RSH > Documents > ANS National Meetings/Sessions > June 1999 >Masahito Kaneko

1. Research Programs on Low-Level Radiation Health Effects Supported by FEPCO

                "The federation of Electric Power Companies (FEPCO) of Japan has been supporting several research projects on low-level radiation health effects for the purpose of the following:

1. to assist in the establishment of a reasonable system of radiation protection.
2. to release the public from unnecessary fear of ionizing radiation.

  We present some of the findings and current research programs funded or supported by FEPCO."

 

"EXPERIMENTAL RESEARCH ON THE MECHANISM OF RADIATION CARCINOGENESIS

                "The purpose of the research contracted by the Nuclear Safety Research Association is to verify the existence of 'thresholds' in radiation carcinogenesis by means of molecular-biological techniques. So far, the adaptive response of cells to low-dose irradiation and induction of delayed instability (genetic instability) have been confirmed.¹ The signal transduction within cells and any differences of radiogenic and naturally occurring cancers at the gene level are now being investigated. The relationship of mutational changes caused by radiation and elimination of damaged cells by p53-dependent apoptosis is being investigated."

 

"LOW DOSE RATE EFFECTS OF RADIATION IN THE INDUCTION OF CANCER IN MICE

                "The experiments carried out by Nomura at Osaka University (total dose: 6.8 and 2.0Gy; dose rate: 0.57 to 0.0002 Gy0 min) have demonstrated a remarkable reduction of leukemia incidence (DDREF = 20) but almost no reduction in all solid cancers (DDREF = 1) (Ref. 2). As the dose rate effect was found to be dependent on the sites of solid cancer, experiments with the lower total dose of 0.4Gyare now underway to clearly demonstrate any low dose rate effects in solid cancers."

 

"EPIDEMIOLOGICAL STUDY OF RESIDENTS IN THE HIGH-NATURALBACKGROUND RADIATION AREAS

                "Because it is important to obtain data on the health effects of continuous exposure to radiation at low dose rates, FEPCO has been supporting through the Health Research Foundation an epidemiological study on the residents in theYangjiangdistrict ofGuandongprovince, China—jointly carried out by Chinese and Japanese scientists since 1992. The epidemiological data from 1979 to 1995 showed no increased cancer mortality (relative risk: 0.99, 95%; CI: 0.88 to 1.11) (Ref. 3), although the frequency of chromosome aberrations in peripheral lymphocytes of residents in the high-background-radiation areas is significantly higher than the nearby control area. To increase the statistical power of the evidence,⁴the epidemiological study of this cohort is being continued. Cooperation with Indian scientists in the epidemiological study of residents in higher-background-radiation areas in theKelaradistrict, India, began in 1998."

 

"RESEARCH ON ADAPTIVE RESPONSE TO LOW-DOSE RADIATION

                "Experimental studies on adaptive response to low-dose radiation began in 1998 at the Institute of Research and Innovation; these studies paid attention to the findings of the Central Research Institute of Electric Power Industryhormesisresearch program. Not only were the fundamental aspects of the stimulatory effects of ionizing radiation (activation ofantioxidativeenzymes and immune system, etc.) studied, but also the application of those effects to human health and welfare was investigated."

 

"EPIDEMIOLOGICAL STUDY ON NUCLEAR INDUSTRYWORKERS IN JAPAN

                "The nuclear utilities and contractors have been cooperating with the Radiation Effects Association in a government-funded epidemiological study on nuclear industry workers. The first analysis of the mortality of Japanese nuclear industry workers for the period from 1986 to 1992 demonstrated no evidence of any effect of low-level radiation upon health, particularly upon cancermortality.^5a "

 

1. M. S. SASAKI, “RadioadaptiveResponse: An Implication for the Biological Consequences of Low Dose-Rate Exposure to Radiations,”Mut.Res., 358, 207 (1996).

 

2. T. NOMURA, Personal Communication, Osaka University (1998).

 

3. S.AKIBA, “Cohort Studies on High Background Areas as Low Dose, Low Dose-Rate Data,” Proc. 41st Annual Mtg. Japan Radiation Research Society, Nagasaki, Japan, December 2– 4, 1998 (in Japanese).

 

4. H. KATO, “Methodology of Epidemiology in Low Dose Radiation Exposure,” Proc. 4th Int. Conf. High Levels of Natural Radiation, Beijing, China, October 21–25, 1996, p. 215, Elsevier Science  (1997).

 

5. “First Analysis of Mortality of Nuclear Industry Workers in Japan, 1986–1992,” J. Health Phys., 32, 173 (1997).

 

^aData of the study include: population: 114 900 male workers, mean cumulative dose: 13.9mSv, averagefollowupperiod: 4.6 yr, and 1758 deaths including 661 malignantneoplasms.