REACH nanoforms

In plain words

European rules requiring companies to register chemicals – including nano-sized forms such as many powders – with information on their form and before making or importing them in quantity in the EU.

Going deeper

Under REACH a substance is registered once, but each nanoform of it has to be described on its own. Two batches of the same chemical can need separate entries if the flakes differ in size or surface treatment.

Registered by tonnage, described by form

REACH requires anyone manufacturing or importing a substance into the EU at one tonne a year or more to register it, with the information demanded increasing at higher tonnage bands. That framework was written for chemicals identified by composition, where a substance is a substance.

Nanomaterials broke that assumption, because the same composition behaves differently depending on how it is divided. A 2018 amendment to the REACH annexes closed the gap: each nanoform placed on the market has to be characterised in its own right, with a number-based particle size distribution, shape and aspect ratio, description of any surface treatment or functionalisation, specific surface area, and crystallinity. Where several nanoforms are similar enough, they may be registered together as a set of similar nanoforms, provided the boundaries of the set are justified – which is what tools such as the ECETOC NanoApp exist to support.

Why layered materials are caught

It would be easy to assume that rules written about nanoparticles do not apply to sheets. They do. The European definition of a nanomaterial is built on the number-based size distribution of particles with external dimensions in the 1 to 100 nm range, and it reaches explicitly further for : a sheet thinner than a nanometre in one dimension is included, even though it is not what anyone pictures as a particle.

That puts graphene , inks, boron nitride powders and every other exfoliated product squarely inside the regime. The exposure route that matters is not the finished device – a in a is not going anywhere – but the powder, the ink and the aerosol that exist during manufacture and disposal. This is also why the toxicology literature on 2D materials is overwhelmingly about dispersions rather than devices.

What it means for a laboratory

For most research groups the tonnage threshold is far away, and the immediate relevance is preparation rather than compliance. The characterisation the regulation asks for is the characterisation a careful group should be doing anyway: the flake size distribution, the surface chemistry, the specific surface area, what the material is, batch by batch. The difference is that it has to be recorded, per batch, and kept.

The practical advice is to build that record from the start, because reconstructing it later for material already shipped to collaborators is unpleasant. Anyone approaching commercial scale should take specialist advice: this is a summary of how the framework works, not a compliance guide, and the details – set boundaries, joint registration, tonnage bands – are where the actual work is.

For specialists

The EU chemicals regulation’s requirement to register and characterise nanoform variants of substances, including many 2D-material powders.

Where this comes from

Commission Regulation (EU) 2018/1881 amending the REACH annexes to address nanoforms of substances European Commission · Official Journal of the European Union L 308, 1 (2018)
Rationale and decision rules behind the ECETOC NanoApp to support registration of sets of similar nanoforms Janer et al. · Nanotoxicology 15, 145 (2020) cited by 27

Toxicity and safety

Whether 2D materials can harm people or the environment, and how to work with them safely. There is no single answer for “graphene”: the size, thickness, surface chemistry and dose of the flakes decide what they do in the body, and a material bound inside a plastic is a very different matter from a fine powder in the air. Some chemicals used to make 2D materials – hydrofluoric acid, hydrogen selenide – are far more dangerous than the materials themselves.

The hazard assessment of 2D materials and their production. Biological effects of graphene-family and other nanosheets depend on lateral size, thickness, stiffness, surface chemistry, dispersibility and dose rather than on the name: large, stiff platelets can frustrate macrophages in a partly asbestos-like way, while small, oxidised, well-dispersed flakes are cleared more readily, and a first controlled human inhalation study of small, thin graphene oxide in 2024 found no acute cardiorespiratory effects. Some compounds carry intrinsic toxicity (lead in halide perovskites; selenium, tellurium, arsenic, antimony), and processes use hazardous precursors – H₂S, H₂Se, HF, organometallics. Nanoforms are registered separately under REACH; workplace exposure is managed as for fine powders, and exposure from flakes bound in composites is generally considered low.

Full explanation

Dispersions and inks

Flakes of a 2D material floating in a liquid, and that liquid used like paint or ink. Stirring or shaking a layered crystal in the right liquid splits it into flakes that stay suspended; spinning away the thick ones leaves a dispersion of thin flakes, which can be sprayed, printed or coated onto almost anything. It is the cheapest way to make 2D materials by the kilogram, but the flakes are small and overlap in a film, so they never match a perfect continuous sheet.

Colloidal suspensions of nanosheets made by liquid-phase exfoliation of layered crystals in solvents whose surface energy matches the crystal (NMP, DMF, cyclohexanone) or in water with surfactants, by electrochemical exfoliation, or – for graphene oxide and MXenes – by chemical routes that leave hydrophilic surfaces. Centrifugation sorts flakes by size and thickness (liquid cascade centrifugation), and optical spectra give mean thickness and lateral size in the liquid. Formulated as inks with tuned viscosity and surface tension, they are inkjet-, screen- or spray-printed or coated into films limited by flake–flake junctions, porosity, residual solvent or surfactant, and oxidation in storage. Powders and dispersions sold as graphene range from monolayers to graphite, which ISO/TS 21356-1 addresses by defining how they are characterised.

Full explanation