National Health and Environmental Effects Research Laboratory, Office of Research and Development, Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA.
Environ Toxicol Chem. 2014 Jul;33(7):1563-9. doi: 10.1002/etc.2583. Epub 2014 May 20.
Toxicity of titanium dioxide nanoparticles (nano-TiO2 ) to aquatic organisms can be greatly increased after exposure to ultraviolet (UV) radiation. This phenomenon has received some attention for water column species; however, investigations of nano-TiO2 phototoxicity for benthic organisms are still limited. In the present study, bioassays of 3 representative benthic organisms (Hyalella azteca, Lumbriculus variegatus, and Chironomus dilutus) were conducted to evaluate nano-TiO2 phototoxicity. When exposed to 20 mg/L of nano-TiO2 and various light intensities (0-30 W/m(2)), H. azteca was the most sensitive, with a median lethal dose of 40.7 (95% confidence interval, 36.3-44.7) Wh/m(2), and hence is a potential model organism in future toxicological guidelines for photoactive nanomaterials to freshwater benthos. Without the presence of nano-TiO2 , no mortality was observed in L. variegatus and C. dilutus exposed to UV intensity ranging from 0 W/m(2) to 41 W/m(2). However, a sharp drop of H. azteca survival was observed when UV intensity was higher than 9.4 W/m(2), demonstrating the importance of UV-only effects on the ultimate phototoxicity of nanomaterials. Furthermore, both bioavailability and surface attachment of nano-TiO2 onto organisms were affected by the exposure scenario, supported by the exposure scenario-dependent phototoxicity seen in H. azteca and C. dilutus. Overall, the present study demonstrates the importance of species sensitivity and exposure scenarios in future test guidelines of nano-phototoxicity.
暴露于紫外线（UV）辐射后，二氧化钛纳米颗粒（nano-TiO2）对水生生物的毒性可能会大大增加。这种现象已经引起了人们对水柱物种的关注；然而，对于底栖生物的纳米 TiO2 光毒性的研究仍然有限。本研究采用 3 种典型底栖生物（Hyalella azteca、Lumbriculus variegatus 和 Chironomus dilutus）进行生物测定，评估了纳米 TiO2 的光毒性。当暴露于 20mg/L 的纳米 TiO2 和不同的光照强度（0-30W/m2）时，H.azteca 最为敏感，其半致死剂量为 40.7（95%置信区间，36.3-44.7）Wh/m2，因此是未来光活性纳米材料对淡水底栖生物毒理学指南的潜在模式生物。在没有纳米 TiO2 的情况下，L.variegatus 和 C.dilutus 在 0W/m2 至 41W/m2 的 UV 强度下暴露时没有观察到死亡率。然而，当 UV 强度高于 9.4W/m2 时，H.azteca 的存活率急剧下降，这表明 UV 单独作用对纳米材料最终光毒性的重要性。此外，纳米 TiO2 在生物体内的生物利用度和表面附着均受到暴露情况的影响，这一点得到了 H.azteca 和 C.dilutus 暴露情况依赖性光毒性的支持。总的来说，本研究表明，在未来的纳米光毒性测试指南中，物种敏感性和暴露情况非常重要。
