Geographic variation of the mortality from cardiovascular disease and drinking water in a French small area (Puy de Dome).

Cardiovascular disease (CVD) has been the first cause of mortality in the population of Puy de Dôme (PDD) (France) between 1988 and 1992. The mortality rates are significantly higher than those observed in the whole population of France (for the female population, 354.8 versus 327.3 per 100,000 persons/year and for the male population, 335.7 versus 287.9 per 100,000 persons/year). Moreover, an ecological study, which used the Standardized Mortality Ratios (SMR) and performed at the canton level, has allowed a special variation of mortality from CVD in PDD to be described. A decreased gradient of mortality (especially, "Ischemic Heart diseases" [ICM-9, codes 410-414] and "Cerebro-vascular Diseases" [ICM-9, codes 430-438]) has been observed from the periphery (rural area) to the middle (urban area) of PDD. Moreover, a statistically significant negative relationship has been observed between the hardness of the drinking water supplies in PDD and the CVD mortality data (i.e., the lower the hardness of drinking water, the higher the SMR). Although, the low hardness of drinking water can contribute to the high CVD mortality observed among the PDD population, the role of other risk factors (i.e., biological, nutritional) must also be taken into consideration in further prospective studies.