Pacific albacore carry only tiny traces of Fukushima radiation, say Oregon State University and NOAA scientists
By Craig Weatherby
We’ve been taking steps to ensure our customers’ safety with regard to radiation from the Fukushima, Japan nuclear accident.
To our knowledge, Vital Choice remains the only U.S. seafood company to conduct and/or publish radiation tests on its Pacific seafood products.
And we found the test results very comforting ... after all, our families are among the biggest consumers of Vital Choice seafood.
And U.S. scientists just released the results of a more extensive series of tests on Pacific albacore tuna … which found no cause for concern.
Oregon State University/NOAA tests find only harmless traces
According to a team of scientists from Oregon State University and the National Oceanic and Atmospheric Administration (NOAA), samples of albacore tuna caught off the West Coast of the U.S. show minute traces of radiation from the Fukushima reactor disaster.
The radiation levels in fish analyzed to date are far below anything that would pose a risk to humans who consume the fish, the research team emphasized. The findings are preliminary; additional fish remain to be tested.
But the findings could reveal new information about where Pacific albacore travel during their migratory lives – and how what happens in one part of the ocean can affect the food web thousands of miles away.
The team has collected and tested fish caught off the U.S. West Coast both before and after the devastating March 2011 Japanese tsunami and subsequent release of radioactive material into the ocean by the Fukushima Daiichi nuclear reactor.
“We're still processing new fish, but so far the radiation we're detecting is far below the level of concern for human safety,” said co-investigator Delvan Neville, a graduate researcher with OSU's Radiation Health Physics program.
People are constantly exposed to radiation from the natural environment, Neville pointed out. “To increase their normal annual dosage of radiation by just 1 percent, a person would have to eat more than 4,000 pounds of the highest (radiation) level albacore we've seen.”
The OSU team's findings are consistent with those of California researchers who announced in May that they had found traces of Fukushima-linked radionuclides in bluefin tuna caught off the California coast.
Shortly after the March 2011 Japanese tsunami and reactor disaster, the U.S. Environmental Protection Agency (EPA), Food and Drug Administration (FDA), and NOAA jointly expressed “high confidence” in the safety of U.S. seafood products, suggesting it was unlikely that migratory fish such as tuna would be contaminated to “significantly elevated radiation levels.”
Experts in radiation and currents had predicted that two-to-five-year-old albacore would be unaffected because their migration patterns do not take them through the waters where the radiation leak occurred.
(These specific fish are a mainstay of the U.S. troll and pole fishery, which is the source of all Vital Choice albacore.)
Where do albacore roam?
Scientists differ on the details of albacore migration and behavior. Some suggest that not all albacore follow the same migration routes between western Pacific waters and feeding grounds off the U.S. West Coast.
Some believe North Pacific albacore may even comprise two separate sub-stocks with different migratory paths.
That's one of the questions Jason Phillips – then a graduate fisheries researcher in OSU's College of Earth, Ocean, and Atmospheric Sciences – was investigating with support from an Oregon Sea Grant, when the 2011 disaster struck Japan.
He wondered whether the radiation released by the Fukushima nuclear plant could be used as a “natural tag” to help unravel some of the questions about fish migration.
So Phillips put together a pilot study, but soon found he needed more fish samples – and access to additional equipment for detecting and measuring extremely low levels of radiation.
Richard Brodeur, the NOAA biologist who serves as lead investigator on the project, introduced him to Neville, a graduate student in OSU's Radiation Health Physics program who had access to the specialized instruments needed.
Phillips also obtained a modest NOAA grant to support the research. The researchers first identified two Fukushima-linked isotopes – Cesium-137 (Cs-137) and Cesium-134 (Cs-134) – this July, in samples of fish caught and frozen in 2011.
This particular combination of radioactive isotopes is produced by fission in nuclear reactors, and less commonly, nuclear weapons.
Cs-134, in particular, is considered key to the Fukushima nuclear “fingerprint” because it decays very rapidly, with a half-life of just more than two years.
While Cs-137, which persists for decades in the environment, could come from other possible sources, scientists say, the Cs-134 could only have come from the Fukushima reactors.
But the team needed more evidence to support the radioactivity findings.
So Phillips spent this summer collecting more fish at sea, off Oregon and Washington, as well as from scientists, fishermen and other sources along the West Coast.
Neville ran more tests, validating his methods against freeze-dried fish standards tested by dozens of labs – and got the same results.
They also shared fish samples with the Washington State Office of Radiation Protection, where radiation health physicist Lynn Albin is analyzing them as an additional check.
As more fish were tested, the results were consistent with the initial findings: No Cs-134 in fish caught before the disaster, but traces of the isotope in a significant number of fish caught since.
“This is what we've seen after testing about 70 pounds of tuna,” Neville said. “When you've run one or two samples, you can't really say much about the population you're testing yet. When you've run five or six, you could make some guesses. When you're up to, at this time, 18 samples and everything has fallen fairly neatly into two groups of results, you can start to make some predictions about that population.”
“What we can say is that we have detected Cs-134 in fish thousands of miles from where that Cs-134 came from, and over a year since it was released,” Neville added. “It's very interesting scientifically, and it can tell us more about tuna migration and what happens to radioactive releases, but it's nowhere near enough to be concerned about food safety.”
Jason Phillips, whose fisheries research launched the investigation, says it will take more work to unravel the mysteries of albacore migration.
- Oregon State University (OSU). Pacific albacore carry barely detectable fingerprints of Fukushima disaster. October 24, 2012. Accessed at http://oregonstate.edu/ua/ncs/archives/2012/oct/pacific-albacore-carry-barely-detectable-fingerprints-fukushima-disaster