Stetten Lucie, Mackevica Aiga, Tepe Nathalie, Hofmann Thilo, von der Kammer Frank
Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, UZA II, 1090 Vienna, Austria.
Nanomaterials (Basel). 2022 Feb 2;12(3):519. doi: 10.3390/nano12030519.
The dissolution of metal-based engineered nanomaterials (ENMs) in aquatic environments is an important mechanism governing the release of toxic dissolved metals. For the registration of ENMs at regulatory bodies such as REACH, their dissolution behavior must therefore be assessed using standardized experimental approaches. To date, there are no standardized procedures for dissolution testing of ENMs in environmentally relevant aquatic media, and the Organisation for Economic Co-operation and Development (OECD) strongly encourages their development into test guidelines. According to a survey of surface water hydrochemistry, we propose to use media with low concentrations of Ca and Mg for a better simulation of the ionic background of surface waters, at pH values representing acidic (5 < pH < 6) and near-neutral/alkaline (7 < pH < 8) waters. We evaluated a continuous flow setup adapted to expose small amounts of ENMs to aqueous media, to mimic ENMs in surface waters. For this purpose, silver nanoparticles (Ag NPs) were used as model for soluble metal-bearing ENMs. Ag NPs were deposited onto a 10 kg.mol membrane through the injection of 500 µL of a 5 mg.L or 20 mg.L Ag NP dispersion, in order to expose only a few micrograms of Ag NPs to the aqueous media. The dissolution rate of Ag NPs in 10 mM NaNO was more than two times higher for ~2 µg compared with ~8 µg of Ag NPs deposited onto the membrane, emphasizing the importance of evaluating the dissolution of ENMs at low concentrations in order to keep a realistic scenario. Dissolution rates of Ag NPs in artificial waters (2 mM Ca(NO), 0.5 mM MgSO, 0-5 mM NaHCO) were also determined, proving the feasibility of the test using environmentally relevant media. In view of the current lack of harmonized methods, this work encourages the standardization of continuous flow dissolution methods toward OECD guidelines focused on natural aquatic environments, for systematic comparisons of nanomaterials and adapted risk assessments.
金属基工程纳米材料（ENMs）在水生环境中的溶解是控制有毒溶解态金属释放的重要机制。因此，对于在诸如《化学品注册、评估、授权和限制法规》（REACH）等监管机构进行ENMs注册时，必须使用标准化实验方法评估其溶解行为。迄今为止，尚无针对ENMs在与环境相关的水生介质中进行溶解测试的标准化程序，经济合作与发展组织（OECD）强烈鼓励将其制定为测试指南。根据对地表水水化学的调查，我们建议使用低钙镁浓度的介质，以更好地模拟地表水的离子背景，pH值分别代表酸性（5＜pH＜6）和近中性/碱性（7＜pH＜8）水体。我们评估了一种连续流动装置，该装置适用于使少量ENMs暴露于水性介质中，以模拟地表水中的ENMs。为此，使用银纳米颗粒（Ag NPs）作为含可溶性金属的ENMs的模型。通过注入500 μL 5 mg/L或20 mg/L的Ag NP分散液，将Ag NPs沉积在10 kDa的膜上，以便仅使几微克的Ag NPs暴露于水性介质中。与沉积在膜上的约8 μg Ag NPs相比，约2 μg Ag NPs在10 mM NaNO₃中的溶解速率高出两倍多，这强调了在低浓度下评估ENMs溶解以保持实际情况的重要性。还测定了Ag NPs在人工水（2 mM Ca(NO₃)₂、0.5 mM MgSO₄、0 - 5 mM NaHCO₃）中的溶解速率，证明了使用与环境相关的介质进行测试的可行性。鉴于目前缺乏统一的方法，这项工作鼓励将连续流动溶解方法标准化，朝着侧重于自然水生环境的OECD指南发展，以便对纳米材料进行系统比较和进行适当的风险评估。
