Harmon Ashley R, Kennedy Alan J, Laird Jennifer G, Bednar Anthony J, Steevens Jeffery A
a Environmental Laboratory , US Army Engineer Research and Development Center , Vicksburg , MS , USA.
b USGS Columbia Environmental Research Center , Columbia , MO , USA.
Nanotoxicology. 2017 Nov-Dec;11(9-10):1127-1139. doi: 10.1080/17435390.2017.1399219. Epub 2017 Dec 1.
As integration of nanoparticles (NPs) into products becomes more common, the need to address the paucity of chronic hazard information for aquatic environments required to determine risk potential increases. This study generated acute and chronic toxicity reference values for Ceriodaphnia dubia exposed to 20 and 100 nm silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) to generate and evaluate potential differences in acute-to-chronic ratios (ACR) using two different feeding methods. A modified feeding procedure was employed alongside the standard procedures to investigate the influence of food on organism exposure. An 8-h period before food was added allowed direct organism exposure to NP dispersions (and associated ions) without food-to-NP interactions. The AgNPs [chronic lethal median concentrations (LC50) between 18.7 and 31.9 µg/L] were substantially more toxic than AuNPs (LC50 = 21 507 to >26 384 µg/L). The modified chronic testing method resulted in greater sensitivity in AgNPs exposures. However, the modified feeding ration had less of an effect in exposures to the larger (100 nm) AgNPs compared to smaller particles (20 nm). The ACRs for AgNPs using the standard feeding ration were 1.6 and 3.5 for 20 nm and 100 nm, respectively. The ACRs for AgNPs using the modified feeding ration were 3.4 and 7.6 for 20 nm and 100 nm NPs, respectively. This supports that the addition of the standard feeding ration decreases C. dubia chronic sensitivity to AgNPs, although it must also be recognized organisms may be sensitized due to less access to food. The ACRs for 20 nm and 100 nm AuNPs (standard ration only) were 4.0 and 3.0, respectively. It is important to also consider that dissolved Ag ions are more toxic than AgNPs, based on both acute toxicity values in the cited literature and chronic toxicity thresholds generated in this study that support existing thresholds that Ag are likely protective of AgNPs effects.
随着纳米颗粒（NPs）在产品中的整合变得越来越普遍，确定潜在风险所需的水生环境慢性危害信息匮乏问题愈发凸显。本研究生成了暴露于20纳米和100纳米银纳米颗粒（AgNPs）及金纳米颗粒（AuNPs）的杜氏哲水蚤的急性和慢性毒性参考值，以使用两种不同喂食方法生成并评估急性与慢性比率（ACR）的潜在差异。采用了一种改良的喂食程序以及标准程序来研究食物对生物暴露的影响。在添加食物前有8小时的时间段，使生物能直接暴露于NP分散液（及相关离子）而不存在食物与NP的相互作用。AgNPs[慢性致死中浓度（LC50）在18.7至31.9μg/L之间]的毒性显著高于AuNPs（LC50 = 21507至>26384μg/L）。改良的慢性测试方法在AgNPs暴露中产生了更高的敏感性。然而，与较小颗粒（20纳米）相比，改良的喂食量对较大（100纳米）AgNPs暴露的影响较小。使用标准喂食量时，20纳米和100纳米AgNPs的ACR分别为1.6和3.5。使用改良喂食量时，20纳米和100纳米NP的AgNPs的ACR分别为3.4和7.6。这表明添加标准喂食量会降低杜氏哲水蚤对AgNPs的慢性敏感性，不过也必须认识到生物可能因获取食物减少而变得敏感。20纳米和100纳米AuNPs（仅标准喂食量）的ACR分别为4.0和3.0。同样重要的是要考虑到，根据引用文献中的急性毒性值以及本研究中生成的慢性毒性阈值，溶解的Ag离子比AgNPs毒性更大，这支持了现有的阈值，即Ag可能对AgNPs的效应具有保护作用。
