Association of Arsenic Exposure with Lung Cancer Incidence Rates in the United States

BackgroundAlthough strong exposure to arsenic has been shown to be carcinogenic, its contribution to lung cancer incidence in the United States is not well characterized. We sought to determine if the low-level exposures to arsenic seen in the U.S. are associated with lung cancer incidence after controlling for possible confounders, and to assess the interaction with smoking behavior.
MethodologyMeasurements of arsenic stream sediment and soil concentration obtained from the USGS National Geochemical Survey were combined, respectively, with 2008 BRFSS estimates on smoking prevalence and 2000 U.S. Census county level income to determine the effects of these factors on lung cancer incidence, as estimated from respective state-wide cancer registries and the SEER database. Poisson regression was used to determine the association between each variable and age-adjusted county-level lung cancer incidence. ANOVA was used to assess interaction effects between covariates.
Principal FindingsSediment levels of arsenic were significantly associated with an increase in incident cases of lung cancer (P<0.0001). These effects persisted after controlling for smoking and income (P<0.0001). Across the U.S., exposure to arsenic may contribute to up to 5,297 lung cancer cases per year. There was also a significant interaction between arsenic exposure levels and smoking prevalence (P<0.05).
Conclusions/SignificanceArsenic was significantly associated with lung cancer incidence rates in the U.S. after controlling for smoking and income, indicating that low-level exposure to arsenic is responsible for excess cancer cases in many parts of the U.S. Elevated county smoking prevalence strengthened the association between arsenic exposure and lung cancer incidence rate, an effect previously unseen on a population level.

【研究背景】尽管已有研究证实高剂量砷暴露具有致癌性，但美国境内砷暴露对肺癌发病率的贡献程度尚未得到充分阐明。本研究旨在明确美国人群中普遍存在的低剂量砷暴露，在控制潜在混杂因素后是否与肺癌发病率存在关联，并评估其与吸烟行为的交互作用。【研究方法】本研究将美国地质调查局（United States Geological Survey, USGS）国家地球化学调查获取的溪流沉积物与土壤砷浓度数据，分别与2008年行为风险因素监测系统（Behavioral Risk Factor Surveillance System, BRFSS）的吸烟患病率估算数据，以及2000年美国人口普查的县级收入数据进行整合，结合各州癌症登记处与监测、流行病学与最终结果（Surveillance, Epidemiology, and End Results, SEER）数据库的肺癌发病率估算结果，分析上述因素对肺癌发病率的影响。本研究采用泊松回归（Poisson regression）分析各变量与年龄校正后县级肺癌发病率之间的关联，并通过方差分析（Analysis of Variance, ANOVA）评估协变量间的交互效应。【主要研究结果】溪流沉积物中的砷浓度与肺癌新增病例数的增加呈显著正相关（P<0.0001）。在控制吸烟与收入因素后，该关联仍然显著（P<0.0001）。据估算，美国每年因砷暴露导致的肺癌新增病例可达5297例。此外，砷暴露水平与吸烟患病率之间也存在显著的交互效应（P<0.05）。【结论与意义】在控制吸烟与收入因素后，美国境内的砷暴露仍与肺癌发病率存在显著关联，提示低剂量砷暴露是美国多个地区超额肺癌病例的潜在诱因。县级吸烟患病率的升高会强化砷暴露与肺癌发病率之间的关联，这一群体层面的效应此前尚未被学界观测到。