Effects of Radiation from Fukushima Daiichi
on the U.S. Marine Environment
Eugene H. Buck
Specialist in Natural Resources Policy
Harold F. Upton
Analyst in Natural Resources Policy
April 15, 2011
Congressional Research Service
7-5700
www.crs.gov
R41751
CRS Report for Congress
P
repared for Members and Committees of Congress

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Effects of Radiation from Fukushima Daiichi 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 Daiichi 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 tuna in the western Pacific and, less likely, 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) have been measured in
seawater adjacent to the Fukushima Daiichi site.
EPA rainfall monitors in California, Idaho, and Minnesota have detected trace amounts of
radioactive iodine, cesium, and tellurium consistent with the Japanese nuclear incident, with
current 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 will very quickly become 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 Daiichi should 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.
Currently, it appears that radioactive contamination of seafood from the recent nuclear disaster in
Japan is not 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 has 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 also to be 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 Daiichi 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 Daiichi 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?......................................................................................................... 5

Figures
Figure 1. Ocean Currents............................................................................................................. 1
Figure 2. Atmospheric Radiation Forecast for March 18, 2011..................................................... 3

Contacts
Author Contact Information ........................................................................................................ 6

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Effects of Radiation from Fukushima Daiichi 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 Daiichi 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 have arisen 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 Daiichi
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 having long half-lives (e.g., cesium-137, with a half-life of about 30
years) could still pose concerns when transported over long distances by ocean currents.
Figure 1. Ocean Currents

Source: American Meteorological Society.
Seawater is monitored by the Tokyo Electric Power Company (TEPCO) near the discharge points
of the Fukushima Daiichi plant. Water with a dose rate of greater than 1,000 millisievert per hour
was confirmed by TEPCO on April 2, 2011, in a pit located next to Fukushima Daiichi’s Unit 2

1 For additional background on this incident, see CRS Report R41694, Fukushima Nuclear Crisis, by Richard J.
Campbell and Mark Holt.
2 Quirin Schiermeier, “Radiation Release Will Hit Marine Life,” Nature, v. 472 (April 12, 2011): 145-146.
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seawater inlet point. A cracked sidewall of this pit is leaking water from the pit directly into the
ocean.3 Analyses of seawater taken from near the discharge from Fukushima Daiichi Units 1-4
have 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 have entered the ocean is unknown, and discharges,
both accidental and deliberate,6 are continuing.7 Radioisotope concentrations at offshore sampling
points appear to be decreasing with time; at sampling points about 30 km east of Fukushima
Daiichi, concentrations are 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
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).10 The U.S. Department of Energy and the
U.S. Environmental Protection Agency (EPA) monitor atmospheric radiation. As of April 2, 2011,
EPA monitors in California, Idaho, and Minnesota have 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.11
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 tuna in
the western Pacific and, less likely, salmon in the North Pacific) might be exposed to radiation in
or near Japanese waters, or might consume prey that have accumulated radioactive contaminants.
A British scientist reportedly has 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.”12 However, this view does not consider the possibility of

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 Daiichi 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 Other projections of atmospheric trajectories can be found at http://www.atmos.umd.edu/~tcanty/hysplit/.
11 See http://www.epa.gov/radiation/data-updates.html; also see http://yosemite.epa.gov/opa/admpress.nsf/
d0cf6618525a9efb85257359003fb69d/3724de8571e1b03f8525785c00041a7a%21OpenDocument.
12 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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bioaccumulation of radioactive elements by fish whose migratory habits subsequently may take
them far from Japanese waters.
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.
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 will very quickly become
diluted and should not be a problem beyond the coast of Japan. The same is true of radiation
carried by winds around the globe. Barring a major unanticipated release, radioactive
contaminants from Fukushima should 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.13
However, there remains the potential for a relatively narrow corridor of highly contaminated
water leading away from Japan and a very patchy distribution of contaminated fish―only
extensive monitoring will be able to determine the exact dispersion of these radioactive
contaminants.

13 See http://www.whoi.edu/page.do?pid=56076&tid=282&cid=94989.
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Concerns
Are There Implications for U.S. Seafood Safety?
It does not appear that nuclear contamination of seafood will become a food safety problem for
consumers in the United States. 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.14 For example, according to the National Federation of Fisheries Cooperative
Associations, the region’s fishing industry has stopped landing and selling fish.15
U.S. fisheries are unlikely to be affected because radioactive material that enters the marine
environment will 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.16 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.17
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
with a value of $258.9 million.18 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

14 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.
15 “Tsukiji wholesaler thinks it may take a year for the market to stabilize,” Reuters, March 23, 2011.
16 Elizabeth Rosethal, “Radiation, Once Free, Can Follow a Tricky Path,” New York Times, March 21, 2011.
17 Frederik Balfour, “Sushi Safe From Japan Radiation as Ocean Dilution Makes Risk Negligible,” Bloomberg, March
31, 2011.
18 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.
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seafood was not included.19 Food products not included on the import alert, but from the areas
near the Fukushima nuclear facility, including seafood, are also to be 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.20 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 be introducing radioactive elements from the Fukushima Daiichi
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, weeks or 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.
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. 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 will reach the U.S. West Coast, dumping debris on California
beaches and the beaches of British Columbia, Alaska, and Baja California.21 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 Daiichi is believed to have occurred after the

19 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.
20 FDA, Radiation Safety, March 29, 2011, http://www.fda.gov/newsevents/publichealthfocus/ucm247403.htm.
21 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).
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tsunami, there is the possibility that some of the tsunami debris might also be contaminated with
radiation from Fukushima Daiichi.

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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