German scientists say vegetables that grow aboveground near the Fukushima nuclear reactor are most suceptible to radiation. However, root vegetables and seafood are less likely to be affected.
Some Japanese spinach may be radioactive
This past week, Japan has halted shipments of food products from certain prefectures around the damaged Fukushima nuclear power station.
People in that prefecture have been warned not to eat 11 different types of vegetables grown in their region. Above all, leafy vegetables including spinach, cabbage and broccoli are particularly vulnerable to contamination, due to their large surface area.
"[Radioactive particles] can be directly deposited on all possible surfaces from, for example, on leaves, stems or branches," said David Tait, a researcher at the Max Rubner Institute, a German research center that focuses on nutrition and food, based in the northern city of Kiel.
"This particle film can be washed off - at least in part," he told Deutsche Welle. "50 to 90 percent of the radioactive materials are removed by washing the vegetables."
So far, health and safety experts in Japan have measured elevated levels of iodine-131, a potentially dangerous isotope that if consumed, can cause thyroid cancer. However, given that it only has a half-life of eight days, that is not enough time for the particles to penetrate into the soil - that's why root vegetables like potatoes, carrots and radishes are not affected.
Cesium stays in the soil for decades
Scientists say that because of its high surface area, broccoli is more likely to absorb radiation
However, another isotope that has been shown to be in the leaking radiation is cesium-137, which has a half-life of around 30 years.
Even today, some mushrooms grown in parts of southern Germany have been shown to have cesium-137, due to fallout from the Chernobyl disaster 25 years ago.
If people eat foods contaminated with cesium-137, it can build up in the body and spread to the blood and muscles.
Radioactive material can contaminate seafood
However, there may be a silver lining as the Japanese diet typically involves a great deal of seafood and seaweed.
Because the radiation is distributed in the ocean, the risk of radioactive particles in seafood is less, according to Ulrich Rieth, a research at the Federal Institute of Fisheries Ecology in Hamburg.
Nevertheless, he added, radioactive particles can be passed down the food chain.
"Fish eat plankton, and people eat fish," he said.
Author: Judith Hartl / cjf
Editor: Nicole Goebel