Mortality in adults and trace elements in water

Representative samples of tap water were collected in 48 local-authority areas in South Wales. The associations between twelve trace elements and both total and ischæmic-heart-disease (I.H.D.) mortality were examined. Interrelationships between the trace elements were found to be strong and complex, but only calcium (Ca) seemed to make an important contribution to mortality. The addition of other elements improved regression only marginally. The association between Ca and total mortality was found to be closer than that with I.H.D. mortality. This is inconsistent with a specific effect of Ca, and hence water hardness, on I.H.D