Studies of Populations Exposed to Environmental Sources

儿童时期暴露于Chornobyl事故中的甲状腺良恶性疾病 1986年乌克兰切尔诺贝利核反应堆事故污染了白俄罗斯、乌克兰西北部和与俄罗斯接壤的省份的大部分地区。白俄罗斯的一项病例对照研究和个人剂量估计表明，甲状腺癌与Chornobyl事故所产生的辐射剂量之间存在统计上的显著联系。在能源部(DOE)和核管理委员会(NRC)的协助下，NCI对白俄罗斯和乌克兰Chornobyl事故的儿童接触者的良性和恶性甲状腺疾病进行了长期跟踪研究。到目前为止，每个国家约有12000名受试者的甲状腺每两年进行一次筛查。一项基于首次筛查数据的甲状腺癌患病率分析已经完成，一家领先杂志正在审查一篇手稿。一篇关于自身免疫性甲状腺炎的论文正在准备中。 俄罗斯马亚克核设施附近特查河放射性废物暴露人群的癌症死亡率 居住在俄罗斯特恰河沿岸的村民暴露在马亚克核设施的长期外部和内部辐射中。癌症死亡率正在接受一组约3万人的评估，这些人接受了倾倒在河流中的放射性废物的大剂量辐射。目前的努力侧重于提高数据质量、跟踪人口以获取重要状态信息以及进行统计分析。癌症死亡率和辐射剂量之间的关系已经被观察到。 儿童时期接触塞米巴拉金斯克试验场核试验的哈萨克斯坦3000名居民中的甲状腺结节作为辐射风险的衡量标准 在哈萨克斯坦受附近塞米巴拉金斯克试验场核弹试验产生的放射性尘埃影响的3000名儿童居民中，通过超声波筛查确定的甲状腺结节患病率被用作与辐射有关的风险的生物标志物。正在进行的剂量重建基于俄罗斯的尘埃沉积模型、关于尘埃事件发生时的居住地、牛奶和奶制品的来源和消费的档案和访谈数据，以及从牧场到食物的碘运输模型，得出了来自外部和内部放射源的甲状腺剂量的个人估计。对结核流行的剂量反应的初步估计表明，与外部来源的伽马射线相比，摄取的131-I辐射的相对生物有效性约为70%，不太可能低于20%。 中国的肺癌与室内高水平氡 来自中国农村地区肺癌的综合病例对照研究的数据与另一项在中国更城市化地区进行的关于肺癌和氡的大型病例对照研究的数据汇集在一起。在该研究中，室内高水平的氡增加了患肺癌的风险。这两项研究的结果与室内研究和矿工数据的荟萃分析一致，表明长期暴露在家里的氡会增加患肺癌的风险。一项为期三年的测量子研究发现，氡水平的时间变化是氡测量不确定度的最大来源。对测量中的这种不确定性进行调整后，肺癌的超额风险估计增加了50%-100%。这表明，使用类似剂量学的氡研究可能低估了氡的影响。

Benign and Malignant Thyroid Disease Among Those Exposed as Children to Fallout from the Chornobyl Accident The Chernobyl nuclear reactor accident in Ukraine in 1986 contaminated large parts of Belarus, northwestern Ukraine, and bordering Russian provinces. A case-control study in Belarus, with individual dose estimates, demonstrated a statistically significant link between thyroid cancer and radiation dose from fallout related to the Chornobyl accident. With the assistance of the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC), NCI has organized long-term follow-up studies of benign and malignant thyroid disease among those exposed as children to fallout from the Chornobyl accident in Belarus and in Ukraine. To date, the thyroid glands of approximately 12,000 subjects in each country have been screened biennially. A prevalence analysis of thyroid cancer based on data from the first screening has been completed and a manuscript is under review at a leading journal. A paper on autoimmune thyroiditis is in preparation. Cancer Mortality Among the Population Exposed to Radioactive Waste Dumped in the Techa River Adjacent to the Mayak Nuclear Facility in Russia Villagers living along the banks of the Techa River in Russia were exposed to chronic external and internal radiation from the Mayak nuclear facility. Cancer mortality is being evaluated in a cohort of approximately 30,000 people who received large doses of radiation from the radioactive waste dumped into the river. Current efforts focus on improving data quality, tracing the population for vital status information, and on statistical analyses. Ans association between cancer mortality and radiation dose has been observed. Thyroid Nodules as a Measure of Radiation Risk Among a Population of 3000 Residents in Kazakhstan Exposed as Children to Fallout from Nuclear Testing at the Semipalatinsk Test Site Thyroid nodule prevalence, ascertained by ultrasound screening, was used as a biomarker for radiation-related risk in a population of 3000 childhood residents of villages in Kazakhstan affected by radioactive fallout from nuclear bomb tests at the nearby Semipalatinsk Test Site. An ongoing dose reconstruction, based on Russian models for fallout deposition, archival and interview data on residence at the time of fallout events, source and consumption of milk and milk products, and models for iodine transport from pasture to food, yielded individual estimates of thyroid dose from external and internal radiation sources. Preliminary estimates of dose response for nodule prevalence suggest that the relative biological effectiveness of radiation from ingested 131-I compared to gamma rays from external sources is about 70% and is unlikely to be less than 20%. Lung Cancer and High Levels of Indoor Radon in China Data from a comprehensive case-control study of lung cancer in rural China in which high levels of indoor radon increased lung cancer risk was pooled with data from another large case-control study of lung cancer and radon conducted in a more urban area of China. Results from both studies were consistent with meta-analyses of indoor studies and from miner data suggesting that long-term exposure to radon in homes increases lung cancer risk. A measurement sub-study conducted over a three-year period found that temporal variation in radon levels represented the greatest source of uncertainty in radon measurements. Adjusting for this uncertainty in measurement increased the excess risk estimates of lung cancer by 50-100%. This suggests that radon studies using similar dosimetry may underestimate radon effects.