Water hardness and mortality in The Netherlands

In 1975 central water softening was discouraged by the Public Health Councilbecause of the statistical negative association found in 23 communities between the hardness of drinking water and death rate from Ischemic Heart Disease (I.H.D.) over the period 1958–1970. Further studies were carried out during the last decade by a specially assigned interdisciplinary Working Group of the Health Aspects of Central Water Softening.Recent studies showed that the release of metals (Pb and Cu) from householdwaterdistribution pipes was positively correlated with water calcium. Furthermore a significant negative correlation was found between hardness and pH for these types of water.The hypothesis that the Ca and Mg deficiency in areas with soft drinking water increases the risk of I.H.D. death rate was supported by the finding that food looses more Ca and Mg when it is cooked in soft water as compared to cooking in hard water.In contrast with earlier statistical investigations no significant relations were found over the period 1970–1977 between I.H.D. mortality and hardness of drinking water in 30 municipalities.The disappearance of the statistical relation could not be attributed to changes in water hardness. However, investigation of a group of 17 municipalities of which mortality and water quality data are known for three periods, 1958–1962, 1965–1970 and 1971–1977, showed that the inverse statistical relation between I.H.D. mortality and water hardness still existed but with decreasing significance of correlation coefficients. The provisional conclusion of the Working Group is that other factors than water hardness overrule to a large extent the potential effect on I.H.D. mortality. Central water softening down to 2–3 meq/1 Ca probably will have no observable effect on mortality. Other studies are still continuing. In 1981 a final report will be presented to the Minister of Health and Environmental Protection.     

Effects of coal mining on ground and surface water quality,Monongalia County,West Virginia

Water quality data are compared. Areas disturbed extensively either by surface or underground mining for bituminous coal in Monongalia County, West Virginia yield water of poorer quality than similar terrain which is not so disturbed. Specifically, the disturbed areas yield hard water of the calcium-sulfate or calcium-magnesium-sulfate type which is low in pH, high in iron and aluminum, and which contains trace elements one or more orders of magnitude greater than water from undisturbed terrain.These hard waters differ from the more common type of hard waters in that sulfate rather than bicarbonate is the dominant anion. As such they may provide further insight into factors affecting the relationship between water hardness and cardiovascular disease rates. The necessary additional data are being collected.     

Water hardness and cardiovascular disease. Elements in water and human tissues.

The hypothesis that the hardness of drinking water has a causal role in the development of cardiovascular disease will be strengthened if it can be demonstrated that elements in drinking water find their way into human tissues in significant amounts. For biologically important metals, the evidence is reviewed for a relationship of tissue levels to levels in drinking water. Hard water can contribute significantly to daily magnesium intake. Residents of hard-water areas may have raised levels of magnesium in coronary arteries, bone, and myocardial tissue. Lead levels in bone and in blood have been shown to be elevated in individuals living in homes with lead plumbing and soft water. Cadmium intake from water is probably small compared to that from other sources, and there is no convincing evidence of alteration in human tissue levels via drinking water cadmium. Human zinc and copper tissue levels are of interest but have not been adequately studied in relation to drinking water levels.     

Magnesium and certain other elements and cardiovascular disease

Cardiovascular disease (CVD) continues to be the major cause of mortality in developed countries. For the past two-and-a-half decades the inverse relationship between water hardness and CVD mortality has stimulated interest among epidemiologists, clinicians and experimental researchers. Much progress has been made in elucidating which element in the water may account for this situation. After reviewing those elements found to have a role in cardiovascular function the authors present the epidemiological evidence and its consistency with recent findings: aside from various trace elements emphasis is placed on magnesium which is recognized as having a vital role.     

从管网供水漏失率分析乡镇供水现状

分析了目前乡镇供水回收率普遍偏低的主要原因：供水主管线老化，深井水硬度较大造成管道严重结垢、渗漏，年久失修；规范中乡镇供水标准制定偏高，与实际使用情况不符，造成供水量与用水量的不平衡；乡镇水厂管理水平低，出现以小带大的管线设置，增加了水头损失，降低了供水压力。提出了加强乡镇技术管理水平和对老管线进行测漏排查的建议，以期为合理规划乡镇用水量标准提供参考依据。     

Geochemistry of well water and cardiovascular diseases in Sri Lanka

A survey carried out on the incidence of cardiovascular diseases in Sri Lanka in relation to the hardness of drinking water reveals that a correlation exists which is geographically related. This correlation however, cannot be considered as a causal relationship and other factors possibly exist that could also play a major role in the incidence of cardiovascular diseases, e.g. trace elements.     

Effect of water hardness on the toxicity of an anionic detergent to fish

The toxicity to fish of anionic detergents in solution varies considerably according to the hardness of the water in which the fish are treated. Trout and goldfish are more susceptible to sodium lauryl sulphate (SLS) in hard water than soft, and the rate of absorption of detergent is greater in hard water. It has been shown that the concentration of bivalent cations has a direct effect on the toxicity of SLS. Acclimatization experiments have shown that the toxicity of SLS depends not only on the hardness of the water in which the fish are treated, but also on the hardness of the water in which the fish have previously been acclimatized. The mechanism whereby water hardness affects detergent toxicity is discussed.     

Chemical qualities of water that contribute to human health in a positive way

The emphasis on harmful substances that may occur in potable waters has almost obscured the fact that important beneficial constituents are commonly present.The chemical substances in water that make positive contributions to human health act mainly in two ways: (i) nutritionally, by supplying essential macro and micro elements that the diet (excluding water) may not provide in adequate amounts (for example, Mg, I and Zn); and (ii) by providing macro and micro elements that inhibit the absorption and/or effects of toxic elements such as Hg, Pb and Cd. Specific examples of these beneficial effects will be given, also examples of harmful effects on health that may result from excessive intake of these ordinarily beneficial elements.Because concentrations of the essential macro and micro elements that occur in natural, potable waters vary greatly, depending upon their source, geographic considerations are very important in any studies attempting to relate water quality to health. In this context, the inverse relationship between hard water and cardiovascular disease will be discussed. Specific data relating hardness and Mg and Ca content of potable waters to specific geographic regions of the U.S.A. will be presented. These data show a strong positive correlation between low Mg content and decreased longevity, and between high Ca and Mg content and increased longevity. In the regions considered, increased longevity correlates strongly with decreased cardiovascular mortality, and the decreased longevity with increased cardiovascular mortality.     

我国西部小城镇给水与污水处理技术需求分析

我国西部地区由于地域辽阔，自然地理环境复杂多样，经济发展水平落后，其城镇给水和污水处理工艺不能简单照搬国外或国内发达地区现有的成熟技术。在对西部30余个小城镇实地调研的基础上，结合西部小城镇社会经济状况和各地区自然环境特点，分析了西部小城镇对给水和污水处理设施的技术需求，并针对自然环境特征不同的地区提出了相对较为适宜的城镇给水和污水处理技术。     

生态网络与生态经济的一体化发展——江苏常州嘉泽镇生态网络建设与都市农业发展策略

生态网络是维护生态安全和景观格局的保障．而三、四级生态网络覆盖区又是城镇、乡村以及耕作区重叠的地区,生态网络建设与社会经济发展的矛盾突出。大城市范围圈内相当部分的小城镇,在市域空间分工中承担了生态斑块、维育生态环境的功能,经济发展产业选择的空间不大．只有实现生态网络建设与生态化的经济发展相融合,一体化的发展才是最佳出路。江苏常武地区嘉泽镇为这种发展方式提供了经验。     

Relationship of hair calcium concentration to incidence of coronary heart disease

This study was designed to evaluate whether hair calcium concentration reflects the mortality from coronary heart disease on a UK-wide basis and to determine the effect--if any--of environmental factors which might affect calcium metabolism on this relationship. The study was based on our earlier findings of an inverse relationship between hair calcium concentration and that in the intima of the aorta and the association of high aorta calcium with severe alterations to the vessel walls which was found never to co-exist with hair calcium concentrations greater than 700 ppm. Hair samples were collected from 4393 males in an ethically approved study in 40 different health districts. These covered the range in known prevalence of heart disease as reflected in the published standardised mortality ratios (SMR). Data on water hardness were obtained from the Water Authorities and on mean annual sunshine hours from the Meteorological Office. Statistical analysis was by regression and multivariate regression techniques. Hair calcium was determined by XRF analysis and the accuracy validated by means of certified reference samples. Significant relationships were found between health district and county SMR and their respective mean hair calcium concentrations accounting for 37 and 55% of their respective variances in SMR. Water hardness and sunshine hours accounted for 39 and 49% of the variance in mortality from CHD. In combination they accounted for 54% of the variance and with the inclusion of hair calcium 65%. South-east England had the highest hair calcium, the hardest water and the most sunshine hours and the lowest mortality from CHD. The converse was true of Scotland. Hair calcium concentration did reflect the risk of CHD on a population basis and was strongly influenced by both the hardness of the water supply and the annual sunshine hours which also independently affected the SMR for CHD.     

Soft deposits, the key site for microbial growth in drinking water distribution networks

In this project we studied the microbiological quality of soft pipeline deposits removed from drinking water distribution networks during mechanical cleaning. Drinking water and deposit samples were collected from 16 drinking water distribution networks located at eight towns in different parts of Finland. Soft pipeline deposits were found to be the key site for microbial growth in the distribution networks. The microbial numbers in the soft deposits were significantly higher than numbers in running water. The highest microbial numbers were detected in the main deposit pushed ahead by the first swab. The deposits contained high numbers of heterotrophic bacteria, actinomycetes and fungi. Also coliform bacteria were often isolated from deposit samples. Manganese and copper in the deposits correlated negatively with the numbers of heterotrophic bacteria. After a year, the viable microbial numbers in the new deposits were almost as high as in the old deposits before the first mechanical cleaning. The bacterial biomass production was higher in the new than in the old deposits.     

Towards sustainable urban water services in developing countries: tariffs based on willingness-to-pay studies

ABSTRACT

Water supply and sanitation (WASH) service providers in most towns of developing countries, such as Godey Town in Ethiopia, the case study reported in this paper, deliver less than basic services. The costs for meeting the more ambitious WASH targets of the Sustainable Development Goals will be much higher than what has previously been invested in the sector. This study showed that a tariff structure designed using affordability and willingness-to-pay data would provide higher revenues than one solely based on estimated customers’ affordability, or Ethiopian government’s tariff guidelines. As in previous studies in Ethiopia, this study highlights government’s low willingness-to-charge amidst a high customers’ willingness-to-pay. Yet, there is need to increase water tariffs in developing countries, hence, moving towards financial sustainability and supplementing the other two Ts – taxes and transfers. Based on accurate and updated socio-economic data, the tariff can also be optimised to fulfil the social equity objective.     

The effect of water hardness on nitrilotriacetate removal and microbial acclimation in activated sludge

The effect of water hardness on microbial acclimation to the removal of nitrilotriacetate (NTA) in the wastewater treatment process was examined in 4 laboratory-scale activated sludge reactors. Consistent high removal (i.e. >90%) was observed in all 4 reactors after acclimation occurred. Removals of greater than 60% of added NTA after 8 days and greater than 90% after 15 days were observed in a continuously fed, hard water (250 mg l⁻¹ as CaCO₃) reactor. In soft water (50 mg l⁻¹ as CaCO₃) comparable removals were observed after 20 and 28 days respectively. In 24 h, semi-continuous activated sludge reactors (24 h, fill-and-draw type) removal was greater in hard water than in soft water initially, but was greater than 95% in both hard and soft water after 4 weeks.The proportion of bacteria in the activated sludge with the ability to utilize NTA increased approx. 100-fold during the acclimation period. This proportion increased faster in hard water than in soft water and faster in semi-continuous activated sludge reactors than continuous activated sludge reactors.Ultimate biodegradation of ¹⁴C[U]NTA was greater than 85% in both hard and soft water acclimated units. Accumulation of ¹⁴C in the sludge solids was negligible (<1%).     

Cold surge: A sudden and spatially varying threat to health?

While cold surge is one of the most conspicuous features of the winter monsoon in East Asia, its impact on human health remains underexplored. Based on the definition by the Central Weather Bureau in Taiwan, we identified four cold surges between 2000 and 2003 and collected the cardiovascular disease mortality data 2 weeks before and 2 weeks after these events. We attempted to answer the following research questions: 1) whether the cold surges impose an adverse and immediate effect on cardiovascular mortality; 2) whether the people living in temperate zones have a higher tolerance of extreme temperature drop than those in the subtropics. With geographic weighting techniques, we not only found that the cardiovascular disease mortality rates increased significantly after the cold surges, but also discovered a spatially varying pattern of tolerance to cold surges. Even within a small study area such as Taiwan, human reaction to severe weather drop differs across space. Needless to say, in the U.S., these findings should be considered in redirecting policy to address populations living in warm places when extreme temperature drops occur.     

German studies on health effects of inorganic drinking water constituents

The influence of drinking water quality on mortality and morbidityof various diseases has been studied for more than 20 years. From these diseases, those of the cardiovascular system have been playing a special role.Better and more specified information on the differences in thecomposition of drinking water may essentially contribute to a solution of the problem of associations between water quality and the incidence of diseases.In more than 600 water supply areas in the Federal Republic of Germanythe composition of the drinking water has been analyzed. From these data, areas of different water quality are to be selected for additional investigations of the problem of health relevance of drinking water quality. So far, the following constituents of drinking water have been measured: Na, Ca, Mg, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, SO₄, PO₄, NO₃, NO₂, Cl, F, I, etc. The methods of analysis used were atomic absorption spectrometry, plasma emission spectrometry, and ion chromatography.Additionally, more than 19 000 data on drinking water in accordancewith standard analytic procedures under the Drinking Water Regulations are available in a comprehensive data bank (BIBIDAT).There have been studies establishing associations between waterhardness and cardiovascular diseases but also studies which do not confirm this association or even present converse results. Also water constituents like magnesium, cadmium, etc. have been associated with cardiovascular diseases.Some investigations have shown correlations between e.g. the concentration of fluoride in drinking water and caries or iodide and goitre.     

Bioaccumulation and toxicity of copper as affected by interactions between humic acid and water hardness

This study evaluated the effects of water hardness and humic acid (HA) on the acute and chronic toxicity of copper to Daphnia pulex and on its accumulation by D. magna. Hardness had little effect on either the acute (3-day) or the chronic (42-day) toxicity of copper. Humic acid significantly reduced both the acute and chronic toxicity of copper when added to waters having hardnesses of 58, 115 and 230 mg l^?1 as CaCO₃. The effect, per unit of HA, on chronic toxicity was very similar for soft and medium water but less in hard water. At each of two HA concentrations, copper was chronically more toxic in hard water than in either medium or soft water. Bioaccumulation of copper varied with relative hardness and HA concentration and this was further affected by age at exposure. For 1-day-old animals, an increase in either hardness or HA- or any combination of the two, tended to decrease bioaccumulation. Results for 7-day-old animals were in general agreement except for animals exposed to copper in hard water at an intermediate HA concentration. These animals accumulated significantly more copper in the presence of HA. This agrees with the fact that this concentration of HA also increased the chronic toxicity of copper in hard water. Both of those phenomena are probably due to the displacement of Cu²⁺ from HA by competition from the increased concentrations of Ca²⁺ and Mg²⁺. The fact that HA had the opposite effect on copper accumulation by young animals in hard water could not be explained.     

小城镇规模与用水量变化规律研究

针对小城镇给水规划中用水量确定不合理的现象，实地调查了10个区域的典型小城镇群（300个样本）1998年—2004年的用水量，采用“二次平均法”计算了不同规模的小城镇人均综合用水量水平。调研统计结果表明，各类小城镇用水日变化系数较大，建议取值为1.75～1．95；各类小城镇用水高峰出现的时间大致相似，但最高峰值与最低峰值之间的振幅随小城镇的规模减小而增大，时变化系数宜取2．0～2．4，小城镇规模越小或生产用水比例低时取高值，基本无生产用水的可适当放大。     

A single bioavailability model can accurately predict Ni toxicity to green microalgae in soft and hard surface waters

The major research questions addressed in this study were (i) whether green microalgae living in soft water (operationally defined water hardness <10 mg CaCO₃/L) are intrinsically more sensitive to Ni than green microalgae living in hard water (operationally defined water hardness >25 mg CaCO₃/L), and (ii) whether a single bioavailability model can be used to predict the effect of water hardness on the toxicity of Ni to green microalgae in both soft and hard water. Algal growth inhibition tests were conducted with clones of 10 different species collected in soft and hard water lakes in Sweden. Soft water algae were tested in a ‘soft’ and a ‘moderately hard’ test medium (nominal water hardness = 6.25 and 16.3 mg CaCO₃/L, respectively), whereas hard water algae were tested in a ‘moderately hard’ and a ‘hard’ test medium (nominal water hardness = 16.3 and 43.4 mg CaCO₃/L, respectively). The results from the growth inhibition tests in the ‘moderately hard’ test medium revealed no significant sensitivity differences between the soft and the hard water algae used in this study. Increasing water hardness significantly reduced Ni toxicity to both soft and hard water algae. Because it has previously been demonstrated that Ca does not significantly protect the unicellular green alga Pseudokirchneriella subcapitata against Ni toxicity, it was assumed that the protective effect of water hardness can be ascribed to Mg alone. The log K_MgBL (= 5.5) was calculated to be identical for the soft and the hard water algae used in this study. A single bioavailability model can therefore be used to predict Ni toxicity to green microalgae in soft and hard surface waters as a function of water hardness.     

Paying for water services: effects of household characteristics

Maximising cost recovery is currently a top priority for managers of urban water utilities in low-income countries. This research was carried out in 11 major towns of Uganda to establish which household characteristics influence payment for water services. A questionnaire was used to collect data on customer satisfaction, customer loyalty and several socio-economic variables. Using regression techniques, it was established that the following attributes of the household head moderated the satisfaction and loyalty relationship: gender, occupation and level of education. Other significant factors were household income and property tenure status. These results could be used to make water utilities customer-focused.