Development of an Integrated Approach to Testing and Assessment for grouping nanomaterials released into aquatic and sediment environments.

Aquatic systems and in particular, sediments are identified as major sinks for a range of substances upon their release into the environment. Numerous benthic and early life stage pelagic species inhabit marine and freshwater sediments and play key roles in their efficient functioning. Understanding the fate, behaviour and potential hazards of sediment-associated contaminants is therefore of utmost importance. Due to their unique physicochemical properties, nanomaterials or nanoforms (NFs) are unlikely to behave in entirely the same way as ‘traditional’ contaminants in the environment and thus, existing measures may not be wholly applicable for their environmental risk assessment. Whilst assessing the potential environmental risks of NFs is crucial, testing each on an individual basis is an unrealistic, unethical and expensive prospect given the number and wide range of variants produced. The aim of the EC H2020 GRACIOUS project is to develop a science-based framework that will streamline NF risk assessment via grouping and read-across, reducing the need to assess exposure and/or toxicity on a case-by-case basis.
Within the GRACIOUS project, a grouping hypothesis approach has been developed whereby key fate and behaviour parameters in water and sediment will identify NFs for which benthic exposure and thus effects to ecologically important species may take place. An associated Integrated Approach to Testing and Assessment (IATA) directs users to gather appropriate information (either pre-existing or via the generation of new experimental data), in order to substantiate the grouping decision. The sediment IATA initially focuses on key drivers of NF sedimentation from the water column and ultimately progresses to assessments of toxicity to benthic species used for decision making within environmental regulation. To limit the need for time consuming, whole-sediment toxicity testing, the IATA is accompanied by a tiered testing strategy, which through increasing levels of complexity, offers alternate testing methods to screen whether NFs will undergo sedimentation and if so, what toxic potential they possess in benthic systems. Through these steps, the GRACIOUS framework aims to increase the efficiency of NF risk management and aid the environmentally sustainable development of NFs and nano-enabled products.