Minority Predoctoral Fellowship Program

这是一项解决与职业和环境发病率和死亡率研究有关的统计设计和分析问题的建议。一般而言，与接触环境中发现的特定有毒和有害物质有关的发病率和死亡率风险的适度上升将难以在人口或社区研究中发现。在某些情况下，对职业接触人群的流行病学研究在量化环境风险方面极为有用，因为工人接触的有毒材料水平通常高于一般人群。这些较高的接触水平使得更容易发现和描述与工作场所发现的有毒和有害物质相关的发病率和死亡率风险的适度上升。然而，职业研究也受到一种被称为健康工人效应（HWE）的选择偏差的困扰，这种偏差会扭曲暴露-反应关系的形状，并导致对暴露与疾病发作之间没有因果关系的零假设的偏见。Tchetgen先生将研究统计方法，这些方法可用于在计算HWE的同时一致地估计职业暴露的因果发病率或死亡率影响。除了方法学工作外，Tchetgen先生将有机会使用这些新方法重新分析在汽车工业金属加工液职业暴露的发病率和死亡率研究中收集的数据。虽然有些重点将放在金属加工液的案例研究，这项研究是最相关的环境健康研究一般风险评估是最重要的。

This is a proposal to address statistical design and analysis issues related to occupational and environmental morbidity and mortality studies. In general, modest elevations in morbidity and mortality risk associated with exposure to particular toxic and hazardous substances found in the environment will be hard to detect in population or community-based studies. In some cases, epidemiological studies of occupationally exposed cohorts are extremely useful in quantifying environmental risks because workers are generally exposed to higher levels of toxic materials than the general population. These higher levels of exposure make it easier to detect and characterize modest elevations in morbidity and mortality risk associated to toxic and hazardous substances found in the workplace. However, occupational studies are also plagued with a form of selection bias known as the healthy worker effect (HWE) which can distort the shape of the exposure-response relationship and lead to bias towards the null hypothesis of no causal association between exposure and disease onset. Mr. Tchetgen will investigate statistical methods that can be used to consistently estimate the causal morbidity or mortality effect of occupational exposure while accounting for the HWE. In addition to methodologic work, Mr Tchetgen will have the opportunity to use these novel methods to re-analyze data collected in a morbidity and mortality study of occupational exposure to metalworking fluids in the automobile industry. Although some emphasis will be placed on the metalworking fluid case study, this research is most relevant to environmental health studies in general where risk assessment is of prime importance.