The Journal of Nihon University School of Dentistry
Online ISSN : 1884-2984
Print ISSN : 0029-0432
ISSN-L : 0029-0432
Correlation between Natural Radiation Expousre and Cancer Mortality (5)
清水 雅美野口 邦和西連寺 永康安斎 育郎
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ジャーナル フリー

1987 年 29 巻 4 号 p. 314-320

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In the previous studies, correlation between natural background radiation exposure rates and cancer mortality rates in 46 Japanese prefectures was statistically studied over the period of 1950-1978. With regard to the correlation between natural background radiation exposure rate and crude (non-age-adjusted) cancer mortality rate, statistically significant positive correlation coefficients were observed in most cases of cancers with only a few exceptions. However, the significance of the correlation mostly disappeared through age-adjustment with only three exceptions. We examined the cause of this apparent correlation and found that natural radiation levels are positively correlated with prefectural population component ratios for those inhabitants older than 40, 50 and 65 years.
The atomic bombings of Hiroshima and Nagasaki could have affected the cancer mortality in these prefectures and it is reasonable to question the validity of statistical analyses by including these areas together with other prefectures. Therefore, in the present investigation, we carried out recalculations while excluding the data for Hiroshima and Nagasaki prefectures. In most cases of cancers, the correlation did not show any change. However, in the case of female pancreas cancer in 1968-1978, the significance level of negative correlatilon changed from 5% to 10%, and total female cancers and liver cancer for both sexes in 1968-1978 came to show a significant positive correlation at the 10% level.

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