to manage positive lists of nanomaterials permitted in cosmetics. Without this, sudden regulatory shifts could disrupt the market, especially for existing products. A targeted amendment of the CPR would allow alignment with science and international standards while avoiding major disruptions for manufacturers and importer.

The timeline for the revision starts with the results of the evaluation expected to be published by mid-2026, followed by an Inception Impact Assessment by the end of that year. A legislative proposal for revising the CPR is anticipated by the end of 2027, with the legislative procedure potentially concluding in 2028. This suggests that a revised CPR could be published in early 2029 (9).

Characterising nanomaterials under the EU 2022 definition presents several technical challenges, especially regarding particle size, shape, and structure. Nanoparticles are often irregular, existing as single particles, aggregates, or agglomerates, raising questions about which dimensions to measure. The EU definition relies on direct physical measurements (e.g., Feret diameter, maximum inscribed circle) rather than indirect equivalents, which can misclassify irregular particles. For elongated or plate-like shapes, cross-sectional dimensions or thickness are key.

Distinguishing between aggregates (strongly bound) and agglomerates (loosely held) is also critical, as constituent particle dimensions are generally preferred for classification—though sometimes only the aggregate can be measured. The JRC requires all identifiable particles to be counted in number-based size distributions, which better reflect the presence of nanoscale particles than mass-based methods.

The definition applies only to solid particles, excluding liquids, gases, and single molecules. Additional complexity arises from nanomaterials' nonlinear, fractal, and dynamic behavior, which challenges traditional models and leads to batch variability.

In cosmetic matrices, nanomaterial detection is further complicated by emulsions, encapsulation, and matrix interference. Advanced imaging techniques like TEM are often required but remain labor-intensive. Overall, accurate classification demands robust, context-specific methods and ongoing scientific refinement.

Under the European Union’s Cosmetics Regulation (EC) No 1223/2009, if an ingredient in a formulation is defined as a nanomaterial, the manufacturer must follow a series of obligations. Conversely, if the ingredient does not meet this definition, these requirements do not apply. This is why it is so important for companies to determine whether a substance truly qualifies as a nanomaterial under the regulation.

Under EU Cosmetic Regulation 1223/2009, only intentionally produced nanomaterials are regulated, excluding incidental or natural particles. Consequently, materials such as cellulose derived from other industries might not be considered nanomaterials if they have not been deliberately engineered to nanoscale dimensions.

In contrast, the broader EU 2022 update encompasses all naturally occurring, incidental, and intentionally produced nanomaterials, applying stricter criteria for classification and potentially widening the regulatory net.

Despite these differences, a harmonised definition remains critical to enable safe innovation in cosmetic formulations while ensuring consistent regulatory compliance and consumer protection (Table 2).

Table 2. Comparison of Nanomaterial Definitions: Cosmetics Regulation vs EU Recommendation 2022.

Changes discussed in Table 1 have profound implications for the classification of various cosmetic ingredients. In essence, materials currently regulated as nanomaterials under the CPR may no longer fall under this category if the revised definition is adopted, while conversely, other substances not previously considered nanomaterials may meet the criteria. A few examples are provided below:

Titanium Dioxide (TiO₂)

Titanium dioxide is widely used in sunscreens and cosmetic formulations as a UV filter. Under the current CPR definition, TiO₂ produced with primary particles in the nanoscale range is regulated as a nanomaterial. However, many commercial grades of nano-TiO₂ are heavily aggregated or surface-coated, which can result in a specific surface area below the 6 m²/cm³ threshold. Should the revised definition be adopted, certain aggregated or coated forms of TiO₂ may no longer qualify as nanomaterials, provided their number-based size distribution reflects a majority of particles exceeding 100 nm and their specific surface area remains low (European Commission JRC, 2022).

Silica (SiO₂)

Similarly, certain forms of silica, such as fumed silica used as rheology modifiers in cosmetic creams, possess primary particle sizes within the nanoscale. However, these materials often exist as large, fused aggregates with relatively low specific surface areas. If their specific surface area is below 6 m²/cm³, they may fall outside the revised nanomaterial definition, even though they have historically been treated as nanomaterials under the CPR.

Carbon Black

Carbon black, used as a pigment in cosmetics such as mascaras and eyeliners, has historically been considered a non-nanomaterial due to its aggregated state. However, primary particles frequently measure 30–50 nm in diameter. Under the revised definition, if particle counting techniques reveal that >50% of the particles in number-based distributions are nanosized and the material’s specific surface area exceeds 6 m²/cm³, carbon black could newly be classified as a nanomaterial, thereby triggering additional regulatory obligations.

Certain Bulk Pigments and Additives

Similarly, some pigments and additives not previously regulated as nanomaterials may become subject to nanomaterial requirements if advanced characterisation techniques detect a high proportion of nanoscale particles. This is particularly relevant for materials with complex manufacturing processes, where micron-sized aggregates conceal nanoscale primary particles that would only be revealed through techniques such as electron microscopy or field-flow fractionation (10).

Nanoemulsions and Labile Nanostructures

It is noteworthy that the revised definition explicitly targets solid particles and excludes non-solid structures. Thus, nanoemulsions, liposomes, micelles, and other labile self-assembled systems would remain outside the nanomaterial definition under both the current CPR and the 2022 Recommendation. These systems disintegrate upon application and lack the solid, persistent character associated with nanomaterials of regulatory concern.

Nanotechnology is reshaping the cosmetics industry, enhancing product performance and consumer benefits. The EU has updated its nanomaterial definition through Commission Recommendation 2022/C 229/01, which, if taken up by the CPR may lead to reclassification of common ingredients like titanium dioxide, silica, or carbon black, prompting new obligations for manufacturers. Dynamic systems, where particles aggregate or disassemble, further complicate compliance. Ongoing regulatory updates and scientific research are vital to ensure effective implementation and to help industry navigate evolving EU requirements for nanomaterials in cosmetics.