Caroline Delbert
POP MECH
4/21/2021
U.S. honey still contains radioactivity dating back to the 1950s.
Radiocesium from nuclear weapons testing continues to appear in local plants.
The radiocesium is absorbed because of its resemblance to potassium.
Drizzle some radioactivity in your tea: Scientists say nuclear fallout from Cold War weapons testing is still showing up in U.S. honey today, and the secret to the lingering traces is a sneaky chemistry twist.
➡ Join Pop Mech Pro and get exclusive answers to your weirdest science questions.
It’s important to note the levels are not high enough to be harmful, say the scientists, from the College of William & Mary. But how is radioactivity still lingering in honey production after 60+ years?
The key ingredient is called radiocesium. Radioactive cesium is a fission product thrown off by hundreds of nuclear weapon test blasts from global superpowers, including the U.S., during the‘50s and‘60s. The isotope’s radioactive half life is 30 years, meaning the worst of the radiation from these specific test blasts is well behind us.
But the decades-old radiocesium is still in circulation for bees because it’s close enough to the element potassium, one of the essential nutrients for plants, humans, and other animals. Plants mistakenly absorb radiocesium, believing it to be potassium.
Honey not only picks up local plants’ chemical composition, but magnifies it because of the mechanism of how honey is made, say the scientists. Bees consume nectar and, like the people who turn maple sap into syrup, concentrate the nectar so it’s up to five times thicker. What’s left has even more of the local chemical composition.
“While soils of the eastern U.S. have a relatively narrow range of [radiocesium] today, concentrations in honey sourced from this region spanned nearly 3 orders of magnitude with far higher levels in the southeast,” the researchers write in their study, which appears in Nature Communications.
Why do the levels spike in the southeast? Blame the geological nature of the region, where there’s less readily available potassium because of the way rocks and soil are arranged. That means plants in the southeast grab more of whatever is around that seems like potassium, including radiocesium.
The William & Mary scientists discovered this by accident, when grad students brought back samples of local foods from spring break destinations around the eastern U.S. to test for radiocesium, according to Science. When one student’s local honey contained cesium levels 100 times higher than the other foods, the scientists dug into honey’s radioactive link.
The scientists ultimately found radiocesium in 68 of 122 American honey samples and found approximately 870,000 atoms per tablespoon—“well below” the U.S. Food and Drug Administration’s line for food safety concerns, according to Science.
While the minuscule radiation levels in honey are completely safe for humans today, that doesn’t mean there isn’t, well, fallout for other species. Scientists should now look into how radiocesium has impacted bees since the weapons testing; bumblebees near Chernobyl were less able to reproduce after the 1986 disaster, for example.
© Tara Moore
Scientists say nuclear fallout from Cold War weapons testing is still showing up in U.S. honey today. Here's why.
U.S. honey still contains radioactivity dating back to the 1950s.
Radiocesium from nuclear weapons testing continues to appear in local plants.
The radiocesium is absorbed because of its resemblance to potassium.
Drizzle some radioactivity in your tea: Scientists say nuclear fallout from Cold War weapons testing is still showing up in U.S. honey today, and the secret to the lingering traces is a sneaky chemistry twist.
➡ Join Pop Mech Pro and get exclusive answers to your weirdest science questions.
It’s important to note the levels are not high enough to be harmful, say the scientists, from the College of William & Mary. But how is radioactivity still lingering in honey production after 60+ years?
The key ingredient is called radiocesium. Radioactive cesium is a fission product thrown off by hundreds of nuclear weapon test blasts from global superpowers, including the U.S., during the‘50s and‘60s. The isotope’s radioactive half life is 30 years, meaning the worst of the radiation from these specific test blasts is well behind us.
But the decades-old radiocesium is still in circulation for bees because it’s close enough to the element potassium, one of the essential nutrients for plants, humans, and other animals. Plants mistakenly absorb radiocesium, believing it to be potassium.
Honey not only picks up local plants’ chemical composition, but magnifies it because of the mechanism of how honey is made, say the scientists. Bees consume nectar and, like the people who turn maple sap into syrup, concentrate the nectar so it’s up to five times thicker. What’s left has even more of the local chemical composition.
“While soils of the eastern U.S. have a relatively narrow range of [radiocesium] today, concentrations in honey sourced from this region spanned nearly 3 orders of magnitude with far higher levels in the southeast,” the researchers write in their study, which appears in Nature Communications.
Why do the levels spike in the southeast? Blame the geological nature of the region, where there’s less readily available potassium because of the way rocks and soil are arranged. That means plants in the southeast grab more of whatever is around that seems like potassium, including radiocesium.
The William & Mary scientists discovered this by accident, when grad students brought back samples of local foods from spring break destinations around the eastern U.S. to test for radiocesium, according to Science. When one student’s local honey contained cesium levels 100 times higher than the other foods, the scientists dug into honey’s radioactive link.
The scientists ultimately found radiocesium in 68 of 122 American honey samples and found approximately 870,000 atoms per tablespoon—“well below” the U.S. Food and Drug Administration’s line for food safety concerns, according to Science.
While the minuscule radiation levels in honey are completely safe for humans today, that doesn’t mean there isn’t, well, fallout for other species. Scientists should now look into how radiocesium has impacted bees since the weapons testing; bumblebees near Chernobyl were less able to reproduce after the 1986 disaster, for example.
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