Taylor Lisa N, Novak Lesley, Rendas Martina, Antunes Paula M C, Scroggins Rick P
Environment Canada, Ottawa, Ontario, Canada.
AquaTox Testing & Consulting, Guelph, Ontario, Canada.
Environ Toxicol Chem. 2016 Oct;35(10):2430-2438. doi: 10.1002/etc.3453. Epub 2016 Jul 7.
Environment Canada has developed a new 42-d sediment toxicity test method that includes a reproduction test endpoint with the freshwater amphipod Hyalella azteca. Because of concerns that existing standard methodologies, whereby adults are transferred to a water-only exposure before release of their first brood at day 28, will lead to internal contaminant depuration and loss of sensitivity, the Environment Canada methodology conducts the entire exposure in sediment. To demonstrate applicability of the method for assessing the toxicity of chemical-spiked sediment, H. azteca were exposed for 42 d to sediment amended with silver nitrate (AgNO ). Mortality was significantly higher at the highest sediment concentration of Ag (2088 mg/kg dry wt); however, there was no significant reduction in biomass or reproduction as a result of Ag exposure despite significant bioaccumulation. Based on Ag measurements and speciation modeling, the principle route of Ag exposure was likely through the ingestion of complexed colloidal or particulate Ag. The techniques used to recover young amphipods from sediment were critical, and although this effort can be labor intensive (20-45 min/replicate), the technicians demonstrated 91% recovery in blind trials. For the first time, Environment Canada will require laboratories to report their recovery proficiency for the 42-d test-without this information, data will not be accepted. Overall, the reproduction test will be more applicable when only a few chemical concentrations need to be evaluated in laboratory-amended sediments or for field-collected contaminated site assessments (i.e., contaminated site vs reference site comparisons). Environ Toxicol Chem 2016;35:2430-2438. © 2016 SETAC.
加拿大环境部开发了一种新的42天沉积物毒性测试方法，该方法包括以淡水双足类动物阿氏摇蚊（Hyalella azteca）为对象的繁殖测试终点。由于担心现有的标准方法（即在第28天首次产卵前将成年个体转移到仅含水体中进行暴露）会导致体内污染物净化和敏感性丧失，加拿大环境部的方法是在沉积物中进行整个暴露过程。为了证明该方法在评估化学物质添加沉积物毒性方面的适用性，将阿氏摇蚊暴露于用硝酸银（AgNO）改良的沉积物中42天。在最高银沉积物浓度（2088毫克/千克干重）下，死亡率显著更高；然而，尽管有显著的生物累积，但银暴露并未导致生物量或繁殖率显著降低。基于银的测量和形态建模，银暴露的主要途径可能是通过摄入络合的胶体或颗粒银。从沉积物中回收幼体双足类动物所使用的技术至关重要，尽管这项工作可能劳动强度大（每个重复20 - 45分钟），但技术人员在盲测中展示了91%的回收率。加拿大环境部将首次要求实验室报告其在42天测试中的回收熟练度——没有这些信息，数据将不被接受。总体而言，当在实验室改良沉积物中仅需评估少数化学浓度时，或用于现场采集的污染场地评估（即污染场地与参考场地比较）时，繁殖测试将更适用。《环境毒理学与化学》2016年；35:2430 - 2438。© 2016 SETAC。
