NCASI, Middleton, WI, USA.
NCASI, Anacortes, WA, USA.
Integr Environ Assess Manag. 2023 Mar;19(2):501-512. doi: 10.1002/ieam.4683. Epub 2022 Oct 4.
National recommendations for numeric human health ambient water quality criteria (AWQC) for toxic substances are derived by the US Environmental Protection Agency (USEPA) using a deterministic approach that combines point estimates for exposure, toxicity, and acceptable risk. In accordance with the Clean Water Act, states, territories, and authorized tribes must either adopt these recommendations or modify and replace them with criteria using an alternative, scientifically defensible method. Recent reports have criticized the deterministic approach, stating that it suffers from compounded conservatism by selecting upper percentiles or maximum values for multiple inputs and that it cannot directly determine what portion of the population a given criterion protects. As an alternative, probabilistic risk assessment (PRA) has been promoted as a more transparent and robust method for deriving AWQC. Probabilistic risk assessment offers several advantages over the deterministic approach. For example, PRA uses entire data distributions rather than upper-percentile point estimates to specify exposures, thereby reducing compounded conservatism. Additionally, because it links acceptable risk targets with specific segments of the exposed population, PRA-based AWQC demonstrably protects multiple subsets of the population. To date, no study has quantitatively compared deterministic and PRA approaches and resulting AWQC using national inputs consistent with USEPA guidance. This study introduces a PRA method for deriving AWQC and presents case studies to compare probabilistically derived AWQC with USEPA's 2015 recommendations. The methods and results of this work will help federal and state regulators, water quality managers, and stakeholders better understand available approaches to deriving AWQC and provide context to assumption- and method-specific differences between criteria. Integr Environ Assess Manag 2023;19:501-512. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
美国环境保护署（USEPA）采用确定性方法，结合暴露、毒性和可接受风险的点估计值，为有毒物质制定国家推荐的数值式人体健康环境水质标准（AWQC）。根据《清洁水法》，各州、领土和授权部落必须采用这些建议，或者使用替代的、具有科学合理性的方法修改和替换这些标准。最近的报告批评了确定性方法，称其在选择多个输入的上限百分位或最大值时存在复合保守性，并且无法直接确定给定标准保护的人群比例。作为替代方法，概率风险评估（PRA）已被推广为一种更透明和稳健的方法，用于推导 AWQC。概率风险评估相对于确定性方法具有几个优势。例如，PRA 使用整个数据分布而不是上限百分位点估计来指定暴露，从而减少复合保守性。此外，由于它将可接受的风险目标与暴露人群的特定部分联系起来，基于 PRA 的 AWQC 可以明显保护人群的多个子集。迄今为止，没有研究使用与 USEPA 指南一致的国家投入，对确定性和 PRA 方法以及由此产生的 AWQC 进行定量比较。本研究介绍了一种用于推导 AWQC 的 PRA 方法，并提出了案例研究，将概率推导的 AWQC 与 USEPA 2015 年的建议进行比较。这项工作的方法和结果将帮助联邦和州监管机构、水质管理人员和利益相关者更好地了解推导 AWQC 的可用方法，并为标准之间的假设和方法特定差异提供背景。2023 年综合环境评估与管理，19：501-512。© 2022 作者。综合环境评估与管理由 Wiley 期刊 LLC 代表环境毒理与化学学会（SETAC）出版。
