The government has advised people not to eat spinach, broccoli and some other vegetables grown in Fukushima Prefecture after radioactive substances at higher than acceptable levels were detected in samples.
The government has advised people not to eat spinach, broccoli and some other vegetables grown in Fukushima Prefecture after radioactive substances at higher than acceptable levels were detected in samples.
Although the official government view is that consumption of the contaminated vegetables will not lead to immediate health problems, health experts, even within the government, are showing more concern.
Officials attributed the high radiation levels of those vegetables and milk samples to the leak of radioactive substances at the quake-stricken Fukushima No. 1 nuclear power plant in Fukushima Prefecture.
Prime Minister Naoto Kan on Wednesday instructed Fukushima Governor Yuhei Sato to tell prefectural residents not to consume those vegetables, including komatsuna green leaf, cabbage and cauliflower, for the time being.
Kan also told Fukushima Prefecture to instruct farmers not to ship turnips, as well as the produce whose intake is restricted.
Ibaraki Prefecture was told to refrain from shipping parsley and milk.
The shipment restrictions came on top of those on spinach and kakina leaf grown in Fukushima, Ibaraki, Tochigi and Gunma prefectures and milk in Fukushima Prefecture.
Officials said farm cooperatives had already stopped shipping vegetables grown in open fields in Fukushima Prefecture.
"The vegetables will cause no immediate health problems even if temporarily eaten now," Chief Cabinet Secretary Yukio Edano told a news conference Wednesday.
"But regrettably, this situation is expected to continue for a long time," he said. "So it is desirable, as a precautionary measure, for producers to refrain from shipping them from an early stage and for consumers to eat as little of them as possible."
Edano stressed that eating the vegetables with the highest radiation levels for 10 days will bring the total to only about half of natural radiation exposure for an entire year.
"It will not lead to a radiation amount that will affect the health in the future, not just immediate problems," he said.
But a health ministry official said the same day that the intake restriction was taken because "continuing to eat (the vegetables) could lead to radiation exceeding the permissible yearly level for ordinary citizens."
According to the results of a health ministry survey released early Wednesday, the highest radiation level was detected in a sample of kukitachina green leaf of Motomiya, Fukushima Prefecture, about 60 kilometers from the plant. It showed 82,000 becquerels per kilogram of radioactive cesium, or 164 times the permissible level.
The ministry reported that higher-than-acceptable cesium levels were found in 25 samples from Fukushima Prefecture, including spinach in Tamura, at 80 times the safety limit, shinobu-fuyuna leaf from Kawamata, at 56 times, santosai leaf from Nishigo, at 48 times, and broccoli from Iitate, at 27.8 times.
High levels of radioactive iodine were found in 21 samples, including shinobu-fuyuna from Kawamata, at 11 times the safety limit, and spinach from Tamura, at 9.5 times.
In Ibaraki Prefecture, iodine 5.7 times higher than acceptable levels was discovered in milk in Mito, and iodine 6.0 times higher in parsley grown in greenhouses in Hokota and Namegata.
Children are especially vulnerable to iodine, which can concentrate in the thyroid gland and cause thyroid cancer if taken in large quantities.
The permissible level of iodine exposure is 1 millisievert per year at normal times. But during emergencies, the Nuclear Safety Commission of Japan sets the maximum level for iodine concentrated in the thyroid gland at 50 millisieverts per year.
The levels of iodine in shinobu-fuyuna in Kawamata, at 22,000 Bq per kilogram, correspond to exposure at 7 millisieverts per year for adults, 33 millisieverts for young children and 62 millisieverts for infants.
This means an infant who consumed 800 grams of this vegetable would have already reached the permissible level for a year.
After the Chernobyl nuclear disaster in the former Soviet Union in 1986, many children developed thyroid cancer after drinking iodine-polluted milk for a long time.
"Infants and young children are especially vulnerable to the impact of radioactive substances, compared with adults, because of the active metabolism in their bodies as they grow up," said Masamichi Nishio, director of the Hokkaido Cancer Center and a specialist of radiology. "Those 40 years or older do not have to worry about thyroid cancer because their metabolism is slow."
Meanwhile, cesium in kukitachina from Motomiya was measured at 82,000 Bq per kilogram, corresponding to radiation exposure at 1.31 millisieverts per year.
That means intake of 3.8 kilograms of the leafy vegetable would exceed the annual limit of 5 millisieverts set by the Nuclear Safety Commission.
Much of the cesium taken into the body is discharged, but it has a long half-life period of two to 30 years.