Increasing amounts of manufactured nanomaterials (MNMs) are produced for their industrial use and released to the environment by the usage or disposal of the products. As depending on their annual production rate, substances are subjected to PBT assessment, the availability of reliable methods to evaluate these endpoints for (corresponding) nanoforms/MNMs becomes relevant. The classical method to elucidate the bioaccumulation potential of chemicals has been the flow-through study with fish, which has limitations as regards meeting the requirements of MNMs. Most MNMs tend to sediment in the aquatic environment. Thus, maintenance of stable exposure conditions for bioaccumulation testing with fish is nearly impossible to achieve when using MNMs. Corbicula fluminea, a freshwater filter-feeding bivalve distributed worldwide, has been previously shown to ingest and accumulate MNMs present in the water phase. To investigate the suitability of C. fluminea for bioaccumulation testing we developed a new flowthrough system to expose mussels under constant exposure conditions. Two nanoparticles (NPs), the AgNP NM 300K and the TiO 2 NP NM 105, were applied. In addition, C. fluminea was exposed to AgNO 3 as a source of dissolved Ag + to compare the bioaccumulation of Ag in dissolved and nanoparticulate forms. For each MNM exposure scenario we were able to determine steady-state bioaccumulation factors. BAF ss values of 31 and 128 for two NM 300K concentrations (0.624 and 6.177 μg Ag per L) and 6150 and 9022for TiO 2 (0.099 and 0.589 μg TiO 2 per L) showed the exposure dependence of the BAF ss estimates. The progression of metal uptake and elimination in the soft tissue provided clear indications that the uptake and thus accumulation is mainly driven by the uptake of NPs and less of dissolved ions.Filter-feeding organisms such as bivalves represent a major target for the bioaccumulation of nanomaterials in the aquatic environment. Therefore, bivalves should be considered as test organisms for the bioaccumulation assessment of nanomaterials. A new flow-through system to expose the freshwater bivalves under constant exposure conditions was developed. Bioaccumulation studies with the freshwater bivalve C. fluminea on two nanoparticles, the AgNP NM 300K and the TiO 2 NP NM 105, demonstrated the suitability of the new test system. The results obtained with this test system can be used to generate useful endpoints required for regulatory purposes and could be included in a tiered bioaccumulation testing strategy for manufactured nanomaterials.

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.

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Background Manufactured nanomaterials (MNMs) are released into the environment in increasing quantities. Consequently, MNMs also reach the aquatic environment, where they can interact with different organisms. Previous studies have already shown that filter-feeding bivalves can ingest nanomaterials from the surrounding water leading to higher concentration of the material. Furthermore, they have been shown to be vectors for environmental chemicals and pathogens to other organisms, as their feces/pseudofeces (F/pF) play a crucial role as a food source for other species. We exposed bivalves (Corbicula sp.) to MNMs and performed experiments to investigate the possible transport of MNMs by their feces to the benthic amphipod Hyalella azteca. Silver (Ag) and gold (Au) nanoparticles (NPs) as well as fluorescent polystyrene nanoparticles were used in this study. They allowed the investigation of the metal content of the bivalves’ feces and the amphipods feeding on it, as well as the localization of the fluorescent particles in the body of the animals. Results Examination of the feces by fluorescence microscope and determination of the total metal content by inductively coupled plasma mass spectrometry (ICP-MS) showed a high accumulation of the exposed MNMs in the F/pF. The examination of fecal matter, using transmission electron microscopy confirmed the nanoparticulate character of the metals in the examined fecal matter. After exposure of amphipods to the MNMs containing fecal matter, the fluorescent MNMs were localized in the animals gut. The chronic exposure of juvenile amphipods over 21 days to feces enriched with Au MNMs caused significant effects on the growth of the amphipods. The transfer of both metals (Ag and Au) from the fecal matter to the amphipods was confirmed after total metal measurements. Conclusion Probably, for the first time, it has been shown that when exposed to MNMs bivalves can transfer these particles to other benthic species. Transfer is via released F/pF upon which the benthic species feed and thus could ingest the particles. The high concentrations of MNMs in the fecal matter raises concerns about the potential accumulation and transfer of the materials and associated ecotoxicological effects in invertebrates such as benthic amphipods.

The uptake potential of Fragrance Encapsulates (FEs) by aquatic or terrestrial organisms was investigated. Due to their size of below 5 mm and their This article is protected by copyright. All rights reserved. Accepted Articlepolymeric nature, FEs fall under the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) definition of microplastics (MPs).After use, FEs enter the sewer system and reach the sewage treatment plant (STP) where >90% of the FEs are likely to be removed by sorption to the sludge. When the STP-generated sludge is used as fertilizer for agricultural soils, this may lead to potential exposure of terrestrial invertebrates to FEs and especially those feeding on particles of a similar size as the FEs. Two aquatic (Corbicula fluminea (water exposure) and Hyalella azteca (water and dietary exposure)) and one terrestrial invertebrate (Eisenia andrei (soil exposure)) species were exposed to 50 mg/L (or mg/kg) double fluorescence labelled FEs (ø 5-50 µm). The results showed that FEs are available to aquatic and terrestrial invertebrates but species specific differences regarding the ability to ingest FEs may exist. The benthic grazer H. azteca showed no ingestion of FEs, whereas the capsules were readily ingested and egested by the unselective freshwater filter-feeder C. fluminea, as well as the terrestrial decomposer E. andrei. No signs of bioaccumulation of FEs were indicated by microscopic assessment.This article includes online-only Supporting Information.

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Regulatory assessment of the bioaccumulation from water is commonly based on bioconcentration factors (BCFs) derived from fish flow-through tests. Such experiments require many laboratory animals and are time-consuming and costly. An alternative test setup for organic, neutral compounds using the amphipod Hyalella azteca was recently suggested, resulting in BCF values which show a strong correlation with fish BCF data. In the present study, the bioconcentration potential of the ionic compound laurate was elucidated in H. azteca. The sodium salt of 1-14 C laurate was applied to H. azteca in a flow-through and a semistatic approach. Because of rapid biodegradation, a semistatic approach with frequent medium replacements was required to ensure a stable medium concentration. Laurate was also rapidly metabolized by H. azteca. A large proportion of the total radioactivity measured in the amphipod tissue was not extractable, suggesting that mineralized laurate was accumulated in the calcified exoskeleton of H. azteca. This was confirmed in a further study using carbonate [ 14 C]. A lipid-normalized (5.0%) Hyalella BCF of 8.9 was calculated for laurate, measured as free fatty acids. The results of the bioconcentration studies with H. azteca confirm the low bioaccumulation potential of the test item previously observed in fish. However, more organic ionic compounds with various properties need to be tested to assess whether a general correlation between fish and Hyalella BCF data exists. Environ Toxicol Chem 2020;39:310-322. Chemicals 14 C-lauric acid (carbonyl carbon-labeled), dissolved in ethanol, was obtained from Hartmann Analytics (98.4% wileyonlinelibrary.com/ETC FIGURE 1: Experimental setup of the flow-through system (left) and the (semi-)static system (right). a = mixing chamber; b = aeration; c = steel grid; d = DECOTAB; e = stirrer (not during study III); f = spiked medium. Bioconcentration of laurate in the amphipod Hyalella azteca-Environmental Toxicology and Chemistry, 2020;39:310-322 311