The United States conducted many nuclear tests in the 1950s-1960s. Surprisingly, radioactive residues can still be detected in U.S. honey today.
Since World War II, the United States and other countries, including the former Soviet Union and China, have conducted hundreds of above-ground nuclear tests. These nuclear bombs ejected into the atmosphere a chemical element called radioactive cesium. This is a radioactive isotope of the element cesium (Cs).
The wind then dispersed it around the world before it fell from the sky in the form of tiny particles. Depending on the monsoon and rainfall patterns in different regions, these radioactive materials are not necessarily evenly distributed. For example, a recent study reported that radioactive contamination on the East Coast of the United States far exceeds that of other regions.
The study began with a simple spring break assignment: James Kaste, a geologist at the College of William and Mary in Williamsburg, Virginia, asked his students to bring back some local food from their spring break sites to be tested for radioactive cesium.
One student brought back honey from Raleigh, North Carolina. To Kaste’s surprise, it contained 100 times more radioactive cesium than the rest of the sample.
Daniel Richter, a soil scientist at Duke University, said in a statement, “It’s truly incredible.” He said the study shows that the consequences of the nuclear bomb tests “are still there and masquerading as major nutrients.
Radioactive cesium is soluble in water and plants mistake it for potassium, a chemically similar nutrient that is important to plants.
To see if plants continue to absorb this nuclear contaminant, Custer and his team collected 122 samples of locally produced, unprocessed honey from the eastern United States and tested them for radioactive cesium. The results showed that 68 samples contained more than 0.03 becquerels per kilogram of radioactive cesium, equivalent to about 870,000 cesium atoms per tablespoon. One sample from Florida had the highest level of radioactivity at 19.1 becquerels per kilogram.
This unexpected result means that even more than 50 years ago and thousands of miles from the nearest nuclear test site, radioactive residues are still circulating among plants and animals.
However, such levels of radioactive elements should not be considered dangerous. In the same statement, the U.S. Food and Drug Administration (FDA) said the levels of radioactive cesium reported in the new study were “well below” 1,200 becquerels per kilogram: the threshold for any food safety concern.
“I’m not trying to tell people they shouldn’t eat honey. I’m giving honey to my kids.” In a separate statement, Custer said, “I eat more honey now than I did when I started this project.”
However, radioactive cesium decays over time. As a result, honey from the past may have contained more residue. Custer’s team looked closely at records of cesium testing in U.S. milk, monitored it for radioactive contamination concerns, and analyzed archived plant samples. They found that cesium levels had fallen dramatically since the 1960s.
“What we see today is only a small fraction of what the radiation was during the 1960s and 1970s,” he said in the above statement.
“And we can’t be sure whether cesium 137 is associated with the colony collapse.” The statement said.
Justin Richardson, a biogeochemist at the University of Massachusetts, said in a previous statement that the new findings raise the question of how cesium has affected bees over the past half-century. “They are being killed by pesticides, but there are other lesser-known toxic effects, such as radioactivity, that can affect their survival.” The statement said.
So even though this new study doesn’t affect the consumption of honey today, understanding how nuclear contaminants travel around is still critical to assessing the health of our ecosystems and agriculture, said Thure Cerling, a geographer at the University of Utah, “We need to be aware of these things.”
The new study is published in the March 29, 2021 issue of Nature Communications.
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