The bad news is, radiation from Fukushima has reached the United States, detected 100 miles away from Eureka, California. The good news is, the traces of radiation were too faint to cause worry.
According to nuclear chemist Ken Buesseler from Cape Cod's Woods Hole Oceanographic Institution, radioactive element cesium-134 was detected in the water but it was at levels way below the point that the radiation would endanger marine or human life. In fact, at 2 becquerels per cubic meter, the radiation is over a thousand times lower than what the U.S. Environmental Protection Agency deems safe in drinking water.
Three years ago, Buesseler took samples of the water off Japan's coast after a tsunami and an earthquake ravaged Japan, destroying three of Fukushima Daiichi's nuclear power reactors. Radiation levels at the time were at tens of millions of becquerels per cubic meter. This number may have dropped a bit after a few years but it will still be at levels considered dangerous.
When Fukushima Daiichi's reactors suffered meltdowns, radiation escaped into the atmosphere while water used for cooling the overheating fuel rods found their way into the ocean. To this day, radiation continues to trickle into the ocean, albeit at lower levels no thanks to contaminated groundwater.
Tepco, operator of the Fukushima Daiichi nuclear plant, said that radiation spreading was to be expected but that the company has dramatically improved water management measures since the tsunami hit.
No federal agency officially monitors radiation levels in ocean waters so Buesseler relies on coastal residents from San Diego to Canada and even around Hawaii who are members of his volunteer organization to collect samples from the water in their area periodically. The samples are then sent to him at Woods Hole where he analyzes them.
Buesseler's findings confirm a report by Canadian scientists in February that radiation is present in North America, detected off British Columbia. He found two radioactive isotopes of cesium in his water samples, both of which were formed because of nuclear accidents.
First, there was cesium-137. It decays slowly, rated with a half-life of 30 years. The other one was cesium-134. With a half-life of two years, it decays more rapidly, leading Buesseler to believe the isotope is from Fukushima as that was the most recent nuclear accident recorded. Cesium-137's presence is attributed to nuclear weapons tests done during the Cold War, which left traces of the isotope in ocean waters.