Nautilus Environmental, Burnaby, British Columbia, Canada.
Environ Toxicol Chem. 2011 Jan;30(1):239-46. doi: 10.1002/etc.365.
Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.S. EPA) in deriving its water quality guideline for chloride may be conservative; a revised ACR of 3.50 is presented here. The endpoints used to calculate the ACR included 24-h to 96-h median lethal concentrations (LC50s) for acute tests, and 48-h to 54-d inhibition concentration (ICx) values for growth or reproduction for chronic exposures. Data from the present chronic toxicity tests, and other investigators, were used to propose a water quality guideline for long-term exposure to chloride using a species sensitivity distribution (SSD) approach. The 5th percentile from the SSD was calculated as 307 mg/L and proposed as the water quality guideline. Cladocerans were the most sensitive species in the dataset. Ceriodaphnia dubia was used to evaluate the relationship between water hardness and sensitivity to chloride. A strong relationship was observed and was used to establish a hardness-related equation to modify the proposed water quality guideline on the basis of water hardness, resulting in values ranging from 64 mg/L chloride at 10 mg/L hardness to 388 mg/L chloride at 160 mg/L hardness (as CaCO₃). These data suggest that current water quality guidelines for chloride may be overly conservative in water with moderate-to-high hardness, and may not be sufficiently protective under soft-water conditions.
采用 9 种淡水物种（大型溞、水蚤、虹鳟、蓝鳃太阳鱼、赤子爱胜蚓、颤蚓、摇蚊幼虫、食蚊鱼和萼花臂尾轮虫）进行毒性测试，以评估它们对氯化物的敏感性。这些测试的急性到慢性比值（ACR）表明，美国环保署（USEPA）在制定其氯化物水质指南时采用的 7.59 的 ACR 可能过于保守；这里提出了一个修订后的 ACR 值 3.50。用于计算 ACR 的终点包括急性测试的 24-96 小时中位数致死浓度（LC50），以及慢性暴露的 48-54 天生长或繁殖抑制浓度（ICx）值。本慢性毒性测试的数据以及其他研究人员的数据，用于使用物种敏感性分布（SSD）方法提出长期暴露于氯化物的水质指南。SSD 的第 5 个百分位数计算为 307 mg/L，并提议作为水质指南。在数据集中，枝角类动物是最敏感的物种。采用大型溞来评估水硬度与对氯化物敏感性之间的关系。观察到两者之间存在很强的关系，并利用这种关系建立了一个与硬度相关的方程，根据水硬度对提出的水质指南进行修正，结果表明，在硬度为 10 mg/L 时，氯化物的浓度范围为 64 mg/L，在硬度为 160 mg/L 时，氯化物的浓度范围为 388 mg/L（以 CaCO₃计）。这些数据表明，当前的氯化物水质指南在中等至高硬度的水中可能过于保守，而在软水条件下可能保护不足。
