Abstract
An outline of risk evaluation on cancer and non-cancer disease made in the UNSCEAR 2006 report had been discussed at the time of the 50th meeting of the Japanese Radiation Research Society. Therefore, the contribution of Japanese epidemiological studies in the UNSCEAR 2006 report will be discussed this time.
Radiation and Cancer Risk:
The study which is widely utilized in the report is the Life Span Study (LSS) of Radiation Effects Research Foundation (RERF), as has been in the past.
In site-specific risk evaluation, the results of LSS have been cited in almost all cancer sites. In particular, risk estimation by gender and age at the time of exposure can be made only by LSS. The dose response observed in the LSS is utilized as one of the bases of risk estimation at lower doses. Results of follow up of in-utero exposed population are also utilized.
In addition, as studies on occupational exposure, nuclear workers study being conducted at Radiation Effects Association (REA) and radiologic technologists study conducted at National Institute of Radiological Sciences (NIRS) are cited in the report. Follow-up of Thorotrast patient is cited as study on medical exposure.
In addition to the above, although not conducted in Japan, studies in high background radiation area in China, and studies on residents in Marshall islands are cited, in which Japanese epidemiologists are involved.
The LSS will continue to provide useful information for risk estimation of cancer, however, it can not directly provide information on the effects of protracted low-dose exposure. It is, therefore, necessary to develop more studies in Japan in order to produce useful in formation on effects of low dose exposure.
Radiation and Non-cancer Disease (Cardiovascular Disease) Risk:
The epidemiological study that is most widely utilized in the report is the LSS of RERF. The RERF Adult Health Study is also cited which provides evidence to complement weakness of mortality data.
In addition, as studies on occupational exposure, nuclear workers study being conducted at REA and radiologic technologists study conducted at NIRS are cited in the report.
Studies of non-cancer disease are insufficiently conducted because most of epidemiological studies put main emphasis on cancer risk.
It is essential to expand studies of this area in order to make more contribution in the future.
