Relationship between the Difference in the Recent Expectation of Life by Prefecture and Constituent of River Water in Japan

Abstract

In order to know the cause of difference in the expectation of life (ex) by prefecture, relationships between ex (e0, e20, e40, e65) by prefecture in every five years from 1965 to 1980 and constituent of river water (19 items) were examined by simple correlation, partial correlation, multiple correlation and multiple regression analysis, and the following results were obtained. 1) Correlation coefficients between ex and pH, Ca, Mg, CO₂, Ca/SO₄, Ca-Na were positive and significant, and those between eX and SiO₂, SO₄, SO₄/CO₃, Na/CO were negative and significant in one or some age of year. These correlations, excepting PH, were relatively strong in female and old age and showed tendencies of getting weaker year by year. 2) Of the partial correlation coefficients excluded influences of the items whose simple correlation coefficients were significant, those between ex and SO4/CO3 were chiefly significant among others until 1975, so were those between ex and PH in 1980. 3) In the multiple regression analyses of ex on items by forward selection proce dure, SO₄/CO₃ were selected for the first variables in the most cases until 1975, so were pH in 1980. Above results suggest that the relation of SO₄/CO₃ to the difference in ex by prefecture was strong, especially for female and old age, getting weaker every year, and making stronger that of pH recently.