Some are unambiguous: communities and ecosystems in Japan close to the reactors have been shattered by the initial meltdown and continuing radiation leakage.  For over 100,000 evacuees, home and future are unknown.

But in North America, fears for our local food chain cause more confusion.  We question the safety of Pacific-caught seafood, a traditionally staple food, celebrated as a rich source of nutrients and sought after by gourmet chefs and home cooks.  We worry that the US Food and Drug Administration (FDA) is not doing enough testing, though the FDA continues to assure consumers that monitoring systems are in place and that levels of radionuclides — such as the cesium-137 found in Pacific Bluefin tuna in 2011 — have thus far been so far below FDA limits that further investigation is unwarranted.

But lack of official data leads to rampant speculation.  As Jan Beranek of Greenpeace puts it, “Given that people’s trust in public authorities has been shaken (and not without a reason!), one can often find alarming but unconfirmed information on social media.”  Beranek goes on to state that according to Greenpeace and other current field research, outlandish but widely-circulated claims of massive waves of radiation hitting the west coast and killing sea life have no basis in fact.

For now, the Fukushima-derived cesium found in Blue Fin tuna remains 600 times lower than levels of naturally occurring ocean radionuclides which, like the now famous radioactive banana, have long been assumed harmless.  Many other commonly eaten Pacific seafood species have yet to show any contamination.  Some prominent health advisers such as Chris Kresser believe that “If there’s any risk you should be concerned about when it comes to fish, it’s the risk of not eating enough!”  Lack of fish intake has been linked to greatly elevated heart-disease risk (36% increase in coronary deaths) as well as overall mortality (17% increase in deaths from all causes).  Given these relative risks, I’m inclined to cautiously follow the lead of environmental scientist David Suzuki who says “I’m taking a precautionary approach: fish will stay part of my diet, as long as they’re caught locally and sustainably, and will remain so until new research gives me pause to reconsider.”

When I contacted Ken Buesseler, Senior Scientist in Marine Chemistry and Geochemistry at Woods Hole Oceanographic Institution, he told me that while the ongoing radioactive water leak warrants urgency, “the concern is for Japan — on land and in their coastal fisheries.”  Looking at Pacific seafood today, how high are radiation levels?  “Off Japan, some of the fisheries are closed due to levels of cesium that are above the Japanese limit,” says Buesseler. “The limit in Japan is more than 10 times more strict than in the US.  None of the fish in North American waters are even close to the Japanese limits, much less US limits.”  He believes ongoing public monitoring of ocean radioactivity is crucial, and predicts that “levels of Fukushima radionuclides will continue to increase over the next two years along the west coast of North America.”  Although even these increased levels are expected to remain below low-risk thresholds, still “we need confirmation of what is in the water as it arrives on the west coast.”

“The limit in Japan is more than 10 times more strict than in the US.  None of the fish in North American waters are even close to the Japanese limits, much less US limits.”

Ken Buesseler

Are all radionuclides alike?

As far as the specific particles released at Fukushima, Buesseler explained that iodine-131, much discussed in the early days following the tsunami, “has an 8 day half-life so is not of concern” in seafood consumption.  Cesium has a longer half-life, but “behaves like a salt and goes rather quickly in/out of fish and humans, so does not bioaccumulate to large degrees.”  Strontium-90, “a bone-seeking isotope [which] replaces calcium, and has a much longer biological half-life in fish and our systems,” may become more troubling if ocean levels increase near Fukushima: Strontium-90 in bones of small fish eaten whole, such as sardines, could find its way into human bones.  But this is speculation, not current reality.

To date, there is no clear consensus on whether there is a “safe” dose of radiation, so low that no health risk is increased.  But even among subsistence fishermen, who might theoretically consume up to 3/4 of a pound of contaminated Bluefin tuna per day, the “worst-case scenario” long-term fatal cancer increase is estimated at 2 cases per 10 million similarly exposed.  Such a small statistical increase is difficult to distinguish from pure chance.  For perspective, don’t forget to consider that many of us voluntarily expose ourselves to much higher doses of radiation in the form of long-distance air travel (up to 5 millirems from a single cross-country flight, equivalent to eating over 6 pounds of contaminated tuna daily for a year!) or medical x-rays.  Incidentally, Bluefin cesium concentrations, considered “very low” in 2011, have since dropped in subsequent tests.

Thus far, the consensus among scientists involved in peer-reviewed research studies seems to be “Go ahead, eat the fish, but stay informed.”  To avoid unnecessary panic and confusion, steer clear of “viral” sensationalist blogs which hint at cover-ups, conspiracy, and impending doom.  These so-called news sources rarely cite legitimate research, and when they do the findings are often twisted.   Are regulatory bodies such as the FDA doing their job, or are they protecting industrial interests at the expense of public health?  Buesseler says “I think they are dismissive of the concerns, but I have no evidence that any results are being suppressed.”

Independent researchers, with no vested interests in instilling false confidence, may be easier for our skeptical and shaken populace to trust.  Fortunately, Woods Hole’s How Radioactive is Our Ocean? project links top scientists with concerned consumers, to generate testing and interpret information.  Through this non-profit “citizen science” initiative, you can suggest a test site, collect seawater samples and raise money for processing, access data, and educate yourself.  This unique collaboration aims to fill a critical information gap: no other organization is yet monitoring the arrival of radioactive water along the west coast.

Only some fish species have a large enough migratory range to make the journey from coastal Japan to North America.  For now, choosing locally-caught non-migratory fish may feel safer.  But as ocean currents bring more diluted radionuclides to our own shores, our options will change.  We live in a world where “contamination” is an environmental inevitability — water and weather systems respect no boundaries.  But if scientists’ predictions come true, our exposure will be minimal.  The answers won’t be simple, and they may change over time.  If we educate ourselves — on the risks of eating or not eating Pacific seafood, as well as the bigger oceanic picture — we can each make our own choices, and sit down to dinner with gratitude for the relative safety and bounty we still enjoy.

References:

FAQ: Radiation from Fukushima: Woods Hole Oceanographic Institution

FDA Response to the Fukushima Dai-ichi Nuclear Power Facility Incident

Radiation Health Risks: Oceanus Magazine

Fukushima’s Radioactive Water Leak: What You Should Know

Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood

Radiation, how much is considered safe for humans? (MIT)