Moore Dwayne R J, Teed R Scott, Richardson G Mark
The Cadmus Group, Inc., 411 Roosevelt Avenue, Suite 204, Ottawa, Ontario K2A 3X9, Canada.
Environ Toxicol Chem. 2003 Dec;22(12):3069-80. doi: 10.1897/02-409.
Mercury is considered to be a serious risk to wildlife. As a result, the Great Lakes Water Quality Initiative and others have developed ambient water quality criteria (AWQC) for the protection of wildlife. These AWQC have been controversial, however, because the AWQC were single values that did not account for site-specific conditions, derivation of the AWQC relied on a single no-observed-adverse-effect level, and the AWQC had an unknown level of conservatism because of reliance on both average and conservative assumptions and uncertainty factors. Rather than develop a single-value AWQC for total mercury, we derived an AWQC model that explicitly incorporates factors controlling bioavailability, methylation rates, and bioaccumulation in the aquatic environment (e.g., pH, dissolved organic carbon). To derive our AWQC model, field data were collected from 31 lakes in Ontario and an additional 10 lakes in Nova Scotia (North America). In the field study, levels of total and methylmercury in water and fish as well as levels of key water quality variables were determined. We conducted multiple-regression analysis to derive a model that estimates mercury levels in prey of mink. Mink are very sensitive to mercury exposure. An independent dataset consisting of 51 water bodies in the United States was then used to confirm the validity and robustness of the AWQC model. Next, we combined the results of chronic-feeding studies with similar protocols and endpoints in a meta-analysis to derive a dose-response curve for mink exposed to mercury in the diet. In the final step, we used a probabilistic risk model to estimate the concentrations of methylmercury in water that would lead to levels in fish sufficient for a 10% probability of exceeding the lethal dose affecting 5% of the mink population. The result is an AWQC equation for mercury for the protection of wildlife that can be used with a variety of site-specific conditions.
汞被认为对野生动物构成严重威胁。因此，五大湖水质量倡议组织及其他机构制定了保护野生动物的环境水质标准（AWQC）。然而，这些AWQC存在争议，因为它们是单一数值，未考虑特定场地条件，AWQC的推导依赖于单一的未观察到不良反应水平，并且由于依赖平均和保守假设以及不确定性因素，AWQC的保守程度未知。我们没有为总汞制定单一数值的AWQC，而是推导了一个AWQC模型，该模型明确纳入了控制水生环境中生物可利用性、甲基化率和生物累积的因素（例如pH值、溶解有机碳）。为了推导我们的AWQC模型，从安大略省的31个湖泊以及新斯科舍省（北美洲）的另外10个湖泊收集了现场数据。在实地研究中，测定了水和鱼类中总汞和甲基汞的含量以及关键水质变量的水平。我们进行了多元回归分析，以推导一个估计水貂猎物中汞含量的模型。水貂对汞暴露非常敏感。然后使用由美国51个水体组成的独立数据集来确认AWQC模型的有效性和稳健性。接下来，我们在一项荟萃分析中结合了具有相似方案和终点的慢性喂养研究结果，以推导饮食中暴露于汞的水貂的剂量反应曲线。在最后一步中，我们使用概率风险模型来估计水中甲基汞的浓度，该浓度将导致鱼类中的汞含量足以使5%的水貂种群有10%的概率超过致死剂量。结果是一个用于保护野生动物的汞的AWQC方程，可用于各种特定场地条件。
