Radioactive bluefin tuna makes a great media dish but there’s no “there’ there. NPR’s science editor Richard Harris, the last best reporter on government radio, weighs in with what the national press won’t tell its readers: the trace amounts of Japanese nuclear material has no health significance – naturally occurring radioactivity already in bluefins is 30X greater.
Fisher says they weren’t actually worried about radioactive cesium as a health risk. They tested the flesh, “mostly just to see if it we could detect it, and we were quite surprised, I must say. We did not expect to see this radioactivity retained by the fish during their trans-Pacific voyage, which we estimates takes from three to four months.”
Yes, radiation in seafood seems scary. But here’s the catch (if you pardon the expression). Tuna, like every other food on the planet, already contains naturally occurring radiation. It has potassium-40 and polonium-210. It always has and it always will. In addition, seafood in general contains a trace of cesium-137 left over from nuclear weapons testing in the 1950s and 1960s.
So the question is, how much more radiation did these particular tuna fish contain? The answer is: A trivial amount. In fact, radiation from the cesium is 30 times less than the radiation that’s already in the fish naturally in the form of potassium-40, according to the research paper. And the natural polonium-210 packs a radiation dose 200 times larger than the dose from the cesium.
Really, the result is a testament to how well scientists can now measure tiny amounts of radiation. And of course it’s a remarkable lesson in how wildlife can be traced using accidental “tags” instead of using the labor-intensive plastic ones.
If you are still worried about the cesium from Fukushima, Robert Emery at the University of Texas Health Science Center at Houston says you’d need to eat 2.5 to 4 tons of tuna in a year to get a dose of cesium-137 that exceeds health limits. That’s a lot of sushi.
Yes, bluefin is used primarily for sushi. And, much of the Pacific bluefin tuna that’s caught off the coast of Mexico and Southern California is shipped right back across the ocean, to be sold at the lucrative seafood markets — in Japan.
This media frenzy isn’t, I don’t believe, part of some vast conspiracy to make people fear their food but rather just a typical example of how mass media treats scientific news: in 3o-second sound bites. The trouble is, thirty seconds exhausts most people’s attention span so that’s the beginning and end of their education. Witness, just as an example, the shut down of Eastern Middle School a few years ago when a classroom thermometer broke and spilled a tiny blob of mercury on the floor. no mere wiping up the spill with a Bounty towel, no sir, not when children’s lives are at stake. We had HazMat teams, yellow police tape and kids sent home from school, where presumably they could toss a burned-out, mercury-laden CFL bulb into the trash. Ain’t stupidity grand?