How to interpret epidemiological associations
Introduction
Cardiovascular disease is among the leading causes of morbidity and mortality in industrialized countries. Hypertensive disease, smoking, excessive alcohol consumption, diet, and physical inactivity have been identified as risk factors, but they do not entirely explain the worldwide variability of cardiovascular disease (Sauvant and Pepin 2002; Hornstra et al. 1998). It has long been suspected that cardiovascular disease mortality may be associated with geochemical constituents, especially water hardness.