Johnston Jill, MacDonald Gibson Jacqueline
Division of Environmental Health, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Int J Environ Res Public Health. 2015 Nov 27;12(12):15040-57. doi: 10.3390/ijerph121214960.
At hazardous waste sites, volatile chemicals can migrate through groundwater and soil into buildings, a process known as vapor intrusion. Due to increasing recognition of vapor intrusion as a potential indoor air pollution source, in 2015 the U.S. Environmental Protection Agency (EPA) released a new vapor intrusion guidance document. The guidance specifies two conditions for demonstrating that remediation is needed: (1) proof of a vapor intrusion pathway; and (2) evidence that human health risks exceed established thresholds (for example, one excess cancer among 10,000 exposed people). However, the guidance lacks details on methods for demonstrating these conditions. We review current evidence suggesting that monitoring and modeling approaches commonly employed at vapor intrusion sites do not adequately characterize long-term exposure and in many cases may underestimate risks. On the basis of this evidence, we recommend specific approaches to monitoring and modeling to account for these uncertainties. We propose a value of information approach to integrate the lines of evidence at a site and determine if more information is needed before deciding whether the two conditions specified in the vapor intrusion guidance are satisfied. To facilitate data collection and decision-making, we recommend a multi-directional community engagement strategy and consideration of environment justice concerns.
在危险废物场地，挥发性化学物质可通过地下水和土壤迁移至建筑物内，这一过程称为蒸气侵入。由于越来越认识到蒸气侵入是一种潜在的室内空气污染来源，2015年美国环境保护局（EPA）发布了一份新的蒸气侵入指导文件。该指导文件规定了证明需要进行修复的两个条件：（1）证明存在蒸气侵入途径；（2）有证据表明人类健康风险超过既定阈值（例如，每10000名接触者中有一例额外癌症病例）。然而，该指导文件缺乏关于证明这些条件的方法的详细信息。我们回顾了当前的证据，这些证据表明，蒸气侵入场地常用的监测和建模方法不能充分表征长期暴露情况，在许多情况下可能会低估风险。基于这一证据，我们推荐了具体的监测和建模方法，以应对这些不确定性。我们提出一种信息价值方法，以整合场地的证据线索，并在决定是否满足蒸气侵入指导文件中规定的两个条件之前，确定是否需要更多信息。为便于数据收集和决策，我们推荐一种多方向的社区参与策略，并考虑环境正义问题。
