Calcium content of river water, trace element concentrations in toenails, and blood pressure in village populations in New Guinea.

Several studies carried out on industrialized population groups have revealed the presence of an inverse relationship between hardness of drinking water and certain cardiovascular parameters, e.g., death rates, blood pressure, blood cholesterol, etc. In the present paper an attempt was made to see whether such an association also exists in primitive population groups who drink untreated water collected directly from rivers. Blood pressure was measured in persons living in villages along the banks of the Wogupmeri river in New Guinea. The water was analyzed for calcium content. Trace element concentrations were also determined in toenails from the same subjects to see whether a correlation existed. Calcium content of river water decreases as the river flows downstream, while blood pressure of the villagers living along this river increases. The trace element analysis of toenails revealed strong correlations between aluminium and vanadium. The concentrations of these two elements decrease with age. This association is present in both sexes, in adults and in children. A similarly strong correlation also exists between these two elements in staple food. The results of the present investigation tend to confirm the findings of other studies indicating an apparently beneficial effect of relatively hard water on cardiovascular parameters. The concentration of aluminium and vanadium in toenails show interesting trends, the biological meaning of which, if any, is still unknown.