Few people will develop cancer as a consequence of being exposed to the radioactive material that spewed from Japan’s Fukushima Daiichi nuclear power plant last year — and those who do will never know for sure what caused their disease. These conclusions are based on two comprehensive, independent assessments of the radiation doses received by Japanese citizens, as well as by the thousands of workers who battled to bring the shattered nuclear reactors under control.
The first report, seen exclusively by Nature, was produced by a subcommittee of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in Vienna, and covers a wide swathe of issues related to all aspects of the accident. The second, a draft of which has been seen by Nature, comes from the World Health Organization (WHO) in Geneva, Switzerland, and estimates doses received by the general public in the first year after the accident. Both reports will be discussed at UNSCEAR’s annual meeting in Vienna this week.
The UNSCEAR committee’s analyses show that 167 workers at the plant received radiation doses that slightly raise their risk of developing cancer. The general public was largely protected by being promptly evacuated, although the WHO report does find that some civilians’ exposure exceeded the government’s guidelines. “If there’s a health risk, it’s with the highly exposed workers,” says Wolfgang Weiss, the chair of UNSCEAR. Even for these workers, future cancers may never be directly tied to the accident, owing to the small number of people involved and the high background rates of cancer in developed countries such as Japan.
Scientists involved in producing the UNSCEAR report hope that their independent summary of the best available data could help to dispel some of the fear about fallout that has grown over the past year (see Nature 483, 138–140; 2012). As well as providing a preliminary assessment of workers’ exposure, the UNSCEAR report concludes that the Japanese government’s estimate of the radiation released was correct to within a factor of ten, and that further study is needed to fully understand the impacts of the accident on plants, animals and marine life near the power station. When a final version of the report is approved by the full UNSCEAR committee next year, it should provide a useful baseline for future studies.