Coronary heart disease and drinking water. A search in two Finnish male cohorts for epidemiologic evidence of a water factor.

IT IS well known that geographic differences exist between populations in the mortality caused by coronary heart disease (C.H.D.). These differences are not entirely explained by the known risk factors of C.H.D. and attention has been drawn to the possibility that the quality of drinking water affects the death rates from C.H.D. [l-14]. There is no general agreement, however, on the identity or even on the existence of a water factor [15-21-J. Finland has an especially high rate of death from C.H.D. [22]. Within Finland there is a marked difference in the mortality from C.H.D. between the southwestern and the eastern parts of the country, the mortality being much higher in eastern Finland [23-25-j. A cohort study on C.H.D. has been conducted since 1959 on two rural male populations, one from the eastern part, the other from the western part of the country [26-291. In 10 yr, the eastern cohort had experienced a rate of death from C.H.D. more than twice as high as the western cohort [30]. Among the eastern men, C.H.D. runs a short course and has a poor prognosis, and this, in fact, seems to be a major characteristic of the epidemic of C.H.D. in the eastern cohort [30-321. The currently known risk factors do not seem to adequately explain the high mortality from C.H.D.