Department of Environmental Science and Analytical Chemistry, Stockholm University, Svante Arrhenius väg 8, SE-11418, Stockholm, Sweden.
Sci Rep. 2019 Jul 23;9(1):10695. doi: 10.1038/s41598-019-47160-1.
The occurrence of microplastic in the environment is of global concern. However, the microplastic hazard assessment is hampered by a lack of adequate ecotoxicological methods because of conceptual and practical problems with particle exposure. In the environment, suspended solids (e.g., clay and cellulose) in the same size range as microplastic, are ubiquitous. Therefore, it must be established whether the addition of microplastic to these background levels of particulate material represents a hazard. We present a novel approach employing a serial dilution of microplastic and reference particles, in mixtures, which allows disentangling the effect of the microplastic from that of the other particulates. We demonstrate the applicability of the method using an immobilization test with Daphnia magna exposed to polyethylene terephthalate (test microplastic; median particle diameter ~5 µm) and kaolin clay (reference material; ~3 µm). In the range of the suspended solids test concentrations (0-10 000 mg L), with microplastic contributing 0-100% of total mass, the LC values for the plastic mixtures were significantly lower compared to the kaolin exposure. Hence, the exposure to polyethylene terephthalate was more harmful to the daphnids than to the reference material alone. The estimated threshold for the relative contribution of the test microplastic to suspended matter above which significantly higher mortality was observed was 2.4% at 32 mg of the solids L. This approach has a potential for standardization of ecotoxicological testing of particulates, including microplastic.
环境中微塑料的出现引起了全球关注。然而，由于颗粒暴露存在概念和实际问题，缺乏足够的生态毒理学方法，阻碍了对微塑料危害的评估。在环境中，与微塑料处于相同尺寸范围的悬浮固体（例如粘土和纤维素）无处不在。因此，必须确定将微塑料添加到这些背景水平的颗粒物质中是否构成危害。我们提出了一种新方法，采用微塑料和参考颗粒的系列稀释混合物，从而可以将微塑料的影响与其他颗粒的影响分开。我们使用暴露于聚对苯二甲酸乙二醇酯（测试微塑料；中值粒径约 5μm）和高岭土（参考材料；~3μm）的大型溞固定化试验证明了该方法的适用性。在悬浮固体测试浓度范围内（0-10000mg/L），当微塑料贡献总质量的 0-100%时，与高岭土暴露相比，塑料混合物的 LC 值明显更低。因此，与参考材料单独暴露相比，暴露于聚对苯二甲酸乙二醇酯对大型溞的危害更大。在 32mg 固体/L 时，观察到明显更高死亡率的测试微塑料对悬浮物的相对贡献的估计阈值为 2.4%。该方法有可能实现对包括微塑料在内的颗粒物质的生态毒理学测试的标准化。
