Preliminary report on nationwide study of drinking water and cardiovascular diseases.

This study was designed to further investigate the association(s) of cardiovascular diseases and drinking water constituents. A sample of 4200 adults were randomly selected from 35 geographic areas to represent the civilian noninstitutionalized population of the contiguous United States. Each participant was interviewed and given a thorough physical examination. A tap water grab sample was collected from each participant's residence and analyzed for 80 inorganic chemical constituents. This paper is limited to measures of association between mortality rates and mean inorganic chemical constituent levels for the 35 study areas. Limited statistical analyses of associations among some of the chemical constituent levels are also included. Hardness and calcium appear to follow the normal trend of negative associations with the mortality rates for most groups of cardiovascular diseases, whereas the area means for copper and lead are positively associated. Zinc and cadmium associations were examined, but the range of constituent levels in the sampled drinking waters is too small for meaningful interpretation of the results. Unexpectedly, the area sodium means were negatively related to the male and female cardiovascular mortality rates; the associations were statistically significant (P less than 0.05) for both the male and female total cardiovascular-renal and ischemic heart disease mortality rates.