title: Accumulation dynamics and acute toxicity of silver nanoparticles to Daphnia magna and Lumbriculus variegatus: implications for metal modeling approaches.
abstract: Frameworks commonly used in trace metal ecotoxicology (e.g., biotic ligand model (BLM) and tissue residue approach (TRA)) are based on the established link between uptake, accumulation and toxicity, but similar relationships remain unverified for metal-containing nanoparticles (NPs). The present study aimed to (i) characterize the bioaccumulation dynamics of PVP-, PEG-, and citrate-AgNPs, in comparison to dissolved Ag, in Daphnia magna and Lumbriculus variegatus; and (ii) investigate whether parameters of bioavailability and accumulation predict acute toxicity. In both species, uptake rate constants for AgNPs were ∼ 2-10 times less than for dissolved Ag and showed significant rank order concordance with acute toxicity. Ag elimination by L. variegatus fitted a 1-compartment loss model, whereas elimination in D. magna was biphasic. The latter showed consistency with studies that reported daphnids ingesting NPs, whereas L. variegatus biodynamic parameters indicated that uptake and efflux were primarily determined by the bioavailability of dissolved Ag released by the AgNPs. Thus, principles of BLM and TRA frameworks are confounded by the feeding behavior of D. magna where the ingestion of AgNPs perturbs the relationship between tissue concentrations and acute toxicity, but such approaches are applicable when accumulation and acute toxicity are linked to dissolved concentrations. The uptake rate constant, as a parameter of bioavailability inclusive of all available pathways, could be a successful predictor of acute toxicity.
authors.affiliation: †School of Life Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom.
authors.forename: Farhan R
authors.initials: FR
authors.lastname: Khan
authors.affiliation: †School of Life Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom.
authors.forename: Kai B
authors.initials: KB
authors.lastname: Paul
authors.affiliation: ‡Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, England.
authors.forename: Agnieszka D
authors.initials: AD
authors.lastname: Dybowska
authors.affiliation: §School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Valsami-Jones
authors.affiliation: ∥SmartState Center for Environmental Nanoscience and Risk (CENR), Arnold School of Public Health, University of South Carolina, Columbia, South Carolina 29088, United States.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Lead
authors.affiliation: †School of Life Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom.
authors.forename: Vicki
authors.initials: V
authors.lastname: Stone
authors.affiliation: †School of Life Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom.
authors.forename: Teresa F
authors.initials: TF
authors.lastname: Fernandes
mesh_terms: D000818:Animals; D001682:Biological Availability; D019343:Citric Acid / Q000378:metabolism; D003621:Daphnia / Q000378:metabolism*; D054750:Ecotoxicology; D053768:Metal Nanoparticles / Q000633:toxicity*; D053758:Nanoparticles; D009835:Oligochaeta / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000378:metabolism; D011205:Povidone / Q000378:metabolism; D012834:Silver / Q000378:metabolism* / Q000633:toxicity; D012835:Silver Nitrate / Q000378:metabolism / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; D019343:Citric Acid; D012834:Silver; D011092:Polyethylene Glycols; D012835:Silver Nitrate; D011205:Povidone