7. cell death mutation loss of structural and functional integrity of tissue genetic instability ・ cancer ・ heritable effect deterministic effects stochastic effects DNA damage is completely repaired within the repair capacity of cells biological effect occurs at doses higher than the threshold incorrect repair takes place regardless of repair capacity of the cells biological effect occurs even at very low doses
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10. Detriment-adjusted nominal risk coefficients after exposure to radiation at low dose rate ICRP recommendations (Publication 103), pp53 (Table 1), 2007 Exposed population Cancer Heritable effects Total Whole population 5.5 x 10 -2 /Sv 0.2 x 10 -2 /Sv 5.7 x 10 -2 /Sv Adult workers 4.1 x 10 -2 /Sv 0.1 x 10 -2 /Sv 4.2 x 10 -2 /Sv
12. Brenner et al., PNAS 100, 13761-137661, 2003 Cancer risks of atomic bomb survivors Estimated excess relative risk (+/- 1SE) of mortality (1950-1997) from solid cancers among groups of survivors who were exposed to low doses (<500mSv) of radiation
13. ａ linear non-threshold (LNT) ｂ downwardly curving ｃ upwardly curving ｄ threshold ｅ hormetic Radiation risks down to very low doses All of these possible extrapolations could be consistent with higher-dose epidemiological data Brenner et al., PNAS 100, 13761-137661, 2003
14. Lobrich and Jeggo, Nature Rev Cancer 7: 861 - 869 , 2007 Encounters with radiation and risk estimation
23. World Nuclear Association, February 2009 Nuclear Power Plant in India Reactor State Type Mwe net, each Commercial operation Tarapur 1&2 Maharashtra BWR 150 1969 Kaiga 1&2 Karnataka PHWR 202 1999-2000 Kaiga 3 Karnataka PHWR 202 2007 Kakrapar 1&2 Gujarat PHWR 202 1993-1995 Kalpakkam 1&2 Tamil Nadu PHWR 202 1984-1986 Narora 1&2 Uttar Pradesh PHWR 202 1991-1992 Rawatbhata 1 Rajasthan PHWR 90 1973 Rawatbhata 2 Rajasthan PHWR 187 1981 Rawatbhata 3&4 Rajasthan PHWR 202 1999-2000 Tarapur 3&4 Maharashtra PHWR 490 2005-2006 17 reactors operating 3,779 Kaiga 4 Karnataka PHWR 202 2009 Rawatbhata 5&6 Rajasthan PHWR 202 2009 Kudankulam 1&2 Tamil Nadu PWR (VVER) 950 Sep-Dec 2009 Kalpakkam Tamil Nadu FBR 470 2011 9 reactors under construction 2,976
24. Annual terrestrial radiation doses in the world http://www.taishitsu.or.jp/genshiryoku/gen-1/1-ko-shizen-2.html Area Mean (mGy/year) Maximum (mGy/year) Ramsar, Iran 10.2 260 Guarapari, Brazil 5.5 35 Kerala, India 3.8 35 Yangiang, China 3.5 5.4 World Average 0.50 Japan 0.43 1.26
25. Jiang T et al., J Radiat Res 41S: 63 - 68 , 2000 Increase in unstable-type chromosome aberrations in inhabitants of high background radiation areas in China
26. Relative risk for cancer in high background radiation areas in China during 1979-1995 Tao Z et al., J Radiat Res 41S: 31 - 41 , 2000 Variable Low Medium High Subtotal Follow-up period 1979-86 1.10 (0.86-1.42) 1.02 (0.79-1.32) 0.98 (0.75-1.29) 1.04 (0.85-1.28) 1987-95 1.04 (0.83-1.30) 0.98 (0.78-1.22) 0.86 (0.68-1.10) 0.96 (0.80-1.15) Sex Male 1.02 (0.83-1.26) 1.09 (0.89-1.34) 0.93 (0.74-1.16) 1.02 (0.86-1.20) Female 1.14 (0.87-1.51) 0.82 (0.61-1.11) 0.89 (0.65-1.21) 0.95 (0.76-1.20) Age 0-59 0.99 (0.80-1.24) 0.98 (0.79-1.22) 0.90 (0.71-1.13) 0.96 (0.80-1.15) 60+ 1.18 (0.91-1.53) 1.02 (0.78-1.32) 0.94 (0.71-1.25) 1.05 (0.85-1.29)
27. Boffetta P et al., Am J Epidemiol 165: 36 - 43 , 2006 Kaplan-Meier curve for total cancer incidence by frequency of chromosomal aberrations in central Europe during 1978-2002
40. A cumulative dose of 100mSv would lead to 9.7% increased mortality from cancers excluding leukaemia. The corresponding figure is 19% for mortality from leukaemia excluding CLL. 1-2% of deaths from cancer among workers in this cohort may be attributable to radiation.
42. Because of the uncertainty on health effects at low doses, the Commission judges that it is not appropriate , for the purposes of public health planning, to calculate the hypothetical number of cases of cancer or heritable disease that might be associated with very small radiation doses received by large numbers of people over very long periods of time . ICRP recommendations (Publication 103), pp51(paragraph 66), 2007
43.
44. The bystander effect of radiation Damage signals may be transmitted from irradiated to non-irradiated cells in a population, leading to the occurrence of biological effects that receive no radiation exposure. irradiated cells non-irradiated cells damage signals biological effect Gap Junctional Intercellular Communication Extracellular Soluble Factors Gene expressions Genetic effects - DNA damage, cell killing, mutation, transformation
45. The bystander effect of low LET radiation Technical approaches Authors Radiation source Method Mothersill & Seymour 1997- 60 Co γ -irradiation medium transfer Balajee et al. 2004 137 Cs γ -irradiation Prise et al. 2003 278eV C K soft X-ray microbeam Yang et al. 2005 250kVp X-ray co-culture
46. Localization of phosphorylated ATM in irradiated nucleus unirradiated 0.5 Gy 1.0 Gy Confocal observation by Zeiss LSM 510 META
47. Phosphorylated ATM in bystander cells before medium transfer 2h after medium transfer from 1Gy-irradiated cells
49. unirradiated culture Number of gamma-H2a.X foci in inirradiated cells 0 0.1 0.2 0.3 0.4 Induction of DNA damage in unirradiated cells co-culture of unirradiated and irradiated cells
51. 0 50 100 150 200 250 300 350 Induction of micronucleus in unirradiated cells Number of micronucleus in 2000 unirradiated cells unirradiated culture co-culture of unirradiated and irradiated cells co-culture in the presence of an anti-oxidant
52. 0 5 9 Induction of mutation in unirradiated cells Mutation frequency at HPRT locus (10 -6 ) unirradiated culture co-culture of unirradiated and irradiated cells
55. The commission recognizes that these biological factors, together with possible tumor-promoting effects of protracted irradiation, and immunological phenomena, may influence radiation cancer risk, but current uncertainties on their mechanisms and tumorigenic consequences of the above processes are too great for the development of practical judgments. ICRP recommendations (Publication 103), pp51(paragraph 67), 2007
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60. Division of Radiation Biology and Protection Center for Frontier Life Sciences, Nagasaki University Domestic projects Yoshida M, Morita N, Takao H, Miura M, Hayashida R, Kaneko M, Takemoto T, Okimura Y Indian projects Selvasekarapandian S, Brahmanandhan GM, Hakkim FL, Takamura N, Suyama A + terrific students in Kalasalingam, Bharathiar, and Nagasaki University நன்றி nandri
Editor's Notes
Irradiation set up for shielded irradiation. (A) Neonatal Ptch1+/− and Ptch1+/+ mice placed in polystyrene boxes were irradiated with heads and upper body shielded by individual custom-built lead cylinders. (B) Demarcation between exposed and shielded regions at P10 due to hair-growth delay in exposed skin. (C) Characteristics of the lead shields.
Radiation damage by expected scatter dose in exposed vs. bystander EGL. (A and B) γ-H2AX positivity in the outer EGL of SH-8.3 Gy mice at 6h postirradiation compared with undetectable staining after exposure to the scatter dose (0.1 Gy). (D and E) Increased apoptosis in EGL of SH-8.3Gy mice at 6 h postirradiation compared with very rare apoptosis after a 0.1 Gy dose. (C and F) Percentage of γ-H2AX-positive and apoptotic cells in cerebellum at 3, 4.5, 6, and 18 h post-8.3-Gy (SH) and 0.1 Gy (WB) irradiation. *, P = 0.0139; **, P = 0.0015; ***, P = 0.0001. (Scale bars, 20 μm.)
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