Environmental Engineering Laboratory, Chemical Engineering Department, Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona, Spain.
Laboratory of Toxicology and Environmental Health, School of Medicine, IISPV, Rovira i Vir-gili University, Sant Llorenç 21, 43201 Reus, Spain.
Int J Environ Res Public Health. 2021 Jan 25;18(3):1037. doi: 10.3390/ijerph18031037.
Microalgae growth inhibition assays are candidates for referent ecotoxicology as a fundamental part of the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of exposed to heavy metals following standardized growth and photosynthesis inhibition assays was assessed in two different scenarios: (1) dilutions of single heavy metals and (2) an artificial mixture of heavy metals at similar levels as those found in natural rivers. Chemical speciation of heavy metals was estimated with Visual MINTEQ software; free heavy metal ion concentrations were used as input data, together with microalgae growth and photosynthesis inhibition, to compare different effects and explain possible toxicity mechanisms. The final goal was to assess the suitability of the ecotoxicological test based on the growth and photosynthesis inhibition of microalgae cultures, supported by mathematic models for regulatory and decision-making purposes. The algae growth inhibition test was more sensitive for As, Zn, and Pb exposure whereas the photosynthesis inhibition test was more sensitive for Cu and Ni exposure. The effects on growth and photosynthesis were not related. evidenced the formation of mucilaginous aggregations at lower copper concentrations. We found that the toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical compounds (as nutrient loads) and biological interactions play an important role in the final toxicity. Predictive mixture effect models tend to overestimate the effects of metal mixtures in for both growth and photosynthesis inhibition tests. Growth and photosynthesis inhibition tests give complementary information, and both are a fast, cheap, and sensitive alternative to animal testing. More research is needed to solve the challenge of complex pollutant mixtures as they are present in natural environments, where microalgae-based assays can be suitable monitoring tools for pollution management and regulatory purposes.
微藻生长抑制试验可作为参考毒理学的候选方法，这是减少鱼类和其他动物模型在水生毒理学中应用的策略的重要组成部分。在本工作中，评估了 在两种不同情况下暴露于重金属后的表现：（1）单一重金属的稀释液，（2）与天然河流中重金属水平相似的人工重金属混合物。使用 Visual MINTEQ 软件估算重金属的化学形态；将自由重金属离子浓度用作输入数据，结合微藻生长和光合作用抑制，比较不同的影响并解释可能的毒性机制。最终目标是评估基于微藻培养物生长和光合作用抑制的生态毒理学试验的适宜性，为监管和决策目的提供数学模型支持。藻类生长抑制试验对 As、Zn 和 Pb 暴露更敏感，而光合作用抑制试验对 Cu 和 Ni 暴露更敏感。生长和光合作用的影响没有相关性。 在较低铜浓度下表现出形成粘性聚集物的证据。我们发现，给定重金属的毒性不仅取决于其化学形态；其他化学化合物（如营养负荷）和生物相互作用在最终毒性中起着重要作用。对于生长和光合作用抑制试验，预测混合物效应模型往往会高估金属混合物的效应。生长和光合作用抑制试验提供互补信息，并且都是替代动物试验的快速、廉价和敏感的方法。需要进一步研究来解决复杂污染物混合物的挑战，因为它们存在于自然环境中，基于微藻的试验可以作为污染管理和监管目的的合适监测工具。
