Moving at a pace "roughly twice the speed of a garden snail," the plume of nuclear radiation created by the Fukushima disaster has finally crossed the Pacific Ocean and arrived off the West Cost of the US, the Statesman Journal reports. Following a massive earthquake and tsunami in 2011, contaminated water escaped Japan's Fukushima nuclear plant into the ocean. More radiation joined the plume when it fell from the sky. Now researchers say a seawater sample taken in Oregon shows traces of Cesium-134. It's the first time Cesium-134, which could only have come from Fukushima, has been found in US waters. Greater levels of Cesium-134 and Cesium-137—already present in the water following nuclear testing decades ago—are expected to arrive with the bulk of the plume in the near future.
However, scientists say that even at those levels there will be no danger to humans or the environment. "To put it in context, if you were to swim everyday for six hours a day in those waters for a year, that additional radiation from the addressed cesium from Japan ... is 1,000 times smaller than one dental X-ray," Ken Buesseler of the Woods Hole Oceanographic Institute tells USA Today. Still, scientists can use this data to better track ocean currents and come up with more accurate models for future, potentially worse, nuclear disasters. Meanwhile, Cesium-134 from Fukushima has also been detected in a Canadian salmon for the first time. Fortunately, the level found in the salmon is more than 1,000 times less than what Canada considers dangerous. (Read more Fukushima Dai-ichi stories.)