Whether any of this actually matters depends on whom you ask. “There’s a nuclear-power side that’s very quick to be dismissive and say, ‘Don’t worry your pretty little heads, you’re not in harm’s way,’ ” Ken Buesseler, a marine-chemistry researcher at Woods Hole and the organizer of the sampling initiative, told me. “The flip side are the people screaming, you know, ‘Stay out of the Pacific, don’t swim in Monterey, I’m going to move, tell your friends, this is a catastrophe!’ ” At the levels detected in Ucluelet, Buesseler has calculated, you’d need to swim six hours a day for a thousand years to get the radiation equivalent of a dental X-ray.
The full impact of nuclear fallout, however, depends on more than becquerels, which merely count the number of times per second that an unstable atom somewhere in the sample fires off a particle. These particles, and the differing amounts of energy with which they are ejected, have a wide range of effects on the body. We process cesium like an electrolyte, which means that it is diffused throughout the body and eventually excreted in urine. Half of the amount that is ingested is lost within a few months, which limits exposure. By contrast, strontium-90, another common component of nuclear waste, is a calcium-like “bone seeker” that becomes concentrated in the skeleton and teeth. Since it stays there for years rather than months, even relatively low doses increase the risk of conditions such as bone cancer and leukemia.
Just as marine radiochemistry has languished since Chernobyl, so, too, has marine radioecology; it remains a matter of considerable uncertainty how fallout progresses through the food chain. Nevertheless, it appears that, so far, Fukushima’s effects have been relatively benign. By August, 2011, researchers from Stanford and Stony Brook Universities had already detected elevated levels of cesium-134 in bluefin tuna caught off the California coast. (Bluefins spawn in the western Pacific, near Japan.) But, as the researchers pointed out in a follow-up paper, the additional dose of radiation was between a thousand and ten thousand times smaller than the dose from naturally occurring polonium-210 in the same fish.
Flip through enough of these reports, and you might reasonably start to wonder whether the seemingly negligent federal agencies that have declined to fund Buesseler’s monitoring program—the Department of Energy, the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, and others—actually have it right. In North America, at least, we’re orders of magnitude away from conservative safety thresholds; why are we worrying our pretty little heads? But this line of thinking overstates the accuracy of ocean-current models: after Fukushima, predictions of how much radioactive material would reach North America varied by a factor of ten, and didn’t even agree on what year it would arrive. Moreover, as Buesseler points out, comparing the model outputs to real data is the only way to improve their performance for next time, whether it’s a strontium-90 leak in Japan or an event elsewhere—almost anywhere, really—in the world. “We’re talking about a field of science that is, in some ways, dying out, and yet we have reactors up and down coastlines around the world, on rivers that drain into the ocean, in nuclear-powered submarines,” he said.
Full article: Is Radioactive Water Worth Worrying About? (The New Yorker)