Tanaka Kosuke, Takahashi Yusuke, Kuramochi Hidetoshi, Osako Masahiro, Suzuki Go
Material Cycles Division, National Institute for Environmental Studies.
Yakugaku Zasshi. 2024;144(2):165-170. doi: 10.1248/yakushi.23-00152-1.
Nanoplastics (NPs) are plastic fragments that are small enough to be absorbed by organisms through ingestion or inhalation. Recent studies indicate that nanoplastics can be ubiquitous in the environment, and there are growing concerns regarding the impacts of nanoplastics on the health of humans and other organisms. However, quantitative information on nanoplastics in the environment is still very limited, and most previous toxicity studies have used only polystyrene (PS) particles because of a lack of appropriate model particles of other plastics. We developed a nanoprecipitation-based method for the preparation of nanoplastic particles of five major polymers: low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene. A major advantage of our method is that the nanoplastic particles are prepared without using reagents that can remain in the particles as impurities. Analysis of the prepared particles' molecular weight (M) distributions, crystallinities, and thermal properties revealed that their compositions and constitutions were within the general ranges for commercial products. The mechanisms underlying the formation of low-density polyethylene particles via our method were investigated by means of a simple population balance model, and particle diameter was found to be linearly correlated with the suspension density of the nanoplastic dispersion up to 0.4 mg·mL. Future studies should focus on improving our method to allow for precise, scale-independent production of nanoplastic particles. Methods for the preparation of labeled particles are also needed so that such particles can be used in nanoplastic risk assessments.
纳米塑料（NPs）是尺寸小到足以被生物体通过摄食或吸入而吸收的塑料碎片。最近的研究表明，纳米塑料在环境中可能无处不在，人们对纳米塑料对人类和其他生物体健康的影响越来越担忧。然而，关于环境中纳米塑料的定量信息仍然非常有限，而且由于缺乏其他塑料的合适模型颗粒，以前的大多数毒性研究仅使用了聚苯乙烯（PS）颗粒。我们开发了一种基于纳米沉淀的方法来制备五种主要聚合物的纳米塑料颗粒：低密度聚乙烯（LDPE）、高密度聚乙烯（HDPE）、聚丙烯（PP）、聚氯乙烯（PVC）和聚苯乙烯。我们方法的一个主要优点是，制备纳米塑料颗粒时不使用可能作为杂质残留在颗粒中的试剂。对制备颗粒的分子量（M）分布、结晶度和热性能的分析表明，它们的组成和结构在商业产品的一般范围内。通过一个简单的总体平衡模型研究了通过我们的方法形成低密度聚乙烯颗粒的机制，发现颗粒直径与纳米塑料分散体的悬浮密度在高达0.4 mg·mL时呈线性相关。未来的研究应侧重于改进我们的方法，以实现纳米塑料颗粒的精确、与规模无关的生产。还需要制备标记颗粒的方法，以便这些颗粒可用于纳米塑料风险评估。
