Magnesium in well water and the spatial variation of acute myocardial infarction incidence in rural Finland

The protective role of water hardness and Mg in cardiovascular illness has been suggested in several epidemiological studies. In the present ecological study, the association of Ca, Mg, Al, Cu, F, Fe, Zn and NO3 in local ground water and spatial variation of acute myocardial infarction (AMI) incidence among men and women 35–74 years of age in rural Finland in 1991–2003 were examined. Data on AMI cases, 67,755 men and 25,450 women, were obtained from the Finnish Cardiovascular Disease Register. The statistical analysis was carried out using Bayesian modeling. 10 × 10 km grid cells were used instead of administrative boundaries to partition the study area. On average, 1 mg/L increment in Mg level in local ground water was associated with 2% (95% HDR −0.0391, −0.0028) decrease in incidence of AMI in the rural population. In conclusion, high AMI incidence in eastern Finland is associated with soft ground water, low in Mg.