The mortality rate (stillbirths and infant deaths) from anencephalus from 1950-1969 in 36 cities of over 50,000 population in Canada showed a negative association (r = -.39) with the concentration of magnesium in water sampled at domestic taps. The mortality rates showed negative associations with mean income and longitude, and a multiple regression model using the three factors showed significant effects of each and accounted for 69% of the intercity variation in rates. There were no significant associations seen with water calcium concentration or total hardness. Income, magnesium and longitude were also negatively associated with mortality rates from spina bifida, hydrocephalus, other congenital abnormalities, and total stillbirth and infant death rates, but the association with magnesium was significant only for total stillbirths. The negative association of anencephalus mortality and magnesium levels was also seen in a sample of 14 smaller towns in Ontario.
The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked.
Mosses collected decades ago and stored in herbaria are often used to assess historical nitrogen deposition. This method is effectively based on the assumption that tissue N concentration remains constant during storage. The present study raises serious doubt about the generality of that assumption. We measured tissue N and C concentrations as well as d15N, d13C, Pb and Mg in herbarium and present day samples of seven bryophyte species from six sites across Denmark. While an increase in nitrogen deposition during the last century is well-documented for the study site, we surprisingly found foliar N concentration to be higher in historical samples than in modern samples. Based on d15N values and Pb concentration, we find nitrogen contamination of herbarium specimens during storage to be the most likely cause, possibly in combination with dilution though growth and/or decomposition during storage. We suggest ways to assess contamination and recommend caution to be taken when using herbarium specimens to assess historical pollution if exposure during storage cannot be ruled out.
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.
Market baskets containing sixty food items included in the average Swedish diet were purchased from three shops in four major Swedish cities during autumn 1987. Food items were selected on the basis of food-balance-sheet data. Freeze-dried homogenates representative of each city were analysed for twelve essential or toxic mineral elements. The energy content of the market baskets (11.5 MJ) corresponded to the reference value for male adults. At this energy level the contents of calcium (1180 mg), magnesium (300 mg), iron (16 mg), zinc (12 mg) and selenium (44 micrograms) were above or close to the Swedish recommended daily intakes. The contents of manganese (3.7 mg) and molybdenum (150 micrograms) were within and that of copper (1.2 mg) was below the safe and adequate intake values given in the US recommended dietary allowance (Food and Nutrition Board, National Research Council, 1989). The content of nickel was 82 micrograms. The contents of lead (17 micrograms), cadmium (12 micrograms) and mercury (1.8 micrograms) in the daily diet were low compared with the provisional tolerable intakes set by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (World Health Organization, 1972, 1989). The market-basket contents of Ca, Mg, Fe and Zn calculated from values in the Swedish food composition tables were close to the analysed values, indicating that the Swedish food tables provide relevant information for the estimation of the dietary supply of these elements.
OBJECTIVES: To evaluate the influence of established liver cirrhosis on muscle strength and muscle contents of magnesium (Mg), potassium (K) and sodium, potassium pumps (Na,K-pumps) in chronic alcoholic patients. DESIGN: An open cross-sectional study. SETTING AND SUBJECTS: Forty consecutive chronic alcoholics (18 with cirrhosis and 22 without cirrhosis) admitted to the Department of Hepatology, Aarhus University Hospital, Denmark, or to a collaborating alcoholism treatment centre, and 36 healthy control subjects. MAIN OUTCOME MEASURES: Evaluation of participant's subjective physical ability and measurement of maximum isokinetic muscle strength and muscle mass, as well as measurements of Mg, K and Na,K-pumps in skeletal muscle. RESULTS: Maximum isokinetic muscle strength and muscle mass were equally reduced in patients with and without cirrhosis (P
Because of excessive reliance on the method of ecological correlation, in which the units of study are entire communities, there have been few agreed conclusions concerning the relation between mineral quality of water and health. However, in recent years there have been attempts to relate water exposure to health outcome in statistical series of individual subjects. Studies in Kitchener, Ontario and Regina, Saskatchewan found that households having domestic water softeners experience lower death rates than others. Kitchener data clearly implied an association between copper piping and mortality rate but this was not confirmed in Regina. Comparison of myocardial tissue between residents of soft and hard water areas has confirmed that insufficient magnesium intake is a likely cause of higher mortality in soft water areas. Within the 'normal' range of myocardial magnesium concentration the risk of IHD death appears to vary by at least one and possibility two orders of magnitude.
