Geochemistry of ground water and the incidence of acute myocardial infarction in Finland

The Relationship between Mortality from Cardiovascular Diseases and Total Drinking Water Hardness: Systematic Review with Meta-Analysis

BACKGROUND

Interest in water chemical activity, its content, and its impact on human health has greatly increased throughout the last decade. Some studies suggest that drinking water with high hardness may have preventative effects on cardiovascular diseases. This study aims to investigate the association between drinking water hardness and cardiovascular disease (CVD) mortality.

METHODS

The study selection process was designed to find the association between drinking water hardness and CVDs mortality. The search included both qualitative and quantitative research and was performed in three databases: Web of Science (Clarivate Analytics, Ann Arbor, MI, USA), PubMed (National Institute of Health, Bethesda, MA, USA), and Scopus (Elsevier, RELX Group plc, London, UK). The project was registered in the International Prospective Register of Systematic Reviews (PROSPERO), registration number: CRD42020213102.

RESULTS

Seventeen studies out of a total of twenty-five studies qualitatively analyzed indicated a significant relation between total water hardness and protection from CVD mortality. The quantitative analysis concluded that high drinking water hardness has a significantly lowering effect on mortality from CVDs, however, the heterogeneity was high.

CONCLUSIONS

This systematic literature review shows that total water hardness could affect CVD prevention and mortality. Due to the many confounding factors in the studies, more research is needed.

Association between magnesium in drinking water and atrial fibrillation incidence: a nationwide population-based cohort study, 2002-2015

BACKGROUND

Atrial fibrillation (AF) is a common heart rhythm disorder and a risk factor of adverse cardiovascular diseases. Established causes do not fully explain the risk of AF and unexplained risk factors might be related to the environment, e.g. magnesium in drinking water. Low magnesium levels in drinking water might be associated with higher risk of cardiovascular diseases including AF. With detailed individual data from nationwide registries and long-term magnesium exposure time series, we had a unique opportunity to investigate the association between magnesium in drinking water and AF.

OBJECTIVE

We evaluated the association between magnesium concentration in drinking water and AF risk.

METHODS

A nationwide register-based cohort study (2002-2015) was used including individuals aged ≥30 years. Addresses were linked with water supply areas (n = 2418) to obtain time-varying drinking water magnesium exposure at each address. Five exposure groups were defined based on a 5-year rolling time-weighted average magnesium concentration. AF incidence rate ratios (IRRs) between exposure groups were calculated using a Poisson regression of incidence rates, adjusted for sex, age, and socioeconomic position. Robustness of results was investigated with different exposure definitions.

RESULTS

The study included 4,264,809 individuals (44,731,694 person-years) whereof 222,998 experienced an incident AF. Magnesium exposure ranged from 0.5 to 62.0 mg/L (mean = 13.9 mg/L). Estimated IRR (95% CI) compared to the referent exposure group (< 5 mg/L) was 0.98 (0.97-1.00) for the second lowest exposure group (5-10 mg/L), and 1.07 (1.05-1.08) for the two highest exposure groups (15-62 mg/L). Strongest positive associations were observed among those aged ≥80 years and with lowest education group. An inverse association was found among individuals with highest education group.

CONCLUSION

There might be a small beneficial effect on AF of an increase in magnesium level in drinking water up to 10 mg/L, though an overall positive association was observed. The unexpected positive association and different associations observed for subgroups suggest a potential influence of unaccounted factors, particularly in vulnerable populations. Future research on magnesium in drinking water and cardiovascular diseases needs to focus on contextual risk factors, especially those potentially correlating with magnesium in drinking water.

Association between exposure to desalinated sea water and ischemic heart disease, diabetes mellitus and colorectal cancer; A population-based study in Israel

BACKGROUND

Drinking water (DW) is an important dietary source of magnesium. Recently, Israel has increased its use of desalinated seawater (DSW) as DW country-wide. Its negligible magnesium content, however, raises concern that consumption of DSW may be associated with hypomagnesemia and increase the risk of ischemic heart disease (IHD), diabetes mellitus (DM), and colorectal cancer (CRC).

OBJECTIVES

We tested whether there was a change in incidence of negative health outcomes (IHD, DM, and CRC) following the introduction of DSW supply in a population-based ecologic study in Israel.

METHODS

A historical prospective analysis was applied to members aged 25-76 during 2004-2013 of Clalit Health Services (Clalit), the largest healthcare provider in Israel, using its electronic medical record database. Multivariable analyses were adjusted for age, sex, socioeconomic status, smoking status, and body mass index.

RESULTS

An increased odds ratio was found for IHD (0.96, 95% CI 0.93-0.99 at baseline and 1.06, 95% CI 1.02-1.11 at the end of the follow-up period), but no time trend was observed.

CONCLUSIONS

We found that the risk for IHD increased during the study period. The risks for DM and CRC were unchanged. Long term studies are needed for assessing the risk for CRC due to the long latency. The higher risk for IHD has practical public health implications and raise the need to add magnesium to DSW.

Review of epidemiological studies on drinking water hardness and cardiovascular diseases

BACKGROUND

Major risk factors do not entirely explain the worldwide variability of morbidity and mortality due to cardiovascular disease. Environmental exposures, including drinking water minerals may affect cardiovascular disease risks.

METHOD

We conducted a qualitative review of the epidemiological studies of cardiovascular disease and drinking water hardness and calcium and magnesium levels.

RESULTS

Many but not all ecological studies found an inverse (i.e., protective) association between cardiovascular disease mortality and water hardness, calcium, or magnesium levels; but results are not consistent. Some case-control studies and one cohort study found either a reduced cardiovascular disease mortality risk with increased drinking water magnesium levels or an increased risk with low magnesium levels. However, the analytical studies provide little evidence that cardiovascular risks are associated with drinking water hardness or calcium levels.

CONCLUSION

Information from epidemiological and other studies supports the hypothesis that a low intake of magnesium may increase the risk of dying from, and possibly developing, cardiovascular disease or stroke. Thus, not removing magnesium from drinking water, or in certain situations increasing the magnesium intake from water, may be beneficial, especially for populations with an insufficient dietary intake of the mineral.

Natural fluoride in drinking water and myocardial infarction: A cohort study in Sweden

Large geographical variation in the coronary heart disease (CHD) incidence is seen worldwide and only a part of this difference is attributed to the classic risk factors. Several environmental factors, such as trace elements in the drinking water have been implicated in the pathogenesis of CHD. The objective was to assess the association between drinking water fluoride exposure and myocardial infarction in Sweden using nationwide registers. This large cohort consisted of 455,619 individuals, born in Sweden between January 1, 1900 and December 31, 1919, alive and living in their municipality of birth at the time of start of follow-up. Estimated individual drinking water fluoride exposure was stratified into four categories: very low (<0.3mg/l), low (0.3-<0.7mg/l), medium (0.7-<1.5mg/l) and high (≥1.5mg/l). In Cox regression analyses, compared to the very low fluoride group, the adjusted Hazard Ratio for the low fluoride group was 0.99 (95% confidence interval, 0.98-1.00), for the medium fluoride group 1.01 (95% confidence interval, 0.99-1.03) and 0.98 (95% confidence interval, 0.96-1.01) for the highest fluoride group. Adding water hardness to the model did not change the results. We conclude that the investigated levels of natural drinking water fluoride content does not appear to be associated with myocardial infarction, nor related to the geographic myocardial infarction risk variation in Sweden. Potential misclassification of exposure and unmeasured confounding may have influenced the results.

Desalinated seawater supply and all-cause mortality in hospitalized acute myocardial infarction patients from the Acute Coronary Syndrome Israeli Survey 2002-2013

BACKGROUND

Consuming desalinated seawater (DSW) as drinking water (DW) may reduce magnesium in water intake causing hypomagnesemia and adverse cardiovascular effects.

METHODS

We evaluated 30-day and 1-year all-cause mortality of acute myocardial infarction (AMI) patients enrolled in the biannual Acute Coronary Syndrome Israeli Survey (ACSIS) during 2002-2013. Patients (n=4678) were divided into 2 groups: those living in regions supplied by DSW (n=1600, 34.2%) and non-DSW (n=3078, 65.8%). Data were compared between an early period [2002-2006 surveys (n=2531) - before desalination] and a late period [2008-2013 surveys (n=2147) - during desalination].

RESULTS

Thirty-day all-cause-mortality was significantly higher in the late period in patients from the DSW regions compared with those from the non-DSW regions (HR=2.35 CI 95% 1.33-4.15, P<0.001) while in the early period there was no significant difference (HR=1.37 CI 95% 0.9-2, P=0.14). Likewise, there was a significantly higher 1-year all-cause mortality in the late period in patients from DSW regions compared with those from the non-DSW regions (HR=1.87 CI 95% 1.32-2.63, P<0.0001), while in the early period there was no significant difference (HR=1.17 CI 95% 0.9-1.5, P=0.22). Admission serum magnesium level (M±SD) in the DSW regions (n=130) was 1.94±0.24mg/dL compared with 2.08±0.27mg/dL in 81 patients in the non-DSW (P<0.0001).

CONCLUSIONS

Higher 30-day and 1-year all-cause mortality in AMI patients, found in the DSW regions may be attributed to reduced magnesium intake secondary to DSW consumption.

On the Analysis of Diseases and Their Related Geographical Data

Electronic medical records (EMRs) store data related to patients information enrolled during their stay in health structures. Data stored into EMRs span from data crawled from biological laboratories to textual description of diseases and diagnostic device results (e.g., biomedical images). Each EMR is related to a diagnosis related group (DRG) record. A DRG record is a record associated with a citizen that has been cured in a hospital. It contains a code, called major diagnostic category (MDC), which summarizes the treated disease and allows to reimburse costs related to patient treatments during his staying in health structures. DRGs are used for administrative process (e.g., costs and reimbursement management) as well as disease monitoring. Associating diagnostic codes with external information (such as environmental and geographical data) and with information filtered from EMRs (e.g., biological results or analytes values) can be useful to monitor citizens wellness status. We propose a methodology to analyze such data based on a multistep process. First, we cross reference data by using a semantics-based clustering procedure, extract information from EMRs, and then, cluster them by looking for similar patterns of diseases. Then, biological records in each disease cluster are analyzed to evaluate intracluster similarity by selecting analytes typologies and values. Finally, biological data is related to diagnosis codes and geometrically projected in areas of interest in order to map calculated outlier patients. We applied the methodology on two case studies: 1) diagnosis codes and biochemical analytes of 20 000 biological analyses about hospitalized patients during one observation year and 2) the correlation between cardiovascular diseases and water quality in a southern Italian region. Preliminary findings show the effectiveness of our method.

Knowledge, attitudes and practice of desalinated water among professionals in health and water departments in Shengsi, China: a qualitative study

Desalination has been considered as an essential way to solve water stress all over the world. Most of previous studies focused on its environmental impacts, energy consumption and desalination technologies rather than human health. However, the safety of desalinated water remains unclear. This study was undertaken to investigate the knowledge, attitude and practice (KAP) of the residents in an island county in eastern China to desalinated water. Seventeen people working in medical and water industries were recruited, and focus group discussion and in-depth interview were conducted among them. Our results showed that the majority of people interviewed knew the definition and local supply pattern of desalinated water, while some of them showed some concern about the safety and nutrition of desalinated water. Current drinking water standard has no specific item for desalination, so we strongly suggest issuing a standard for desalinated water.

A review of spatial methods in epidemiology, 2000-2010

Understanding the impact of place on health is a key element of epidemiologic investigation, and numerous tools are being employed for analysis of spatial health-related data. This review documents the huge growth in spatial epidemiology, summarizes the tools that have been employed, and provides in-depth discussion of several methods. Relevant research articles for 2000-2010 from seven epidemiology journals were included if the study utilized a spatial analysis method in primary analysis (n = 207). Results summarized frequency of spatial methods and substantive focus; graphs explored trends over time. The most common spatial methods were distance calculations, spatial aggregation, clustering, spatial smoothing and interpolation, and spatial regression. Proximity measures were predominant and were applied primarily to air quality and climate science and resource access studies. The review concludes by noting emerging areas that are likely to be important to future spatial analysis in public health.

Relationship between tap water hardness, magnesium, and calcium concentration and mortality due to ischemic heart disease or stroke in The Netherlands

BACKGROUND

Conflicting results on the relationship between the hardness of drinking water and mortality related to ischemic heart disease (IHD) or stroke have been reported.

OBJECTIVES

We investigated the possible association between tap water calcium or magnesium concentration and total hardness and IHD mortality or stroke mortality.

METHODS

In 1986, a cohort of 120,852 men and women aged 5569 years provided detailed information on dietary and other lifestyle habits. Follow-up for mortality until 1996 was established by linking data from the Central Bureau of Genealogy and Statistics Netherlands. We calculated tap water hardness for each postal code using information obtained from all pumping stations in the Netherlands. Tap water hardness was categorized as soft [< 1.5 mmol/L calcium carbonate (CaCO3)], medium hard (1.62.0 mmol/L CaCO3), and hard (> 2.0 mmol/L CaCO3). The multivariate case-cohort analysis was based on 1,944 IHD mortality and 779 stroke mortality cases and 4,114 subcohort members.

RESULTS

For both men and women, we observed no relationship between tap water hardness and IHD mortality [hard vs. soft water: hazard ratio (HR) = 1.03; 95% confidence interval (CI), 0.851.28 for men and HR = 0.93; 95% CI, 0.711.21 for women) and stroke mortality (hard vs. soft water HR = 0.90; 95% CI, 0.661.21 and HR = 0.86; 95% CI, 0.621.20, respectively). For men with the 20% lowest dietary magnesium intake, an inverse association was observed between tap water magnesium intake and stroke mortality (HR per 1 mg/L intake = 0.75; 95% CI, 0.610.91), whereas for women with the 20% lowest dietary magnesium intake, the opposite was observed.

CONCLUSIONS

We found no evidence for an overall significant association between tap water hardness, magnesium or calcium concentrations, and IHD mortality or stroke mortality. More research is needed to investigate the effect of tap water magnesium on IHD mortality or stroke mortality in subjects with low dietary magnesium intake.

Evaluating the effect of neighbourhood weight matrices on smoothing properties of Conditional Autoregressive (CAR) models

BACKGROUND

The Conditional Autoregressive (CAR) model is widely used in many small-area ecological studies to analyse outcomes measured at an areal level. There has been little evaluation of the influence of different neighbourhood weight matrix structures on the amount of smoothing performed by the CAR model. We examined this issue in detail.

METHODS

We created several neighbourhood weight matrices and applied them to a large dataset of births and birth defects in New South Wales (NSW), Australia within 198 Statistical Local Areas. Between the years 1995-2003, there were 17,595 geocoded birth defects and 770,638 geocoded birth records with available data. Spatio-temporal models were developed with data from 1995-2000 and their fit evaluated within the following time period: 2001-2003.

RESULTS

We were able to create four adjacency-based weight matrices, seven distance-based weight matrices and one matrix based on similarity in terms of a key covariate (i.e. maternal age). In terms of agreement between observed and predicted relative risks, categorised in epidemiologically relevant groups, generally the distance-based matrices performed better than the adjacency-based neighbourhoods. In terms of recovering the underlying risk structure, the weight-7 model (smoothing by maternal-age 'Covariate model') was able to correctly classify 35/47 high-risk areas (sensitivity 74%) with a specificity of 47%, and the 'Gravity' model had sensitivity and specificity values of 74% and 39% respectively.

CONCLUSION

We found considerable differences in the smoothing properties of the CAR model, depending on the type of neighbours specified. This in turn had an effect on the models' ability to recover the observed risk in an area. Prior to risk mapping or ecological modelling, an exploratory analysis of the neighbourhood weight matrix to guide the choice of a suitable weight matrix is recommended. Alternatively, the weight matrix can be chosen a priori based on decision-theoretic considerations including loss, cost and inferential aims.

Calcium and magnesium in drinking water and risk of death from acute myocardial infarction in Taiwan

Many studies have examined the association between cardiovascular disease mortality and water hardness. However, the results have not been consistent. This report examines whether calcium and magnesium in drinking water are protective against acute myocardial infarction (AMI). All eligible AMI deaths (10,094 cases) of Taiwan residents from 1994 to 2003 were compared with deaths from other causes (10,094 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 have been 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 sex, year of birth, and year of death. The adjusted odd ratios (95% confidence interval) were 0.79 (0.73-0.86) for the group with water calcium levels between 25.1 and 42.4 mg/L and 0.71 (0.65-0.77) for the group with calcium levels of 42.6 mg/L or more. After adjustment for calcium levels in drinking water, there was no difference between the groups with different levels of magnesium. The results of the present study show that there is a significant protective effect of calcium intake from drinking water on the risk of death from AMI.

Calcium:magnesium ratio in local groundwater and incidence of acute myocardial infarction among males in rural Finland

Several epidemiologic studies have shown an association between calcium and magnesium and coronary heart disease mortality and morbidity. In this small-area study, we examined the relationship between acute myocardial infarction (AMI) risk and content of Ca, Mg, and chromium in local groundwater in Finnish rural areas using Bayesian modeling and geospatial data aggregated into 10 km times symbol 10 km grid cells. Data on 14,495 men 35-74 years of age with their first AMI in the years 1983, 1988, or 1993 were pooled. Geochemical data consisted of 4,300 measurements of each element in local groundwater. The median concentrations of Mg, Ca, and Cr and the Ca:Mg ratio in well water were 2.61 mg/L, 12.23 mg/L, 0.27 microg/L, and 5.39, respectively. Each 1 mg/L increment in Mg level decreased the AMI risk by 4.9%, whereas a one unit increment in the Ca:Mg ratio increased the risk by 3.1%. Ca and Cr did not show any statistically significant effect on the incidence and spatial variation of AMI. Results of this study with specific Bayesian statistical analysis support earlier findings of a protective role of Mg and low Ca:Mg ratio against coronary heart disease but do not support the earlier hypothesis of a protective role of Ca.

Daily Intake of Magnesium and Calcium From Drinking Water in Relation to Myocardial Infarction

BACKGROUND

A decreased risk for cardiovascular disease has been related to the hardness of drinking water, particularly high levels of magnesium. However, the evidence is still uncertain, especially in relation to individual intake from water.

METHODS

We used data from the Stockholm Heart Epidemiology Program, a population-based case-control study conducted during 1992-1994, to study the association between myocardial infarction and the daily intake of drinking water magnesium and calcium. Our analyses are based on 497 cases age 45-70 years, and 677 controls matched on age, sex, and hospital catchment area. Individual data on magnesium, calcium, and hardness of the domestic drinking water were assessed from waterwork registers or analyses of well water.

RESULTS

After adjustment for the matching variables and smoking, hypertension, socioeconomic status, job strain, body mass index, diabetes, and physical inactivity, the odds ratio for myocardial infarction was 1.09 (95% confidence interval = 0.81-1.46) associated with a tap water hardness above the median (>4.4 German hardness degrees) and 0.88 (0.67-1.15) associated with a water magnesium intake above the median (>1.86 mg/d). There was no apparent sign of any exposure-response pattern related to water intake of magnesium or calcium.

CONCLUSIONS

This study does not support previous reports of a protective effect on myocardial infarction associated with consumption of drinking water with higher levels of hardness, magnesium, or calcium.

Mineral water intake reduces blood pressure among subjects with low urinary magnesium and calcium levels

Background

Several previous epidemiological studies have shown a relation between drinking water quality and death in cardiovascular disease whereas others have not found such a relationship. An intervention study was undertaken to evaluate the effect of water with added magnesium and natural mineral water on blood pressure.

Methods

A group of 70 subjects with borderline hypertension was recruited and consumed 1) a water low in minerals, 2) magnesium enriched water or 3) natural mineral water, in a random, double blind fashion during four weeks.

Results

Among persons with an initial low excretion of magnesium or calcium in the urine, the urinary excretion of magnesium was increased in the groups consuming the two waters containing magnesium after 4 weeks. A significant decrease in blood pressure was found in the group consuming mineral water at 2 and 4 weeks.

Conclusion

The results suggest that minerals taken in water are significant for the body burden and that an intake of mineral water among persons with a low urinary excretion of magnesium or calcium may decrease the blood pressure. Further studies should investigate the extent of mineral deficiency in different populations and the efficiency of different vehicles for supplying minerals, particularly magnesium and calcium.