工程纳米材料(ENM)在水介质中的独特行为和颗粒沉降的动态变化,团聚和溶解速率是对一致性的挑战,标准水生危害生物测定结果的可靠性和解释。而毒理学终点(例如,生存,增长,繁殖,等。)在生态毒性生物测定中,主要适用于ENM,溶解物质的标准方法被动态沉降所混淆,生物测定过程中颗粒ENM的聚集和溶解。设计了一个测试框架,以作为确定持续进行水生危害测试的方法的起点,这些方法说明了ENM在测试介质中的行为以及支持代表性暴露计量学的适当数据收集。通过进行三个案例研究来测试具有功能上不同特征和行为的ENM,从而证明了该框架。对颗粒浓度进行时间采样的预测试,在测试介质中对每个ENM进行团聚和溶解。结果表明,银纳米粒子(AgNP)粉末是不可分散的,纳米TiO2粉末是可分散的,但不稳定,和聚乙烯吡咯烷酮涂覆的AgNP在测试介质中相对稳定。基于这些功能结果,进行了Ceriodaphniadubia生物测定,以比较不同的暴露汇总方法(标称,算术平均,几何平均,时间加权平均值)用于计算和表达毒性终点。结果表明,虽然算术平均值对表达更稳定材料的毒性有效,时间加权平均浓度适用于不稳定的纳米TiO2。
The unique behavior of engineered nanomaterials (ENM) in aqueous media and dynamic changes in particle settling, agglomeration and dissolution rates is a challenge to the consistency, reliability and interpretation of standard aquatic hazard bioassay results. While the toxicological endpoints (e.g., survival, growth, reproduction, etc.) in ecotoxicity bioassays are largely applicable to ENMs, the standard methods as written for dissolved substances are confounded by the dynamic settling, agglomeration and dissolution of particulate ENMs during the bioassay. A testing framework was designed to serve as a starting point to identify approaches for the consistent conduct of aquatic hazard tests that account for the behavior of ENMs in test media and suitable data collection to support representative exposure metrology. The framework was demonstrated by conducting three
case studies testing ENMs with functionally distinct characteristics and behaviors. Pretests with a temporal sampling of particle concentration, agglomeration and dissolution were conducted on each ENM in test media. Results indicated that a silver nanoparticle (AgNP) powder was not dispersible, a nano-TiO2 powder was dispersible but unstable, and a polyvinylpyrrolidinone-coated AgNP was relatively stable in test media. Based on these functional results, Ceriodaphnia dubia bioassays were conducted to compare different exposure summary methods (nominal, arithmetic average, geometric average, time-weighted average) for calculating and expressing toxicity endpoints. Results indicated that while arithmetic means were effective for expressing the toxicity of more stable materials, time-weighted averaged concentrations were appropriate for the unstable nano-TiO2.