A Tiered Approach for Reliable Bioaccumulation Assessment of Manufactured Nanomaterials in the Environment Whilst Minimising the Use of Vertebrate Testing

The overall aim of this scoping review was to explore the possible options for a tiered approach to bioaccumulation testing, the available tools or test methods, and to provide data to show potential linkages between the possible tiers in the testing strategy, as well as the evidence-base for seeking alternatives to using live fish. An example scheme is outlined here, with four possible tiers to show the thinking on how such a scheme might work in practise. The tiers include: (i) chemistry triggers as alternatives to the log Kow test that are more relevant to the behaviour of nanomaterials (MNs); (ii) the inclusion of data from invertebrate tests, cell cultures, and/or in silico models to provide a weight of evidence for a bioaccumulation concern; (iii) an in vitro tier using fish gut tissue; and finally, tier (iv), the dietary method of TG 305.