Weyer P J, Cerhan J R, Kross B C, Hallberg G R, Kantamneni J, Breuer G, Jones M P, Zheng W, Lynch C F
Center for Health Effects of Environmental Contamination, University of Iowa, USA.
Epidemiology. 2001 May;12(3):327-38. doi: 10.1097/00001648-200105000-00013.
Nitrate contamination of drinking water may increase cancer risk, because nitrate is endogenously reduced to nitrite and subsequent nitrosation reactions give rise to N-nitroso compounds; these compounds are highly carcinogenic and can act systemically. We analyzed cancer incidence in a cohort of 21,977 Iowa women who were 55-69 years of age at baseline in 1986 and had used the same water supply more than 10 years (87% > 20 years); 16,541 of these women were on a municipal supply, and the remainder used a private well. We assessed nitrate exposure from 1955 through 1988 using public databases for municipal water supplies in Iowa (quartile cutpoints: 0.36, 1.01, and 2.46 mg per liter nitrate-nitrogen). As no individual water consumption data were available, we assigned each woman an average level of exposure calculated on a community basis; no nitrate data were available for women using private wells. Cancer incidence (N = 3,150 cases) from 1986 through 1998 was determined by linkage to the Iowa Cancer Registry. For all cancers, there was no association with increasing nitrate in drinking water, nor were there clear and consistent associations for non-Hodgkin lymphoma; leukemia; melanoma; or cancers of the colon, breast, lung, pancreas, or kidney. There were positive associations for bladder cancer [relative risks (RRs) across nitrate quartiles = 1, 1.69, 1.10, and 2.83] and ovarian cancer (RR = 1, 1.52, 1.81, and 1.84), and inverse associations for uterine cancer (RR = 1, 0.86, 0.86, and 0.55) and rectal cancer (RR = 1, 0.72, 0.95, and 0.47) after adjustment for a variety of cancer risk/protective factors, agents that affect nitrosation (smoking, vitamin C, and vitamin E intake), dietary nitrate, and water source. Similar results were obtained when analyses were restricted to nitrate level in drinking water from 1955 through 1964. The positive association for bladder cancer is consistent with some previous data; the associations for ovarian, uterine, and rectal cancer were unexpected.
饮用水中的硝酸盐污染可能会增加患癌风险，因为硝酸盐在体内会被还原为亚硝酸盐，随后的亚硝化反应会产生N-亚硝基化合物；这些化合物具有高度致癌性，且会在全身起作用。我们分析了爱荷华州21,977名女性队列的癌症发病率，这些女性在1986年基线时年龄为55至69岁，且使用同一水源超过10年（87%超过20年）；其中16,541名女性使用市政供水，其余使用私人水井。我们利用爱荷华州市政供水的公共数据库评估了1955年至1988年期间的硝酸盐暴露情况（四分位数切点：每升硝酸盐氮0.36、1.01和2.46毫克）。由于没有个人用水量数据，我们为每位女性分配了基于社区计算的平均暴露水平；使用私人水井的女性没有硝酸盐数据。1986年至1998年的癌症发病率（N = 3,150例）通过与爱荷华州癌症登记处的数据关联来确定。对于所有癌症，饮用水中硝酸盐增加与之并无关联，对于非霍奇金淋巴瘤、白血病、黑色素瘤、结肠癌、乳腺癌、肺癌、胰腺癌或肾癌也没有明确且一致的关联。膀胱癌存在正相关[硝酸盐四分位数的相对风险（RRs）分别为1、1.69、1.10和2.83]，卵巢癌也存在正相关（RR = 1、1.52、1.81和1.84），在对各种癌症风险/保护因素、影响亚硝化的因素（吸烟、维生素C和维生素E摄入量）、膳食硝酸盐和水源进行调整后，子宫癌存在负相关（RR = 1、0.86、0.86和0.55），直肠癌也存在负相关（RR = 1、0.72、0.95和0.47）。当分析仅限于1955年至1964年饮用水中的硝酸盐水平时，得到了类似的结果。膀胱癌的正相关与一些先前的数据一致；卵巢癌、子宫癌和直肠癌的关联则出乎意料。
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