TITLE: Fluoride in the drinking water and the geographical variation of coronary heart disease in Finland.
AUTHORS: Kaipio J, Nayha S, Valtonen V.
SOURCE: Eur J Cardiovasc Prev Rehabil. 2004 Feb;11(1):56-62.
BACKGROUND: Fluoride in drinking water prevents dental disease, which in turn has been reported to increase the risk of coronary heart disease (CHD). Since mortality from CHD in Finland is high in the north-east where the fluoride content of drinking water is low, the association was examined here in more detail. DESIGN: Mortality from CHD during the period 1961-1995 in 365 rural areas of Finland (188 888 deaths) was linked with 2131 drinking water fluoride determinations performed in 1958 using negative binomial regression, adjustments being made for sex, age, mean income of the resident commune and drinking water magnesium and calcium. RESULTS: An inverse J-shaped relationship was found between drinking water fluoride and CHD, the association being most pronounced in the 1960s and levelling off consistently as a function of time. In 1961-1970, the adjusted mortality from CHD was 22% (95% confidence interval 18-27%) lower in the fourth quintile of fluoride (0.15-0.30 mg/l) than in the first quintile (0.00-0.06 mg/l) but this deficit reduced to 13% (7-18%) in 1991-1995. CONCLUSIONS: Although causality cannot be asserted, the geographical pattern of CHD in Finland is consistent with the concentration of fluoride in drinking water. One mechanism could be that fluoride prevents dental infections, which in turn reduces mortality from CHD. The more widespread use of fluoridated toothpastes, soft drinks and certain food items since the 1960s may have reduced the significance of drinking water as a source of fluoride.

TITLE: Ecologic study of water hardness and cerebrovascular mortality in Japan.
AUTHORS: Miyake Y, Iki M.
SOURCE: Arch Environ Health. 2003 Mar;58(3):163-6.
ABSTRACT: Elevated levels of water hardness have been associated with reduced mortality from cardiovascular and cerebrovascular diseases. In this ecologic study, the authors examined the relationship between water hardness and cerebrovascular mortality in the 44 municipalities of Osaka Prefecture, Japan. Data on cerebrovascular death rates and water hardness in each municipality were obtained from public records; information on socioeconomic and health-care status in each municipality was incorporated with multiple logistic-regression analysis. The authors were unable to substantiate an inverse association of water hardness with cerebrovascular mortality--although the adjusted odds ratio in which the highest vs. lowest tertiles of water hardness were compared was 0.90 (95% confidence interval = 0.79, 1.02) in females. In addition, the difference between the sexes was not significant. In summary, the authors found no evidence that water hardness protected against cerebrovascular mortality.

TITLE: Drinking water hardness and chronic degenerative diseases. II. Cardiovascular diseases
AUTHORS: Monarca S, Zerbini I, Simonati C, Gelatti U.
SOURCE: Ann Ig. 2003 Jan-Feb;15(1):41-56.
ABSTRACT: Since the 1950s a causal relation between water hardness and cardiovascular diseases (CVD) in humans has been hypothesized. In order to evaluate the influence of calcium and magnesium, the minerals responsible for the hardness of drinking water, on human health, a review of all the articles published on the subject from 1980 up to today has been carried out. Many but not all geographic correlation studies showed an inverse association between water hardness and mortality for CVD. Most case-control and one cohort studies showed an inverse relation, statistically significant, between mortality from CVD and water levels of magnesium, but not calcium. Consumption of water containing high concentrations of magnesium seems to reduce of about 30-35% the mortality for CVD, but not the incidence. This inverse association is supported by clinical and experimental findings and is biologically plausible and in line with Hill's criteria for a cause-effect relationship.

TITLE: Contribution of food products and drinking water to the intake of minerals by elderly
AUTHORS: Kaluza J, Zysk A, Brzozowska A.
SOURCE: Rocz Panstw Zakl Hig. 2002;53(4):407-17.
ABSTRACT: The aim of this paper was to assess the contribution of food product groups and drinking water to mineral and trace elements supply. On the basis of 3-day record data it was found that the intake of calcium and copper by 75-80 years old elderly living in Warsaw area (Poland) was insufficient. The same for iron among women and zinc among men was observed. The RDA for energy was covered in 90% by men's diets and in 78% by women's diets. Dairy products were the main source of calcium (48%), cereals were the main source of magnesium (29%), while iron came mainly from cereals (31%) and meat products (21%). Two latter groups of products also significantly contributed in zinc intake by the elderly (29% and 25% respectively). Cereals (33%) and potatoes (16%) were the main sources of copper. Drinking water had significant share only in calcium (14%) and zinc (9%) intake. Cereals, vegetables, dairy and meat products gave relatively more minerals to men's diets, while potatoes, fruits, eggs and other products (fats, sugar, sweets etc.)--to women's diets.

TITLE: Magnesium in drinking water in relation to morbidity and mortality from acute myocardial infarction [In Process Citation]
AUTHORS: Rubenowitz E; Molin I; Axelsson G; Rylander R
SOURCE: Epidemiology 2000 Jul;11(4):416-21
ABSTRACT: We investigated the importance of magnesium and calcium in drinking water in relation to morbidity and mortality from acute myocardial infarction. Cases were men and women 50-74 years of age living in 18 Swedish municipalities who had suffered an acute myocardial infarction some time between October 1, 1994, and June 30, 1996. Controls were randomly selected from the same study base. We interviewed the surviving cases (N = 823) and controls (N = 853), focusing on risk factors for acute myocardial infarction. We collected individual data on drinking water levels of magnesium and calcium. We ubjects by quartile of water magnesium or calcium levels. The total number of cases was similar in the four quartiles. The risk of death was 7.6% (95% confidence interval = 2.1-13.1) lower in the quartile with high magnesium levels (> or = 8.3 mg/liter). The odds ratio for death from acute myocardial infarction in relation to water magnesium was 0.64 (95% confidence interval = 0.42-0.97) for the highest quartile relative to the three lower ones. Multivariate analyses showed that other risk factors were not important confounders. For calcium, this study was inconclusive. The data suggest that magnesium in drinking water is associated with lower mortality from acute myocardial infarction, but not with the total incidence.

TITLE: Magnesium in drinking water supplies and mortality from acute myocardial infarction in north west England.
AUTHORS: Maheswaran R; Morris S; Falconer S; Grossinho A; Perry I; Wakefield J; Elliott P
SOURCE: Heart 1999 Oct;82(4):455-460 [Record as supplied by publisher]
ABSTRACT: OBJECTIVES: To examine whether higher concentrations of magnesium in drinking water supplies are associated with lower mortality from acute myocardial infarction at a small area geographical level; to examine if the association is modified by age, sex, and socioeconomic deprivation. DESIGN: Small area geographical study using 13 794 census enumeration districts. Water constituent concentrations (magnesium, calcium, fluoride, lead) measured at water supply zone and assigned to enumeration districts. SETTING: 305 water supply zones in north west England. SUBJECTS: Resident population of 1 124 623 men and 1 372 036 women (1991 census) aged 45 years or more. MAIN OUTCOME MEASURE: Mortality from acute myocardial infarction, International Classification of Diseases, ninth revision (ICD-9) 410. Subsidiary analysis examined deaths from ischaemic heart disease, ICD 410-414. RESULTS: There were 21 339 male and 17 883 female deaths from acute myocardial infarction in 1990-92. Drinking water magnesium concentrations in water zones ranged from 2 mg/l to 111 mg/l (mean (SD) 19 (20) mg/l, median 12 mg/l); 24% of variation in magnesium concentrations was within zone and 76% was between zone. The relative risk of mortality from acute myocardial infarction (standardised for age, sex, and Carstairs deprivation quintile) for a quadrupling of magnesium concentrations in drinking water (for example, 20 mg/l v 5 mg/l) was 1.01 (95% confidence interval (CI) 0.99 to 1.03). When adjusted for north-south and east-west trends in mortality from acute myocardial infarction and for drinking water calcium, fluoride, and lead concentrations, this relative risk was 1.01 (95% CI 0.96 to 1.06). There was no evidence of a protective effect for acute myocardial infarction even among age, sex, and deprivation groups that were likely to be relatively magnesium deficient. For ischaemic heart disease mortality there was an apparent protective effect of magnesium and calcium (with calcium predominating in the joint model), but these were no longer significant when the geographical trends were incorporated. CONCLUSIONS: No evidence was found of an association between magnesium concentrations in drinking water supplies and mortality from acute myocardial infarction. These results do not support the hypothesis that magnesium is the key water factor in relation to mortality from heart disease.

TITLE: Magnesium in drinking water and the risk of death from diabetes mellitus.
AUTHORS: Yang CY; Chiu HF; Cheng MF; Tsai SS; Hung CF; Tseng YT
SOURCE: Magnes Res 1999 Jun;12(2):131-7
ABSTRACT: This report examines whether magnesium in drinking water is protective against the probability of dying from diabetes mellitus. All eligible deaths from diabetes (6781 cases) of Taiwan residents from 1990 through 1994 were compared with deaths from other causes (6781 controls), and the levels of magnesium in the drinking water of these residents was determined. Data on magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). Controls were pair matched to the cases by , ear of birth, and year of death. The results of the present study show that there seems to be a significant protective effect of magnesium intake from drinking water on the risk of dying from diabetes mellitus. This is an important finding for the Taiwan water industry and human health.

TITLE: Magnesium and calcium in drinking water and death from acute myocardial infarction in women.
AUTHORS: Rubenowitz E; Axelsson G; Rylander R
SOURCE: Epidemiology 1999 Jan;10(1):31-6
ABSTRACT: A relation between water hardness and cardiovascular death has been shown in previous studies. In this case-control study, we investigated the levels of magnesium and calcium in drinking water and death from acute myocardial infarction among women. The study population encompassed 16 municipalities in southern Sweden. Cases were women who had died from acute myocardial infarction between the ages of 50 and 69 years during 1982-1993 (N = 378), and controls were women who had died from cancer (N = 1,368). We obtained magnesium and calcium concentrations of the individual water sources. We divided the subjects into quartiles and found that odds ratios (ORs) were lower at higher levels of both magnesium and calcium. For the quartile with the highest magnesium levels (> or =9.9 mg/liter), the OR adjusted for age and calcium was 0.70 (95% confidence interval = 0.50-0.99). For calcium, the adjusted OR for the quartile with the highest level (> or =70 mg/liter) was 0.66 (95% confidence interval = 0.47-0.94). The results suggest that magnesium and calcium in drinking water are important protective factors for death from acute myocardial infarction among women.

TITLE: Magnesium in drinking water and body magnesium status measured using an oral loading test.
AUTHORS: Rubenowitz E; Axelsson G; Rylander R
SOURCE: Scand J Clin Lab Invest 1998 Aug;58(5):423-8
ABSTRACT: Epidemiological studies have shown an inverse relationship between magnesium in drinking water and death from ischaemic heart disease. The question is whether magnesium in drinking water can be critical for the body magnesium status. The aim of this study was to investigate, using an oral loading test, whether a change in body magnesium status could be found among people who change from drinking water with a low magnesium concentration to water with higher concentrations. The subjects participating in the study were 9 men and 3 women 65-70 years old, living in the city of Goteborg, Sweden, where the magnesium concentration in the tap water is low (1.6 mg/l). Drinking water was prepared with 200 mg MgCl2 x 6H2O added per litre to a level of 25 mg/l, and was distributed to the subjects twice a week for 6 weeks. Excretion of magnesium, potassium and creatinine, basal and after oral magnesium loading (tablets containing 575 mg), was measured in 24 h urine before and after the supplementation period. Calculations were made for the total excretion (mmol/24 h), and in relation to creatinine. The subjects' intake of magnesium via food and water was estimated using a questionnaire. There was a difference between the post load excretion of magnesium, expressed as the magnesium/creatinine ratio, before and after the supplementation period. The mean percentage change was a 14.6% (p=0.047) increase. No changes were found for potassium. In summary, the results indicate that magnesium in drinking water can affect body magnesium status.

TITLE: Variation in the mineral content of commercially available bottled waters: implications for health and disease.
AUTHORS: Garzon P; Eisenberg MJ
SOURCE: Am J Med 1998 Aug;105(2):125-30 A
BSTRACT: PURPOSE: Although the annual consumption of bottled water in North America is 12.7 gallons per capita, little is known about the potential health effects of these waters. We reviewed the amounts of major minerals found in commercially available bottled waters, the recommended daily allowances for these minerals, and their beneficial and harmful effects. METHODS: We obtained the mineral content of various commercially available bottled waters in North America and Europe from The Pocket Guide to Bottled Water. We then conducted a Medline search to identify articles examining the beneficial and harmful effects of magnesium, sodium, and calcium. RESULTS: Great variation exists in the mineral content of commercially available bottled waters. Among the bottled waters that we reviewed, the magnesium content ranges from 0 to 126 mg per liter, the sodium content ranges from 0 to 1,200 mg per liter, and the calcium content ranges from 0 to 546 mg per liter. Epidemiologic and clinical studies suggest that magnesium may reduce the frequency of sudden death, that sodium contributes to the occurrence of hypertension, and that calcium may help prevent osteoporosis. CONCLUSION: The ideal bottled water should be rich in magnesium and calcium and have a low sodium content. Because there is great variation in the mineral content of commercially available bottled waters, the actual mineral content of bottled water should be considered when selecting one for consumption.

TITLE: Calcium and magnesium in drinking water and risk of death from rectal cancer.
AUTHORS: Yang CY; Chiu HF
SOURCE: Int J Cancer 1998 Aug 12;77(4):528-32
ABSTRACT: The possible association between the risk of rectal cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal-cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with a sample of deaths from other causes (986 controls), and the levels of calcium and magnesium in the drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes, and the controls were pair- matched to the cases by gender, year of birth and year of death. Compared with those with calcium levels below 22.0 mg/liter, the adjusted odd ratios (95% confidence interval) were 0.72 (0.53-0.98) for the group with water calcium levels between 22.0 and 40.8 mg/liter and 0.63 (0.45-0.87) for the group with calcium levels of 40.9 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and rectal cancer. The results of the present study show that there may be a significant protective effect of calcium intake from drinking water on the risk of rectal cancer.

TITLE: Colon cancer mortality and total hardness levels in Taiwan's drinking water.
AUTHORS: Yang CY; Hung CF
SOURCE: Arch Environ Contam Toxicol 1998 Jul;35(1):148-51
ABSTRACT: The possible association between the risk of colon cancer and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible colon cancer deaths (1,714 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (1,714 controls) and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan have been collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and the controls were pair matched to the cases by , ear of birth, and year of death. The results show a significant negative relationship between drinking water hardness and colon cancer mortality. Odds ratio and 95% confidence intervals were 1.22 (1.04-1. 43) and 1.46 (1.22-1.75), respectively, for exposure to moderately hard water and soft water compared with the use of hard water. Trend analyses showed an increasing odds ratio for colon cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health.

TITLE: Calcium, magnesium, and nitrate in drinking water and gastric cancer mortality.
AUTHORS: Yang CY; Cheng MF; Tsai SS; Hsieh YL
SOURCE: Jpn J Cancer Res 1998 Feb;89(2):124-30
ABSTRACT: The possible association between the risk of gastric cancer and the levels of calcium, magnesium, and nitrate in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. Records of gastric cancer deaths among eligible residents in Taiwan from 1987 through 1991 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by , ear-of-birth, and year-of-death. Each matched control was selected randomly from the set of possible controls for each case. Data on calcium, magnesium, and nitrate levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The municipality of residence of the cases and controls was assumed to be the source of the subject's calcium, magnesium, and nitrate exposure via drinking water. The subjects were divided into tertiles according to the levels of calcium, magnesium, and nitrate in their drinking water. The results of the present study show that there is a significant positive association between drinking water nitrate exposure and gastric cancer mortality. The present study also suggests that there was a significant protective effect of calcium intake from drinking water on the risk of gastric cancer. Magnesium also exerts a protective effect against gastric cancer, but only for the group with the highest levels.

TITLE: Magnesium in drinking water and ischemic heart disease.
AUTHORS: Marx A; Neutra RR
SOURCE: Epidemiol Rev 1997;19(2):258-72
ABSTRACT: The associations found in the general populations of a number of different countries are suggestive and warrant an integrated program of laboratory and epidemiologic research to reject or confirm the magnesium-IHD hypothesis. Singling out this particular risk factor has two justifications. First, as would be the case with any epidemiologic risk factor for IHD whose attributable risk was large enough to be detectable through epidemiology, applying that attributable risk to the vast annual morbidity and mortality from IHD would translate into tens of thousands of lives benefited and millions of dollars in hospital costs avoided per year. Second, this particular risk factor could conceivably be eliminated by an inexpensive supplementation program. For example, a low-sodium, higher-magnesium and -potassium table salt has been recommended and used in Finland for many years, during a period when the prevalence of hypertension in population surveys was said to decrease (117). Interventions which do not require behavioral change have always been the most cost-effective in public health. We therefore urge funding agencies to give priority to studies determining whether there are unforeseen adverse effects of magnesium for some population subgroups and whether the apparent benefit derived from low doses of magnesium in the development of IHD or IHD death is real. Furthermore, researchers should determine which chemical form of magnesium is best absorbed and most effective. We need to better understand the interrelation of various water and food constituents, as well as individual risk factors, in the pathogenesis of IHD. Susceptible individuals who are at higher risk of being depleted of magnesium need to be identified, and potential untoward effects of magnesium should be studied. Future research must provide better answers about low level waterborne magnesium before recommendations to the public can be made.

TITLE: Calcium and magnesium in drinking water and risk of death from cerebrovascular disease.
AUTHORS: Yang CY
SOURCE: Stroke 1998 Feb;29(2):411-4
ABSTRACT: BACKGROUND AND PURPOSE: Many studies have demonstrated a negative association between mortality from cardiovascular or cerebrovascular diseases and water hardness. This report examines whether calcium and magnesium in drinking water are protective against cerebrovascular disease. METHODS: All eligible cerebrovascular deaths (17133 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (17133 controls), and the levels of calcium and magnesium in drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The control group consisted of people who died from other causes, and the controls were pair matched to the cases by , ear of birth, and year of death. RESULTS: The adjusted odds ratios (95% confidence interval) were 0.75 (0.65 to 0.85) for the group with water magnesium levels between 7.4 and 13.4 mg/L and 0.60 (0.52 to 0.70) for the group with magnesium levels of 13.5 mg/L or more. After adjustment for magnesium levels in drinking water, there was no difference between the groups with different levels of calcium. CONCLUSIONS: The results of the present study show that there is a significant protective effect of magnesium intake from drinking water on the risk of cerebrovascular disease. This is an important finding for the Taiwan water industry and human health.

TITLE: Calcium and magnesium in drinking water and risk of death from colon cancer.
AUTHORS: Yang CY; Chiu HF; Chiu JF; Tsai SS; Cheng MF
SOURCE: Jpn J Cancer Res 1997 Oct;88(10):928-33
ABSTRACT: The possible association between the risk of colon cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible colon cancer deaths (1714 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (1714 controls), and the levels of calcium and magnesium in drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The control group consisted of people who died from other causes and the controls were pair-matched to the cases by , ear-of-birth, and year-of-death. The adjusted odd ratios (95% confidence interval) were 0.79 (0.64-0.98) for the group with water calcium levels between 24.4 and 42.3 mg/liter and 0.58 (0.47-0.73) for the group with calcium levels of 42.4 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and colon cancer. The results of the present study show that there is a significant protective effect of calcium intake from drinking water against colon cancer.

TITLE: Magnesium and calcium in drinking water and cerebrovascular mortality in Taiwan.
AUTHORS: Yang CY; Chiu HF; Chiu JF; Wang TN; Cheng MF
SOURCE: Magnes Res 1997 Mar;10(1):51-7
ABSTRACT: The relationship between death from cerebrovascular disease and the levels of magnesium and calcium in drinking water was examined using an ecological design. The study area consisted of 227 municipalities in Taiwan. Data on the levels of magnesium and calcium in drinking water have been collected from the Taiwan Water Supply Corporation (TWSC). These levels of magnesium and calcium were compared using the standardized mortality ratios (SMRs) for cerebrovascular disease (1981- 1990). A statistically significant inverse relationship was present between cerebrovascular mortality and levels of both magnesium and calcium after adjusting for urbanization index. After adjustment for calcium levels in drinking water and urbanization index, the weighted multivariate-adjusted regression coefficient indicated a decrease of 0.248 in the standardized mortality ratios (SMRs) for every 100 mg/L increase in magnesium levels in drinking water. The results from this study strengthen the hypothesis that magnesium in drinking water helps to prevent death from cerebrovascular disease.

TITLE: Magnesium in drinking water and death from acute myocardial infarction.
AUTHORS: Rubenowitz E; Axelsson G; Rylander R
SOURCE: Am J Epidemiol 1996 Mar 1;143(5):456-62
ABSTRACT: The relation between death from acute myocardial infarction and the level of magnesium in drinking water was examined using mortality registers and a case-control design. The study area comprised 17 municipalities in the southern part of Sweden that have different magnesium levels in the drinking water. Cases were men in the area who had died of acute myocardial infarction between ages 50 and 69 years during the period 1982-1989 (n = 854). The controls were men of the same age in the same area who had died from cancer during the same time period (n = 989). In both groups, only men who consumed water supplied from municipal waterworks were included in the study. The subjects were divided into quartiles according to the drinking water levels of magnesium and calcium and the quotient between magnesium and calcium. The odds ratios for death from acute myocardial infarction in the groups were inversely related to the amount of magnesium in drinking water. For the group with the highest levels of magnesium in drinking water, the odds ratio adjusted for age and calcium level was 0.65 (95 percent confidence interval 0.50-0.84). There was no such relation for calcium. For the magnesium/calcium quotient, the odds ratio was lower only for the group with the highest quotient. These data suggest that magnesium in drinking water is a important protective factor for death from acute myocardial infarction among males.

TITLE: Environmental magnesium deficiency as a cardiovascular risk factor.
AUTHORS: Rylander R
SOURCE: J Cardiovasc Risk 1996 Feb;3(1):4-10
ABSTRACT: Magnesium is abundant in nature and the major routes of intake are through food and water. Through changes in the treatment of foodstuffs and altered diets, as well as increased use of surface water with low magnesium content, magnesium deficiency is present in modern society. Magnesium deficiency causes cardiac arrhythmia and several studies suggest that a low level of magnesium in drinking water is a risk factor for myocardial infarction, particularly among men. Before general prevention programmes can be recommended, risk groups must be defined and experimental intervention programmes performed.

TITLE: Rectal cancer mortality and total hardness levels in Taiwan's drinking water.
AUTHORS: Yang CY; Tsai SS; Lai TC; Hung CF; Chiu HF
SOURCE: Environ Res 1999 May;80(4):311-6
ABSTRACT: The possible association between the risk of rectal cancer and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with deaths from other causes (986 controls), and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan were collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and the controls were pair matched to the cases by , ear of birth, and year of death. The results show a significant negative relationship between drinking water hardness and rectal cancer mortality. Odds ratio and 95% confidence intervals were 1.24 (1.01-1. 55) and 1.38 (1.10-1.73), respectively, for exposure to moderately hard water and soft water compared with the use of hard water. Trend analyses showed an increasing odds ratio for rectal cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health. Copyright 1999 Academic Press.

TITLE: Pancreatic cancer mortality and total hardness levels in Taiwan's drinking water.
AUTHORS: Yang CY; Chiu HF; Cheng MF; Tsai SS; Hung CF; Tseng YT
SOURCE: J Toxicol Environ Health 1999 Mar 12;56(5):361-9
ABSTRACT: The possible association between the risk of pancreatic cancer mortality and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible pancreatic cancer deaths (883 cases) of Taiwan residents from 1990 through 1994 were compared with deaths from other causes (883 controls), and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan was collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and were pair matched to the cancer cases by , ear of birth, and year of death. The results show that there is a 39 % excess risk of mortality from pancreatic cancer in relation to the use of soft water. Trend analyses showed an increasing odds ratio for pancreatic cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health.

TITLE: Colon cancer mortality and total hardness levels in Taiwan's drinking water.
AUTHORS: Yang CY; Hung CF
SOURCE: Arch Environ Contam Toxicol 1998 Jul;35(1):148-51
ABSTRACT: The possible association between the risk of colon cancer and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible colon cancer deaths (1,714 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (1,714 controls) and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan have been collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and the controls were pair matched to the cases by , ear of birth, and year of death. The results show a significant negative relationship between drinking water hardness and colon cancer mortality. Odds ratio and 95% confidence intervals were 1.22 (1.04-1. 43) and 1.46 (1.22-1.75), respectively, for exposure to moderately hard water and soft water compared with the use of hard water. Trend analyses showed an increasing odds ratio for colon cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health.