1.

2. Deinococcus radiodurans theworldstoughestbacterium Naturalhabitatunknown extraordinarilyresistanttodesiccationandradiation Cansurviveat30,000,00050,000,000Gy humaneffectivedose:100mSv/yr EfficientDNArepairsystem within1224hourscanrepairchromosomesfragmentedby exposuretoradiation 3. 1. 2. 3. 4. 4. (activity) (Bq)1Bq=1 5. Backgroundradiation (Gy) 1Gy=1J/kg Humaneffectivedose:100mSv/yr 1 4 6. http://radioactivity.nsr.go .jp/map/ja/area.html Max:202.94mSv/yr 7. - http://www.aec.gov.tw/g ammadetect.html 0.74mSv/yr 0.51mSv/yr 0.37mSv/yr 8. - http://wapp4.taipower.com.tw/nsis/web/new_screen_page/001s/intime_grap h_1.asp Max:0.61mSv/yr 9. - http://wapp4.taipower.com.tw/nsis/web/new_screen_page/005l/intime_gr aph_5.asp Max:0.59mSv/yr 10. Oneofthemostabundantinnature:Radon222andPotassium40 11. So,doyoustillcarethebiologicaleffect? 12. 13. 14. Mutation 1. DNA (e.g.transposons) 2. 15. DNA 16. Cancer oncogene tumorsuppressor Carcinogenesis:protooncogeneoncogene tumorsuppressorinhibited DNA tumorsuppressorprotein(e.g.p53) (byturnontheoncogenetransformation) 17. 5 18. Butinfact,themajoreffectofradiationisnotDNA damage Createfreeradicals 19. Antioxidants Radicalinhibitor 20. Linearnothresholdmodel(LNT) ICRP1mSv 50mSv 100mSvLNT 100mSvLNT (Thresholdexists?)