Hildesheim M E, Cantor K P, Lynch C F, Dosemeci M, Lubin J, Alavanja M, Craun G
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA.
Epidemiology. 1998 Jan;9(1):29-35.
We evaluated the association between chlorination byproducts and colon and rectal cancer risk in a population-based case-control study conducted in Iowa in 1986-1989. Data were gathered from 685 colon cancer cases, 655 rectal cancer cases, and 2,434 controls. We calculated odds ratios for the 560 colon cancer cases, 537 rectal cancer cases, and 1,983 controls for whom water exposure information was available for at least 70% of their lifetime. We estimated exposure to chlorination byproducts with two types of measures: duration of lifetime at residences served by chlorinated water and estimated lifetime trihalomethane exposure. For rectal cancer, we observed an association with duration of chlorinated surface water use, with adjusted odds ratios of 1.1, 1.6, 1.6, and 2.6 for 1-19, 20-39, 40-59, and > or =60 years of exposure, compared with no exposure. Rectal cancer risk was also associated with several different measures of estimated lifetime trihalomethane exposure. For colon cancer and subsites, we detected no important increase in risk associated with duration of chlorinated surface water, nor with trihalomethane estimates. When we evaluated chlorination byproducts jointly with other factors, we found larger relative risk estimates for rectal cancer among subjects with low dietary fiber intake. The risk related to > or =40 years of exposure to a chlorinated surface water source was 2.4 (95% confidence interval = 1.5-4.0) for persons with low fiber intake and 0.9 (95% confidence interval = 0.4-1.8) for persons with high fiber intake, relative to the risk of persons with high-fiber diets and no exposure to chlorinated surface water. We observed a similar risk differential for low and high levels of physical activity.
在1986 - 1989年于爱荷华州开展的一项基于人群的病例对照研究中，我们评估了氯化副产物与结肠癌和直肠癌风险之间的关联。数据收集自685例结肠癌病例、655例直肠癌病例以及2434名对照。对于560例结肠癌病例、537例直肠癌病例和1983名对照，我们计算了比值比，这些对象至少70%的生命期有饮水暴露信息。我们用两种测量方法估计氯化副产物暴露：饮用氯化水的居住时长以及估计的终生三卤甲烷暴露量。对于直肠癌，我们观察到其与使用氯化地表水的时长存在关联，暴露1 - 19年、20 - 39年、40 - 59年以及≥60年的调整后比值比分别为1.1、1.6、1.6和2.6，与无暴露情况相比。直肠癌风险还与几种不同的估计终生三卤甲烷暴露量测量方法有关。对于结肠癌及其亚部位，我们未发现与氯化地表水时长以及三卤甲烷估计值相关的风险有显著增加。当我们将氯化副产物与其他因素联合评估时，发现膳食纤维摄入量低的受试者患直肠癌的相对风险估计值更大。相对于高纤维饮食且未接触氯化地表水的人群风险，纤维摄入量低的人群暴露于氯化地表水水源≥40年的风险为2.4（95%置信区间 = 1.5 - 4.0），而纤维摄入量高的人群为0.9（95%置信区间 = 0.4 - 1.8）。我们观察到身体活动水平低和高的人群也存在类似的风险差异。
