Is radioactive water worth worrying about? — The New Yorker

” On a sunny lunch hour last June, Tricia Stevens and one of her colleagues from Lush, a cosmetics company with offices in Vancouver, British Columbia, headed to the beach with a collapsible five-gallon jug, a funnel, two zip ties, and a red plastic crate with a prepaid U.P.S. shipping label. They waded into Burrard Inlet and filled the jug with seawater (the same seawater that gives Lush’s Sea Spray Hair Mist its pep), then sealed it up and sent it across the continent, to the Woods Hole Oceanographic Institution, in Massachusetts, where it was tested for radiation. A week later, the results were in: Stevens’s sample had a cesium-137 level of 0.4 becquerels per cubic metre, making it about two thousand times less radioactive than the average banana.

The good news for Stevens, and for the more skittish consumers of her company’s products, was that, besides containing very little cesium-137, her sample showed none of the isotope cesium-134. Whereas cesium-137, which has a half-life of thirty years, has been present in the oceans, in some degree, since the nuclear-weapons tests of the fifties and sixties, cesium-134, which has a half-life of only two years, is a result of far more recent contamination—namely, the 2011 meltdown at Japan’s Fukushima Daiichi nuclear plant. The fallout from that accident, more than ninety per cent of which ended up in the Pacific, took nearly four years to reach North American waters. Earlier this year, it made landfall in the small town of Ucluelet, British Columbia, where a dockside sample registered 1.4 becquerels per cubic metre of the telltale cesium-134 and about fifteen times the cesium-137 levels of Stevens’s test.

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.

From a human health perspective, Buesseler sees a potential strontium leak as far more worrying than a little cesium. Fukushima cleanup crews have collected a hundred and fifty million gallons of radioactive water in more than a thousand temporary storage tanks, and are adding another hundred thousand gallons a day as groundwater seeps into contaminated reactor buildings. They have been able to extract cesium from this water, but getting the strontium out is proving to be a greater challenge. There have already been two leaks from individual tanks, and Buesseler estimates that the total amount of strontium sitting in the remaining tanks is at least a hundred times greater than the amount of radioactive material released in the initial aftermath of the earthquake. It is partly for this reason, he says, that the existing fallout is worth tracking—to see where and how quickly the ocean currents might carry future contamination. Since no U.S. federal agency has taken on the task, he has recruited volunteers like Stevens to collect samples up and down the Pacific coast.

Buesseler started his Ph.D. at Woods Hole in 1981, studying plutonium isotopes left over in the Atlantic from decades of aboveground bomb testing. (Such fallout is widely distributed across the globe: forensic scientists can calculate a corpse’s age at death to within a year by measuring levels of weapons-derived radioactive carbon-14 in the tooth enamel.) In 1986, the Chernobyl accident diverted Buesseler to the Black Sea, where he and his colleagues studied radiation dispersion while playing cat and mouse with the Soviet Navy. After a few years, though, interest started to fade, and Buesseler’s colleagues, who had been studying ocean radioactivity since the sixties, the heyday of nuclear fallout, began to retire. “Chernobyl gave another shot in the arm to the field, but really that generation was not replaced,” Buesseler told me. “I just happened to be young, and thus one of the few guys still around when Fukushima happened.”

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.

For now, Buesseler’s citizen-science initiative is humming along. Donations from more than four hundred people and a range of organizations, including Lush, have enabled testing at more than sixty sites along the Pacific coast of North America. Inevitably, though, interest will fade again. To keep measurements going during his next stint in the wilderness, not to mention after he retires, Buesseler is working with his Woods Hole colleagues on drones that could automate sample collection, and on isotope-absorbing ankle bracelets for surfers (“So you can see what the surf is like and what the cesium is like off Redondo Beach”). The real challenge, though, isn’t technical; it’s persuading people that we need to know what is in the ocean, and how it spreads, before the next Fukushima. “It is tempting to just run models, but to me that isn’t enough,” Buesseler said. “Let’s get some real data.” ”