At present, Fuksuhima radiation in Pacific is not a serious health problem for America’s West Coast

My take home is always, don’t trivialize it or dismiss it, but also don’t exaggerate what the effects might be,” says Woods Hole’s Ken Buesseler.

Radiation from Fukushima is reaching the West Coast — but you don’t need to freak out, WP  By Chris Mooney December 29 “…….many Americans have been concerned — sometimes overly so — that radiation from Fukushima, traveling through the vast Pacific ocean, would eventually make its way to the waters off the West Coast of the United States and Canada. And according to a new scientific paper just out in the Proceedings of the National Academy of Sciencesthat has indeed happened.

The paper, by John N. Smith of Fisheries and Oceans Canada (a government agency) and several colleagues, is the “first systematic study…of the transport of the Fukushima marine radioactivity signal to the eastern North Pacific,” and concludes that radiation reached the continental shelf of Canada by June of last year, and has increased somewhat since.

But– and here’s the good news — the levels of radiation are very low, well below levels that public health authorities cite as grounds for concern. The radiation “does not represent a threat to human health or the environment,” reports the paper.

The new study is not the first to reach that conclusion. “We came up with something like 500 to 1000 times less of a dose, the hazard of the radiation of swimming in the Pacific, as a dental X Ray,” says senior scientist Ken Buesseler of the Woods Hole Oceanographic Institution, who was not involved in the current study. Buesseler heads a crowd-funded, citizen research project, Our Radioactive Oceans, which first reported the presence of small quantities of Fukushima radiation in a sample taken in August 2014 100 miles off the coast of Eureka, Calif. The radiation was at low levels, similar to that reported in the current research.

In fact, what’s truly amazing about the work is that scientists are able to actually measure these very low levels of radiation at all — as well as to chemically fingerprint them and thereby prove that certain radioisotopes of the chemical element Cesium, which arise as a by-product of nuclear fission, actually arrived off of North American waters after traveling all the way from Fukushima.

In the current paper, the researchers accomplished this  by taking a series of measurements, from 2011-2014, on ocean vessels which traveled 1,500 kilometers out from Canadian coastal waters into the Pacific. Water samples were taken to look for two radioisotopes, Cesium-134 and Cesium-137, both of which were released as part of the radioactivity from Fukushima.

Cesium-134 has a two-year half-life (meaning half of it will have decayed within 2 years), whereas Cesium-137 has a 30 year half life. What that means is that the presence of Cesium-134 allows scientists to conclusively separate out Fukushima-generated radiation from the other major human source of radiation in the Pacific — nuclear weapons testing, which happened decades ago (there would be no more Cesium-134 detectable from this source). This simple fact allows for “unequivocal” detection of radiation originating from Fukushima, even thousands of miles away, noted the new study.

In light of this, the paper found that radiation from Fukushima was definitely detectable in waters of the Canadian continental shelf by June 2013, and had apparently increased somewhat by February of 2014. However, the levels of radiation are quite low. For nuclear power nerds, the Fukushima radiation levels were under 1 Becquerel per cubic meter of ocean water, where a Becquerel refers to one nuclear decay per second and a cubic meter of ocean is 1000 liters (or 260 gallons).

“A Becquerel per cubic meter is not a lot of radioactivity,” says Stony Brook University’s Nicholas Fisher, another researcher who has published on Fukushima radioactivity’s contamination of the oceans, but was not involved in the current study. For reference, the background levels of Cesium-137 in many parts of the world ocean is actually higher than that:

Indeed, the number underscores just how much the Fukushima radiation has been diluted and dispersed in its three-year journey across the Pacific. In the waters right off the Fukushima plant, just after the accident, radiation levels were 50 million Becquerels per cubic meter — extremely dangerous — explains Woods Hole’s Ken Buesseler. A few months later, levels were in the low thousands, he adds — still worrisome if you are consuming seafood.

But now that the radiation has reached the waters of the West Coast, levels of 1 or 2 Becquerels per cubic meter are pretty tiny and dilute………

“My take home is always, don’t trivialize it or dismiss it, but also don’t exaggerate what the effects might be,” says Woods Hole’s Ken Buesseler. http://www.washingtonpost.com/blogs/wonkblog/wp/2014/12/29/radiation-from-fukushima-is-reaching-the-west-coast-but-you-dont-need-to-freak-out/

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