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 While some children — fewer than a thousand — might
have received radiation doses that in theory could increase the risk
of thyroid cancer, the probability of that developing also remains
low, the United Nations Scientific Committee on the Effects of
Atomic Radiation (UNSCEAR) said in a new study.
The Chernobyl reactor explosion sent radioactive dust across much of
Europe, while people close to the plant were exposed to radioactive
iodine that contaminated milk.
Although Fukushima was the world's worst nuclear disaster since
then, the Japanese authorities took action including evacuations
that significantly reduced exposure to radioactive substances.
"No discernible changes in future cancer rates and hereditary
diseases are expected due to exposure to radiation as a result of
the Fukushima nuclear accident," UNSCEAR said in a statement
accompanying its nearly 300-page study.
"The expected low impact on cancer rates of the population is
largely due to prompt protective actions on the part of the Japanese
authorities following the accident."
Nevertheless, the U.N. body's report "notes a theoretical
possibility that the risk of thyroid cancer among the group of
children most exposed to radiation could increase," it said.
The thyroid — a gland in the neck that produces hormones that
regulate vital bodily functions — is the most exposed organ as
radioactive iodine concentrates there. Children are deemed
especially vulnerable.
UNSCEAR said thyroid cancer was a rare disease among young children
and their normal risk was very low.
"The occurrence of a large number of radiation-induced thyroid
cancers as were observed after Chernobyl can be discounted because
doses were substantially lower," it said.
NO SIGNIFICANT CANCER CHANGE SEEN
In Belarus, Russia and Ukraine, the countries most affected by
Chernobyl, more than 6,000 cases of thyroid cancer had been reported
by 2005 in children and adolescents who were exposed at the time of
the accident, UNSCEAR says on its website.
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In Japan on March 11, 2011, a magnitude 9 earthquake and tsunami
devastated the Fukushima Daiichi nuclear plant, spewing radiation
and forcing about 160,000 people to flee their homes.
UNSCEAR said about 35,000 children aged up to five lived in
districts where the average absorbed dose to the thyroid was between
45 and 55 milliGrays (mGy), a radiation measurement.
But doses varied considerably among individuals, from about two to
three times higher or lower than the average.
UNSCEAR "considered that fewer than a thousand children might have
received absorbed doses to the thyroid that exceeded 100 mGy and
ranged up to about 150 mGy," the report said.
"The risk of thyroid cancer for this group could be expected to be
increased," it said. UNSCEAR's press statement made clear it was
still not seen as a big risk, however, with a headline saying: "Low
risk of thyroid cancer among children most exposed."
UNSCEAR said 80 leading scientists had worked on the report — "Levels and effects of radiation exposure due to the nuclear
accident after the 2011 great east-Japan earthquake and tsunami" — and that the material was reviewed by its 27 member states.
(Editing by Hugh Lawson)
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