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Reminder: There's Still Fall-Out from Nuclear Weapons Out There

But hey, nothing to worry about.
via Wikimedia Commons

A study published in the journal Nature Communications demonstrated that there are still radionuclides in the stratosphere from nuclear testing that was banned 51 years ago. Plutonium and caesium isotopes that date back to the Cold War are still in the upper atmosphere and can be driven down by global atmospheric events, like massive volcanic eruptions.

Lead author Jose Corcho Alvarado, from the Institute of Radiation Physics at Lausanne University Hospital in Switzerland, told the BBC: "Most of the radioactive particles are removed in the first few years after the explosion, but a fraction remains in the stratosphere for a few decades or even hundreds or thousands of years."

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Rain, snow, and gravity have “washed out” the isotopes from the lower layer of the atmosphere, the troposphere, fairly quickly. But 6-30 miles above the Earth’s surface, in the stratosphere, the concentrations remain 1,000 to 1,500 levels higher than in the troposphere.

Of course, the researchers point out, even there the levels aren’t high enough to be harmful for people. That’s good news, because, as the Centers for Disease Control reminds us on their website, “All people who were born since 1951 have received some exposure to radiation from weapons testing-related fallout.”

This might seem surprising or unlikely, but recall that an equivalent of 29,000 of the bombs dropped on Hiroshima—428 megatons—were added to the air through nuclear testing. Radioactive caesium-137, which is produced when uranium and plutonium absorb neutrons and undergo fission, has a half-life of about 30 years. The largest source of caesium-137 remains fall-out from those nuclear weapons tests in the 50s and 60s, and through the soil and water around us we have all absorbed a little bit every year, even those of us born well after nuclear testing above ground was banned.

The most significant radionuclide from nuclear weapons testing is iodine-131, according to a 1998 study by the US Department of Health and Human Services, which estimated that somewhere between 11,300 and 212,000 thyroid cancers “would be expected to occur among the United States population from exposure to iodine-131 from nuclear test sites.” The study admits that that’s a really wide range, but explains the estimate was really rough because it was only a preliminary estimate, in order to estimate how difficult a future, more accurate estimate would be. In 2002, early releases from the follow-up study stated that fall-out from nuclear tests probably caused around 15,000 cancer deaths in the United States and 22,000 cancers in total.

Chris Clarke, a nature writer and journalist, wrote eloquently in a piece from September about the immediate and lingering effects that the early bomb tests in Nevada, like the Shot Fizeau on September 14, 1957 have had on the desert to this day.

“56 years and a week after Shot Fizeau, one quarter of the Strontium 90 that bomb created is yet with us. A quarter of Fizeau's radioactive cesium 137 is as well. 50 years since the Senate ratified the Partial Test Ban treaty, 21 years since the U.S. last tested a nuclear weapon underground, and the soil in central Nevada still sets off Geiger counters.”

We’re assured by the CDC that, if you were born after 1971, you have nothing to worry about from the nuclear weapons tests in Nevada. Unfortunately the same wasn't the case for years after the testing ended, when people were unwittingly exposing themselves to radioactive dust from the site, including famously the cast of a John Wayne-playing-Genghis Khan movie, to say nothing of Pacific Islanders displaced by US bomb tests, Chinese villagers dangerously exposed by their government’s nuclear tests, and on and on. For a well-written, if tragic, account of how little nuclear weapons testers knew or were willing to account for, I’d recommend Rudolph Herzog’s A Short History of Nuclear Folly.

Of course, the trace radiation that surrounds us now is nothing compared to the dangers at the time of nuclear weapons testing, but it's a lasting reminder of what occurred. The effects of those 428 megatons detonated in atmospheric nuclear weapons tests remain visible today, as both the US government and now this team of Swiss researchers reminds us. If those clouds are tasting metallic, though, it's probably just your imagination.