The New York Times reported a sample of Japanese tea contained radioactive elements—specifically, cesium 137. The radioactive form of the element is produced when uranium and plutonium absorb neutrons and undergo fission as they would at a nuclear powerplant. The tea, which was exported to Hong Kong, only contained trace amounts far below legal limits, but the tea manufacturer still recalled its product.
Cesium 137 tends to be one of the longest remaining byproducts of a meltdown. Exposure to higher levels could increase the risk of cancer, and very high exposure can result in serious burns and even death.
In all, 140,000 samples have been tested annually for radioactive elements since the Fukushima-Daiichi nuclear power plant meltdown in 2011. In 2012, 3.3 percent tested above allowable limits (though Japan’s limits are the strictest in the world). The number increased to 4 percent in 2013 and then dropped to .6 percent at the end of 2014. According to Wired, cesium doesn't absorb very well into plants because it's biologically similar to potassium. Since the soil tends to be rich in potassium, plants absorb the real thing instead of the imposter.
A recent study from Colorado State University found after analyzing nearly 900,000 samples, food grown near the power plant posed little threat four years later (though initially a small percentage of vegetables exceeded the limits for radioactive elements).
“We can conclude that the number of people getting an unacceptably high exposure was probably very, very low,” Georg Steinhauser, an assistant professor in CSU’s Department of Environmental and Radiological Health Sciences said in a statement.
However, Steinhauser concluded Japanese officials should also be testing for strontium-90, which could be a threat and is more easily absorbed in soil. Many scientists are concerned the long-term impact of the element could be dangerous. The disaster at the Chernobyl nuclear power plant introduced large amounts of the element to the environment. Strontium-90 tends to deposit into the bone like calcium, and has been linked to bone cancer and cancer near the soft tissue of the bone. The level of risk depends on the amount of the element in the environment.
“The currently valid regulatory limits in Japan and Europe are based on potentially erroneous assumptions concerning the occurrence of strontium-90 in foodstuffs,” Stefan Merz of the Vienna University of Technology in Austria said in a statement. “In politics and even in the scientific field of physics this topic may not be very popular; for the sake of human health it was definitely necessary to shed some light on this question. Many scientists in Japan and globally are concerned about the current strontium-90 policy. In our study, we present evidence that this concern is actually quite real.”
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Image of green tea from Shuttershock