Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Environ Sci Technol. 2010 Mar 15;44(6):2131-7. doi: 10.1021/es9013085.
We present a model that integrates the economic input-output approach of life cycle assessment with environmental fate, exposure, and risk assessment to estimate the spatial distribution of air toxic health risks due to sector-specific economic activity in the U.S. The model is used to relate the economic activity and exposure potential (population density and meteorology) associated with point source emissions of the heavy metal and carcinogen, hexavalent chromium, or Cr(VI), on a county basis. Total direct annual airborne emissions of Cr(VI) in the U.S. were 44 tonnes in 2002, with 97% from facilities in four major sectors: power generation, wood, plastics, and chemicals, metals, and scientific services. These include 6 tonnes of Cr(VI) emitted in the supply chains of these sectors. A highly variable national distribution of lifetime cancer risk is predicted, with a population-weighted mean of 2.7 x 10(-7), but with hot-spot counties with lifetime risks as high as 6 x 10(-6). Furthermore, high exposures and risks tend to occur in more highly populated counties. In particular, the population of Los Angeles County is exposed to the highest level of risk in the country and almost three-quarters of the total predicted cancer incidence due to inhalation of airborne Cr(VI) emissions. This finding can be attributed largely to the use of Cr(VI) as a corrosion inhibitor by the scientific services sector facilities in the county, the use of shorter facility stacks, and their sitting within a highly populated area. These results indicate that linking economic activity, emission estimates, and fate and transport models for air toxics can inform both life cycle impact and comparative health risk assessments, allowing us to better target emission reductions to minimize hot-spots of risk.
我们提出了一个模型，该模型将生命周期评估的经济投入产出方法与环境归宿、暴露和风险评估相结合，以估计由于美国特定经济活动导致的空气有毒健康风险的空间分布。该模型用于根据点源排放相关的经济活动和暴露潜力（人口密度和气象）来关联重金属和致癌物六价铬（Cr(VI)）的县一级排放。2002 年，美国空气中 Cr(VI)的直接年排放量总计为 44 吨，其中 97%来自四大行业：发电、木材、塑料和化学品、金属以及科学服务行业的设施。这些设施包括这些行业供应链中排放的 6 吨 Cr(VI)。预计全国范围内的终生癌症风险分布高度可变，人口加权平均值为 2.7 x 10(-7)，但存在高达 6 x 10(-6)的热点县。此外，高暴露和高风险往往发生在人口密度较高的县。特别是，洛杉矶县的人口面临全国最高水平的风险，并且由于吸入空气中的 Cr(VI)排放而导致的总预测癌症发病率中有近四分之三归因于此。这一发现主要归因于该县科学服务行业设施将 Cr(VI)用作腐蚀抑制剂、使用较短的设施烟囱以及位于人口稠密地区。这些结果表明，将经济活动、排放估计以及空气毒物的归宿和传输模型联系起来，可以为生命周期影响和比较健康风险评估提供信息，从而使我们能够更好地将减排目标定位于最小化风险热点。
