Marina Kovalevskaya, 49, and her daughter, Yana Kovalevskaya, 26, were hospitalized February 24 in Moscow with a serious illness, which the service overseeing consumer protection and welfare said earlier Tuesday might have been caused by thallium, a chemical used in rat poison and insecticides.
"The results of the analysis, which confirmed thallium poisoning, became known yesterday," Nikolai Filatov said.
He said he did not have detailed information on the patients' condition, but did not rule out that they could leave Russia as early as Wednesday.
"The consequences of such poisoning depend on the individual, the dose and the duration of contact [with the toxic substance]," the official said.
Thallium is odorless, tasteless, and can be easily dissolved in water.
In the case of former Russian intelligence officer Alexander Litvinenko, who died last year in London, doctors also initially suspected that he had been poisoned with thallium. A closer medical examination subsequently revealed a large dose of radioactive polonium-210 in his body.
Investigators are looking into the reasons and circumstances of the women's poisoning. The U.S. Embassy in Moscow is in touch with the patients.
