The generalized bioavailability model (gBAM) has been proposed as an alternative to the biotic ligand model (BLM) for modeling bioavailability and chronic toxicity of copper (Cu). The gBAM combines a log‐linear effect of pH on free Cu²⁺ ion toxicity with BLM‐type parameters for describing the protective effects of major cations (calcium [Ca]²⁺, magnesium [Mg]²⁺, and sodium [Na]⁺). In the present study, a Windermere Humic Aqueous Model (WHAM) VII‐based gBAM for fish was parametrized based on an existing chronic (30‐d) dataset of juvenile rainbow trout (Oncorhynchus mykiss). The model, with defined parameters (pH slope parameter [S_pH] = 0.4449 and biotic ligand competition constants [log K_CaBL = 4.0, log K_MgBL = 3.4, and log K_NaBL = 3.0]), was shown to accurately predict the effects of pH, dissolved organic carbon, Ca, and Mg on chronic Cu toxicity to juvenile rainbow trout at the effect levels relevant for environmental risk assessment (i.e., median prediction error of 1.3‐fold for 10 and 20% lethal concentrations). The gBAM predicted the effect of pH more accurately than a previously published Cu BLM for juvenile rainbow trout, especially at pH > 8. We also evaluated the cross‐species and cross‐life stage applicability of the newly developed juvenile rainbow trout gBAM using existing chronic Cu toxicity data with early life stages of fathead minnow (Pimephales promelas) and rainbow trout. We did this because using a single bioavailability model for all fish species and life stages is practical from a regulatory point of view. Although the early life stage datasets exhibit considerable uncertainties, 91% of the considered toxicity values at the effect levels most relevant in European environmental regulations (10% effect on survival or growth) were predicted within a 2‐fold error. Overall, the chronic Cu gBAM we developed is a valuable alternative for the existing chronic Cu BLM for rainbow trout and performs sufficiently well to be used in risk assessment according to currently accepted standards of bioavailability model performance (from the current European regulatory point of view). However, our analysis also suggests that bioavailability relations differ between different fish life stages and between endpoints (e.g., mortality vs growth), which is currently not accounted for in environmental risk assessments. Environ Toxicol Chem 2020;39:2424–2436. © 2020 SETAC

中文翻译：

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用于预测铜对淡水鱼的慢性毒性的通用生物利用度模型（gBAM）。

提出了通用生物利用度模型（gBAM）作为生物配体模型（BLM）的替代品，用于建模铜（Cu）的生物利用度和慢性毒性。gBAM结合了pH值对游离Cu ²⁺离子毒性的对数线性效应和BLM类型参数，用于描述主要阳离子（钙[Ca] ²⁺，镁[Mg] ²⁺和钠[Na] ⁺）。在本研究中，基于鱼虹鳟（Oncorhynchus mykiss）的现有慢性（30-d）数据集对基于温德米尔腐殖酸水模型（WHAM）VII的鱼进行了参数化。具有定义参数的模型（pH斜率参数[ S _pH] = 0.4449和生物配体竞争常数[log  K _CaBL  = 4.0，log  K _MgBL  = 3.4，log  K _NaBL = 3.0]），可以准确预测pH，溶解的有机碳，Ca和Mg对铜对少年虹鳟鱼的慢性毒性的影响，其影响水平与环境风险评估相关（即中位预测误差为1.3倍） 10％和20％的致死浓度）。gBAM预测的pH值比以前发表的Cu BLM更准确地预测了虹鳟鱼的幼鱼，特别是在pH> 8的情况下。我们还使用现有的慢性病评估了新开发的虹鳟gBAM的跨物种和跨生命阶段的适用性fat头min鱼早期生命阶段的铜毒性数据（Pimephales promelas）和虹鳟鱼。我们这样做是因为从监管角度来看，对所有鱼类和生命阶段使用单一生物利用度模型是可行的。尽管生命早期阶段的数据集显示出很大的不确定性，但在欧洲环境法规中最相关的影响水平（对生存或生长的影响为10％）下，所考虑的毒性值的91％预计会出现2倍误差。总体而言，我们开发的慢性Cu gBAM是现有的虹鳟用慢性Cu BLM的宝贵替代品，其性能足以根据当前公认的生物利用度模型性能标准（从当前欧洲法规的角度）用于风险评估。然而，2020年《环境毒理学》； 39：2424-2436。©2020 SETAC