BOMBS AND THE BEES: LEGACY RADIATION IN HONEY SHOWS MODERN PLANT CYCLING OF A COLD WAR CONTAMINANT

Hundreds of atmospheric nuclear weapons tests during the middle-20^th century covered the earth’s surface with radioactive fission products of the detonated uranium and plutonium bomb cores. The eastern United States (U.S.) received a disproportionately large fraction of radioactive fallout during this time, despite being thousands of kilometers away from the detonations. One of the longer-lived fission products dispersed by these tests was ¹³⁷Cs, which has a similar biogeochemical behavior as potassium, and thus is prone to uptake by plants. We collected 110 honey samples primarily from small-scale beekeepers in the eastern U.S. and found that more than half had detectable ¹³⁷Cs (>1 million atoms/tablespoon), and samples in the southeastern U.S. had up to 550 million atoms/tablespoon. The magnitude of ¹³⁷Cs in honey was not correlated with fallout, but had a strong (p<0.01) inverse relationship with soil potassium. Measurements of ¹³⁷Cs and potassium indicate that soil-plant-insect focusing effects can locally magnify contaminants in honey by over two orders of magnitude. Given that chronic low-dose radiation has an adverse effects on plants and animals, nuclear contamination should receive more attention as a possible factor in the recent collapse of pollinating insects.