Flowering plants can transmit radiocesium from soil to honeybees, which can then concentrate the contamination in honey.
Arx0nt / iStock
By Nikk Ogasa
According to a new study, the failure of nuclear bomb tests in the 1950s and ’60s appeared in American honey. Although levels of radioactivity are not dangerous, they may have been much higher in the 1970s and ’80s, researchers say.
“It’s really amazing,” says Daniel Richter, a soil scientist at Duke University who is not involved in the work. According to the study, the dropout shows ‘still’ and disguises itself as an important nutrient. ‘
In the aftermath of World War II, the United States, the former Soviet Union and other countries detonated hundreds of nuclear warheads in the above tests. The bombs emit radiocesium – a radioactive form of the element cesium – into the upper atmosphere, and the winds scattered it around the world before falling into microscopic particles from the sky. However, the distribution was not uniform. For example, much more fallout has dusted off the U.S. east coast, thanks to local wind and rainfall patterns.
Radiocesium is soluble in water, and plants can compare it to potassium, an important nutrient that has similar chemical properties. James Kaste, a geologist at the College of William & Mary in Williamsburg, Virginia, instructed his undergraduate students to see if plants continue to absorb this nuclear pollution: Bring local food back from their spring vacation destinations to radiocesium to test.
One student returned with honey from Raleigh, North Carolina. To Kaste’s surprise, it contains cesium levels that are 100 times higher than the rest of the collected food. He wondered if eastern American bees that collect nectar from plants and turn it into honey concentrated the radiocessium in the bomb tests.
So Kaste and his colleagues – including one of his subterraneans – collected 122 samples of local, raw honey from across the eastern United States and tested them on radiocesium. They detected it in 68 of the samples, at levels of more than 0.03 cups per kilogram – about 870,000 radiocesium atoms per tablespoon. The highest levels of radioactivity were found in a sample in Florida – 19.1 cups per kilogram.
The findings, reported last month in 2005 Nature communication, reveals that, thousands of miles from the nearest bomb site and more than 50 years after the bombs fell, radioactive fallout is still cycling through plants and animals.
However, the US Food and Drug Administration still says the numbers need not worry about this. Science. The radiocesium levels reported in the new study drop ‘well below’ 1200 cups per kilogram – the cut-off for any food safety problem, the agency says.
“I’m not worried at all,” Kaste adds. ‘I’m eating more honey now than before I started the project. And I have children, I give them honey. ‘
Radiocesium decays over time, so honey in the past probably contained more of it. To find out how much more, Kaste’s team went through the records of cesium tests in American milk – which were monitored out of concern about radiation – and analyzed the archives of plant samples.
In both data sets, the researchers found that radiocesium levels had fallen sharply since the 1960s – a similar trend that was likely to occur in honey. “Cesium levels in honey were probably ten times higher in the 1970s,” Kaste speculates. “Because of radioactive decay, what we are measuring today is just a hint of what was there.”
The findings raise questions about how cesium has affected bees over the past half-century, says Justin Richardson, a biogeochemist at the University of Massachusetts, Amherst. “They are wiped out of pesticides, but there are other less toxic effects from humans, such as precipitation, that can affect their survival.”
After the Chernobyl nuclear disaster in 1986, scientists have shown that radiation levels in the environment can impede the reproduction of bumble bee colonies. But these levels were 1000 times higher than the modern levels reported here, says Nick Beresford, a radioecologist at the UK Center for Ecology & Hydrology.
Although the new study should not sound the alarm about today’s honey, it’s still important to understand how nuclear pollution is spoken in the environment of our ecosystems and our agriculture, says Thure Cerling, a geologist at the University of Utah . “We need to pay attention to these things.”