Nearly half the children surveyed in three towns near the stricken Fukushima Daiichi nuclear plant received low-grade internal exposure to radiation during the early days of the accident there, the government said Thursday, fueling concerns about long-term health effects on local residents.

The government in late March tested 1,150 children in the three towns located outside of the government mandatory evacuation zones and said that all of them cleared its health standard. After Fukushima parents and radiation experts demanded more details, the government revealed this week that 45% of the children were exposed to radiation, albeit at low levels.

While the government has released a few reports on radiation exposure for workers at the Fukushima complex, this is the first time officials have made public the results for tests to detect internal exposure on residents near the reactors. Internal radiation, which enters the human body through breathing in contaminated air or consuming contaminated food or drinks, can have a greater health effect than what's known as external radiation, in which radiation is confined to the surrounding environment.

Since the accident, the government has tested 219,000 residents for external exposure. Some initially showed elevated levels, but once clothes were removed and showers were taken, none had showed results high enough to warrant health concerns, according to a NISA statement. The government has promised to do further tests in the coming weeks on potentially affected populations.

A spokesman for the Nuclear and Industrial Safety Agency, the main nuclear regulatory body, said Thursday that the doses the Fukushima children received were below the levels at which health effects become a concern. Children, particularly younger ones, are more susceptible to the effects of radiation, facing higher risks than adult of developing thyroid cancer later in life, experts say.

One independent expert, Yoshio Hosoi, a professor at the Research Institute for Radiation Biology and Medicine at Hiroshima University , said in an interview that, assuming the results reported are accurate, "I think the possibility of these children developing thyroid cancer is extremely low."

However, he raised some questions about the government's testing methodology, saying that officials didn't conduct the tests quickly enough after the initial exposure to measure radioactive elements known to disintegrate rapidly, such as iodine 132 and tellurium. NISA officials couldn't be reached late Thursday for comment.

The latest news follows a series of reports raising concerns about the protection against radiation exposure provided by the government to local residents during the days and weeks following the accident. For example, government officials had data a few days after the accident indicating that Iitate-one of the three towns where the children were tested - had become what they later called a nuclear "hot spot" with elevated levels of contamination. But officials didn't order an evacuation until more than a month later, prompting criticism that the residents were subjected to unnecessary radiation exposure.

The tests were conducted between March 24 and 30 on the thyroid glands of children in Iitate, Kawamata and Iwaki-three municipalities located outside of the government's 20 kilometer evacuation zone established the day after the March 11 earthquake and tsunami struck the plant. The move came after the government confirmed in late March its radiation projection system known as Speedi showed these towns had received relatively large doses of exposure. The tests were conducted on children ranging in age from infancy to 15 years old.

According to the breakdown of the test results--first revealed to some Fukushima parents on Wednesday--55% of the children showed "zero" exposure to radiation. Another 26% were found to have received 0.01 microsievert per hour, well below 0.2 microsievert per hour that the government considers a health risk.

The exposure level was 0.02 microsievert for 11% of the children, 0.03 microsievert for 4.7%, and 0.04 microsievert for 1.4%. The highest dose of 0.1 microsievert was found in a single individual, the NISA spokesman said.

"The health conditions of these children will be monitored very closely over the long term," the spokesman said, adding that Fukushima prefecture has already started a far-reaching health monitoring program.

Fukushima prefecture will send out questionnaires to survey all of its 2 million residents later this month, and plans to monitor over the next three decades the 200,000 considered most at risk.

Meanwhile, all of the 28,000 residents in three different municipalities deemed high risk were offered opportunities to receive a whole body scan to detect internal radiation.

Some 2,000 have taken the scan, but none showed results that raised health concerns, the Fukushima spokesman said.

In addition, all Fukushima residents 18 years-old or younger will go through a test of the thyroid gland over the next three years, and then be tested every other year thereafter. Mr. Hosoi of Hiroshima University said children found to have received exposure through the March tests should be examined once a year.

Διαβάστε ακόμα