This post was updated Tuesday, February 26.

A radioactive plume released from the Fukushima meltdown may have already reached the west coast of North America and is expected to reach the U.S. in April, said a panel of researchers in Honolulu Monday. However, without any federal or international monitoring, scientists are bereft of "actual data," guessing at the amount of radiation coming at us.

Monitors along the Pacific U.S. coast have yet to detect any traces of cesium-134, said Ken Buesseler, a chemical oceanographer at the Woods Hole Oceanographic Institution (WHOI), speaking on a panel at the meeting of the American Geophysical Union's Ocean Sciences.

However, sampling undertaken by Dr. John Smith at the Bedford Institute of Oceanography has found traces in the waters outside of Vancouver, B.C.

LiveScience reports:

Smith and his colleagues tracked rising levels of cesium-134 at several ocean monitoring stations west of Vancouver in the North Pacific beginning in 2011. By June 2013, the concentration reached 0.9 Becquerels per cubic meter, Smith said. All of the cesium-134 was concentrated in the upper 325 feet (100 m) of the ocean, he said. They are awaiting results from a February 2014 sampling trip.

Their water samples have helped develop models that forecast the "probable future progression of the plume," said Smith.

According to Buesseler, based on those models, initial traces of radioactive isotopes from Fukushima should be detectable along the Pacific coast of the United States in April.

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One of the radioactive isotopes that is formed during a nuclear accident is cesium-134. With a short half-life of two years, any traces of it detected by monitoring instruments can be specifically attributed to the Fukushima nuclear accident.

Another isotope, cesium-137, decays very slowly with a half-life of 30 years. Though traces of cesium-137 have been detected in the world's oceans, their source may be attributed to previous nuclear-weapons tests.

One shortcoming of the current models available to the scientists is that lack of solid data is creating varying predictions about the amount of radiation and when it is expected to reach the U.S.. And though the estimated levels fall far shorter than acceptable drinking water concentrations, according to the WHOI, the concern is not direct exposure but rather the "uptake by the food web and, hence, the potential for human consumption of contaminated fish."

"To my mind, this is not really acceptable," said Buesseler, speaking of the variation between the predictive models. "We need better studies and resources to do a better job, because there are many reactors on coasts and rivers and if we can’t predict within a factor of 10 what cesium or some other isotope is downstream—I think that’s a pretty poor job."

Individuals have recently spread alarm about the presence of radioactive isotopes already found along the Pacific coast, although those concerns were debunked.

Without any federal or international agencies currently monitoring ocean waters from Fukushima on this side of the Pacific, Buesseler and the WHOI have had to recruit volunteers to collect seawater at 16 sites along the California and Washington coasts and two in Hawaii and ship the samples back to the Cape Cod, Mass. laboratory.

"We need to know the real levels of radiation coming at us," said Bing Dong, a retired accountant and one of the volunteers with the WHOI project. "There's so much disinformation out there, and we really need actual data."

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