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radiation resource

Some Good News

The following correspondence is from Jim Lewis, dated August 9th, 2016 - and was addressed to the public through the Mendocino Community Network Email Listserve.

Dear Listservers,

Just over a year ago I put out a request on Listserve for crowd-funding support to sample Mendocino ocean waters on behalf of, and under the direction of, the Woods Hole Oceanographic Institute. Woods Hole has been tracking the migration of cesium-134 in the Pacific Ocean since the melt down of the Fukushima Daichi nuclear power plant five years ago.

Because Woods Hole does not have the budget to fund all of the sampling sites it would like to test, they rely on crowd-funded efforts such as ours in Mendocino. Over the past year very small traces of cesium-134 (less than that from a dental X-ray) have been detected on the coast of Washington state and Northern Oregon shoreline. Because cesium-134 diminishes by 50% in two years there was speculation that it has not, and may never, reach Mendocino.

On July 7th I, and my assistant, Max McKee, collected a 20 liter sample of sea water at high tide on the Mendocino shore. That sample was shipped to the Woods Hole Institute in Boston on July 8th. Woods Hole has the most sophisticated ocean sampling technology in the scientific community, and last Friday they emailed to inform me that there WAS ABSOLUTELY NO CESIUM-134 PRESENT IN THE MENDOCINO SAMPLE. An excerpt from Woods hole appears below" Thank you to all who contributed to this effort! Jim

"Hi Jim, we counted your sample over the weekend and got the following results: We did not detect cesium 134, evidence of Fukushima, in your sample. This is obviously good news but maybe not as interesting of a result. Cesium 134 has a half life of only 2 years, and there are no other sources of this element in the Pacific, so if we see it there we know it came from Fukushima. Though, now that it is 5 years after the accident it is getting more and more reduced and so harder to detect on the coasts of the Americas. If you want to see more about radiation doses and what different levels mean there is information on our webpage at ourradioactiveocean.org under "learn about radiation" (scroll down and there is a human health section)."

Radiation Testing

For the last four years, Rising Tide Sea Vegetables has submitted samples from its seaweed harvest to U.C. Berkeley’s Department of Nuclear Engineering.

We are pleased to report that for the 2014 harvest, “no radioactive isotopes that can be attributed to Fukushima were detected.” http://radwatch.berkeley.edu/

Seaweed is harvested during the spring. Typically, a spring harvest is sold well into the following year, so seaweed harvested during the spring of 2014 will be sold throughout 2015.

The seaweed samples are part of a larger food chain study for which the Department was awarded a Presidential Citation from the American Nuclear Society. http://www.prweb.com/releases/prwebAmerican-Nuclear-Society/UC-Berkeley-Nuclear-Eng/prweb9613442.htm.

Rising Tide can’t speak for the future and we certainly won't speak to the credibility of many recent news stories, however, we can continue to have a world-leader in radiation testing analyze our seaweed and we will share the results with our seaweed family.

Test Results

“Below [are] the limits…derived for the different isotopes that could have come from Fukushima -- at this point, only the longer-lived isotopes Cesium-134 and Cesium-137. The units are in becquerels per kilogram (Bq/kg) -- one becquerel is one nuclear decay per second. The limits mean that if there were radioactivity above those limits, we would have seen it with our detectors. These limits should be compared to the level of the naturally occurring isotope potassium-40 (K-40), also given below, which for dried seaweed typically has an activity of hundreds of becquerels per kilogram.”

Specific Activity (Bq/kg)

Sample Name



Cs-137 Limit

Cs-134 Limit






< 0.09

< 0.10






< 0.17

< 0.16

Sea Palm





< 0.11

< 0.10






< 0.10

< 0.10

Radiation Resources

One of our main concerns is the ongoing health of the ocean, so we are trying, like you, to stay apprised of good studies and scientifically-based articles. For those you who like Pinterest, you may see similar information by going to: http://www.pinterest.com/risingtidesv/radiation-information/











Radiation Shelf Talker

Wholesale customers: Please post the Radiation Shelf Talker near or above the seaweed section within your store. Click here for a printable Shelf Talker.

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