School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
Sci Total Environ. 2020 Sep 1;733:138802. doi: 10.1016/j.scitotenv.2020.138802. Epub 2020 May 12.
Samples of beached plastics and historical and contemporary consumer plastics containing hazardous elements derived from reaction residues or functional additives have been micronised and subject to extraction conditions representative of the digestive environment of seabirds. Mobilisation of Br, Cd, Cr, Hg, Pb and Sb into NaCl solution, an avian physiologically-based extraction test (PBET) and a dietary-adapted PBET (DA-PBET) incorporating fish oil as part of the avian diet was monitored by ICP-MS over a 168-h period. Kinetic data were subsequently fitted using pseudo-first-order and parabolic diffusion models in order to derive rate constants for the release of hazardous elements during avian digestion of microplastics. Rate constants were variable and dependent on the nature and origin of plastic, type of residue or additive, extractant solution employed and model applied. Resulting estimates of bioaccessibility, defined as the equilibrium or maximum concentration of an element mobilised over the time course relative to its total concentration, were variable but considerable in many cases. Specifically, maximum values of about 65% of Cd and 100% of Pb were observed in consumer polycarbonate-acrylonitrile butadiene styrene exposed to the avian PBET and beached polyurethane exposed to the DA-PBET, respectively. The potential health risks of hazardous elements in microplastics are addressed and criteria for classification based on the European Toy Safety Directive migration (mobilisation) limits are proposed.
已将海滩塑料和含源自反应残留物或功能添加剂的有害元素的历史和当代消费塑料样品进行了微细化处理，并采用了代表海鸟消化环境的提取条件进行了提取。通过 ICP-MS 监测了 Br、Cd、Cr、Hg、Pb 和 Sb 在 NaCl 溶液中的迁移情况，这是一种基于生理的鸟类提取试验（PBET）和一种包含鱼油的适应饮食的 PBET（DA-PBET），作为鸟类饮食的一部分。在 168 小时的时间内，通过使用拟一级和抛物线扩散模型对动力学数据进行拟合，以得出在鸟类消化微塑料过程中释放有害元素的速率常数。速率常数是可变的，取决于塑料的性质和来源、残留物或添加剂的类型、所使用的提取剂溶液以及应用的模型。根据生物可利用性的定义（即相对于其总浓度，在时间过程中被动员的元素的平衡或最大浓度），对生物可利用性进行了估计，结果在许多情况下是可变的，但相当大。具体而言，在暴露于鸟类 PBET 的消费级聚碳酸酯-丙烯腈-丁二烯-苯乙烯和暴露于 DA-PBET 的海滩级聚氨酯中，Cd 的最大值约为 65%，Pb 的最大值为 100%。文中还讨论了微塑料中有害元素的潜在健康风险，并提出了基于欧洲玩具安全指令迁移（动员）限值的分类标准。
