Testing the Bioaccumulation of Manufactured Nanomaterials

Nano-HYBIT

A promising approach for bioaccumulation testing of nanomaterials (NMs) may be the bioaccumulation test using the benthic freshwater amphipod Hyalella azteca (HYBIT) that was described by Schlechtriem et al., 2019 (Ref. 1). H. azteca is a well established test organism for ecotoxicological studies and is sensitive to environmental chemicals and metals in the environment. The amphipod can be easily cultured in the laboratory, is available all year round and shows a high reproduction rate and fast growth. H. azteca has already been successfully used in studies on the bioavailability of NMs present in the water and diet (Kuehr et al., 2020, Ref. 2). Therefore, the benthic species might also be a suitable test organism for the determination of the bioaccumulation potential of NMs.

A study at Fraunhofer IME has shown that bioconcentration and biomagnification studies with H. azteca in an adapted test system are suitable for testing the bioaccumulation potential of metal and metal oxide nanoparticles (NPs). The test concept presented allows testing of NMs under controlled test conditions and provides results of high value which might be considered within a tiered approach for bioaccumulation assessment of NPs (Kuehr et al., 2020, Ref. 2).

Tiered Approach for Testing Nanomaterials

An assessment scheme for bioaccumulation assessment of MNMs was presented by Kuehr et al. 2021 (Ref. 3). The results from amphipod bioconcentration and biomagnification tests can be included in the tiered assessment allowing a clear grading of the tested nanomaterials as “bioaccumulative” or “non-bioaccumulative.” Due to the worst-case scenario of the amphipod test, this approach may allow a waiver of further vertebrate tests.