CORRELATIONS BETWEEN WATER HARDNESS AND CARDIOVASCULAR DEATHS IN OKLAHOMA COUNTIES

Environmental factors and stroke: A selective review

Despite numerous prior stroke risk factor investigations, much remains unknown about the effect of environmental factor changes on stroke incidence and mortality rates. Yet these data might be important for defining a number of measures to prevent stroke and for developing a greater understanding of the origin and incidence trends of stroke in different regions and populations. In this paper we review the current state of knowledge about certain environmental stroke risk factors.

Magnesium in drinking water in relation to morbidity and mortality from acute myocardial infarction

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 classified subjects 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.

The water factor and mortality from ischemic heart disease: a review and possible explanations for inconsistent findings with additional data from Manitoba

The question of the relationship between water hardness and mortality from cardiovascular diseases is far from being settled. Marked discrepancies in the results of various studies in this area exist and there is a great need for closer examination of the reliability of measuring water hardness and other water characteristics. There is also a need for standardizing these measurements and for accounting for certain important questions in designing studies of this nature. This article reviews the results of various studies on the "water factor," points out their discrepancies, presents additional evidence from the Province of Manitoba against the "water factor;" and explains possible sources for discrepancies in the findings of various studies. Based on the evidence so far available, it is too early to universally accept the "water story" and to make recommendations for discouraging the softening of hard water as a measure for preventing cardiovascular disease mortality.

Current status of the epidemiology of brain infarction associated with occlusive arterial disease

Although large gaps in our knowledge concerning the epidemiology of cerebrovascular disease are apparent, careful inspection of all existing data now makes it possible to see certain patterns emerging which suggest certain risk factors for stroke.

While the problem of differential diagnosis of the various categories of cerebrovascular disease presents a major obstacle to obtaining an undistorted picture of the epidemiological features of stroke from death certificate mortality data, the addition of evidence from prospective studies, including those in Framingham, Massachusetts, reveals that various types of arterial occlusion with cerebral infarction are by far the most prevalent type of stroke. Any specific origin of atherosclerosis remains obscure, as possible etiological candidates including dietary alterations in salt, fat and refined carbohydrate, sedentary living, excessive calories promoting obesity, the cigarette habit and even the mineral content of water in addition to marital status have all been incriminated. However uncertain the final answer is, certain precursors for atherosclerosis, such as hypertension, diabetes, and hyperlipidemia, are important. Of these, hypertension is clearly the most important contributor to stroke incidence. Certain combinations of items carry more risk than do the same items singly. For example, the risk of a brain infarction in diabetics with hypertension is probably about six times that of normal subjects. In persons under 50 at the time of measurement risk of cerebral infarction is possibly ten times higher in those with hypertension and elevated lipids than in those without either elevated. This compounding of risk has pathogenetic, preventive and public health implications. For purposes of stroke screening alone the most efficient and practical method would be to determine casual blood pressure, although it must be stated that as yet there is uncertainty concerning the change in the risk if such blood pressure is treated.

Death statistics for cerebrovascular disease: a review of recent findings

There is a large margin of error in death statistics. Mortality statistics for cerebrovascular disease show, however, the well-known rise in frequency with age, the higher frequency in men than women which is likely to affect all countries in the coming years, and the greater involvement of nonwhite Americans and Japanese than of white Americans and Japanese Americans. I believe that incidence figures, when they become available in future years, will confirm these findings. Environmental factors, such as a "water factor," also relate to cerebrovascular death rates. Possibly the biggest factor in the medical environment, causing artificial swings in both mortality and incidence figures, will be shown to be the changing diagnostic habits of physicians.

From the viewpoint of etiology, the coexistence of hypertension and cerebrovascular disease dominates the epidemiological picture. The geographic distribution of cerebrovascular mortality in the U.S.A., and the higher mortality in Negroes and in the elderly, particularly relate to underlying hypertension. Ongoing and future population studies, focusing on morbidity as well as mortality, are likely to contribute much in clarifying the relative importance of other causal factors whose harmful effects can be controlled.

Cardiovascular mortality in relation to radioactivity and hardness of local water supplies in the USA

Several authors have reported an inverse correlation between death rates from cardiovascular diseases and local water hardness, but the significance of such a relationship is still debated. To investigate further this relationship, another indicator of water quality was used, namely, the alpha-radioactivity level of raw river waters in the USA. This indicator also showed a negative correlation with cardiovascular death rates, particularly from hypertensive heart disease, which was consistent whether the data were analysed by state, by river basin, by county, or by community. The fact that the negative relationship holds true for raw river waters indicates that broader environmental and geochemical factors may be involved. The effects of trace elements present in the soil and in the water on man's mineral balance, and eventually on the cardiocirculatory function, are discussed.