SILICA, SILICOSIS, AND LUNG CANCER IN DIATOMITE WORKERS

全世界数百万工人正在或已经接触到晶体 硅石 最近，国际癌症研究机构（International Agency for Research on Cancer） 将结晶二氧化硅归类为可能的人类肺部致癌物。 然而，几乎所有关于这一主题的流行病学研究都 缺乏剂量反应所需的详细接触数据 估计，很少有关于胸部X光片读数的数据， 将允许澄清纤维化的潜在前体作用， 肺癌发生 这项拟议的研究将在先前的研究基础上增加6年的随访时间。 对2，961名女性进行了历史队列死亡率研究， （三）接触结晶二氧化硅的工人。 原始研究 表明在2008年至2009年间， 192-87（SMR=1.43），与晶体的剂量-反应关系较强 二氧化硅暴露（最高暴露类别中的相对风险=2.74）。 本研究的主要目的是：1）量化 结晶二氧化硅与肺癌之间的剂量-反应关系; 2） 通过阅读胸片，来检验肺结核的假设， 纤维化是二氧化硅诱导的肺癌的必要前体;以及3） 评价非恶性肿瘤死亡风险的剂量-反应关系 呼吸道疾病和其他死亡原因， 被观察到。 接触和工作历史数据，以及 吸烟，将从现有的行业记录中获得。 死亡率 将使用国家死亡指数进行随访。 定量 估计结晶二氧化硅的工作历史记录的信息。 胸部X光片，大多数工人都有 自20世纪30年代以来，将被阅读和分类标准国际 劳工局肺尘埃沉病的标准。 这将允许 将工人分为“缺席”“可能”的类别， “当前”矽肺。 这些群体之间肺癌风险的比较 将作为纤维化/致癌假说的检验。 这项调查将产生重要的新信息， 二氧化硅与肺之间剂量-反应关系的定量 癌症，这是基于科学的风险评估所必需的， 环境标准的制定。 此外，研究结果将增加 进一步了解肺结核的发病作用， 纤维化在癌变中的作用

Millions of workers world-wide are or have been exposed to crystalline silica. Recently, the International Agency for Research on Cancer classified crystalline silica as a probable human lung carcinogen. However, nearly all of the epidemiologic studies on this topic have suffered from a lack of detailed exposure data needed for dose-response estimation, and few have had data on chest radiograph readings which would permit clarification of a potential precursor role of fibrosis on lung carcinogenesis. The proposed study will add 6 years of follow-up to a previously conducted historical cohort mortality study of 2,961 diatomaceous earth (diatomite) workers exposed to crystalline silica. The original study indicated a lung cancer mortality excess overall in the cohort during 192-87 (SMR=1.43), and strong dose-response relations with crystalline silica exposure (Relative Risk=2.74 in the highest exposure category). The research objectives of the proposed study are: 1)to quantify the dose-response association between crystalline silica and lung cancer; 2) by reading chest radiographs, to test the hypothesis that pulmonary fibrosis is a necessary precursor of silica-induced lung cancer; and 3) to evaluate dose-response relations for mortality risks for non-malignant respiratory diseases and other causes of death for which overall excesses are observed. Exposure and work history data, and information on smoking, will be obtained from available industry records. Mortality follow-up will be conducted using the National Death Index. Quantitative estimates of crystalline silica does information to work history records. Chest radiographs, which have been maintained for the majority of workers since the 1930s, will be read and classified by standard International Labour Office criteria for the pneumoconioses. This will permit stratification of workers into categories of "absent" "possible," and "present" silicosis. Comparisons of lung cancer risks among these groups will serve as a test of the fibrosis/carcinogenesis hypothesis. This investigation will generate significant new information needed for quantification of the dose-response relation between silica and lung cancer, which is essential for scientifically-based risk assessments and environmental standard setting. Moreover, the study findings will add further to an understanding of the pathogenetic role of pulmonary fibrosis in carcinogenesis.