Terrestrial radiation and cancer
mortality in Japan
Imanaka T.
September 7, 2010
Terrestrial radionuclides
Geochemical map of Japan, AIST HP
2
Natural radiation: terrestrial origin
Geochemical map of Japan, AIST HP
Gamma-ray radiation rate at 1 m above ground:
D(Gy/h）＝5.4U(ppm)＋2.7Th(ppm)＋13.0K(%)
HASL-258(1972)
Example：Hiroshima U：2.4ppm、Th:14.3ppm、K：2.4％
13 Gy/h (U) + 39 Gy/h (Th) + 30 Gy/h (K) → 83 Gy/h
3
Terrestrial -radiation in Japan
Minato, J Geography, 2006
4
Natural radiation other than terrestrial
0.4
0.41
0.38
0.29
Terrestrial
Cosmic
Internal
Radon
Natural radiation in Japan: 1.5 mSv/year
5
Cancer mortality in Japan: total cancer
Male
Female
6
National Cancer Center HP
Cancer mortality in Japan: leukemia
Male
Female
National Cancer Center HP
7
Cancer mortality in Japan: lung, breast
Male lung
Female
breast
National Cancer Center HP
8
Relation between terrestrial- and cancer mortality
100
5
Deaths per 10 person-year
150
50
Male
Female
0
20
40
60
80
Gamma-ray radiation rate, nGy/h
Total cancer
9
Relation between terrestrial- and cancer mortality
Male
Female
8
6
5
Deaths per 10 person-year
10
4
2
0
20
40
60
80
Gamma-ray radiation rate, nGy/h
Leukemia
10
Relation between terrestrial- and cancer mortality
Male
Female
8
Nagasaki
Miyazaki
Kagoshima
Okinawa
6
Kumamoto
Oita
5
Deaths per 10 person-year
10
Saga
Fukuoka
4
2
0
20
40
60
80
Gamma-ray radiation rate, nGy/h
Leukemia
Closed circles are prefectures in Kyushu island and Okinawa.
11
Relation between terrestrial- and cancer mortality
5
Deaths per 10 person-year
40
Male lung
Female breast
30
20
10
0
20
40
60
80
Gamma-ray radiation rate, nGy/h
Male lung cancer and female breast cancer
12
Natural and medical radiation in Japan
Natural radiation
Medical
2.25
Natural
1.48
0.38
Terrestrial
0.29
Cosmic
0.41
0.4
Internal
Radon
mSv/year
Data by Radiation Effects Foundation
13
Summary
• Preliminary analysis by Imanaka failed to indicate a
relationship between terrestrial radiation and cancer
mortality in Japan.
• Considering the natural radiation of 1.5 mSv/yr for 130
million population and the cancer risk factor of 0.05
/Sv, about 10,000 cancer deaths are expected annually
due to natural radiation, which corresponds to 3 % of
total cancer deaths in Japan.
• If the real risk factor is 10 times larger than the above,
30 % will be due to natural radiation.
• The study by Tondel is interesting and worthy to be
challenged.
14