Sørensen Sara Nørgaard, Holten Lützhøft Hans-Christian, Rasmussen Rose, Baun Anders
Department of Environmental Engineering, Technical University of Denmark, Building 115, DK-2800 Kgs. Lyngby, Denmark.
Department of Environmental Engineering, Technical University of Denmark, Building 115, DK-2800 Kgs. Lyngby, Denmark.
Aquat Toxicol. 2016 Nov;180:209-217. doi: 10.1016/j.aquatox.2016.10.004. Epub 2016 Oct 4.
Aquatic toxicity testing of nanoparticles (NPs) is challenged by their dynamic behavior in test suspensions. The resulting difficulties in controlling and characterizing exposure concentrations are detrimental to the generation of concentration-response data needed for hazard identification of NPs. This study explores the applicability of short-term (1, 2 and 3h) pulse exposures as means to keep the exposure stable and at the same time disclose acute and chronic effects of AgNPs and CuONPs in D. magna. Dissolution, agglomeration and sedimentation were found to have less influence on exposure concentrations during 1-3h pulses than for 24-48h continuous exposures. For AgNPs, preparation of test suspensions in medium 24h before toxicity testing (aging) increased stability during the short-term pulses. In pulse tests, organisms were exposed to the test materials, AgNPs and CuONPs for 1, 2 and 3h, and afterwards transferred to clean medium and observed for 48h (post-exposure period) for acute effects and for 21 d for chronic effects. AgNO and CuCl were used as reference materials for dissolved silver and copper, respectively. For all test materials, a 3h pulse caused comparable immobility in D. magna (observed after 48h post-exposure) as 24h continuous exposure, as evidenced by overlapping 95% confidence intervals of EC-values. In the 21 d post-exposure period, no trends in mortality or body length were identified. AgNP and AgNO pulses had no effect on the number of moltings, days to first live offspring or cumulated number of offspring, but the number of offspring increased for AgNPs (3h pulse only). In contrast, CuONP and CuCl pulses decreased the number of moltings and offspring, and for CuONPs the time to first live offspring was prolonged. After CuONP exposures, the offspring production decreased more with increasing concentrations than for CuCl exposures when taking the measured dissolved copper into account. This indicates a nanoparticle-specific effect for CuONPs, possibly related to the CuONPs accumulated in the gut of D. magna during the pulse exposure. Pulse exposure is an environmentally relevant exposure scenario for NPs, which for AgNPs and CuONPs enables more stable exposures and cause acute immobility of D. magna comparable to continuous 24h exposures. Pulse exposure is likely relevant and applicable for other toxic and dissolving metal NPs, but this requires further research.
纳米颗粒（NPs）在测试悬浮液中的动态行为给其水生毒性测试带来了挑战。由此在控制和表征暴露浓度方面产生的困难不利于生成纳米颗粒危害识别所需的浓度-反应数据。本研究探讨了短期（1、2和3小时）脉冲暴露作为保持暴露稳定的手段的适用性，同时揭示了银纳米颗粒（AgNPs）和氧化铜纳米颗粒（CuONPs）对大型溞（D. magna）的急性和慢性影响。结果发现，与24 - 48小时连续暴露相比，溶解、团聚和沉降在1 - 3小时脉冲暴露期间对暴露浓度的影响较小。对于AgNPs，在毒性测试前24小时在培养基中制备测试悬浮液（老化）可提高短期脉冲期间的稳定性。在脉冲测试中，将生物暴露于测试材料AgNPs和CuONPs中1、2和3小时，然后转移到清洁培养基中，并观察48小时（暴露后时期）以检测急性影响，观察21天以检测慢性影响。分别使用硝酸银（AgNO）和氯化铜（CuCl）作为溶解态银和铜的参考材料。对于所有测试材料，3小时脉冲在大型溞中导致的不动性（暴露后48小时观察到）与24小时连续暴露相当，这由EC值的95%置信区间重叠证明。在暴露后21天期间，未发现死亡率或体长的趋势。AgNP和AgNO脉冲对蜕皮次数、首次产生活后代的天数或后代累积数量没有影响，但AgNPs（仅3小时脉冲）使后代数量增加。相比之下，CuONP和CuCl脉冲减少了蜕皮次数和后代数量，并且对于CuONPs，首次产生活后代的时间延长。在考虑测量的溶解铜后，CuONP暴露后，随着浓度增加，后代产量下降的幅度比CuCl暴露时更大。这表明CuONPs存在纳米颗粒特异性效应，可能与脉冲暴露期间在大型溞肠道中积累的CuONPs有关。脉冲暴露是纳米颗粒与环境相关的暴露情景，对于AgNPs和CuONPs而言，它能实现更稳定的暴露，并导致大型溞出现与24小时连续暴露相当的急性不动性。脉冲暴露可能与其他有毒和可溶解金属纳米颗粒相关且适用，但这需要进一步研究。
