Pharmaceutical and cosmetic silica nanoparticles: towards an understanding of their structure, fate and behaviour in aquatic systems

工程化氧化物纳米颗粒广泛用于化妆品和个人护理产品（例如防晒霜、牙膏、护肤霜）以及局部施用的药物制剂（例如用于局部和透皮施用的乳膏）中，并且通常释放到废水中。这项小额资助研究了典型家庭使用的化妆品和药物配方中SiO2纳米颗粒对废水沃茨的负载，通过废水化学处理（絮凝和沉淀）去除SiO2纳米颗粒的效率，以及SiO2纳米颗粒在天然沃茨中的稳定性、结构和行为。选择SiO2纳米颗粒用于本研究，因为这些类型的氧化物纳米颗粒广泛用于所研究的制剂中。先前的研究表明，离散的纳米颗粒和小的聚集体可能比较大的聚集体对水生生物更具生物利用性/毒性，并且纳米颗粒的絮凝和沉降可能减轻生态毒性并减少纳米颗粒在水生系统中的分散。因此，本研究提供了一系列的实验室实验，以测量在一系列的水化学条件下的SiO2纳米粒子的分散-聚集行为，从而评估是否SiO2纳米粒子有可能凝聚和沉淀出来，在化学水处理过程中，当排放到地表沃茨。我们的假设是：（1）化妆品（防晒霜、牙膏）和药物（局部应用的乳膏）为废水提供了SiO2纳米颗粒的重要来源。(2)化学水处理（絮凝和沉淀）在去除SiO2纳米颗粒方面的有效性有限。因此，纳米氧化物有可能通过处理后的污水排放到地表沃茨中。（3）纳米SiO2在水环境中的稳定性、迁移和归宿（相对于聚集体的大小、结构和沉积速率）受以下因素的影响：（a）含水基质化学（pH值、离子强度和组成），（B）与天然有机物的相互作用和（c）与水生沉积物的相互作用。

Engineered oxide nanoparticles are widely used in cosmetics and personal care products (e.g. sunscreens, toothpastes, skin creams) and in topically-applied pharmaceutical formulations (e.g. creams for local and transdermal application) and are routinely released into wastewaters. This Small Grant examines the loadings of SiO2 nanoparticles to wastewaters from typical domestic use of cosmetic and pharmaceutical formulations, the efficiency of removal of SiO2 nanoparticles by wastewater chemical treatment (flocculation and sedimentation) and stability, structure and behaviour of SiO2 nanoparticles in natural waters. SiO2 nanoparticles were selected for this study as these types of oxide nanoparticles are widely used in the formulations under study. Previous research indicates that discrete nanoparticles and small aggregates are likely to be more bioavailable/toxic to aquatic organisms than larger aggregates and that flocculation and sedimentation of nanoparticles are likely to mitigate ecotoxicity and reduce dispersion of nanoparticles within aquatic systems. Therefore, this study provides a series of laboratory experiments to measure the dispersion-aggregation behaviour of SiO2 nanoparticles under a range of aquatic chemical conditions, thereby assessing whether SiO2 nanoparticles are likely to agglomerate and sediment out during chemical water treatment and when discharged into surface waters. Our hypotheses are: (1) Cosmetics (sunscreens, toothpaste) and pharmaceuticals (topically applied creams) provide a significant source of SiO2 nanoparticles to wastewaters. (2) Chemical water treatment (flocculation and sedimentation) is limited in its effectiveness in removing SiO2 nanoparticles. There is therefore potential for discharge of oxide nanoparticles via treated effluent into surface waters (3) The stability, transport and fate of SiO2 nanoparticles in aquatic environments (in relation to aggregate size, structure and rates of sedimentation), are influenced by: (a) aqueous matrix chemistry (pH, ionic strength and composition), (b) interactions with natural organic matter and (c) interactions with aquatic sediments.