Epidemiological studies of Fukushima residents exposed to ionising radiation from theFukushima Daiichi Nuclear Power Plant prefecture—a preliminary review of currentplans

Abstract

It is now more than six months since the beginning of the accident on 11 March 2011 at theFukushima Daiichi Nuclear Power Plant in Japan. The Japanese government and localhealth authorities have started to collect the information necessary to estimate radiationdoses received by those living in the area around the plant, drafted plans for the healthcare of residents, and started to implement some of them. This paper reviews and discussesthe studies necessary for risk evaluation of cancer and non-cancer diseases, includingthose already planned, mainly from the view point of evaluating health risk usingepidemiological approaches. In the long run, it is important to establish a cohort with acontrol group. Even if the cumulative doses are estimated to be so low that it isdifficult to evaluate the risk of cancer and non-cancer diseases, it is necessary toconduct such a study to reassure residents. The health care programme of theFukushima Prefecture government, including health check-ups of residents, will help toassess indirect effects of radiation exposure, including psychological problems.The success of any studies of radiation epidemiology depends on the collection of accurateinformation on radiation doses received by the study subjects. However, some of thedosimetry surveys were not conducted in a timely manner. (It should be recognised,though, that such a problem might have been inevitable, considering the chaotic conditionafter the nuclear accident.) Accurate estimation of the radiation dose received by eachresident is not only important for scientific risk evaluation but also to inform each residentabout his or her potential risk. Otherwise, residents will bear an undue psychologicalburden from uncertainties regarding their radiation exposure and its health consequences.One of other important tasks in Fukushima is the improvement of the quality of theregional cancer registry in this prefecture. It is also important to start thyroid cancerscreening in a year or two since the expected minimum latent period among thoseexposed in early childhood is about 4 years. Recently, local health authoritiesdecided to start a thyroid screening programme for those aged 18 years or younger.Any scientific efforts in Fukushima, which need to gain the trust of study subjects aboutthe objectivity of research, may suffer from the fact that residents in Fukushima Prefecturehave begun to suspect that the Japanese government and local authorities are keepingimportant information from them. It seems necessary to make more effort to reflect theopinions of residents when planning health care programmes and to gain theunderstanding of the public for the programme. In summary, there are many problemsthat make the evaluation of cancer and non-cancer disease risk in Fukushimadifficult. The help of international colleagues will be invaluable for overcoming thoseproblems. In this paper, these efforts are briefly summarised and some comments aremade.