Abstract
Japanese nuclear power plants (NPPs) located in four main islands from Hokkaido to Kyushu islands. Radiation dose to the public from NPP are too small in normal operation to be of concern for daily life. A relationship between geographical temporal pattern of 1993-97 cancer mortality and nine social-demographic factors including tobacco tax, physician number and financial index have been examined to provide a scientific interpretation of the observations in NPP areas by ecological study. Area variation analysis of standard mortality ratio (SMR) was mainly based on prefecture-level (47 units) in all Japan. Municipality-level analysis was limited to Ibaraki prefecture (85 units as the end of 1997) where the earliest NPP with the 1966 commissioning year was located. Baseline rate of SMR is thought to be weighted-average of each area-specific rate with the corresponding cancer death number. In prefecture-level the death number by area grouping with quintile of the above factors shows relatively equal for physician number and large unbalanced for financial index. Cancer mortality was high in the highest quintile of tobacco tax for lung and interestingly high in the lowest one for lymphoid-hemopoietic tissue although these SMR variations were small. In municipality-level the 5-years period observations limited to Ibaraki prefecture were not sufficient to recognize directly the relationship of the above social-demographic factors with cancer mortality. However, it is useful to demonstrate municipality frequency by these factors for leading to reasonable ecological interpretation.
