Nicholas School of the Environment , Duke University , Durham , North Carolina 27708 , United States.
North Carolina School of Science and Mathematics , Durham , North Carolina 27705 , United States.
Environ Sci Technol. 2019 Jul 16;53(14):8405-8415. doi: 10.1021/acs.est.9b02003. Epub 2019 Jul 1.
Plastics are recognized as a worldwide threat to the environment, possibly affecting human health and wildlife. Small forms of plastics such as micro- and nanoplastics can interact with other organic contaminants, potentially acting as chemical carriers and modulating their toxicity. In this study, we investigated the toxicity of polystyrene nanoparticles (Nano-PS) and a real-world environmental PAH mixture (Elizabeth River Sediment Extract, ERSE, comprised of 36 detected PAHs) to zebrafish embryos and larvae. Embryos were exposed to Nano-PS (0.1-10 ppm) or ERSE (0.1-5% v/v, equivalent to ΣPAH 5.07-25.36 ppb) or coexposed to a combination of both. Larvae exposed to Nano-PS did not exhibit developmental defects, while larvae exposed to ERSE (2-5%) showed classic signs of PAH toxicity such as heart malformation and deformities in the jaw, fin, and tail. ERSE (5%) also impaired vascular development in the brain. When coexposed, Nano-PS decreased the developmental deformities and impaired vascular development caused by ERSE. This was strongly correlated to the lower PAH bioaccumulation detected in the coexposed animals (whole larvae, as well as the yolk sac, brain, and heart). Our data suggest that PAHs are sorbing to the surface of the Nano-PS, decreasing the concentration, uptake, and toxicity of free PAHs during the exposure. Such sorption of PAHs increases the agglomeration rate of Nano-PS during the exposure time, potentially decreasing the uptake of Nano-PS and associated PAHs. Despite that, similar induction of EROD activity was detected in animals exposed to ERSE in the presence or not of Nano-PS, suggesting that enough PAHs were accumulated in the organisms to induce cellular defense mechanisms. Nano-PS exposure (single or combined with ERSE) decreased the mitochondrial coupling efficiency and increased NADH production, suggesting an impairment on ATP production accompanied by a compensatory mechanism. Our data indicate that nanoplastics can sorb contaminants and potentially decrease their uptake due to particle agglomeration. Nanoplastics also target and disrupt mitochondrial energy production and act as vectors for the mitochondrial uptake of sorbed contaminants during embryonic and larval stages. Such negative effects of nanoplastics on energy metabolism and efficiency could be detrimental under multiple-stressors exposures and energy-demanding scenarios, which remains to be validated.
塑料被公认为对环境的全球性威胁，可能影响人类健康和野生动物。微塑料和纳米塑料等小形式的塑料可以与其他有机污染物相互作用，可能充当化学载体并调节其毒性。在这项研究中，我们研究了聚苯乙烯纳米颗粒（Nano-PS）和实际环境多环芳烃混合物（伊丽莎白河沉积物提取物，ERSE，由 36 种检测到的多环芳烃组成）对斑马鱼胚胎和幼虫的毒性。胚胎暴露于 Nano-PS（0.1-10 ppm）或 ERSE（0.1-5％v/v，相当于ΣPAH 5.07-25.36 ppb）或两者的组合。暴露于 Nano-PS 的幼虫未表现出发育缺陷，而暴露于 ERSE（2-5％）的幼虫表现出多环芳烃毒性的典型迹象，如心脏畸形和颌骨，鳍和尾巴畸形。ERSE（5％）还损害了大脑中的血管发育。当共同暴露时，Nano-PS 降低了 ERSE 引起的发育畸形和血管发育受损。这与共同暴露动物中检测到的较低的多环芳烃生物积累强烈相关（整个幼虫，以及卵黄囊，大脑和心脏）。我们的数据表明，多环芳烃被吸附到 Nano-PS 的表面上，在暴露过程中降低了游离多环芳烃的浓度，吸收和毒性。在暴露时间内，这种多环芳烃的吸附增加了 Nano-PS 的团聚率，从而可能降低 Nano-PS 和相关多环芳烃的吸收。尽管如此，在存在或不存在 Nano-PS 的情况下，暴露于 ERSE 的动物中检测到类似的 EROD 活性诱导，表明足够的多环芳烃在生物体中积累以诱导细胞防御机制。Nano-PS 暴露（单独或与 ERSE 联合）降低了线粒体偶联效率并增加了 NADH 的产生，表明在 ATP 产生过程中存在损伤，同时存在代偿机制。我们的数据表明，纳米塑料可以吸附污染物，并由于颗粒团聚而可能降低其吸收。纳米塑料还靶向和破坏线粒体能量产生，并作为胚胎和幼虫阶段吸附污染物的线粒体摄取的载体。在多压力暴露和能量需求情况下，纳米塑料对能量代谢和效率的这种负面影响可能是有害的，这仍有待验证。
