A decade after the Fukushima accident: Radiation-linked increases in cancer rates not expected to be seen

VIENNA, 9 March (UN Information Service) – A decade after the triple tragedy that occurred in Japan in March 2011, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) said that future health effects, e.g. cancer directly related to radiation exposure are unlikely to be discernible, in its 2020 Report launched today.

“Since the UNSCEAR 2013 Report, no adverse health effects among Fukushima residents have been documented that could be directly attributed to radiation exposure from the accident,” noted Ms. Gillian Hirth, Chair, UNSCEAR.

Titled “Levels and effects of radiation exposure due to the accident at the Fukushima Daiichi Nuclear Power Station: Implications of information published since the UNSCEAR 2013 Report”, the UNSCEAR 2020 report summarizes all relevant scientific information (peer reviewed literature and monitoring data) available up to the end of 2019. These data relate to the levels and effects of radiation exposure due to the accident at the Fukushima Daiichi nuclear power station (FDNPS). The aim of the report is to provide a summary of all scientific information and an appraisal of the implications of this information for the UNSCEAR 2013 Report. Overall, the UNSCEAR 2020 Report broadly confirms the major findings and conclusions of the UNSCEAR 2013 Report.

In the last decade, a significant amount of new information has emerged with regard to exposure estimates. This new information has enabled the Scientific Committee to perform an improved and more robust evaluation of the levels and effects of radiation due to exposure from the accident. The improved models, based on additional monitoring data and more comprehensive information about people’s actual diet and behaviour in Japan, led to the Committee reviewing and updating its dose estimates. The updated dose estimates to members of the public have either decreased or are comparable with the Scientific Committee’s previous estimates. The Committee therefore continues to consider that future health effects directly related to radiation exposure are unlikely to be discernible.

The Scientific Committee has also assessed the incidence of thyroid cancer that could be inferred from the estimated radiation exposure and concluded that this is not likely to be discernible, in any of the age groups considered, including to children and those exposed in utero to radiation. The Committee believes that, on the balance of available evidence, the large increase, (relative to that expected), in the number of thyroid cancers detected among exposed children is not the result of radiation exposure. Rather, they are the result of ultrasensitive screening procedures that have revealed the prevalence of thyroid abnormalities in the population not previously detected. In addition, in the general public, there has been no credible evidence of excess congenital anomalies, stillbirths, preterm deliveries or low birthweights related to radiation exposure.

With regard to workers, the Scientific Committee concluded that an increase in the incidence of cancers is unlikely to be discernible in workers for leukaemia, and total solid cancers (including thyroid cancer).

The Scientific Committee also evaluated the information on the transfers of released radioactive material through the terrestrial, freshwater and marine environments. By 2012, the concentrations of Caesium-137, even in the coastal waters off the FDNPS site, were little above the levels prevailing before the accident. The Committee continues to consider that regional impacts on wildlife populations with a clear causal link to radiation exposure resulting from the FDNPS accident is unlikely, although some detrimental effects in some plants and animals have been observed in areas of enhanced radiation levels. Radionuclide concentrations in most monitored foodstuffs have declined rapidly following the accident.

The Scientific Committee considered that further studies could be useful on regional impacts on wildlife populations and the impacts of radiation exposure on non-human biota under field conditions that are able to take account of higher levels of biological organization, within natural environments, and elements of ecosystem function and structure.

The full report can be accessed on: http://www.unscear.org/unscear/en/publications.html.

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For further information, contact:

UNSCEAR secretariat
Ms. Jaya Mohan
Email: jaya.mohan[at]un.org
Website: www.unscear.org

Background information for journalists


On 11 March 2011, at 14.46 local time, a 9.0-magnitude earthquake occurred near Honshu, Japan, creating a devastating tsunami that left a trail of death and destruction in its wake. The earthquake and subsequent tsunami, which flooded over 500 square kilometres of land, resulted in the loss of more than 20,000 lives and destroyed property, infrastructure and natural resources. They also led to the worst civil nuclear disaster since the one at Chernobyl in 1986. The loss of off-site and on-site electrical power and compromised safety systems at the Fukushima Daiichi nuclear power station (FDNPS) led to severe core damage to three of the six nuclear reactors on the site; this resulted in the release, over a prolonged period, of very large amounts of radioactive material into the environment.

UNSCEAR 2013 Report

The mandate of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), established in 1955, is to undertake broad reviews of the sources of ionizing radiation and the effects on human health and the environment. Its assessments provide a scientific foundation for United Nations agencies and governments to formulate standards and programmes for protection against ionizing radiation. It does not deal with or assess nuclear safety or emergency planning issues. The secretariat in Vienna, which is administratively linked to UN Environment Programme, organizes the annual sessions and manages the preparation of documents for the Committee's scrutiny.

In May 2011, the Committee embarked upon a two-year assessment of the levels and effects of radiation exposure from the accident. It reported its findings to the General Assembly in October 2013 (A/68/46), and a detailed publication titled "Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami" with the supporting scientific data and evaluation was published online in April 2014.

The report set out the Committee’s assessment of the levels of exposure of defined groups of the general public in Japan, including those evacuated and different age groups, and of workers. On the basis of this assessment, the Committee concluded that health risks resulting from the Fukushima accident were far lower than those for Chernobyl, due to the substantially lower doses received by the public and workers, and did not expect discernible increased incidences of radiation-related health effects among those exposed. Increases in cancer rates, in the context of exposure to radiation, were not expected to be discernible. It also noted that the impact on wildlife was expected to be transient and localized.

However, most of the scientific information used in the UNSCEAR 2013 Report was limited to that published or disclosed by the end of October 2012. The Committee continued to monitor the new information that continued to become available, as a result of which, it published three White Papers in subsequent years (2015, 2016 and 2017). The findings of these generally confirmed the assumptions and findings of the UNSCEAR 2013 Report[1], and remained broadly robust within their inherent uncertainties.

UNSCEAR 2020 Report

As more information became available with time, there was increasing evidence that some of the doses to the public set out in the 2013 Fukushima Report were overestimated, with those from ingestion significantly so. More authoritative and robust statements (i.e. with reduced uncertainty) could also be made on a number of issues owing to the more extensive information available. Hence, the Committee embarked on a two-year project to update the UNSCEAR 2013 Report. The UNSCEAR 2020 Report summarizes all of the relevant scientific information available (up to the end of 2019) relating to the levels and effects of radiation exposure due to the accident at the FDNPS appraises the implications of this information for the UNSCEAR 2013 Report.

The UNSCEAR 2020 Report uses the more up to date information and analyses to validate, and where necessary, revise the estimates of doses to the public. Where possible, it also aims to better address issues and objectives not fully addressed in the UNSCEAR 2013 Report.

While self-standing, this report is intended to be read in conjunction with the UNSCEAR 2013 Report and the subsequent White Papers and does not repeat all the information available in these publications. In the UNSCEAR 2013 Report, the main focus was on the exposure to radiation of various groups of the population, and the effects in terms of radiation-induced risks for human health and the environment. The report itself was divided into thematic areas, a format that was followed and added to in later work, i.e.: Radionuclide releases to atmosphere, dispersion and deposition; Radionuclide releases to water, dispersion and deposition; Transfer in terrestrial and freshwater environments; Evaluation of doses for public; Evaluation of doses for workers; Health implications for workers and public; and, Evaluation of doses and effects for non-human biota.

UNSCEAR Reports and White Papers are among the most comprehensive international scientific analyses on the subject to date.


[1] http://www.unscear.org/unscear/en/publications/2013_1.html

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