Baun, Anders

Rasmussen, Rose

Sørensen, Sara Nørgaard

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 21, 2017Pulse exposure of silver nanoparticles in acute and chronic toxicity tests with D.magnaSørensen, Sara Nørgaard; Rasmussen, Rose; Baun, AndersPublication date:2015Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Sørensen, S. N., Rasmussen, R., & Baun, A. (2015). Pulse exposure of silver nanoparticles in acute and chronictoxicity tests with D. magna. Poster session presented at 10th International Conference on the EnvironmentalEffects of Nanoparticles and Nanomaterials, Vienna, Austria.AgNP pulse exposure1h 2h 3h01002003004005000H post exposure24h post exposure48h post exposureEC50[µg Ag/L]Nanoparticles in suspension (B) behave differently than soluble chemicals (A) and may undergo dissolution (C), interact with media components (D), be submitted to surface/coating alterations (E), aggregation (F) and sedimentation (G). These processes challenge our attempt to control or even describe the exposure concentration and characteristics of NPs during ecotoxicity testing (Sørensen et al., Integrated Environmental Assessment and Management in press).   For silver nanoparticles (AgNPs), the use of aged test suspensions in a short-term (2h) algal test generated reproducible concentration-response data  (Sørensen & Baun 2015, Nanotoxicology), indicating stable exposure concentrations. Here, we explore the same approach for another standard ecotoxicity test.   The aim is to investigate the applicability of a short-term (1-3h) pulse exposure to disclose acute and chronic effects of aged AgNP suspensions and dissolved silver (AgNO3) in Daphnia magna. Introduction & objectives Tested NP     Citrate stabilized AgNPs nominal size 30 nm Reference     Dissolved silver (AgNO3)  Medium         Elendt M7 (OECD 211) Organism      Daphnia magna neonates (<24h old)               24h               transfer            aging            to clean M7         Suspending        1,2 and 3h           monitoring endpoints    AgNPs in M7     pulse exposure       acute (48h) or chronic (21d)  Acute endpoint (48h)  Immobilization (according to OECD 202) Chronic endpoints (21d) Mortality, growth and reproduction  Pulse exposure of silver nanoparticles in acute and chronic toxicity tests with D. magna Sara Nørgaard Sørensen*, Rose Rasmussen, and Anders Baun  Department of Environmental Engineering, Technical University of Denmark *sans@env.dtu.dk Chronic endpoints (mortality & growth) Discussion & conclusion Acute endpoint (Immobilization) Chronic endpoints (reproduction) This research is kindly funded by the ERC starting grant EnvNano                             Materials & Methods AgNP pulse exposure1h 2h 3h01002003004005000H post exposure24h post exposure48h post exposureEC50[µg Ag/L]AgNPs Pulse exposure period AgNO3 Pulse exposure period AgNPsControl 10 20 30 40 5002040601h2h3hExposure [µg Ag/L]Mortality (%)AgNO3Control 0.2 0.4 0.8 1.2 202040601h2h3hExposure [µg Ag/L]Mortality (%)AgNO3Control 0.2 0.4 0.8 1.2 202040601h2h3hExposure [µg Ag/L]Mortality (%)AgNPsControl 10 20 30 40 503.03.54.04.5 1h2h3hExposure [µg Ag/L]Length [mm]AgNO3Control 0.2 0.4 0.8 1.2 23.03.54.04.5 1h2h3hExposure [µg Ag/L]Length [mm]AgNPsControl 10 20 30 40 50020406080 1h2h3hExposure [µg Ag/L]No of offspring/surviving motherAgNO3Control 0.2 0.4 0.8 1.2 2020406080 1h2h3hExposure [µg Ag/L]No of offspring/surviving motherAgNO3Control 0.2 0.4 0.8 1.2 202040601h2h3hExposure [µg Ag/L]Mortality (%)AgNPsControl 10 20 30 40 50481216 1h2h3hExposure [µg Ag/L]Days to first live offspringAgNO3Control 0.2 0.4 0.8 1.2 2481216 1h2h3hExposure [µg Ag/L]Days to first live offspringACUTE ENDPOINTS  • The aging prior to testing increases toxicity of AgNPs and AgNO3, indicating that ions play a role  • The 24-48h immobility from 1-3h pulses of aged AgNPs are similar to that of 24h continuous exposure to freshly suspended AgNPs – i.e. this pulse setup is as sensitive as the continuous test but the short exposure makes monitoring and characterization of AgNPs during testing more feasible  • The toxicity generally increases slightly with pulse duration (1-3h) – this trend is less pronounced for AgNPs than AgNO3 – i.e. 1h pulse can be applied in stead of 3h CHRONIC ENDPOINTS  • Mortality decreases with pulse duration for AgNPs – not for AgNO3. The double transfer of daphnids in short time may cause stress. High AgNO3 control mortality (1-2h), so only 3h is considered  • No trends in growth between exposures  • Reproduction overall: No trend for pulse duration  • A very sligth tendency for daphnids to reproduce sooner and have more offspring with AgNP-conc. Linear regression (pooled data 1-3h) confirms this (slope ≠ 0, P=0.04), but only the 50 µg/L (No of offspring) and 30 µg/L (Days to offspring) differs significantly from controls (P<0.05) by oneway ANOVA. For AgNO3 (3h pulse) the same trend is observed for No of offspring   • The stimulation in reproduction may result from silver’s antibacterial effect: Higher concentrations and/or other endpoints may be further tested  EC50,24h [µgAg/L] for continuous exposures (lines in graphs):  Freshly made Aged AgNPs 134 [120;149] < 80 AgNO3 4.5 [4.0;5.2] 2.6 [-] AgNO3 pulse exposure1h 2h 3h05101520EC50[µg Ag/L]

Pulse exposure of silver nanoparticles in acute and chronic toxicity tests with D. magna

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Pulse exposure of silver nanoparticles in acute and chronic toxicity tests with D. magna

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