Recent research highlights the complexities surrounding the regulation of manufactured multicomponent nanomaterials (MCNMs) under the European chemicals’ regulation REACH. Although most of these materials are covered by REACH and its nano-specific updates, uncertainties remain regarding their categorisation and assessment. More precise definitions and guidelines are needed to ensure safe and sustainable management of these advanced materials as technology evolves. 

Examining the readiness of REACH for MCNMs

In a recent article in NanoImpact researchers from the EU European Union (European Union ) project SUNSHINE (including three co-authors from RIVM) looked into how well European laws on chemicals, known as REACH, cover MCNMs. REACH came into force in 2007 and updates specifically for nanomaterials  took effect in 2020. These updates address challenges related to the unique characteristics of nanomaterials, such as their size, shape, and functionalisation. While these updates may help the registration of MCNMs, it remains uncertain if these highly complex materials could bring up new regulatory issues that haven’t been addressed for nanomaterials in general.

The need for implementing a new definition of nanomaterials

In their publication, the authors discuss the confusion surrounding the categorisation of MCNMs under REACH. It is not always clear whether these materials should be considered a substance, a substance in nanoform, a mixture or an article. This distinction is important because it determines the type of information required for registration.

Interestingly, some MCNMs that appear to be nanomaterials may not meet the current criteria under REACH. These criteria are based on the former European Commission’s 2011 recommendation for defining a nanomaterial. For example, if a nanomaterial is coated and its overall size, including the coating, exceeds the dimensions established for defining a nanomaterial, it would not fit the definition. Moreover, the current criteria don’t cover materials with nanoscale structures either inside or on the surface.

The revised recommendation on a definition of a nanomaterial from 2022 is expected to clarify this latter issue. In general, the authors believe that implementing this new definition in REACH would help eliminate much of the confusion regarding the categorisation of these materials.

Practical challenges to assess MCNMs

In addition, the paper highlights the importance of clarifying whether a coating that lightly adheres to a material’s core (known as physisorption) should be regarded as surface functionalisation. This distinction is important because different types of surface modifications might require separate registrations, while a physisorbed coating could be viewed more like a constituent, an additive or even an impurity. Understanding whether materials are bonded by strong chemical bonds (chemisorption) or weak attractions (physisorption) is crucial and currently presents a regulatory challenge.

The authors also point out practical difficulties related to MCNMs. For instance, when testing their solubility and dissolution, it is unclear whether the assessment should focus on a single or multiple components.

In conclusion, the authors stress that MCNMs are more complex than regular nanomaterials in terms of their structure, composition and function. While many of these MCNMs are currently covered by REACH regulations, several challenges and uncertainties still need to be addressed.

RIVM perspective

The authors have identified several challenges related to the registration of MCNMs under REACH. Nevertheless, they conclude that many MCNMs are likely already covered by REACH. At the same time, there are instances where the current rules are unclear for certain MCNMs, and RIVM recognises that clearer guidance would help register these novel materials. Ultimately, having clear rules is important for better management of the human and environmental safety of chemicals and materials.

As technology advances, new substances and materials are constantly being developed. Therefore, it is essential for regulations to keep pace with these innovations to ensure their safe and sustainable use. However, updating regulations like REACH can take a long time, often several years, so it is important to anticipate the introduction of new materials. This should be coupled with creating flexible regulatory mechanisms that can swiftly adapt to accommodate new advanced materials such as MCNMs. Issues to consider include the need for definition(s) for (groups of) advanced materials and addition or adjustments of specific information requirements (including methods to comply with such requirements).

In the short term, providing clear guidance on how specific MCNMs should be categorised—whether they are considered a substance, a nanoscale substance, a mixture, or an article would be highly recommended. In addition, there should be more clarity on the concept of surface functionalisation. In parallel, it is essential to prioritise and quickly update testing guidelines at the OECD level to ensure methods are available to comply with regulatory information needs.