* No "discernible" change in cancer rates expected, UN
* Risk of thyroid cancer may increase for most exposed
* But risk still low; no Chernobyl-style rise in cases seen
By Fredrik Dahl
VIENNA, April 2 Japan's Fukushima nuclear
reactor meltdown in March 2011 is unlikely to lead to a large
number of people developing thyroid and other cancers like after
Chernobyl in 1986, U.N. scientists said on Wednesday.
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
"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
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.
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
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)