Approximately 800 trillion becquerel of Cesium-137 is expected to reach the West Coast of North America by 2016, according to Michio Aoyama, a professor at Japan’s Fukushima University Institute of Environmental Radioactivity. Professor Aoyama says that this would be the equivalent of 5 percent of the total discharge of 3,500 trillion Bq of Cs-137 into the Pacific Ocean from the Fukushima nuclear disaster.
However, Aoyama says that the isotope’s impact on human health won’t be significant. "Even if all the 800 tera bq Cs-137 have arrived, the radiation levels will stay at relatively low level that aren’t expected to harm human health," said Aoyama.
The Woods Hole Oceanographic Institute has detected the presence of Cesium-134 off of the coast of California, of which can only have come from the Fukushima site in Japan, due to it’s half-life of only two years. WHOI’s recent readings for the longer-lived Cesium-137 isotope have been found to be 6.9 Bq per cubic meter. Although these levels are a number of times higher than the typical 1 to 2 Bq/m³ found normally, this is still well below the safety limit set by the World Health Organization.