Does Radioactive Water from Fukushima Pose Any Risk to the United States?

Ask a Scientist - March 2014

D. Curlette of Boulder, CO, asks "Does the leaking radioactive water from the Fukushima Daiichi nuclear plant pose any risk to the United States? Is it safe to eat fish caught on the U.S. West Coast?" and is answered by Dr. Edwin Lyman, a senior scientist in the Union of Concerned Scientists’ Global Security Program.  

Radioactively contaminated water from Fukushima is expected to reach waters off Oregon’s coast as early as this April and the California coast sometime later this year, according to computer simulations of water currents, but it will not pose a significant health threat. As the radioactive plumes travel across the great expanse of the Pacific, they will become so diluted that any radiation exposure from swimming in the ocean off the West Coast or eating locally caught fish is likely to be well below national and international regulatory limits.

Conversely, one should exercise caution in eating fish caught in the western Pacific near Fukushima, where contamination levels remain high. The Japanese government closed most local fisheries after the accident and are closely monitoring them, and scientists have found high radioactivity levels in bottom-feeding species from the isotopes that have accumulated in ocean floor sediment. Tuna and other large commercial fish that could ingest radioactive material near the site and migrate long distances would quickly flush out most of the radioactive cesium-137, a byproduct of nuclear fission. Certain species that tuna and other predory fish eat whole, such as sardines, may pose a greater hazard because strontium-90, a radioactive isotope now being detected in the waters off Fukushima, accumulates in bones. Therefore, it is critical that the Japanese government continue to monitor radioactivity levels in certain types of fish before they enter the food supply. Apparently the Japanese government is doing that, although it may not be sufficient to prevent contaminated fish from occasionally reaching the market. 

On February 27, for example, the Japanese fisheries agency found a fish called Hilgendorf’s saucord in the ocean near Fukushima with elevated levels of radioactive contaminants. The agency immediately prohibited the sale (pdf) of any Hilgendorf’s saucord on the market, and ordered a voluntary recall of the same type of fish that had been caught the day before, even though it had tested clean. This recent incident indicates there can be substantial variation in contamination levels.

Stay apprised of developments in Japan and learn more about how we are using lessons learned from Fukushima to improve nuclear power safety here at home.

Dr. Edwin Lyman is an internationally recognized expert on nuclear proliferation and nuclear terrorism as well as nuclear power safety and security. He earned a doctorate degree in physics from Cornell University in 1992.

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