Nov. 10 (UPI) -- Traces of nonharmful radioactive pollution that appeared weeks ago over Europe likely originated from Russia or Kazakhstan -- but not a nuclear reactor, French and German authorities said.
The French Institute of Radioactive Protection said Thursday the cloud likely resulted from an accident between the Volga river and the Ural Mountains in late September. It released a map showing the probable location of the release.
Involved in the release was ruthenium-106, a radioactive isotope.
Germany's Federal Office for Radiation Protection said the cloud likely originated from the southern Urals in Russia, though "other regions in the South of Russia must still be considered."
"Ruthenium-106 is used as a radiation source in cancer therapy for the treatment of ocular tumors," the German agency said. "Ruthenium can also occur during the reprocessing of nuclear fuel elements."
The IRSN said nonharmful particles were detected in France, Germany, Austria, Italy and Switzerland starting Sept. 27. They had disappeared by Oct. 13.
"The concentration levels of ruthenium-106 in the air that have been recorded in Europe and especially in France are of no consequence for human health and for the environment," the IRSN said.
The institute said it's extremely unlikely any food products in France were contaminated.
"The matter is closed as far as France is concerned. It's not a problem," IRSN Health director Jean-Christophe Gariel told The Guardian. "What is not satisfactory is that ruthenium-106 has been detected across Europe and that poses a question."
If this type of accident of this magnitude had occurred in France, people would need to be evacuated several miles from the site, he added.
A representative for the Russian emergencies ministry did not immediately comment.