In the December 2016 issue of Nature Nanotechnology, Maynard and Aitken took a look at how far we have come in the past ten years, and where we still need to go, by reflecting on their landmark article on the grand challenges to support the safe handling of nanotechnology1. The state of nanomaterial regulation is not mentioned in the article although it is of paramount importance when it comes to addressing these grand challenges, especially in regions of the world where the burden of ensuring safety prior to use is supposedly on the manufacturers and importers of nanomaterials. Another landmark work published a decade ago is the report by Davies2, who, as one of the authors of what became the Toxic Substances Control Act in the United States of America, provided an in-depth analysis of existing US laws and legal authorities related to nanomaterials and argued that only a separate, specific regulation on nanomaterials can be tailored to the unique properties of nanotechnology.

Despite recent revisions made in order to take the specific properties of nanomaterials into account, many pieces of existing legislative frameworks still hold a vast amount of weaknesses. For instance, in Europe, we have several different nanomaterial definitions in areas such as cosmetics, biocidal products, food and feed, which have all been hard to operationalize. We still do not have an overview of what and how much is produced and used and why. Furthermore, we lack understanding of how different nanomaterials interact with living systems and how to assess the relevant end-points for nanomaterial toxicity and we have a paucity of usable data on, especially, the exposure and environmental hazards of nanomaterials. Finally, we still lack test methods that would enable safety assessment of the numerous novel nanomaterials1,3,4.

After having spent most of a decade trying to implement drop-by-drop revisions of existing legislation to address these issues, representatives of the European Commission have recently acknowledged that nanomaterials are “difficult to regulate” due to a lack of information, their complexity, and a regulatory framework tailored for chemicals rather than manufactured materials5.

I propose and present a new legislative framework tailored for nanomaterials and their applications called Registration, Evaluation, Authorization, Categorization and Tools to Evaluate Nanomaterials — Opportunities and Weaknesses (REACT NOW).

Manufacturers and importers of nanomaterials are required to register their nanomaterials prior to commercialization, independent of production and import volumes6. For nanomaterials already in commerce, manufacturers and importers should be required to register and fulfil the REACT NOW requirements within six months of the adoption of REACT NOW, whereas product and process activities related to research and development activities are exempted from registration, as is general practice in the EU. In REACT NOW, a material is considered to be a nanomaterial when >0.15% of the particle size distribution is <100 nm or, for dry materials, when the volume-specific surface area is >60 m2 cm−3, as suggested by the European Commission's Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)7. The reason that SCENIHR's definition is preferred is that there is a serious risk that some nanomaterials will not be captured by the definition recommended by the European Commission8 if a 50% threshold is applied, as noted by the European Parliament9.

Primary particle size distribution, shape (including aspect ratio), specific surface area and surface treatment are considered unique, which means that any variation of a nanomaterial's size, shape, surface area and surface-treatment that is commercialized has to be identified, named, registered and safety-evaluated separately. This requirement is in line with the recommendation made in 2011 by the “non-industry stakeholders” involved in the so-called REACH Implementation Project on Nanomaterials (RIP-oN 1)10. The burden of proof of safety should be placed on industry to ensure that user-relevant data are generated on time. In order to ensure protection of health and the environment, I recommend that the registrant is required to explain the functional use and effectiveness of their nanomaterial and justify the necessity of the specific use(s) prior to commercialization. In cases of doubt, the European Commission's Joint Research Centre (EC JRC) should provide technical and scientific support, especially to small- to medium-sized enterprises (SMEs).

Once registered, all nanomaterials have to be evaluated according to the NanoRiskCat safety evaluation framework developed by Hansen et al.11. In its simplest form, the final evaluation outcome for a specific nanomaterial in a given application will be communicated in the form of a short title (for example, TiO2 in sunscreen or carbon nanotubes in ship paint), describing the use of the nanomaterial, and a colour code, whereby the first three coloured symbols always refer to the potential exposure of professional end-users, consumers and the environment — in that order — and the last two coloured symbols always refer to the hazard potential for humans and the environment. The colours that can be assigned to the exposure and hazard potential are green, yellow, red and grey, corresponding to low, medium, high and unknown, respectively. The assignment of the different colours to the various symbols is based on the location of the nanoelement (solid, liquid and so on) as well as hazard information such as high aspect ratio nanoparticles (HARN), classification of the bulk form of the nanomaterial, acute toxicity, genotoxicity and mutagenicity, carcinogenicity and respiratory toxicity, aquatic toxicity, freshwater tests for degradation, bioaccumulation, ecosystem effects and novelty11.

NanoRiskCat holds a number of advantages compared to chemical risk assessment and other suggested decision-support tools as it can be used effectively even when there is very little information available, the results of the NanoRiskCat evaluation are easy to communicate and, finally, it can be used to support an authorization process when it comes to the uses of nanomaterials11.

The health and environmental hazard information required as part of the information requirements are focused on enabling this application of NanoRiskCat (Supplementary Table 1). It is important to note that NanoRiskCat uses a tiered approach and that the registrant only has to submit enough information to enable the categorization of health and environmental hazard potential of the specific nanomaterial.

Depending on the outcome of the NanoRiskCat evaluation, manufacturers and importers of nanomaterials and producers of nanomaterial products might have to seek authorization, and authorization can only be given in REACT NOW for specific uses of nanomaterials and nanoproducts that are deemed necessary, efficient and that have a functional use.

The registrant is required to complete and submit an Alternatives Assessment12 for uses of nanomaterials that have a NanoRiskCat evaluation that falls into REACT NOW Category 1 (Fig. 1), meaning that they have: (1) a red professional end-user and/or a red consumer exposure profile combined with a red human health hazard profile and/or (2) a red environmental exposure profile combined with a red environmental hazard profile. As part of the Alternatives Assessment, the registrant has to identify candidate alternatives that can achieve the same purpose or function served by the nanomaterial of concern for a given application; evaluate and compare alternatives and the nanomaterial of concern at critical lifecycle points (for example, manufacturing, use and disposal), as well as evaluate and compare technical and economic feasibility characteristics.

Figure 1
figure 1

Overall registration, evaluation and authorization process related to information requirements and NanoRiskCat safety evaluation under REACT NOW.

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The authorities are subsequently required to seek an opinion on the Alternatives Assessment from the European scientific committee of relevance, for example, the Scientific Committee on Consumer Safety and the Scientific Committee on Health and Environmental Risks. In such cases, authorization should be granted, but only if the specific use under consideration is deemed safe and necessary. Uses of nanomaterials deemed not to be safe by the scientific committees, such as indoor consumer uses of spray products with nanomaterials associated with respiratory toxicity and dispersive uses of HARN, should not be granted authorization and should therefore not be given permission to be marketed in Europe.

For all other combinations of exposure and hazard profiles, that is, Categories 2–4 (Fig. 1), the authorities can ask for an opinion from the scientific committees of relevance on a case-by-case basis. As a general rule, authorization should only be given for specific professional end-user and consumer applications of nanomaterials and nanoproducts, if they have a green human health hazard profile combined with green professional end-user and consumer exposure profiles. The same goes for uses that are expected to lead to environmental exposure that should only be granted authorization if the nanomaterial in question has a green environmental hazard profile. Should the authorities or the scientific committees have questions about the safety of the nanomaterial and its specific use, the authorities can request additional information to be generated within three years. During these three years, conditional authorization can be granted. For combinations with yellow exposure and hazard profiles, conditional authorization is possible for a time-limited period, for example, three years. During the three years, the authorities should request generation of additional information by the registrant. In order to assist industry and especially SMEs in the process of implementing REACT NOW, technical and non-technical assistance is needed and should be provided by the authorities, such as the European Chemicals Agency.

REACT NOW is the first attempt to present a truly comprehensive and transparent regulatory decision-making framework tailored for nanomaterials. It might seem premature to implement a proposal like REACT NOW that is so fundamentally different in the sense that it ends up with semi-qualitative conclusions and non-quantitative estimations about risks. I would, however, argue that we have many of the pieces needed in order to set up a whole new legislative framework for nanomaterials. REACT NOW put them together and provides a flexible and holistic framework that is able to provide timely decision support before the risks of nanomaterials have materialized themselves. Furthermore, REACT NOW limits the administrative burden on regulators as importers of nanomaterials and producers of nanomaterial products will only register truly necessary applications of nanomaterials, and manufacturers are pushed to innovate and create nanomaterials and products that are truly safe-by-design.

We do not have all the answers to the scientific questions that are relevant to raise, as noted by Maynard and Aitken1, but we know enough to start asking producers and importers to provide information about the nanoform that they produce and/or use in their products. We can provide them with guidance on how to submit this information, which methods to use and how they should explain the opportunities and weaknesses of their characterization and test methods. We also know how to evaluate the applicability of the submitted information and we have clear ideas about how the information itself and the quality of it can be assessed and evaluated and can subsequently provide the basis of an authorization procedure.