The present environmental exposure concentrations to engineered nanomaterials may be low, but the long term exposure and effect will depend on the degree of bioaccumulation behaviour of the nanomaterials. Our goal in TP3 is to study uptake and depuration of nanoparticles in aquatic organisms especially the influence of particles sizes, functionalizations and interaction with aqueous media.
As it was the case in TP2, initial studies will be carried out with AuNP in different sizes, shapes, and coatings. Therefore, similar statistical test designs will be used in TP3, but focussed at uptake and depuration processes. The research in TP3 is to a large extent focused at method evaluation and development, since one of the major knowledge gaps in risk assessment of ENPs is how to obtain meaningful data on bioaccumulation.
Test organisms are unicellular green algae, pelagic crustaceans, and sediment-dwelling invertebrates. In TP3 bioaccumulation studies will be performed in which direct exposure via the water as well as indirect exposure via the food will be investigated and compared. To identify differences due to changes physicochemical properties of the environment the bioaccumulation studies will be performed in different aqueous media with freshwater species. In all experiments the kinetics of the processes will be a main factor that will be monitored throughout uptake and depuration experiments.
A major issue when assessing the bioconcentration is the possibility of discrete localization of ENPs in tissues, organs or cell organelles. Therefore, a large part of the activities in TP3 will be directed toward histological examinations of exposed organisms. This will be carried out by EM techniques in collaboration with the Centre for Nanoscopy at DTU.
For bioaccumulation studies, it is mandatory to establish the ecotoxic effects of nanomaterials on aquatic organisms. Therefore, this activity also is dependent on toxicity data for hazard identification and comparisons of toxicity generated in TP2. Besides this relation to TP2, the activities in TP3 are strongly related to the characterisation and analysis in TP1 (shown in Figure 1), as well as delivering input to TP4.