An Overview of the Session;A Challenge to Scientific Risk Estimation on Health Effects of Low Dose Radiation Tetsuya Ono Dept Cell Biol, Tohoku Univ Grad Sch Med Sendai, Japan
We are facing many environmental toxic agents. The risk estimation of these agents should be based on dose response curve. Response Dose The response in a low dose range could be extrapolated from high doses if it is a physical system. However, it is not true in biological systems.
Biological response to low dose radiation is complicated. Bystander effect Biological Response ICRP (International Commission on Radiological Protection) Adaptive response Dose
Bystander effect X X Adaptive response
In the biological systems, the dose response at low dose level cannot be extrapolated from high dose response. Instead, experimental as well as epidemiological studies are needed to clarify the dose response.
Biological responses at low dose rate radiation is different from those at high dose rate radiation Total dose Dose rate
8Gy/400d 2mGy/yr (BG) 20mGy/400d 0.4Gy/400d Institute for Environmental Sciences
Schematic illustration of gpt-delta mouse Chr. 17 80 gpt-delta mouse red gam 48kbp T. Nohmi et al., Env Mol Mutag 28 (1996) 465-470
920 mGy/min 1 mGy/min
920 mGy/min 1 mGy/min 12.5μGy/min
Speakers of the session Wei Zhang: Chromosomal abnormality in people living in high background area. Takehiko Nohmi: DNA changes induced when chemical carcinogen and low dose radiation are exposed at the same time. Mitsuru Nenoi: Changes in gene expression after a long period of exposure to low dose rate radiation. Noriyuki Ouchi: Computer modeling of radiation effects including DNA damage and repair.