Effects of Radiation From Fukushima Dai-ichi on the U.S. Marine Environment [January 20, 2012] [open pdf - 564KB]
From the 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."
CRS Report for Congress, R41751