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Saturday, July 23, 2011
Are worries over meat warranted?
About 1,500 cows that were fed hay containing radioactive cesium in excess of the government limit were found to have been shipped from Fukushima and other prefectures to all of Japan except Okinawa, as of Thursday.
The cows ate hay that was left outside after the hydrogen explosions at the Fukushima No. 1 nuclear plant's reactors in mid-March.
Some consumers have already eaten meat from the cows, raising questions about whether it remains safe to eat beef, or even chicken and pork.
Do people who have eaten contaminated beef need to worry about their health?
Not unless a person continues to consume tainted beef over a long period of time. As of Thursday, the most highly contaminated beef found contained radioactive cesium of 4,350 becquerels per kilogram, according to the Health, Labor and Welfare Ministry. The meat did not reach the market.
Eating 1 kg of the meat is roughly equal to a radiation dose of 82.65 microsieverts for a period during which radioactive cesium remains in one's body. If a person eats food with radioactive cesium, half the amount remains in the body for nine days for a baby younger than 1. But the duration gets longer as people age, and it takes 90 days for those aged 50.
The 82.65 microsieverts compares with the 100 microsieverts of radiation a person would be exposed to during a one-way flight from Tokyo to New York.
Where has tainted beef been sold?
At various shops and restaurants in all prefectures except for Okinawa. Every cow has a 10-digit identification number and the Agriculture, Forestry and Fisheries Ministry can trace the buyers of beef from contaminated cows.
At what level of radiation does the government ban distribution of contaminated meat?
For radioactive cesium in meat, eggs and fish, the maximum limit is 500 becquerels per kg, the same level as in the European Union and Thailand. That compares with 1,000 becquerels in Singapore and Hong Kong, 1,200 in the United States and 370 in South Korea and Taiwan, according to the "Food and Radiation" booklet produced by the Consumer Affairs Agency.
There is no provisional maximum level of radioactive iodine for meat and eggs because its half-life is as short as eight days, compared with 30 years for cesium, and it takes longer than eight days from the time they are produced to the time they are eaten, according to the agency's booklet.
The level of radioactive iodine found in beef is at most 50 becquerels per kg, according to the agriculture ministry.
What has the government done to inspect cows and is it planning to bolster its regime?
The government banned the shipment of cows from Fukushima Prefecture on Tuesday and will not allow a resumption until safety can be ensured.
The agriculture ministry has urged prefectures to check "more thoroughly" whether farmers fed cows hay that had been left outside after the Fukushima No. 1 nuclear accident started.
Prefectures will send their officials or other people to quiz every cattle farmer, said Kazutoshi Nobuto of the agriculture ministry's Meat and Egg Division. Fukushima has been doing so in designated areas near the crippled nuclear plant since it began leaking radiation.
The ministry also urged the prefecture to continue to check the radiation level of cow necks and legs with a Geiger counter, but the device can only detect external radiation, not internal exposure.
The authorities have not monitored and do not intend to check the internal radiation dose of cows because the technical process is difficult.
Why is checking the internal radiation difficult?
There is no machine able to check the internal radiation dose of cows, unlike the so-called whole body counter that can be used for humans.
Whole body counters rely on the subject remaining still for a few minutes while it is scanned, making it difficult to verify the credibility of measurements for cows, said Yoshinobu Harada, a spokesman of the National Institute of Radiological Sciences. Checking a cow's urine will only give a "wild guess" of the radiation level of the cow's meat, he added.
How is beef checked?
The health ministry has instructed 14 prefectures in eastern Japan to randomly check meat, including beef, chicken, pork, milk and eggs, said Tomohiro Hagiya, an official at the ministry's Inspection and Safety Division.
According to the instruction, meat processing factories in the 14 prefectures check meat with a germanium semiconductor detector, a machine that costs millions of yen and weighs more than 1 ton.
The machine takes a few hours to detect radioactive cesium and iodine, and can also check milk and eggs.
Even though cesium-tainted beef was distributed nationwide, the ministry "currently has no plan" to instruct more prefectures to check food because "the idea is to check food where it is produced," Hagiya said, adding that the agriculture ministry is in charge of live animals and is supposed to check them thoroughly.
Are domestic chicken and pork safe?
They are probably safer than domestic beef, but also need to be thoroughly monitored.
Domestic chickens and pigs are mainly fed imported grains that are usually packaged, as opposed to hay that is sometimes left uncovered outdoors, the agriculture ministry's Nobuto said.
However, as some farmers also feed the animals hay and other greens that may have been left outside, the ministry will extend the alert to chicken and pig farmers as well, he added.
Are milk and dairy products safe?
Milk products are probably safer than meat because the milk production process makes it easy to check milk before it is distributed, Otake from the agriculture ministry's Milk and Diary Products Division said.
Milk is checked by prefectures and municipalities at so-called cooler stations, where farmers collect raw milk.
Every prefecture has several cooler stations, which are run by local agricultural cooperatives and distribute raw milk to milk producing companies such as Megmilk Snowbrand Co.
"Milk from different prefectures can be mixed in the same package. But contaminated milk being distributed is impossible," Otake said.
According to the agriculture ministry, milk with a radiation level higher than the maximum allowable level has always been detected before being distributed to the market.
A small number of dairy farmers sell milk directly to customers without taking it to cooler stations, and the agriculture ministry has instructed them not to use hay that was left outside as feed, Otake said.
Why is food not being checked for other radioactive materials such as uranium, plutonium and strontium?
Because the amount of these substances in the soil and atmosphere is far smaller than radioactive iodine and cesium, according to Hirotaka Oku, an official at the Education, Culture, Sports, Science and Technology Ministry.
When the ministry checked soil in areas between 20 and 30 km of the Fukushima No. 1 complex in April, no radioactive uranium or plutonium from the plant was found, he said.
However, minute amounts of radioactive strontium measuring 89 becquerels per kg were detected in June in soil in places including the city of Fukushima, about 60 km from the crippled nuclear plant. In the same survey, 1,500 becquerels per kg of radioactive strontium were found in soil at Namie, Fukushima Prefecture, 24 km from the plant.
The health and welfare ministry's Hagiya said the ministry will check strontium, uranium and plutonium in food at a later date.