Radiation effects from the Fukushima nuclear accident

The radiation effects from the Fukushima nuclear accident are the observed and predicted effects as a result of the release of radioactive isotopes from the Fukushima Daiichi Nuclear Power Plant following the 2011 Tōhoku earthquake and tsunami. The release of radioactive isotopes from reactor containment vessels was a result of venting in order to reduce gaseous pressure, and the discharge of coolant water into the sea. This resulted in Japanese authorities implementing a 30 km exclusion zone around the power plant and the continued displacement of approximately 156,000 people as of early 2013. The number of evacuees has declined to 49,492 as of March 2018. Radioactive particles from the incident, including iodine-131 and caesium-134/137, have since been detected at atmospheric radionuclide sampling stations around the world, including in California and the Pacific Ocean. Preliminary dose-estimation reports by the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) indicate that, outside the geographical areas most affected by radiation, even in locations within Fukushima Prefecture, the predicted risks remain low and no observable increases in cancer above natural variation in baseline rates are anticipated. In comparison, after the Chernobyl reactor accident, only 0.1% of the 110,000 cleanup workers surveyed have so far developed leukemia, although not all cases resulted from the accident. However, 167 Fukushima plant workers received radiation doses that slightly elevate their risk of developing cancer. Estimated effective doses from the accident outside of Japan are considered to be below, or far below the dose levels regarded as very small by the international radiological protection community. The United Nations Scientific Committee on the Effects of Atomic Radiation is expected to release a final report on the effects of radiation exposure from the accident by the end of 2013. A June 2012 Stanford University study estimated, using a linear no-threshold model, that the radioactivity release from the Fukushima Daiichi nuclear plant could cause 130 deaths from cancer globally (the lower bound for the estimate being 15 and the upper bound 1100) and 199 cancer cases in total (the lower bound being 24 and the upper bound 1800), most of which are estimated to occur in Japan. Radiation exposure to workers at the plant was projected to result in 2 to 12 deaths. However, a December 2012 UNSCEAR statement to the Fukushima Ministerial Conference on Nuclear Safety advised that "because of the great uncertainties in risk estimates at very low doses, UNSCEAR does not recommend multiplying very low doses by large numbers of individuals to estimate numbers of radiation-induced health effects within a population exposed to incremental doses at levels equivalent to or lower than natural background levels."

Health effects Preliminary dose-estimation reports by the World Health Organization and the United Nations Scientific Committee on the Effects of Atomic Radiation indicate that 167 plant workers received radiation doses that slightly elevate their risk of developing cancer, but that this risk may not be statistically detectable, as has happened in the case of the Chernobyl disaster. After the Chernobyl accident, only 0.1% of the 110,000 cleanup workers surveyed have so far developed leukemia, although not all cases resulted from the accident Estimated effective doses from the Fukushima accident outside Japan are considered to be below (or far below) the dose levels regarded as very small by the international radiological protection community. According to the Japanese Government, 180,592 people in the general population were screened in March 2011 for radiation exposure, and no case was found which affects health. Thirty workers conducting operations at the plant had exposure levels greater than 100 mSv. It is believed that the health effects of the radioactivity release are primarily psychological rather than physical effects. Even in the most severely affected areas, radiation doses never reached more than a quarter of the radiation dose linked to an increase in cancer risk (25 mSv, whereas 100 mSv has been linked to an increase in cancer rates among victims in Hiroshima and Nagasaki). However, people who have been evacuated have suffered from depression and other mental health effects. While there were no deaths caused by radiation exposure, approximately 18,500 people died due to the earthquake and tsunami. Very few cancers would be expected as a result of the very low radiation doses received by the public. John Ten Hoeve and Stanford University professor Mark Z. Jacobson suggest that according to the linear no-threshold model (LNT) the accident is most likely to cause an eventual total of 130 (15–1100) cancer deaths, while noting that the validity of the LNT model at such low doses remains subject to debate. Radiation epidemiologist Roy Shore contends that estimating health effects in a population from the LNT model "is not wise because of the uncertainties". The LNT model did not accurately model casualties from Chernobyl, Hiroshima, or Nagasaki; it greatly overestimated the casualties. Evidence that the LNT model is a gross distortion of damage from radiation has existed since 1946 and was suppressed by Nobel Prize winner Hermann Müller in favour of assertions that no amount of radiation is safe. Two years after the incident (in 2013), the World Health Organization (WHO) indicated that the residents of the area who were evacuated were exposed to little radiation and that radiation induced health impacts are likely to be below detectable levels. The health risks in the WHO assessment attributable to the Fukushima radioactivity release were calculated by largely applying the conservative Linear no-threshold model of radiation exposure, which assumes that even the smallest amount of radiation exposure has a negative health effect.

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