By Fredrik Dahl and Alister Doyle
VIENNA/OSLO (Reuters) - Miniscule numbers of radioactive particles believed to have come from Japan's crippled Fukushima nuclear power plant have been detected as far away as Iceland, diplomatic sources said on Tuesday.
They stressed the tiny traces, measured by a network of international monitoring stations as they spread eastwards from Japan across the Pacific, North America, the Atlantic and to Europe, were far too low to cause any harm to humans.
"It's only a matter of days before it disperses in the entire northern hemisphere," Andreas Stohl, a senior scientist at the Norwegian Institute for Air Research, said. "Over Europe there would be no concern about human health."
The Comprehensive Test Ban Treaty Organization (CTBTO), a Vienna-based U.N. body for monitoring possible breaches of the atom bomb test ban, has 63 stations worldwide for observing such particles, including one in the Icelandic capital Reykjavik.
They can pick up tiny amounts, in this case of iodine isotopes. The CTBTO continuously provides data to its member states, but does not make the details public.
"They measure extremely small amounts," one Vienna-based diplomat said. "It has nothing to do with any health risks."
Another source said about 15 CTBTO stations had so far detected particles believed to originate from the Fukushima nuclear complex, which leaked some radioactivity in the days after it was hit on March 11 by a huge earthquake and tsunami.
"Reykjavik is the first in Europe," the source added.
NOWHERE NEAR CHERNOBYL LEVELS
But the Icelandic Radiation Safety Authority said it had not been informed about any radiation from Fukushima.
"We were very surprised that it has been found here on our doorstep," Sigurdur Emil Palsson, head of its emergency preparedness, said. He said the Authority was checking.
The U.S. Energy Department and the Environmental Protection Agency late last week confirmed "miniscule" amounts of radiation that appeared to have come from Japan's damaged reactors were detected in California, where the CTBTO also has a station.
They said the radiation amounted to one-millionth of the dose rate that a person normally receives from natural sources such as rocks, bricks and the sun.
France's nuclear safety authority ASN said tiny radiation concentrations, perhaps 1,000 or 10,000 times less than from the 1986 Chernobyl disaster, were set to reach the country on Wednesday.
While only minor traces of radiation have been detected in countries outside Japan, the U.N. nuclear watchdog said on Monday "high levels of contamination" have been measured around the Fukushima plant itself.
At the site on Tuesday, smoke and steam rose from two of the most threatening reactors at Japan's quake-crippled nuclear plant on Tuesday, suggesting the battle to avert a disastrous meltdown and stop the spread of radiation was far from won.
Radiation from Chernobyl spread around the globe and reached the west coast of the United States in 10 days, its levels measurable but small.
(Editing by Louise Ireland)
