Tag Archives: Japan

Residents Living South of the Fukushima Dai-ichi Have Minimal Internal Radiation Exposure

Areas to the south of the Fukushima Daiichi nuclear power plant. WBC measurement were performed at the Jyoban Hospital in central Iwaki, which is located about 50 km south of the Fukushima Daiichi nuclear power plant. Study subjects were mainly hospital visitors from Iwaki and its suburbs.

By Jay T. Cullen

The purpose of this post is to relate findings published (open access) in the peer-reviewed journal PLOSOne by Akiyama and colleagues who investigated internal radiocesium contamination in residents living south of the Fukushima Dai-ichi Nuclear Power Plant. This post is the most recent in a series dedicated to sharing the results of scientific research into the impact of the nuclear power plant disaster on ecosystem and public health. The Akiyama study builds on recent work by this group using a whole body counter (WBC) to look for internal contamination of residents living near (north and west) the reactors at the time of the meltdowns. Measurements were made on 9,206 affected individuals, including 6,446 school children (4-15 years) living south of the reactors or evacuated to Iwaki city following the bulk of radionuclide releases. Measurements began one year after the accident and continued for two years. The authors conclude that, despite lack of data for the first year following the disaster, internal doses experienced by residents to the south of the FNPP were minimal. This suggests that efforts to mitigate foodborne exposure have been largely successful and that nearly all the annual effective doses for this segment of the population more than one year after the disaster are likely due to external exposure. Continue reading Residents Living South of the Fukushima Dai-ichi Have Minimal Internal Radiation Exposure

Advertisements

Fukushima Derived Contamination of Whales and Dolphins in Northern Japan

By Jay T. Cullen

Pacific white sided dolphins (Photo from the Nakamura et al. (2015) study published in MEPS)


The purpose of this post is to report on a recently published, peer-reviewed study documenting the contamination of whales and dolphins in northern Japan following the Fukushima Dai-ichi Nuclear Power Plant disaster in March 2011. This post is the most recent in an ongoing series that documents scientific research into the impacts of the FDNPP disaster on the health of the marine environment. The paper by Nakamura and colleagues investigated the levels of artificial radionuclides 134Cs (half life ~ 2 years) and 137Cs (half life ~30 years) and naturally occurring 40K (half life 1.25 x 109 years) in stranded whales and dolphins in 2011 and 2012 following the disaster. While there was little radiocesium present in the seawater around the northern island of Hokkaido after the disaster some of the animals had detectable levels of radiocesium from the FDNPP in the months following the disaster. By 2012 most stranded animals did not have detectable levels of FDNPP derived radiocesium. According to the authors, the sudden rise in radiocesium levels in the animals following the disaster suggests that the contamination in the animals reflected the seawater activities of the radionuclides through which they swam north rather than bioconcentration through the marine food web. Levels of artificial radionuclides were about 10-fold lower than naturally occurring isotopes in the organisms and are not likely to be causing negative health impacts but may be useful for helping to better understand the migration routes of these animals. Continue reading Fukushima Derived Contamination of Whales and Dolphins in Northern Japan

Fukushima Radionuclides in Pacific: Doses to Japanese and World Public Unlikely to Cause Health Damage

By Jay T. Cullen

The purpose of this post is to summarize a the most recent, peer reviewed scientific study to examine the likely impact of Fukushima contamination of the North Pacific on human health. The blog is part of a continuing series that seeks to communicate the results of scientific studies aimed at determining the impact of the triple meltdowns at the Fukushima Dai-ichi nuclear power plant (FDNPP) on ecosystem and public health. Povinec and Hirose’s recent paper in Scientific Reports examined the variation in Fukushima derived 90-Strontium (90Sr half life 28.8 years), 134-Cesium (134Cs half life ~2 years) and 137-Cesium (137Cs half life ~30 years) in seawater and biota offshore of the FDNPP and in the northwest Pacific. These isotopes are most likely to represent radiologically health risks to consumers of Pacific seafood given their propensity to concentrate in organisms and, in the case of 90Sr and 137Cs, their longevity in the environment. Doses to the Japanese and world population were estimated and compared to doses attributable to naturally occurring isotopes present in food. Doses from food caught in coastal waters right next to the FDNPP to 20 km offshore were similar to doses from naturally occurring isotopes (primarily 210Po) while doses from the consumption off fish caught in the open northwest Pacific were much lower than natural doses. In each case the individual doses are well below levels where any negative health effects would be measurable in Japan or elsewhere. Continue reading Fukushima Radionuclides in Pacific: Doses to Japanese and World Public Unlikely to Cause Health Damage

Dramatic Decrease of Fukushima Derived Radionuclides in the Northwest Pacific Ocean 2011-2012

By Jay T. Cullen

A schematic view of the formation and subduction of mode waters in the North Pacific

The purpose of this diary is to report on a recently published (Jan 2015) open-access, peer reviewed study which examined the activities of 137Cs (half life 30.2 yr), 134Cs (half life ~2.1 yr) and 90Sr (half life ~28.8 yr) in the northwest Pacific off the coasts of Japan and China. The diary is part of a ongoing effort to communicate the results of scientific research into the impact of the Fukushima Dai-ichi nuclear disaster on environmental and public health. Men and colleagues report on how activities of these fission produced isotopes changed between three research expeditions in June 2011, December 2011 and June 2012. Activities in seawater decreased dramatically through time for all three isotopes consistent with very high release rates measured from the Fukushima site in March-April 2011 followed by ongoing but many orders of magnitude (10,000 – 100,000 fold) lower releases from the site thereafter. By 2012 the impact of the Fukushima releases could be still be detected in most samples for Cs isotopes however 90Sr distributions were much more uniform with the highest measured activity only slightly above the pre-Fukushima background. These results are consistent with:

  1. the relatively small source term for 90Sr from compared with the Cs isotopes from Fukushima as determined by measurements of air, soil and water after the disaster
  2. the much lower Fukushima derived activities for these isotopes in the eastern Pacific off of North America being measured given decay and mixing of the contamination as it is transported by ocean currents

Continue reading Dramatic Decrease of Fukushima Derived Radionuclides in the Northwest Pacific Ocean 2011-2012

Most Recent Measurements of Plutonium in Pacific: Fukushima Fallout Undetectable

By Jay T. Cullen

@JayTCullen and @FukushimaInFORM

The purpose of this post is to report results from two recently published studies on plutonium releases from Fukushima to the Pacific Ocean. The post contributes to an ongoing series where results from peer-reviewed studies on the impact of the triple meltdowns at the Fukushima Dai-ichii nuclear power plant on the health of the Pacific ecosystem and residents of the west coast of North America are reported. A frequently asked question of those involved in monitoring the health of the North Pacific is why more measurements of the long lived, alpha-emitting isotopes of plutonium (239Pu half-life 24,100 years; 240Pu 6,570 years) are not being made given the potential for these isotopes to pose radiological health risks. Previous work indicates that 239+240Pu releases from Fukushima were about 100,000 and 5,000,000 times lower than releases from the Chernobyl disaster in 1986 and 20th century weapons testing respectively. Initial measurements of Pu isotopes in seawater and marine sediments off the coast from Fukushima indicated no detectable change occurred in Pu inventories in the western Pacific after the disaster. These two most recent studies monitored the activity and isotopic composition of Pu in seawater and marine sediments off of Japan from 2008-2013. Similar to earlier work these studies find that the release of Pu isotopes by the Fukushima accident to the Pacific Ocean has been negligible. The Fukushima signal is not detectable in the ocean off Japan relative to legacy sources from atmospheric weapons testing in the 20th century. Given these accumulating results 239+240Pu from Fukushima is unlikely to negatively impact the health of the Pacific Ocean ecosystem and levels in the environment from Fukushima will not pose a danger to the population of North America.
Continue reading Most Recent Measurements of Plutonium in Pacific: Fukushima Fallout Undetectable