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Flowering plants can transfer radiocesium from soils to honey bees, who can then concentrate the contaminant in honey.
Fallout from nuclear bomb tests in the 1950s and '60s is showing up in U.S. honey, according to a new study. Although the levels of radioactivity aren't dangerous, they may have been much higher in the 1970s and '80s, researchers say.
"It's really quite incredible," says Daniel Richter, a soil scientist at Duke University not involved with the work. The study, he says, shows that the fallout "is still out there and disguising itself as a major nutrient."
In the wake of World War II, the United States, the former Soviet Union, and other countries detonated
hundreds of nuclear warheads in aboveground tests. The bombs ejected radiocesium — a radioactive form of the element cesium — into the upper atmosphere, and winds dispersed it around the world before it fell out of the skies in microscopic particles. The spread wasn't uniform, however. For example, far more fallout dusted the U.S. east coast, thanks to regional wind and rainfall patterns.
Radiocesium is soluble in water, and plants can mistake it for potassium, a vital nutrient that shares similar chemical properties. To see whether plants continue to take up this nuclear contaminant, James Kaste, a geologist at the College of William & Mary in Williamsburg, Virginia, gave his undergraduate students an assignment: Bring back local foods from their spring break destinations to test for radiocesium.
One student returned with honey from Raleigh, North Carolina. To Kaste's surprise, it
contained cesium levels 100 times higher than the rest of the collected foods. He wondered whether eastern U.S. bees gathering nectar from plants and turning it into honey were concentrating radiocesium from the bomb tests.
Comment: Meanwhile a record number of asteroids were observed flying past Earth in 2020 - Despite lockdowns interrupting surveys.