The European Union (EU) Observatory for Nanomaterials (EUON) announced on December 7, 2022, publication of a June 2022 report by the European Chemicals Agency (ECHA) entitled Assessment of the potential impact of graphene, graphene oxide and other 2D materials on health, and the environment. Commissioned by EUON, the report provides a systematic review and critical assessment of the health and environmental effects of graphene, graphene oxide, and other two-dimensional (2D) materials, based on existing public information. The key research questions addressed can be divided into two groups:
- Structured literature review: potential adverse effects of graphene, graphene oxide, and other 2D materials on human health and available methods for their assessment; and
- Structured literature review: potential adverse effects of graphene, graphene oxide, and other 2D materials on the environment and available methods for their assessment.
The systematic review covered publications, books, research reports, and research and review papers. The report includes the following conclusions and recommendations:
Conclusion 1: It is mandatory to provide in any study a thorough characterization of each type of graphene and 2D material in terms of chemical composition, structure, lateral size, and number of layers to link any identified concern during use and disposal with the particular characteristic of the material. Not all 2D materials are graphene alike.
Recommendation 1: The application of the definitions and available documentary standards should allow stakeholders to identify clearly the type of graphene and 2D materials used for the different applications and the evidence of potential toxicity issues and risks.
Conclusion 2: There is a strong need for specific and multiple analytical and spectroscopic methods for the detection and quantification of graphene and related carbon nanomaterials in biological and environmental matrices.
Recommendation 2: Multiple characterization techniques should be applied to identify and quantify clearly graphene materials in cells, tissues, organs, and the environment.
Conclusion 3: Evidenced human and environmental toxic effects of graphene and 2D materials depend on their physicochemical characteristics.
Recommendation 3: Conclusions on toxicity and ecotoxicity should not be generalized and need to be associated with a precise description of the material used in the tests.
Conclusion 4: Cytotoxic effects have been identified for specific graphene and 2D materials both on health and the environment, mainly dose dependent.
Recommendation 4: When health and environmental risks are reported or identified for a specific graphene or 2D material, doses and exposure scenarios should be considered for their manipulation and use.
Conclusion 5: Long-term/chronic studies are still limited, particularly for in vivo and repeated-dose administrations.
Recommendation 5: To assess chronic toxicity of graphene and 2D materials, protocols for repeated-dose studies should be considered.
Conclusion 6: Studies using immune-suppressed or diseased models are still lacking, particularly for in vivo and repeated-dose administrations.
Recommendation 6: To assess potential toxicity of graphene and 2D materials, relevant immune-suppressed or diseased animal models should be considered.
Conclusion 7: Studies on genotoxicity of graphene and 2D materials are still very limited.
Recommendation 7: To assess the potential genotoxic risks, reliable testing methods should be developed; response mechanisms associated with genotoxicity should be evaluated in depth; appropriate description of the type of graphene and 2D material tested should be reported; and different dosages and exposure times should be applied.
Conclusion 8: Toxicity studies of chemically exfoliated graphene and 2D materials lack appropriate controls.
Recommendation 8: The solvents and the molecules used to exfoliate bulk materials into single- or multiple-layer graphene or 2D materials might remain as residues in the end products, likely affecting the (eco)toxicity results. It is recommended to consider and include these potential impurities in the tests to exclude their implication and responsibility on (eco)toxicity.