Beckingham B, Ghosh U
Department of Geology & Environmental Geosciences, College of Charleston, 66 George Street, Charleston, SC 29424, United States.
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States.
Environ Pollut. 2017 Jan;220(Pt A):150-158. doi: 10.1016/j.envpol.2016.09.033. Epub 2016 Sep 17.
Microplastic particles are increasingly being discovered in diverse habitats and a host of species are found to ingest them. Since plastics are known to sorb hydrophobic organic contaminants (HOCs) there is a question of what risk of chemical exposure is posed to aquatic biota from microplastic-associated contaminants. We investigate bioavailability of polychlorinated biphenyls (PCBs) from polypropylene microplastic by measuring solid-water distribution coefficients, gut fluid solubilization, and bioaccumulation using sediment invertebrate worms as a test system. Microplastic-associated PCBs are placed in a differential bioavailability framework by comparing the results to several other natural and anthrogenic particles, including wood, coal, and biochar. PCB distribution coefficients for polypropylene were higher than natural organic materials like wood, but in the range of lipids and sediment organic carbon, and smaller than black carbons like coal and biochars. Gut fluid solubilization potential increased in the order: coal < polypropylene < biochar < wood. Interestingly, lower gut fluid solubilization for polypropylene than biochar infers that gut fluid micelles may have solubilized part of the biochar matrix while bioaccessibility from plastic can be limited by the solubilizing potential of gut fluids dependent on the solid to liquid ratio or renewal of fluids in the gut. Biouptake in worms was lower by 76% when PCBs were associated with polypropylene compared to sediment. The presence of microplastics in sediments had an overall impact of reducing bioavailability and transfer of HOCs to sediment-ingesting organisms. Since the vast majority of sediment and suspended particles in the environment are natural organic and inorganic materials, pollutant transfer through particle ingestion will be dominated by these particles and not microplastics. Therefore, these results support the conclusion that in most cases the transfer of organic pollutants to aquatic organisms from microplastic in the diet is likely a small contribution compared to other natural pathways of exposure.
在各种栖息地中越来越多地发现微塑料颗粒，并且发现许多物种会摄取它们。由于已知塑料会吸附疏水性有机污染物（HOCs），因此存在一个问题，即与微塑料相关的污染物会对水生生物群造成何种化学暴露风险。我们通过测量固 - 水分配系数、肠道液溶解作用，并以沉积物无脊椎动物蠕虫作为测试系统来研究生物累积，从而调查来自聚丙烯微塑料的多氯联苯（PCBs）的生物可利用性。通过将结果与其他几种天然和人为颗粒（包括木材、煤炭和生物炭）进行比较，将与微塑料相关的多氯联苯置于差异生物可利用性框架中。聚丙烯的多氯联苯分配系数高于木材等天然有机材料，但在脂质和沉积物有机碳的范围内，且小于煤炭和生物炭等黑碳。肠道液溶解潜力按以下顺序增加：煤炭＜聚丙烯＜生物炭＜木材。有趣的是，聚丙烯的肠道液溶解作用低于生物炭，这表明肠道液胶束可能溶解了部分生物炭基质，而塑料的生物可及性可能受到肠道液溶解潜力的限制，这取决于固液比或肠道中液体的更新。与沉积物相比，当多氯联苯与聚丙烯相关联时，蠕虫中的生物摄取量降低了76%。沉积物中微塑料的存在总体上降低了HOCs向摄取沉积物的生物的生物可利用性和转移。由于环境中绝大多数沉积物和悬浮颗粒是天然有机和无机材料，通过颗粒摄取的污染物转移将由这些颗粒主导，而非微塑料。因此，这些结果支持以下结论：在大多数情况下，与其他天然暴露途径相比，饮食中微塑料向水生生物转移有机污染物的贡献可能较小。
