Coronary heart disease and drinking water: A search in two Finnish male cohorts for epidemiologic evidence of a water factor

Abstract

A search for the hypothetical factor in drinking water that might influence the mortality from C.H.D. was made in two rural areas in western and eastern Finland. A 10-yr follow-up of the resident males had shown a higher death rate from C.H.D. in the eastern area. The difference is only partly explained by the currently known risk factors of C.H.D. The levels of 22 water characteristics were investigated in 327 wells and six tap-water samples. In both areas the water used for drinking is soft but the mean concentrations of several components differ. In general, the concentrations are lower in the eastern area. The difference is significant for pH, F, Ca, Mg, Na, and Cr. The concentrations of NO 3, K, Cu, Co, Ni, and Ba are significantly higher in the eastern area. In both populations there were indications that death from, or the development of, C.H.D. was connected with the quality of the water, particularly with low concentrations of constituents. Assuming that a single water constituent is responsible for the difference in mortality from C.H.D. between the cohorts, the elements most suspect were chromium and, to a lesser degree, copper. C.H.D. was associated with low concentrations of chromium and high concentrations of copper in drinking water. Findings on magnesium were equivocal, and no association was observed with calcium. The relationships of the components of drinking water to the following risk factors of death from C.H.D. were also investigated: systolic blood pressure, serum cholesterol, extrasystoles in ECG, and cigarette smoking. In the eastern area the concentration of serum cholesterol correlated negatively with the concentration of chromium in drinking water.