Nearly four years after the Fukushima nuclear disaster, people in Japan are still hesitant to eat foods grown around the site of the accident. They worry that anything grown in the region will contain dangerous levels of radioactive elements, increasing their risk of cancer.
Sometimes, food from Fukushima will bear a photo of the farmer who grew it or a number to dial to learn more about each bag of rice or vegetables, just to ease customers' concerns.
Now there might be one more way to make customers feel confident that they aren't munching on a radioactive dinner. It's a chemical called CsTolen A, for Cesium Tolerance Enhancer.
Radioactive cesium is one of the biggest concerns following nuclear disasters. It takes a long time to decay — as much as 20 years for half of the cesium in the soil to disappear. And it dissolves in water, so plants draw it out of the soil just as they would nutrients. CsTolen A aims to block this uptake.
"The CsTolen A binds to cesium in the soil," explains Ryoung Shin, a researcher at the RIKEN Center for Sustainable Resource Science in Yokohama, Japan. In a study published this week in the journal Scientific Reports, Shin and her colleagues report that this binding prevents the cesium from entering the plant.
So far, the chemical has only been tested in the lab on the model plant Arabidopsis thaliana — not on any field crops. Shin and her collaborators identified the cesium-blocking chemical from a library of commercially available compounds. After screening for the best cesium-blocking contenders, they chose five and added them to the water they used on the plant, the soil around the plant, the seeds, and the plant itself.
Then they tested the plant tissue for cesium accumulation. They found that the only cesium they could detect in the plants was normal, from background trace levels present in the atmosphere. The cesium in the soil was not radioactive, but it behaves the same way as radioactive cesium on the molecular level.
The study was conducted in a plant that doesn't produce food, but the researchers are confident that the chemical will work on other kinds of plants, too. Because the chemical does its job before it enters the plant, Shin says it shouldn't matter what kind of plant is growing in the soil. Plus, CsTolen A is available commercially, meaning that it is relatively easy to get and distribute.
Of course, Shin notes, it's still too early to start applying this chemical to the fields around Fukushima. There are many layers of government regulation standing between Fukushima farmers and CsTolen A. And researchers aren't 100 percent sure that the chemical has no impact on human health, because they haven't tested it on people yet. But Shin says it looks promising: Since CsTolen A should stay in the soil and never enter the plant, it should never enter the human body, either.
Even now, there are still farmers who haven't returned to their land because many areas around Fukushima remain restricted. After prohibiting anyone from entering a radius of about 12 miles from the plant, the government started to let residents back in last spring. Shin hopes that in the future, CsTolen A will help get more people within the restricted zone back on their land and back to farming.
As for Fukushima foods grown outside that circle of concern, extensive testing shows they're just fine to eat, a group of researchers reported last week.
The researchers analyzed 900,000 food samples, including tea, beef, fruits, mushrooms, and vegetables grown and raised in the Fukushima region from 2011 to 2014. Their testing revealed that radiation in these foods had returned to pre-accident levels. Even so, consumers are still shying away from foods with the Fukushima label.
Shin says it's too bad, because the produce from the region is very high quality and tasty.
"Fukushima used to be a very famous place for agricultural products," she says. "There is plenty of produce, but people don't want [it]."
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