Toxicity and safety

Everyday term

In plain words

Whether 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 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.

Going deeper

What a 2D material does in the body depends on the size, form and dose of its flakes: immune cells clear small flakes but cannot engulf large, stiff platelets. Some layers contain toxic elements such as lead or selenium, and the chemicals used to make them are often more hazardous than the materials themselves.

Form, not name

“Graphene” covers everything from a pristine to an oxidised powder, and these behave very differently in the body. What matters is the size, thickness, stiffness and surface chemistry of the flakes, whether they clump or stay dispersed, how much reaches the body and by which route. Small, thin, oxygen-rich flakes tend to be taken up and cleared by immune cells, while large, stiff platelets can be too big to engulf completely – a problem that partly resembles the one posed by long asbestos fibres, and a reason platelet size is watched closely.

In a controlled trial published in 2024, healthy volunteers inhaled highly purified, very small graphene oxide flakes for two hours without measurable effects on lung function, blood pressure or markers of inflammation – reassuring, though it says nothing about long-term or high-dose exposure.

What the materials contain

Some 2D materials are hazardous because of their elements. Lead perovskites contain lead, and several chalcogenides and pnictides contain selenium, tellurium, arsenic or antimony, whose release during processing or from discarded devices needs control. Black phosphorus and degrade in air and water into other compounds whose effects differ from those of the original flakes. A lead-free or low-toxicity alternative is therefore often part of a material’s appeal, as for bismuth oxyhalide photocatalysts.

Making them safely

The greater risk often lies in production. Growing selenides and sulfides by uses hydrogen selenide and hydrogen sulfide, highly toxic gases that need gas cabinets and detectors; making MXenes uses hydrofluoric acid or fluoride salts in acid, which burn and poison through the skin; some organometallic precursors ignite in air. Dry powders are handled like other fine powders, in enclosures with extraction and suitable masks, while flakes bound inside a or a device are generally regarded as a low risk to users. Under European law, nanoforms of a substance are registered and described separately under .

For specialists

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.

Where this comes from

Graphene-based nanoplatelets: a new risk to the respiratory system as a consequence of their unusual aerodynamic properties Schinwald et al. · ACS Nano 6, 736 (2012)
Safety assessment of graphene-based materials: focus on human health and the environment Fadeel et al. · ACS Nano 12, 10582 (2018)
First-in-human controlled inhalation of thin graphene oxide nanosheets to study acute cardiorespiratory responses Andrews et al. · Nature Nanotechnology 19, 705 (2024)

Chalcogenide, halide and pnictide

Family names for compounds, taken from the element in them that carries the negative charge. Chalcogenides contain sulfur, selenium or tellurium; halides contain fluorine, chlorine, bromine or iodine; pnictides contain phosphorus, arsenic, antimony or bismuth. Most layered crystals belong to one of these families, and the catalogue groups many of them that way.

Compounds named for their most electronegative constituent: chalcogenides of group 16 (S, Se, Te; oxides are conventionally counted apart), halides of group 17 (F, Cl, Br, I) and pnictides of group 15 (P, As, Sb, Bi; nitrides usually keep their own name). Down each group the anion grows larger and less electronegative, so bonding turns more covalent, gaps shrink and spin–orbit coupling grows. Chalcogenides give the MX₂ semiconductors and metals, halides mostly ionic, often magnetic insulators built from edge-sharing octahedra, and pnictides many metals, semimetals and the parents of the iron-based superconductors; mixed-anion compounds such as oxychalcogenides and chalcohalides combine two.

Full explanation

Composites and coatings

The biggest market for 2D materials so far: flakes of graphene or other layered materials mixed in small amounts into plastics, rubber, concrete, paints or battery electrodes, to make them stiffer, tougher, more conductive or less permeable. Sold by the tonne, these products use cheap flakes made in bulk rather than perfect single layers. Whether a few percent of flakes really helps depends on how well they are spread out, how they line up and how firmly they hold on to the material around them.

Bulk uses in which exfoliated or chemically derived flakes – graphene nanoplatelets, reduced graphene oxide, hBN, MXenes, clays – are dispersed in a matrix or applied as a film. In polymer composites a few weight percent can raise stiffness and toughness, cross the percolation threshold for electrical conduction – as low as about 0.1 percent by volume for thin, wide flakes – and raise thermal conductivity; aligned flakes in barrier coatings lengthen the diffusion path of water, oxygen and ions and slow corrosion; flakes used as conductive additives replace part of the carbon black in battery electrodes; MXene films give strong electromagnetic shielding. Performance depends on flake size and thickness, dispersion without restacking, alignment and bonding to the matrix, and on powders whose properties vary widely between suppliers.

Full explanation