Nanomaterials: ZVO advocates for particle size-dependent classification

The nanoparticles, which are only 1 to 100 nanometers in size, offer a variety of technical possibilities but are subject to regulations due to potential health hazards. (Image: CC-4.0-International/TiberiusRufus)

Nanomaterials are the basis of many innovations and are becoming increasingly important technologically. However, according to the latest assumptions, nanomaterials also pose a potential risk to human health, as they can possess special properties due to their size that the substance does not have at larger particle dimensions. The European Commission has therefore extended the registration obligations explicitly to nano forms of substances with Regulation (EU) 2018/1881. However, some definitions and considerations cited are, in the opinion of the Central Association of Surface Technology e.V. (ZVO), not tenable.

In the European Commission's recommendation on the definition of nanomaterials 2011/696/EU, a material is attributed to a nanomaterial if it has at least 50 percent of its particles with a size between 1 and 100 nanometers.

From the ZVO's perspective, this boundary is not scientifically substantiated and therefore not sufficiently justified. However, it is sensible to use particle size and particle size distribution as measurement parameters for classification.

It also seems questionable to include agglomerates and aggregates in this definition. The assumption that nanomaterials can be released from the matrix is also not scientifically supported and is at least unlikely. Studies by the paint industry have already shown in various cases 1, 2 that even during grinding processes, the risks posed by nanolacquers are not higher than those from conventional paints. No indications of health or environmental hazards were found in these studies.

Material-specific considerations lead to excessive effort

With the publication of Regulation (EU) 2018/1881, a comprehensive change took place in Annexes I, III, VI, VII, VIII, IX, X, XI, and XII of the REACH Regulation (EC) 1907/2006. Their summarized requirement to also examine nanomaterials or nano forms during the registration of a substance contradicts the causal relationship. It must also be assessed to what extent a group approach to evaluation makes sense. The inadequacy of a group approach for regulation has been demonstrated by the ZVO elsewhere 3. Accordingly, all relevant or possible exposure pathways of nanomaterials must be considered when placing them on the market. The employer is obliged to consider, evaluate, and develop a measures concept within the framework of the risk assessment to prevent potential hazards for workers.

This material-specific consideration of particle properties will lead to content-wise unnecessary and disproportionate efforts. Since the potential hazards considered here are independent of the substance, it is even to be expected that this area of registration will show similar results for many different substances. Therefore, a general regulation based on particle size (analogous to Annex 1, No. 2, of the German Hazardous Substances Ordinance) would be more appropriate.

Substitution of nanomaterials in surface technology is nearly impossible

In surface technology, nanomaterials are used to control surface properties through particle size. Consequently, in these application areas, no substances that differ significantly in their size distribution from the original material are suitable as alternatives.

Examples:

- Titanium dioxide as a filler
- Carbon black/rouge as an additive in black-colored formulations
- Zinc oxide as a pigment
- Silicon dioxide as a post-treatment like top coats/sealers

For possible alternative substances, it cannot be assumed that they fall outside the definition of nanomaterials, meaning they cannot serve as process- or property-based alternatives for surface technology.

Overall, it remains clear that substitution of nanomaterials will always be impossible when the particle size is crucial for the property profile.

The ZVO advocates treating particle size-dependent properties separately from substance properties. In particular, an appropriate substance-independent categorization must be incorporated into the CLP Regulation (Classification, Labelling, and Packaging of substances and mixtures).