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

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 halflife 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.


Date of Report: January 20, 2012
Number of Pages: 10
Order Number: R41751
Price: $29.95

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