Physicochemical properties of chemicals affect their exposure, toxicokinetics/fateand hazard, and for nanomaterials, the variation of these properties results in a wide variety ofmaterials with... Show morePhysicochemical properties of chemicals affect their exposure, toxicokinetics/fateand hazard, and for nanomaterials, the variation of these properties results in a wide variety ofmaterials with potentially different risks. To limit the amount of testing for risk assessment,the information gathering process for nanomaterials needs to be efficient. At the same time,sufficient information to assess the safety of human health and the environment should beavailable for each nanomaterial. Grouping and read-across approaches can be utilised tomeet these goals. This article presents different possible applications of grouping andread-across for nanomaterials within the broader perspective of the MARINA RiskAssessment Strategy (RAS), as developed in the EU FP7 project MARINA. Firstly,nanomaterials can be grouped based on limited variation in physicochemical properties tosubsequently design an efficient testing strategy that covers the entire group. Secondly,knowledge about exposure, toxicokinetics/fate or hazard, for example via properties suchas dissolution rate, aspect ratio, chemical (non-)activity, can be used to organise similarmaterials in generic groups to frame issues that need further attention, or potentially toread-across. Thirdly, when data related to specific endpoints is required, read-across can beconsidered, using data from a source material for the target nanomaterial. Read-acrosscould be based on a scientifically sound justification that exposure, distribution to thetarget (fate/toxicokinetics) and hazard of the target material are similar to, or less than, thesource material. These grouping and read-across approaches pave the way for better use ofavailable information on nanomaterials and are flexible enough to allow future adaptationsrelated to scientific developments. Show less