Bioaccumulation assessment of nanomaterials using freshwater invertebrate species

Abstract

Background The high production volume of engineered nanomaterials (ENMs) may lead to high pressure on the environment, and a scientific assessment of ENMs that bioaccumulate in organisms and biomagnify in the food web is necessary. Within the regulation of chemicals in several jurisdictions, such as the European regulation REACH, the bioconcentration factor is the standard endpoint. The bioconcentration factor is mostly determined by flow-through fish tests. However, nanomaterials tend to agglomerate, which may lead to sedimentation in aquatic environments. The bioavailability of the tested nanomaterials may be thus impaired for pelagic species, including fish, in comparison to benthic or filtrating species. Several risk assessment regulations allow the usage of data gained during tests using invertebrates and such data may allow a waiver of further tests using vertebrates. The aim of this study was to elucidate the potential of different freshwater invertebrate species to be used in laboratory bioaccumulation studies on ENMs and to give some guidance for the use of bioaccumulation endpoints derived from studies using aquatic invertebrate species in the risk assessment process for ENMs. Results The existing literature related to the testing of nanomaterial bioaccumulation with freshwater invertebrates was screened and reviewed to find suitable test species with regard to their ecology and physiology, as well as laboratory test systems allowing to investigate the bioavailability/bioaccumulation of nanomaterials with the respective species. Bivalvia, gastropoda, isopoda, amphipoda, and branchiopoda were reviewed and their suitability for bioaccumulation testing was assessed. Amphipods and bivalves represent worst-case scenarios and show clear advantages to be used as test organisms. However, only amphipods allow the examination of two clearly independent exposure pathways (water and diet). Conclusion Amphipods are suitable test organisms for bioaccumulation testing of ENMs. The results from amphipod bioconcentration and biomagnification tests can be included in a tiered assessment suggested at the end of this study 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.

Ingestion of bivalve droppings by benthic invertebrates may lead to the transfer of nanomaterials in the aquatic food chain

“…The ingestion of the MNMs by the amphipods and potential chronic effects of the MNMs present in the F/pF were investigated. H. azteca has previously been used in a wide range of bioavailability and bioaccumulation tests using neutral and ionic organic compounds, metals and nanomaterials [59][60][61][62][63][64][65][66][67] and has recently been proposed as a test organism for the regulatory bioaccumulation assessment of MNMs [68]. The results of this study help to further elucidate the role of filter feeding bivalves and their F/pF in the transfer of MNMs along the aquatic food chain.…”

The bioaccumulation testing strategy for nanomaterials: correlations with particle properties and a meta-analysis ofin vitrofish alternatives toin vivofish tests

“…To achieve regulatory acceptance, the evidence-base demonstrating the linkages between the tiers in this proposed testing strategy must be shown; preferably for a range of different types of MNs. Recently, the use of bioaccumulation tests with aquatic invertebrates to waive, or include, TG 305 have been discussed, 21 along with a metaanalysis showing the utility of bioaccumulation data from earthworms. 22 However, there may be more regulatory acceptance of in vitro fish alternatives to in vivo fish tests, and with a dietary exposure method proposed for MNs in TG 305, the focus of attention is on alternatives ways to predict bioaccumulation via the gut.…”

Are Fragrance Encapsulates Taken Up by Aquatic and Terrestrial Invertebrate Species?

“…The freshwater bivalve Corbicula fluminea was used as a representative filter feeder, whereas the benthic freshwater amphipod Hyalella azteca allows investigation of the aqueous and dietary exposure pathways. Both species have already been used to study the accumulation of nanomaterials (Kuehr, Kaegi, et al, 2020; Kuehr, Klehm, et al, 2020; Kuehr, Meisterjahn, et al, 2020) and microplastics (Au et al, 2015) and have been proposed as suitable test organisms for the bioaccumulation assessment of nanomaterials (Kuehr, Kosfeld, & Schlechtriem, 2021). In addition, they may be a suitable test species for particles in the micrometer range (Kuehr, Kosfeld, & Schlechtriem, 2021).…”