Payne-Sturges Devon C, Burke Thomas A, Breysse Patrick, Diener-West Marie, Buckley Timothy J
Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
Environ Health Perspect. 2004 Apr;112(5):589-98. doi: 10.1289/ehp.6496.
Human exposure research has consistently shown that, for most volatile organic compounds (VOCs), personal exposures are vastly different from outdoor air concentrations. Therefore, risk estimates based on ambient measurements may over- or underestimate risk, leading to ineffective or inefficient management strategies. In the present study we examine the extent of exposure misclassification and its impact on risk for exposure estimated by the U.S. Environmental Protection Agency (U.S. EPA) Assessment System for Population Exposure Nationwide (ASPEN) model relative to monitoring results from a community-based exposure assessment conducted in Baltimore, Maryland (USA). This study is the first direct comparison of the ASPEN model (as used by the U.S. EPA for the Cumulative Exposure Project and subsequently the National-Scale Air Toxics Assessment) and human exposure data to estimate health risks. A random sampling strategy was used to recruit 33 nonsmoking adult community residents. Passive air sampling badges were used to assess 3-day time-weighted-average personal exposure as well as outdoor and indoor residential concentrations of VOCs for each study participant. In general, personal exposures were greater than indoor VOC concentrations, which were greater than outdoor VOC concentrations. Public health risks due to actual personal exposures were estimated. In comparing measured personal exposures and indoor and outdoor VOC concentrations with ASPEN model estimates for ambient concentrations, our data suggest that ASPEN was reasonably accurate as a surrogate for personal exposures (measured exposures of community residents) for VOCs emitted primarily from mobile sources or VOCs that occur as global "background" source pollutant with no indoor source contributions. Otherwise, the ASPEN model estimates were generally lower than measured personal exposures and the estimated health risks. ASPEN's lower exposures resulted in proportional underestimation of cumulative cancer risk when pollutant exposures were combined to estimate cumulative risk. Median cumulative lifetime cancer risk based on personal exposures was 3-fold greater than estimates based on ASPEN-modeled concentrations. These findings demonstrate the significance of indoor exposure sources and the importance of indoor and/or personal monitoring for accurate assessment of risk. Environmental health policies may not be sufficient in reducing exposures and risks if they are based solely on modeled ambient VOC concentrations. Results from our study underscore the need for a coordinated multimedia approach to exposure assessment for setting public health policy.
人体暴露研究一直表明，对于大多数挥发性有机化合物（VOCs）而言，个人暴露情况与室外空气浓度差异极大。因此，基于环境测量的风险估计可能会高估或低估风险，从而导致管理策略无效或低效。在本研究中，我们考察了暴露误分类的程度及其对美国环境保护局（U.S. EPA）全国人口暴露评估系统（ASPEN）模型估计的暴露风险的影响，并将其与在美国马里兰州巴尔的摩市进行的一项基于社区的暴露评估监测结果进行了比较。本研究首次直接比较了ASPEN模型（美国环境保护局用于累积暴露项目以及随后的全国性空气毒物评估）和人体暴露数据，以估计健康风险。我们采用随机抽样策略招募了33名不吸烟的成年社区居民。使用被动式空气采样徽章评估每位研究参与者3天的时间加权平均个人暴露情况以及室内和室外住宅环境中VOCs的浓度。一般来说，个人暴露大于室内VOC浓度，而室内VOC浓度又大于室外VOC浓度。我们估计了实际个人暴露所导致的公共健康风险。在将测量的个人暴露以及室内和室外VOC浓度与ASPEN模型对环境浓度的估计进行比较时，我们的数据表明，对于主要由移动源排放的VOCs或作为全球“背景”源污染物且无室内源贡献的VOCs而言，ASPEN作为个人暴露（社区居民的测量暴露）的替代指标具有合理的准确性。否则，ASPEN模型的估计值通常低于测量的个人暴露和估计的健康风险。当将污染物暴露合并以估计累积风险时，ASPEN较低的暴露估计值导致累积癌症风险按比例被低估。基于个人暴露的终生累积癌症风险中位数比基于ASPEN模型浓度的估计值高3倍。这些发现证明了室内暴露源的重要性以及室内和/或个人监测对于准确评估风险的重要性。如果仅基于模拟的环境VOC浓度，环境卫生政策可能不足以降低暴露和风险。我们的研究结果强调了采用协调一致的多媒体方法进行暴露评估以制定公共卫生政策的必要性。
