Chang H Y, Chen C R, Wang J D
Department of Environmental and Occupational Health, National Cheng Kung University, Tainan, Taiwan.
Arch Environ Health. 1999 May-Jun;54(3):194-201. doi: 10.1080/00039899909602259.
Estimates from environmental risk assessments are criticized by professionals who indicate that inaccuracies occur in exposure assessment, model selection, and determination of the population at risk. In the current study, we tackled the aforementioned issues and estimated the risks of lung cancer and mesothelioma caused by airborne asbestos among individuals who lived near asbestos factories in Taiwan. We conducted 8-h full-period samplings upwind and downwind from each factory, and we used transmission-electronic microscopy (10,000x) and phase-contrast microscopy to determine asbestos concentrations in and around each factory. We estimated the numbers of residents who lived in concentric circles of 200-m, 400-m, and 600-m diameters around each factory. A dose-response model for asbestos-induced lung cancer was adopted from a summary of seven epidemiological studies. The asbestos-mesothelioma models were patterned after the first-exposure-effect models developed by Peto and Finkelstein. The data obtained from phase-contrast microscopy significantly overestimated the risk, compared with transmission-electronic microscopy. The estimates we calculated from adopting the arithmetic mean were approximately 2-fold higher than those we calculated with the geometric mean. There were relatively low concentrations of asbestos in the study areas, thus causing an absence of a significant difference in risk estimates between different models for mesothelioma. Among the more than 20,000 residents who lived near 41 asbestos factories in Taiwan, we found that the numbers of expected excess deaths from lung cancer and mesothelioma were 5 and less than 1, respectively. We concluded that in future risk assessments for ambient asbestos exposure, investigators should adopt transmission-electronic microscopy and the geometric mean estimate. Moreover, Taiwan should enhance asbestos-control programs to assure the safety of residents who live near asbestos factories.
环境风险评估的结果受到专业人士的批评，他们指出暴露评估、模型选择以及风险人群确定过程中存在不准确之处。在本研究中，我们解决了上述问题，并估算了台湾石棉工厂附近居民因空气中石棉导致肺癌和间皮瘤的风险。我们在每个工厂的上风和下风方向进行了8小时的全周期采样，并使用透射电子显微镜（10000倍）和相差显微镜来测定每个工厂及其周边的石棉浓度。我们估算了居住在每个工厂周围直径为200米、400米和600米同心圆范围内的居民数量。石棉诱发肺癌的剂量反应模型采用了七项流行病学研究的总结。石棉致间皮瘤模型是仿照Peto和Finkelstein开发的首次暴露效应模型构建的。与透射电子显微镜相比，相差显微镜获得的数据显著高估了风险。我们采用算术平均值计算的估计值比采用几何平均值计算的估计值高出约2倍。研究区域内石棉浓度相对较低，因此不同间皮瘤模型的风险估计值没有显著差异。在台湾41家石棉工厂附近居住的20000多名居民中，我们发现肺癌和间皮瘤预期超额死亡人数分别为5人和不到1人。我们得出结论，在未来环境石棉暴露的风险评估中，研究人员应采用透射电子显微镜和几何平均值估计。此外，台湾应加强石棉控制计划，以确保石棉工厂附近居民的安全。
