A case-control study of nitrate in drinking water and non-Hodgkin's lymphoma in Minnesota

Nitrate in drinking water has been implicated as a possible risk factor for non-Hodgkin's lymphoma. The authors examined the association between non-Hodgkin's lymphoma and waterborne nitrate through a population-based case-control study of white men in Minnesota. The authors, by linking residential histories with community water records, estimated average long-term exposure to nitrate in drinking water from 1947 to 1975 for 73 cases diagnosed between 1980 and 1982 and for 147 controls who used community water supplies. No association was found between nitrate levels in community water supplies and non-Hodgkin's lymphoma within the range of study exposures (median of highest exposure category = 2.4 mg nitrate/l [range = 0.1-7.2 mg/l]). The findings provide some safety assurance for those who use water systems that have nitrate levels that are less than 2.4 mg/l.     

Lead in drinking water of Vienna in comparison to other European countries and accordance with recent guidelines

Due to the decrease of lead intake via inhalation route, the oral route, particularly from drinking water in cities with lead installations, gains relative importance. In two surveys a total of 288 objects were investigated and 1768 samples were analysed. The first series with 51 objects using a field experimental approach systematically investigated the effects of daytime, floor and flushing. Because only objects built before 1945 and suspected of lead plumbing were chosen, the first series approaches worst case conditions. The second series investigating 237 randomly chosen objects stratified according to time of consumption should allow inferences about the present situation in Viennese households. Each sampling procedure comprised one sample without flushing and three further samples with flushing of 1 l, 3 l and 10 l, respectively. Statistically significant decreases occurred between these flushing conditions. The sampling data of the upper floors showed significantly higher lead contents compared to the lower floors, which indicates that house installations are the main causes of lead contamination in Viennese drinking water. In comparison to other European countries the percentage of samples exceeding the guideline levels (50 micrograms/l as current value and 10 micrograms/l as target value) was lower.     

Evaluation of nitrate and nitrite accumulation in drinking water supplies]

Levels of the nitrate and nitrite content in water sources of Kiev and Cherkassy regions were studied. Highest concentrations of nitrite (1.33 mg N/l) and nitrate (168 mg N/l) were defined in local water sources. Peculiarity of nitrate and nitrite distribution is discussed.     

紫外分光光度法测定饮用水中硝酸盐氮

目的:应用紫外分光光度法测定饮用水中硝酸盐氮。方法:同时使用紫外分光光度法和麝香草酚比色法测定饮用水中硝酸盐氮。结果:使用紫外分光光度法测定饮用水中硝酸盐氮呈现良好线性(r>0.999)。结论:实验结果表明,紫外分光光度法操作简单、方便、快捷,干扰少,测定结果准确可靠,适用于饮用水中硝酸盐氮的测定,值得推广使用。     

Gastric cancer mortality and nitrate levels in Wisconsin drinking water.

The association between nitrate levels in public and private sources of drinking water and gastric cancer mortality in Wisconsin was investigated in a case-control study. All gastric cancer deaths of Wisconsin residents from 1982 through 1985 were compared with deaths from other causes (controls), and nitrate levels in the home drinking water of these residents were determined. Nitrate measures for public sources were obtained from historic nitrate data from municipal sources that existed in 1970. Nitrate measures for private water sources were obtained by testing the wells individually at the existing residences. Controls were matched individually to gastric cancer cases with respect to sex, year of birth, year of death, Wisconsin birth, and Wisconsin residency at the time of death. Matched-pair analyses were performed on the paired data, and the following levels of nitrate-nitrogen exposure were used as indicators of exposure: 0.5, 2.5, 5.0, and 10.0 mg/l. Matched-pair analysis was also performed for which private water supply constituted exposure. Odds ratios and 95% confidence intervals were, respectively, 0.92 (0.75, 1.12); 0.97 (0.74, 1.35); 0.86 (0.69, 1.08); 1.50 (0.12, 18.25); and 1.09 (0.82, 1.47) for exposure to private well-water sources. These results did not indicate an increased risk of gastric cancer at any level.     

Pancreatic cancer and drinking water and dietary sources of nitrate and nitrite

N-Nitroso compounds, known animal carcinogens, are formed endogenously from drinking water and dietary sources of nitrate and nitrite. The authors conducted a population-based case-control study of pancreatic cancer in Iowa to determine whether increased consumption of nitrate and nitrite from drinking water and dietary sources was associated with risk. They linked detailed water source histories to nitrate measurements for Iowa community water supplies. After exclusions for insufficient data, 1,244 controls and 189 pancreatic cancer cases were available for analysis. Among controls, the median average nitrate level (1960-1987) was 1.27 (interquartile range, 0.6-2.8) mg of nitrate nitrogen per liter of water. No association was observed between pancreatic cancer risk and increasing quartiles of the community water supplies' nitrate level. Increasing intake of dietary nitrite from animal sources was associated with an elevated risk of pancreatic cancer among men and women (highest quartile odds ratios = 2.3, 95% confidence interval: 1.1, 5.1, for men and 3.2, 95% confidence interval: 1.6, 6.4, for women). In contrast, dietary nitrate intake showed an inverse association with risk among women and no association among men. This study suggests that long-term exposure to drinking water nitrate at levels below the maximum contaminant level of nitrate nitrogen (10 mg/liter) is not associated with pancreatic cancer; however, the consumption of dietary nitrite from animal products may increase risk.     

Chlorination byproducts and nitrate in drinking water and risk for congenital cardiac defects

Drinking water disinfection byproducts have been associated with an increased risk for congenital defects including cardiac defects. Using Swedish health registers linked to information on municipal drinking water composition, individual data on drinking water characteristics were obtained for 58,669 women. Among the infants born, 753 had a cardiac defect. The risk for a cardiac defect was determined for ground water versus surface water, for different chlorination procedures, and for trihalomethane and nitrate concentrations. Ground water was associated with an increased risk for cardiac defect when crude rates were analyzed but after suitable adjustments this excess rate was found to be determined by chlorination procedures including chlorine dioxide. Chlorine dioxide appears itself as an independent risk factor for cardiac defects (adjusted odds ratio 1.61 (95%CI 1.00-2.59)). The risk for cardiac defects increased with increasing trihalomethane concentrations (P=0.0005). There was an indicated but statistically nonsignificant excess risk associated with nitrate concentration. The individual risk for congenital cardiac defect caused by chlorine dioxide and trihalomethanes is small but as a large population is exposed to public drinking water, the attributable risk for cardiac defects may not be negligible.     

Public response to elevated nitrate in drinking water wells in Wisconsin.

The authors conducted a survey by mail of Wisconsin families who had their well water tested for nitrate to (a) assess their awareness and compliance with the state's health advisories for nitrate, (b) evaluate their reaction(s) to their test results, and (c) compare demographic differences between exposure levels. Owners of contaminated wells (i.e., > 12.9 mg/l nitrate-nitrogen) were more likely to have lived on a farm, had lower annual incomes, and had older and shallower wells than families whose wells were low in nitrate (i.e., < 2.0 mg/l nitrate-nitrogen). Most respondents were aware of the advisories for pregnant women and infants and, in accordance with these advisories, the majority of families with nitrate-contaminated drinking water took no remedial action. Given that many rural families consume nitrate-contaminated water daily, scientists should conduct additional research to determine whether chronic ingestion of nitrate-contaminated water poses a significant health threat to these families.     

Risk of non-Hodgkin lymphoma and nitrate and nitrite from drinking water and diet

INTRODUCTION: Nitrate and nitrite are precursors in the in vivo formation of N-nitroso compounds, potent animal carcinogens. METHODS: We conducted a population-based case-control study of non-Hodgkin lymphoma (NHL) in 1998 to 2000 in Iowa, Detroit, Seattle, and Los Angeles. Because nitrate levels were elevated in many drinking water supplies in Iowa, but not in the other study centers, we evaluated water nitrate levels and risk of NHL in Iowa only. Monitoring data for public supplies were linked to water source histories from 1960 onward. Nitrate was measured at interview homes with private wells. We limited most analyses to those with nitrate estimates for > 70% of their person-years since 1960 (181 cases, 142 controls). For those in the diet arm of the study (458 cases, 383 controls from 4 centers) and for Iowa participants in both the diet and drinking water analyses, we estimated dietary nitrate and nitrite intake using a 117-item food-frequency questionnaire that included foods high in nitrate and nitrite. Odds ratios and 95% confidence intervals were calculated using logistic regression, adjusting for the study matching factors, education, and caloric intake (diet analyses only). RESULTS: We found no overall association with the highest quartile of average drinking water nitrate (> 2.90 mg/L nitrate-N: odds ratios = 1.2; 95% confidence interval = 0.6-2.2) or with years > or = 5 mg/L (10+ years: 1.4; 0.7-2.9). We observed no evidence of an interaction between drinking water nitrate exposure and either vitamin C or red meat intake, an inhibitor and precursor, respectively, of N-nitroso compound formation. Among those in the diet arm, dietary nitrate was inversely associated with risk of NHL (highest quartile: 0.54; 0.34-0.86). Dietary nitrite intake was associated with increasing risk (highest quartile: 3.1; 1.7-5.5) largely due to intakes of bread and cereal sources of nitrite. CONCLUSION: Average drinking water nitrate levels below 3 mg/L were not associated with NHL risk. Our study had limited power to evaluate higher levels that deserve further study.     

饮用水配水系统中微生物研究方法的进展

饮用水在输配水管网中的二次污染是不容忽视的问题,对饮用水中微生物的了解有助于饮用水安全的保障。随着微生物检测技术的发展,人们对饮用水配水系统中微生物的复杂性和多样性的认识更加深入。笔者对饮用水配水系统中微生物的存在形式、数量和多样性的研究方法进行综述,包括传统培养方法,基于PCR技术的现代分子生物学方法,DNA序列分析技术和基因芯片技术等,并着重介绍这些方法的基本原理、优缺点及应用前景。     

饮用水中硝酸盐氮的新型全自动硫酸肼还原测定法

目的研究和评价一种新型快速测定饮用水中硝酸盐氮的全自动硫酸肼还原法。方法基于硫酸肼还原法,该方法全自动取样、添加试剂、孵育、检测和处理数据。结果该方法测定范围为0~11.3 mg/L,相关系数0.999 5,检出限为0.01 mg/L,RSD为0.81%~2.7%,自来水加标回收率为95.0%~105%。结论新型全自动比浊法具有简便快速,高效准确等优点,样品和试剂用量少,节约环保,适合大批量水样中硝酸盐氮的快速测定与筛查。     

全国实验室生活饮用水中硝酸盐氮测定的能力验证研究

目的通过能力验证计划,对全国实验室的生活饮用水中硝酸盐氮含量检测能力进行分析和评价。方法能力验证计划中使用的被测样品参考二级标准物质制备方法制备,采用单因子方差分析法和t检验法分别对其进行均匀性检验和稳定性检验。将全国多个行业系统所属的608家实验室提交的结果进行迭代稳健统计分析,采用Z比分数评定各参加实验室的测试结果。结果获得满意结果的实验室541家,结果满意率为89.0%;可疑结果的有20家,结果可疑率为3.3%;离群结果的有47家,结果离群率为7.7%。结论能力验证统计结果表明,国内实验室的生活饮用水中硝酸盐氮检测能力总体较好,少部分实验室的检测能力有待改进提高。     

Reducing lead exposure from drinking water: recent history and current status

This article discusses the issue of lead contamination of drinking water, noting the various regulatory-driven measures that have been adopted in the U.S. since 1986 to address this public health issue. The article summarizes the literature on the dynamics of tap water lead contamination and discusses this widespread source of lead exposure in the context of the latest research evidence.     

日照市东港区农村生活饮用水硝酸盐污染调查

目的了解山东日照市东港区农村各类型饮水中硝酸盐分布状况,为农村改水和水质管理提供科学依据。方法对辖区内25处小型集中式供水地表水源点(各取水源水和末稍水),40处自备井的末稍水,实施监测并进行统计分析。结果2013年农村各类型水中以井水中的硝酸盐含量最高,均值达15.6,接近GB 5749-2006《生活饮用水卫生标准》中小型集中式供水限值(≤20mg/L),不合格率为20.00%;总计90份样品中,12份不合格,不合格率为13.33%,作为水源的地表水和末稍水的硝酸盐含量非常接近,经水厂处理后,硝酸盐的平均去除率为0.49%。结论各类型水硝酸盐都有超标情况,应选好水源,加强管理。     

生活饮用水中硝酸盐氮的3种测定方法的比较

目的比较3种不同方法(麝香草酚分光光度法、紫外分光光度法和离子色谱法)测定生活饮用水中的硝酸盐氮。方法通过3种不同方法的测试,分别从检出限、准确度、精密度和加标回收率进行分析和比较。结果2种化学方法测量范围较宽,能正确反映被测样本中硝酸盐的真实含量,但操作复杂、费时、费力而且实验废液对环境有一定的影响;离子色谱法无论从检出限、准确度还是精密度、加标回收率等方面均优于两种化学法。结论离子色谱法比另两种化学方法操作更简便快捷,准确、灵敏。