Küster Eberhard, Addo George Gyan, Aulhorn Silke, Kühnel Dana
Department Ecotoxicology (former Department Bioanalytical Ecotoxicology), Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
UCL Open Environ. 2025 Jan 29;7:e3037. doi: 10.14324/111.444/ucloe.3037. eCollection 2025.
International standard test guidelines for the ecotoxicological characterisation of various substances use organisms such as algae, daphnids and fish embryos. These guidelines recommend or use relatively high volumes of water for the process of testing, for example, 200 mL for a complete dose-response relationship in a daphnia assay. However, for various samples such as concentrated extracts from environmental monitoring or leachates from microplastic ageing experiments, the amount of available sample volume is limited, that is, rather in the range of 10-50 mL/biotest. Using the exposure volumes as recommended in test guidelines would not allow to test a range of different concentrations or to repeat tests or use multiple different organismic bioassays. Lower media volumes would allow the testing of more samples (more concentrations per sample, more test repetitions for statistical robustness, etc.) but it may also decrease the possible number of organisms tested in the same volume. Here, we aimed at reducing the test volumes in the acute daphnia assay (using a maximum of 30 mL for a complete dose-response relationship) without impacting animals' sensitivity towards toxicants. A literature review on existing miniaturisation approaches was used as a starting point. Subsequently, assays employing conventional as well as reduced test volumes were compared for 16 selected test substances with a diverse spectrum of lipophilicity. Results showed that there are differences in EC between the two approaches, but that these differences were overall only within a range of a factor of two to three. Further, by retrieving EC values for the genus and 16 test substances from the United States Environmental Protection Agency database, we demonstrated that our results are well in line with the general differences in sensitivities.
各种物质生态毒理学特性的国际标准测试指南使用藻类、水蚤和鱼类胚胎等生物。这些指南在测试过程中推荐或使用相对大量的水，例如，在水蚤试验中确定完整的剂量-反应关系需要200毫升水。然而，对于各种样品，如环境监测的浓缩提取物或微塑料老化实验的浸出液，可用样品体积有限，即每次生物测试的体积在10-50毫升范围内。按照测试指南中推荐的暴露体积，将无法测试一系列不同浓度，或重复测试，或使用多种不同的生物测定方法。较低的培养基体积可以测试更多的样品（每个样品更多的浓度，为保证统计稳健性进行更多的测试重复等），但也可能减少在相同体积中测试的生物数量。在这里，我们旨在减少急性水蚤试验中的测试体积（确定完整的剂量-反应关系最多使用30毫升），同时不影响动物对毒物的敏感性。我们以对现有小型化方法的文献综述为起点。随后，对16种具有不同亲脂性的选定测试物质，比较了采用常规测试体积和减少测试体积的试验。结果表明，两种方法之间的半数效应浓度（EC）存在差异，但总体而言，这些差异仅在两到三倍的范围内。此外，通过从美国环境保护局数据库中检索该属和16种测试物质的EC值，我们证明我们的结果与敏感性的总体差异非常吻合。
