Radiation effects from the Fukushima Daiichi nuclear disaster

[45] A 2019 study evaluated the first and the second screening rounds of the Fukushima Health Management Survey (FHMS, 2011–2016) separately as well as combined covering 184 confirmed cancer cases in 1.080 million observed radiation-exposed person-years.

[48][49] In the 47 prefectures of Japan from 2012 onward, the annual proportion of low birth weight babies (< 2500 g) was associated with the prefecture-specific dose-rate derived from Cs-137 deposition after the nuclear power plant accidents.

After a nuclear power plant disaster, residents of the affected areas are at a higher risk for mental health illnesses such as depression, anxiety, post-traumatic stress disorder (PTSD), medically unexplained somatic symptoms, and suicide.

Stressors that were identified as risk factors for these negative mental outcomes include: length of duration of evacuation, house damage, separation from family members, inability to family members and friends after the disaster, watching the earthquake on television, life-threatening experience during the quake and tsunamis, injury, plant explosion, unemployment among middle-aged men, burying loved ones themselves, lack of social support, pre-existing health problems, misunderstanding of radiation exposure risk, lack of clarity regarding benefits, on-going stigma regarding radiation, distrust of government, distrust of public health authorities, distrust of the Tokyo Electric Power Company (TEPCO) management, burnout among mental health workers, low income, loss of colleagues, and intra-family conflict.

[54] The populations at the highest risk for mental health illnesses following the disaster are the nuclear power plant workers, mothers with infants, children, and middle-aged unemployed males.

[3] Also, one study looking at elderly individuals from Iwanuma City in the Miyagi prefecture found that exercise may help decrease depressive symptoms among older adults who survived the earthquake and tsunami disaster.

[4] Programs (including mental health screenings), treatments, and resource distribution should be focused on high-risk groups immediately after the disaster, such as mothers and infants and nuclear power plant workers.

In the first half of September 2011 the amount of radioactive substances released from the plant was about 200 million becquerels per hour, according to TEPCO, which was approximately one-four millionths of the level of the initial stages of the accident in March.

[88] On 30 September 2011, the Japanese Ministry of Education and Science published the results of a plutonium fallout survey, for which in June and July 50 soil samples were collected from a radius of slightly more than 80 km around the Fukushima Daiichi plant.

[92] According to a report published in October 2011 by the French Institute for Radiological Protection and Nuclear Safety, between 21 March and mid-July around 2.7 × 1016 Bq of caesium-137 (about 8.4 kg) entered the ocean, about 82 percent having flowed into the sea before 8 April.

[96] In August 2013, a Nuclear Regulatory Authority task force reported that contaminated groundwater had breached an underground barrier, was rising toward the surface and exceeded legal limits of radioactive discharge.

[99] Dose rates of 1,000 mSv/h were reported (but not confirmed by the IAEA)[100] close to the certain reactor units on 16 March, prompting a temporary evacuation of plant workers, with radiation levels subsequently dropping back to 800–600 mSv/h.

[147] Noting that limited, uncontrolled chain reactions might occur at Fukushima I, a spokesman for the International Atomic Energy Agency (IAEA) "emphasized that the nuclear reactors won't explode.

[212] On 31 October 2011 a scientist from the Worcester Polytechnic Institute, Marco Kaltofen, presented his findings on the releases of radioactive isotopes from the Fukushima accidents at the annual meeting of the American Public Health Association (APHA).

[178] A detailed map of ground contamination within 80 kilometers of the plant, the joint product of the U.S. Department of Energy and the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), was released on 6 May.

Contamination levels "as high as those inside Fukushima's no-go zone have been detected, with officials speculating that the hotspot was created after radioactive caesium carried in rain water became concentrated because of a broken gutter".

[230] Based on radiation measurements made all over Japan between 20 March and 20 April 2011, and the atmospheric patterns in that period, computer simulations were performed by an international team of researchers, in cooperation with the University of Nagoya, in order to estimate the spread of radioactive materials like caesium-137.

Professor Tetsuzo Yasunari of the University of Nagoya called for a national soil testing program because of the nationwide spread of radioactive material, and suggested identified hotspots, places with high radiation levels, should be marked with warning signs.

[239] On 5 January 2012 the Nambu (south) Clean Center, a waste incinerator in Kashiwa, Chiba, was taken out of production by the city council because the storage room was completely filled with 200 metric tons of radioactive ash that could not disposed of in landfills.

On 21 March, IAEA confirmed that "in some areas, iodine-131 in milk and in freshly grown leafy vegetables, such as spinach and spring onions, is significantly above the levels set by Japan for restricting consumption".

The urine of all cattle for sale was tested in order to return those cows that showed levels of radioactive substances higher than the government-set limit to farms so they could be decontaminated by feeding them safe hay.

[250] In March 2012 up to 18,700 becquerels per kilogram radioactive caesium was detected in yamame, or landlocked masu salmon, caught in the Niida river near the town Iitate, which was over 37 times the legal limit of 500 becquerels/kg.

[253] In April 2012 radioactive caesium concentrations of 110 becquerels per kilogram were found in silver crucian carp fish caught in the Tone River north of Tokyo, some 180 kilometers away from the Fukushima Daiichi Plant.

[255] High levels of radioactive caesium were found in 23 varieties of freshwater fish sampled at five rivers and lakes in Fukushima Prefecture between December 2011 and February 2012 and in 8 locations on the open sea.

In an attempt to ease consumer concern the Japanese government promised to impose inspections on all this beef, and to buy the meat back when higher-than-permissible caesium levels were detected during the tests.

The plan included: Other measurements were the expansion of subsidies to beef cattle farmers: On 19 August 2011 was reported, the meat of 4 cows from one Fukushima farm had been found to be contaminated with radioactive caesium in excess of the government-set safety limits.

"This is unlikely to be the result of new radioactive materials being introduced, because no other elements were detected, especially the more sensitive iodine", into the water supply, were the comments of Hironobu Unesaki, a nuclear engineering professor at Kyoto University.

Because of this caesium-contaminated milk powder, the Japanese minister of health Yoko Komiyama said on 9 December 2011 at a press conference, that her ministry would start regularly tests on baby food products in connection with the Fukushima Daiichi nuclear plant crisis, every three months and more frequently when necessary.

[339][340] These predictions were tested by a worldwide network of highly sensitive radiative isotope measuring equipment, with the resulting data used to assess any potential impact to human health as well as the status of the reactors in Japan.

[360] The aircraft carrier USS George Washington was docked for maintenance at Yokosuka Naval Base, about 280 kilometres (170 mi) from the plant, when instruments detected radiation at 07:00 JST on 15 March.