Effects of Radiation from Fukushima Dai-ichi
on the U.S. Marine Environment
Eugene H. Buck
Specialist in Natural Resources Policy
Harold F. Upton
Analyst in Natural Resources Policy
January 20, 2012
Congressional Research Service
7-5700
www.crs.gov
R41751
CRS Report for Congress
Pr
epared for Members and Committees of Congress
Effects of Radiation from Fukushima Dai-ichi on the U.S. Marine Environment
Summary
The massive Tohoku earthquake and tsunami of March 11, 2011, caused extensive damage in
northeastern Japan, including damage to the Fukushima Dai-ichi nuclear power installation,
which resulted in the release of radiation. Some have called this incident the biggest manmade
release ever of radioactive material into the oceans. Concerns have arisen about the potential
effects of this released radiation on the U.S. marine environment and resources.
Both ocean currents and atmospheric winds have the potential to transport radiation over and into
marine waters under U.S. jurisdiction. It is unknown whether marine organisms that migrate
through or near Japanese waters to locations where they might subsequently be harvested by U.S.
fishermen (possibly some albacore tuna or salmon in the North Pacific) might be exposed to
radiation in or near Japanese waters, or might consume prey that have accumulated radioactive
contaminants.
High levels of radioactive iodine-131 (with a half-life of about 8 days), cesium-137 (with a half-
life of about 30 years), and cesium-134 (with a half-life of about 2 years) were measured in
seawater adjacent to the Fukushima Dai-ichi site after the March 2011 events. EPA rainfall
monitors in California, Idaho, and Minnesota detected trace amounts of radioactive iodine,
cesium, and tellurium consistent with the Japanese nuclear incident, at concentrations below any
level of concern. It is uncertain how precipitation of radioactive elements from the atmosphere
may affect radiation levels in the marine environment.
Scientists have stated that radiation in the ocean very quickly becomes diluted and should not be a
problem beyond the coast of Japan. The same is true of radiation carried by winds. Barring a
major unanticipated release, radioactive contaminants from Fukushima Dai-ichi should be
sufficiently dispersed over time that they will not prove to be a serious health threat elsewhere,
unless they bioaccumulate in migratory fish or find their way directly to another part of the world
through food or other commercial products.
Radioactive contamination of seafood from the nuclear disaster in Japan has not emerged as a
food safety problem for consumers in the United States. According to the U.S. Food and Drug
Administration (FDA), the damage to infrastructure in Japan limited food production and
associated exports from areas near the Fukushima nuclear facility. Food products from the areas
near the Fukushima nuclear facility, including seafood, are tested by FDA before they can enter
the U.S. food supply.
Based on computer modeling of ocean currents, debris from the tsunami produced by the Tohoku
earthquake is projected to spread eastward from Japan in the North Pacific Subtropical Gyre. In
three years, the debris plume likely will reach the U.S. West Coast, dumping debris on California
beaches and the beaches of British Columbia, Alaska, and Baja California. Although much of the
radioactive release from Fukushima Dai-ichi is believed to have occurred after the tsunami, there
is the possibility that some of the tsunami debris might also be contaminated with radiation.
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Effects of Radiation from Fukushima Dai-ichi on the U.S. Marine Environment
Contents
Situation........................................................................................................................................... 1
Concerns .......................................................................................................................................... 4
Are There Implications for U.S. Seafood Safety? ..................................................................... 4
How Likely Is It That Radiation Will Reach U.S. Marine Waters, Through Either
Ocean Currents or Atmospheric Transport? ........................................................................... 5
What Are the Likely Responses If Radiation Is Detected?........................................................ 5
What Are Other Possible Effects of the Tohoku Earthquake and Tsunami on the U.S.
Marine Environment?............................................................................................................. 6
Figures
Figure 1. Ocean Currents................................................................................................................. 1
Figure 2. Atmospheric Radiation Forecast for March 18, 2011....................................................... 3
Contacts
Author Contact Information............................................................................................................. 7
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Effects of Radiation from Fukushima Dai-ichi on the U.S. Marine Environment
Situation
The massive Tohoku earthquake and tsunami of March 11, 2011, caused extensive damage in
northeastern Japan, including damage to the Fukushima Dai-ichi nuclear power installation,
which resulted in the release of radiation.1 Some have called this incident the biggest manmade
release ever of radioactive material into the oceans.2 Concerns arose about the potential effects of
this released radiation on the U.S. marine environment and resources.
The North Pacific Current is formed by the collision of the Kuroshio Current, running northward
off the east coast of Japan in the eastern North Pacific, and the Oyashio Current, running
southward from Russia (Figure 1). As it approaches the west coast of North America, the North
Pacific Current splits into the southward California Current and the northward Alaska Current.
Although these currents have the potential for bringing radiation from Japan’s Fukushima Dai-
ichi nuclear accident to U.S. waters, their flow is slow, and no radiation above background levels
has yet been detected in marine waters under U.S. jurisdiction. Regardless of the slow flow,
radioactive contaminants with long half-lives (e.g., cesium-137, with a half-life of about 30 years)
could still pose concerns if transported over long distances by ocean currents.
Figure 1. Ocean Currents
Source: American Meteorological Society.
Seawater was monitored by the Tokyo Electric Power Company (TEPCO) near the discharge
points of the Fukushima Dai-ichi plant following the March 2011 events. Water with a dose rate
of greater than 1,000 millisievert per hour was confirmed by TEPCO on April 2, 2011, in a pit
1 For additional background on this incident, see CRS Report R41694, Fukushima Nuclear Disaster, by Mark Holt,
Richard J. Campbell, and Mary Beth Nikitin.
2 Quirin Schiermeier, “Radiation Release Will Hit Marine Life,” Nature, v. 472 (April 12, 2011): 145-146.
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located next to Fukushima Dai-ichi’s Unit 2 seawater inlet point. A cracked sidewall of this pit
was leaking water from the pit directly into the ocean.3 Analyses of seawater taken from near the
discharge from Fukushima Dai-ichi Units 1-4 yielded readings of 130,000 Becquerels/liter (Bq/l)
of iodine-131 (half-life of about 8 days), 32,000 Bq/l of cesium-137 (half-life of about 30 years),
and 31,000 Bq/l of cesium-134 (half-life of about 2 years).4 Although the leak in the cracked
sidewall was stopped after several days,5 the total amount of radioactive contaminants that
entered the ocean was unknown, and discharges, both accidental and deliberate,6 continued for
several weeks.7 Radioisotope concentrations at offshore sampling points decreased with time; by
early April 2011, at sampling points about 30 km east of Fukushima Dai-ichi, concentrations were
between 5 and 18 Bq/l for iodine-131 and between 1 and 11 Bq/l for cesium-137. The highest
concentrations, found closest to the coast, were about 38 Bq/l for iodine-131 and 4.5 Bq/l for
cesium-137.8 The occurrence of cesium-137 is of greater concern because of its much longer half-
life. The natural radioactivity of seawater is 13 or 14 Bq/l, of which 95% comes from potassium-
40.9 Experts cite this incident as the largest recorded accidental release of radiation to the ocean.10
Atmospheric transport (i.e., wind) also is capable of transporting radiation eastward, where it may
settle or precipitate into U.S. marine waters (Figure 2).11 The U.S. Department of Energy and the
U.S. Environmental Protection Agency (EPA) monitor atmospheric radiation. In early April 2011,
EPA monitors in California, Idaho, and Minnesota detected trace amounts of radioactive iodine,
cesium, and tellurium in rainwater, consistent with the Japanese nuclear incident; to date,
concentrations have been far below any level of concern.12 One study estimated a total
atmospheric release of 35.8 petabecquerels of cesium-137, with the highest release from March
12 to 19 and about 79% of subsequent deposition over the North Pacific Ocean.13
It is unknown whether marine organisms that migrate through or near Japanese waters to
locations where they might subsequently be harvested by U.S. fishermen (possibly some albacore
tuna or salmon in the North Pacific) might be exposed to radiation in or near Japanese waters, or
might consume prey that have accumulated radioactive contaminants. Two minke whales
harvested by Japanese whalers off the coast of Hokkaido in May 2011 were found to have slightly
3 Fukushima Nuclear Accident Update Log (April 2, 2011), at http://www.iaea.org/newscenter/news/2011/
fukushima020411.html.
4 Fukushima Nuclear Accident Update Log (March 31, 2011), at http://www.iaea.org/newscenter/news/2011/
fukushima310311.html.
5 Fukushima Nuclear Accident Update Log (April 6, 2011), at http://www.iaea.org/newscenter/news/2011/
fukushima060411.html.
6 Water with comparatively lower radioactive contamination is being discharged to the sea to provide room at and near
Fukushima Dai-ichi to store water with higher levels of radioactivity in a safer manner.
7 Quirin Schiermeier, “Radiation Release Will Hit Marine Life,” Nature, v. 472 (April 12, 2011): 145-146.
8 Fukushima Nuclear Accident Update Log (April 5), at http://www.iaea.org/newscenter/news/2011/
fukushima050411.html.
9 Idaho State University, Radioactivity in Nature, at http://fizisist.web.cern.ch/fizisist/funny/NaturalRadioactivity.pdf.
10 Ken Buesseler, Michio Aoyama, and Masao Fukasawa, “Impacts of the Fukushima Nuclear Power Plants on Marine
Radioactivity,” Environmental Science & Technology, v. 45 (December 1, 2011): 9931-9935.
11 Other projections of atmospheric trajectories can be found at http://www.atmos.umd.edu/~tcanty/hysplit/.
12 See http://www.epa.gov/radiation/data-updates.html; also see http://yosemite.epa.gov/opa/admpress.nsf/
d0cf6618525a9efb85257359003fb69d/3724de8571e1b03f8525785c00041a7a%21OpenDocument.
13 Andreas Stohl, et al. “Xenon-133 and Caesium-137 Releases into the Atmosphere from the Fulushima Dai-ichi
Nuclear Power Plant: Determination of the Source Term, Atmospheric Dispersion, and Deposition,” Atmospheric
Chemistry and Physics Discussion, v. 11, no. 10 (2011): 2819-394.
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elevated radioactive cesium-137 levels.14 To monitor for longer-term effects, NOAA’s National
Ocean Survey and EPA are exploring monitoring of seawater and sediment along the U.S. west
coast.15
Figure 2. Atmospheric Radiation Forecast for March 18, 2011
Source: Comprehensive Nuclear Test Ban Treaty Organization, Vienna, Austria.
Notes: This forecast shows how weather patterns might be expected disperse radiation from a continuous
source in Fukushima, Japan. The forecast does not show actual levels of radiation. The colors correspond
to the projected intensity of radiation, with yellow being most intense and progressing to less intensity through
the green, blue, to violet end of the spectrum.
A British scientist reportedly stated that, “given the scale of the Pacific—the world’s vastest body
of water—radioactivity in the sea at Fukushima will be flushed out beyond the local area by tides
and currents and dilute to very low levels. It [radioactive contamination] will get into the (ocean)
food chain but only in that vicinity. Should people in Hawaii and California be concerned? The
answer is no.”16 However, this view does not consider the possibility of bioaccumulation of
radioactive elements by fish whose migratory habits subsequently may take them far from
Japanese waters.
Scientists at the Woods Hole Oceanographic Institution advise that radiation levels in seafood
should continue to be monitored, but state that radiation in the ocean very quickly becomes
diluted and should not be a problem beyond the coast of Japan. The same is true of radiation
14 Mary Yamaguchi, Traces of Radiation Found in 2 Whales Off Japan, Associated Press, June 15, 2011.
15 Jeff McMahon, “EPA Halts Extra Radiation Monitoring; Focus Shifts to Imported Seafood,” Forbes, May 5, 2011;
available at http://www.forbes.com/sites/jeffmcmahon/2011/05/04/epa-halts-extra-radiation-monitoring-focus-shifts-to-
seafood/.
16 Simon Boxall, a lecturer at Britain’s National Oceanography Centre at the University of Southampton, England,
quoted in http://news.discovery.com/earth/japan-seafood-110330.html.
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carried by winds around the globe. Radioactive contaminants from Fukushima appear to have
become sufficiently dispersed over time that they will not prove to be a serious health threat
elsewhere, unless they bioaccumulate in migratory fish or find their way directly to another part
of the world through food or other commercial products.17 However, there remains the slight
potential for a relatively narrow corridor of highly contaminated water leading away from Japan
and a very patchy distribution of contaminated fish―extensive monitoring will determine the
exact dispersion of these radioactive contaminants.
Concerns
Are There Implications for U.S. Seafood Safety?
It does not appear that nuclear contamination of seafood will be a food safety problem for
consumers in the United States.18 Among the main reasons are that:
• damage from the disaster has limited seafood production in the affected areas,
• radioactive material will be diluted before reaching U.S. fishing grounds, and
• seafood imports from Japan are being examined before entry into the United
States.
According to the U.S. Food and Drug Administration (FDA), because of damage from the
earthquake and tsunami to infrastructure, few if any food products are being exported from the
affected region.19 For example, according to the National Federation of Fisheries Cooperative
Associations, the region’s fishing industry has stopped landing and selling fish.20
U.S. fisheries are unlikely to be affected because radioactive material that enters the marine
environment would be greatly diluted before reaching U.S. fishing grounds. However, some
advocate vigilance, especially for seafood from areas near the damaged nuclear facility. It has
been suggested that cesium-137 may move up the food chain and become concentrated in fish
muscle or that radiation hot spots may occur.21 The Fisheries Research Agency (Japan) has tested
samples from areas south of the damaged nuclear facility, and it has been reported that radiation
levels are far below the standards set by Japan’s health ministry.22
The most common foods imported from Japan include seafood, snack foods, and processed fruits
and vegetables. In 2010, the United States imported 49.0 million pounds of seafood from Japan
17 See http://www.whoi.edu/page.do?pid=56076&tid=282&cid=94989.
18 For additional information, see U.S. Environmental Protection Agency, U.S. Food and Drug Administration, and
National Oceanic and Atmospheric Administration, U.S. Seafood Safe and Unaffected by Radiation Contamination
from Japanese Nuclear Power Plant Incident; U.S. Monitoring Control Strategy Explained, available at
http://www.nmfs.noaa.gov/mediacenter/docs/2011/may/seafoodsafetyfactsheet_03may2011.pdf.
19 U.S. Dept. of Health and Human Services, Food and Drug Administration, Radiation Safety, March 29, 2011,
http://www.fda.gov/newsevents/publichealthfocus/ucm247403.htm.
20 “Tsukiji wholesaler thinks it may take a year for the market to stabilize,” Reuters, March 23, 2011.
21 Elizabeth Rosethal, “Radiation, Once Free, Can Follow a Tricky Path,” New York Times, March 21, 2011.
22 Frederik Balfour, “Sushi Safe From Japan Radiation as Ocean Dilution Makes Risk Negligible,” Bloomberg, March
31, 2011.
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with a value of $258.9 million.23 The FDA has primary responsibility for the safety of all
domestic and imported seafood, under the Federal Food, Drug, and Cosmetic Act (FFDCA), as
amended (21 U.S.C. §301 et seq.). The FFDCA requires that all foods be safe, wholesome, and
accurately labeled. FDA’s general approach to ensuring the safety of seafood imports is based on
identifying risks from the production process, from specific types of seafood, and from certain
countries or firms.
FDA’s import tracking system is being used to identify all shipments of FDA-regulated products
from Japan, with special attention to shipments from companies within the affected area. On
March 25, 2011, an import alert was updated for food items from specific regions of Japan, but
seafood was not included.24 Food products not included on the import alert, but from the areas
near the Fukushima nuclear facility, including seafood, are also tested by FDA before they can
enter the U.S. food supply. For these products, FDA is to conduct field examinations and collect
samples for radionuclide analysis by FDA laboratories.25 FDA also reports that it is increasing
surveillance for all food products imported from Japan.
How Likely Is It That Radiation Will Reach U.S. Marine Waters,
Through Either Ocean Currents or Atmospheric Transport?
Since radiation has been detected reaching various U.S. locations by atmospheric transport,
rainfall is likely to already have introduced radioactive elements from the Fukushima Dai-ichi
accident into U.S. marine waters. Transport by ocean currents is much slower, and additional
radiation from this source might eventually also be detected in North Pacific waters under U.S.
jurisdiction, even months after its release. Regardless of slow ocean transport, the long half-life of
radioactive cesium isotopes means that radioactive contaminants could remain a valid concern for
years.
What Are the Likely Responses If Radiation Is Detected?
If only low levels of radiation are detected, continued monitoring of the situation will be the
likely response. In the unlikely event that higher levels of radiation are detected, measures (e.g.,
removal of contaminated products from commerce) are to be taken to prevent or minimize human
exposure to the contaminated media.
For background information on radiation and its potential for harm, see CRS Report R41728, The
Japanese Nuclear Incident: Technical Aspects, by Jonathan Medalia.
23 U.S. Dept. of Commerce, National Marine Fisheries Service, Fisheries Statistics and Economics Division, “U.S.
Foreign Trade Query,” March 31, 2011, http://www.st.nmfs.noaa.gov/st1/trade/index.html.
24 All products identified by the import alert will not be allowed to enter the United States unless it is shown they are
free from radionuclide contamination.
25 FDA, Radiation Safety, March 29, 2011, http://www.fda.gov/newsevents/publichealthfocus/ucm247403.htm.
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What Are Other Possible Effects of the Tohoku Earthquake and
Tsunami on the U.S. Marine Environment?
Based on computer modeling of ocean currents, debris from the tsunami produced by the Tohoku
earthquake of March 11, 2011, is projected to spread eastward from Japan in the North Pacific
Subtropical Gyre. Initial models suggested that in a year, debris could reach the Northwestern
Hawaiian Islands Marine National Monument; in two years, the remaining Hawaiian islands
could see this debris; in three years, the debris plume likely would reach the U.S. west coast,
dumping debris on California beaches and the beaches of British Columbia, Alaska, and Baja
California.26 An animation of the projected movement of the marine debris is available at
http://iprc.soest.hawaii.edu/users/nikolai/2011/Pacific_Islands/Simulation_of_Debris_from_
March_11_2011_Japan_tsunami.gif. Although much of the radioactive release from Fukushima
Dai-ichi is believed to have occurred after the tsunami, there is the possibility that some of the
tsunami debris might be contaminated with radiation from Fukushima Dai-ichi.
More recent observations indicate that some debris could be traveling faster than predicted. The
debris field has been estimated to contain possibly millions of tons of debris and be
approximately 3,700 kilometers long and 1,800 kilometers wide.27 In mid-November 2011,
Canadian ocean modelers predicted that initial debris from the Tohoku earthquake and tsunami,
especially large debris more subject to wind effects, might soon begin appearing on Pacific
Northwest beaches.28 Fishing vessels and other large pieces of debris could pose hazards to
navigation. Items that some believe might be initial debris from the tsunami began to be reported
on Pacific Northwest beaches in early December 2011.29 The majority of the debris is still not
anticipated to reach U.S. shores before 2013. British Columbia has established a provincial
tsunami debris coordinating committee to plan how to manage arriving debris, and is
communicating with Japanese authorities for guidance on how best to treat debris items of
potential personal, symbolic, and cultural value. NOAA is requesting that reports of significant
debris sightings be e-mailed to disasterdebris@noaa.gov for compilation.30
26 Press release from the International Pacific Research Center (IPRC) of the School of Ocean and Earth Science and
Technology (SOEST) at the University of Hawaii at Manoa, available at
http://www.sciencedaily.com/releases/2011/04/110406102203.htm?utm_source=feedburner&utm_medium=feed&utm
_campaign=Feed%3A+sciencedaily+(ScienceDaily%3A+Latest+Science+News).
27 Steve Herman, “Tsunami Debris Could Hit Mid-Pacific Island Soon,” November 22, 2011; available at
http://www.voanews.com/english/news/asia/east-pacific/Tsunami-Debris-Could-Hit-Mid-Pacific-Island-Soon-
134312748.html.
28 Yasmin Aboelsaud, “Japanese Tsunami Debris Could Soon Reach Local Coastline,” November 17, 2011; available
at http://www.canada.com/story_print.html?id=5723823.
29 “Flotsam from Japanese Tsunami Reaches West Coast; Wind Pushes Drum-Size Debris to Wash. Beach,”
Washington Post, December 15, 2011; Dennis Ryan, “Debris from Japan Tsunami Washes Up on B.C. Shores,”
Vancouver Sun, December 29, 2011.
30 For additional information, see http://marinedebris.noaa.gov/info/japanfaqs.html.
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Author Contact Information
Eugene H. Buck
Harold F. Upton
Specialist in Natural Resources Policy
Analyst in Natural Resources Policy
gbuck@crs.loc.gov, 7-7262
hupton@crs.loc.gov, 7-2264
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