Pilotto L S
National Centre for Epidemiology and Population Health, Australian National University, Canberra.
Aust J Public Health. 1995 Feb;19(1):89-93. doi: 10.1111/j.1753-6405.1995.tb00304.x.
Chlorine, commonly used to disinfect drinking water, produces by-products known from animal studies to be carcinogenic and mutagenic. Most epidemiological studies into the possible association between chlorination by-products in drinking water and cancer have been ecological in nature, or have relied on case-control designs based on death certificates. Interpretation of results arising from these studies is limited. Individual levels of toxicant exposure and many potential confounders and effect modifiers are unable to be accounted for in the analyses. At best, these studies generate hypotheses that require more definitive investigation. Misclassification of individuals based on inaccurate assessment of the level of exposure is probable. The few analytic studies able to overcome or minimise these problems suggest a clear link between exposure to chlorinated drinking water and the development of urinary bladder cancer. They also suggest a possible link with rectal cancer. However, these studies have classified subjects by exposure to chlorinated drinking water, rather than to levels of chlorine and its by-products in drinking water. To date, the link between levels of chlorine and its by-products in water, levels of consumption and cancer has not been made. Information on the levels of chlorine and some by-products is available in many water jurisdictions in Australia. Further, epidemiological methods can be employed to quantify water consumption. Case-control studies linking these parameters would help us to understand the magnitude of the risk to human populations and provide a basis to investigate mechanisms for risk reduction.
常用于饮用水消毒的氯会产生一些副产品，动物研究表明这些副产品具有致癌性和致突变性。大多数关于饮用水中氯化副产品与癌症之间可能存在的关联的流行病学研究本质上都是生态学研究，或者依赖基于死亡证明的病例对照设计。这些研究结果的解释受到限制。在分析中无法考虑个体的毒物暴露水平以及许多潜在的混杂因素和效应修饰因素。充其量，这些研究只能产生需要更明确调查的假设。基于对暴露水平的不准确评估而对个体进行错误分类是很有可能的。少数能够克服或尽量减少这些问题的分析性研究表明，饮用氯化水与膀胱癌的发生之间存在明显联系。它们还表明可能与直肠癌有关。然而，这些研究是根据饮用氯化水的情况对受试者进行分类的，而不是根据饮用水中氯及其副产品的含量。迄今为止，水中氯及其副产品的含量、饮水量与癌症之间的联系尚未明确。在澳大利亚的许多供水辖区都可以获取有关氯和一些副产品含量的信息。此外，可以采用流行病学方法来量化饮水量。将这些参数联系起来的病例对照研究将有助于我们了解人群面临的风险程度，并为研究降低风险的机制提供依据。
