Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
Aquatic Ecology and Water Quality Management Group, Wageningen University and Research, Wageningen, The Netherlands.
Environ Toxicol Chem. 2024 Aug;43(8):1717-1727. doi: 10.1002/etc.5820. Epub 2024 Feb 12.
Sediment toxicity tests have applications in ecological risk and chemical safety assessments. Despite the many years of experience in testing and the availability of standard protocols, sediment toxicity testing remains challenging with very hydrophobic organic chemicals (VHOCs; i.e., chemicals with a log octanol/water partition coefficient of more than 6). The challenges primarily relate to the chemicals' low aqueous solubilities and slow kinetics, due to which several experimental artifacts may occur. To investigate the potential artifacts, experiments were performed, focusing on spiking and equilibrating (aging) sediments, as well as exposure quantification with passive sampling. The results demonstrated that generally applied, Organisation for Economic Co-operation and Development-recommended spiking (coating) methods may lead to significant chemical losses and the formation of nondissolved, nonbioavailable VHOCs. Direct spiking appeared to be the most optimal, provided that intensive mixing was applied simultaneously. Passive dosing was tested as a novel way of spiking liquid VHOCs, but the approach proved unsuccessful. Intensive postspiking mixing during sediment equilibration for 1 to 2 weeks was shown to be essential for producing a homogeneous system, minimizing the presence of nondissolved chemical (crystals or nonaqueous phase liquids; NAPLs), and creating a stable toxicological response in subsequent toxicity tests. Finally, exposure quantification of VHOCs in sediments through passive sampling was found to be feasible with different polymers, although prolonged equilibration times may be required, and determining sampler/water partition coefficients can be extremely challenging. The results of additional experiments, focusing on toxicity test exposure duration, concentrations above which NAPLs will occur, and ways to distinguish actual toxicity from false-positive results, are presented in Part 2 of this publication series. Environ Toxicol Chem 2024;43:1717-1727. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
沉积物毒性测试在生态风险和化学安全评估中具有应用。尽管在测试方面拥有多年的经验并且有标准协议可用，但对于非常疏水的有机化学品（VHOC；即，具有大于 6 的对数辛醇/水分配系数的化学品），沉积物毒性测试仍然具有挑战性。这些挑战主要与化学物质的低水溶解度和缓慢的动力学有关，由于这些原因，可能会发生几种实验假象。为了研究潜在的假象，进行了实验，重点是添加和平衡（老化）沉积物，以及使用被动采样进行暴露量化。结果表明，通常应用的经济合作与发展组织推荐的添加（涂层）方法可能导致化学物质大量损失，并形成不溶解的、不可生物利用的 VHOC。直接添加似乎是最理想的方法，只要同时应用强烈混合即可。作为一种添加液体 VHOC 的新方法测试了被动给药，但该方法被证明是不成功的。在沉积物平衡期间，在 1 到 2 周内进行强烈的添加后混合对于产生均匀的系统、最小化不溶解化学物质（晶体或非水相液体；NAPL）的存在以及在随后的毒性测试中产生稳定的毒性反应至关重要。最后，通过不同的聚合物发现通过被动采样量化沉积物中 VHOC 的暴露是可行的，尽管可能需要延长平衡时间，并且确定采样器/水分配系数可能极具挑战性。本出版物系列的第 2 部分介绍了针对毒性测试暴露持续时间、发生 NAPL 的浓度以及区分实际毒性和假阳性结果的方法的其他实验的结果。环境毒理化学 2024；43：1717-1727。©2024 作者。环境毒理化学由 Wiley Periodicals LLC 代表 SETAC 出版。
