Concern-driven integrated approaches to nanomaterial testing and assessment--report of the NanoSafety Cluster Working Group 10

Abstract

Bringing together topic-related European Union (EU)-funded projects, the so-called "NanoSafety Cluster" aims at identifying key areas for further research on risk assessment procedures for nanomaterials (NM). The outcome of NanoSafety Cluster Working Group 10, this commentary presents a vision for concern-driven integrated approaches for the (eco-)toxicological testing and assessment (IATA) of NM. Such approaches should start out by determining concerns, i.e., specific information needs for a given NM based on realistic exposure scenarios. Recognised concerns can be addressed in a set of tiers using standardised protocols for NM preparation and testing. Tier 1 includes determining physico-chemical properties, non-testing (e.g., structure-activity relationships) and evaluating existing data. In tier 2, a limited set of in vitro and in vivo tests are performed that can either indicate that the risk of the specific concern is sufficiently known or indicate the need for further testing, including details for such testing. Ecotoxicological testing begins with representative test organisms followed by complex test systems. After each tier, it is evaluated whether the information gained permits assessing the safety of the NM so that further testing can be waived. By effectively exploiting all available information, IATA allow accelerating the risk assessment process and reducing testing costs and animal use (in line with the 3Rs principle implemented in EU Directive 2010/63/EU). Combining material properties, exposure, biokinetics and hazard data, information gained with IATA can be used to recognise groups of NM based upon similar modes of action. Grouping of substances in return should form integral part of the IATA themselves.

Figure 1.

Physico-chemical characterisation, dispersion and in situ characterisation of NM for toxicity testing.

Figure 2.

Targeted integrated approach to NM toxicity testing and assessment addressing the specific concerns for an individual NM.

Figure 3.

Identification of potential health concerns of an individual NM based on its physico-chemical properties and relevant exposure scenarios (numberings of tiers relate to Figure 2).

Figure 4.

Building blocks for integrated approaches to ecotoxicity testing and assessment, that is, different types of test methods and purposes for ecotoxicity testing.

Figure 5.

(A). Proposal for tier 1 of an integrated approach to ecotoxicity testing and assessment (numberings 1a and 1c refer to the respective building blocks presented in Figure 4). (B). Proposal for tier 2 of an integrated approach to ecotoxicity testing and assessment (numberings 1b, 1c and 2 refer to the respective building blocks presented in Figure 4).

Figure 6.

Illustration of grouping of NM based on material properties and/or biological effects. This schematic example shows three groups of NM and also NM not assignable to any group.