U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA.
Sci Total Environ. 2014 Jan 1;466-467:800-8. doi: 10.1016/j.scitotenv.2013.07.059. Epub 2013 Aug 25.
This study investigated phototoxicity of TiO₂ nanoparticles (nano-TiO₂) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (>77%) in LSW was observed after 0.5h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m(2). Phototoxicity of nano-TiO₂ under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5-23.3)Wh/m(2) when exposed to 20 mg/L nano-TiO₂. Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO₂ to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms.
本研究采用 48 小时和 96 小时生物测定法，调查了 TiO₂ 纳米颗粒（纳米 TiO₂）对淡水底栖片脚类动物（Hyalella azteca）的光毒性。通过动态光散射、紫外/可见光谱和扫描电子显微镜，对颗粒与暴露介质（苏必利尔湖湖水，LSW）和生物表面的相互作用进行了全面监测。在 0.5 小时后，观察到 LSW 中发生了>77%的大团聚和沉淀。观察到纳米颗粒在模拟太阳辐射（SSR）下有利于表面附着，表明随着附着的增加，光毒性增强。在 H. azteca 中计算出的 96 小时半数致死浓度（LC50）为 29.9mg/L，每日 4 小时紫外线暴露为 2.2 W/m²。与环境实验室光相比，SSR 下纳米 TiO₂的光毒性增加了 21 倍。这种光毒性也依赖于紫外线剂量，当暴露于 20mg/L 纳米 TiO₂时，计算出的 LC50 值约为 22.9（95%置信区间，20.5-23.3）Wh/m²。此外，H. azteca 在有遮蔽物的情况下表现出负趋光性，表明其他因素可能在环境系统中起作用。最后，说明了纳米 TiO₂对底栖生物的环境影响，强调了各种环境因素在最终光毒性中的重要性。这种增加的光毒性及其与各种环境因素的复杂相互作用表明，对于光活性纳米材料对底栖生物的未来风险评估，需要进一步进行研究。
