Doctors were trying to determine how two American women hospitalized for suspected thallium poisoning fell ill while vacationing in Russia.
The two women, Dr. Marina Kovalevsky, 49, and her daughter, Yana, 26, had little to say after they arrived at Los Angeles International Airport Wednesday from Moscow, reports .
"I don't feel well ... We're going straight to the hospital. No comment. I'll talk to all you guys later, I promise," Yana Kovalevsky said.
They were taken in wheelchairs past news media into waiting ambulances, and admitted to Cedars-Sinai Medical Center. They were in stable condition, said hospital spokeswoman Simi Singer.
"It is too early to determine what may have caused their illness," Singer said.
The women had been treated at a Moscow hospital after they fell sick on Feb. 24. A U.S. Embassy spokesman there said Russian officials were investigating how and when they could have come into contact with the poison.
Moscow police declined comment, but the Ekho Moskvy radio reported authorities were checking cafes and restaurants in the area of the hotel where they stayed.
The Kovalevskys are Soviet-born and emigrated to the United States in 1989. Six or seven years ago, Marina Kovalevsky opened an internal medicine practice in West Hollywood, Calif., which has a large Russian-speaking immigrant community.
Relatives said the two left for Moscow on Feb. 14 to attend a friend's party. Marina Kovalevsky was "in a good state of health, in good spirits" when she left, said a colleague, Dr. Arkady Stern.
After it was suspected she was poisoned, Marina Kovalevsky was given dialysis and took an antidote and her condition began to improve, Stern said. Although both women had the same symptoms, he believed it was "some sort of tragic mistake."
How the two might have ingested the poison — a colorless, tasteless substance that can be fatal in doses of as little as one gram — was not clear.
Thallium is the reputed poison of choice for assassins. The poison was initially suspected to be the toxin used in last year's fatal poisoning in London of former Russian KGB agent Alexander Litvinenko, but it was later determined he had ingested the rare radioactive isotope polonium-210.
Hospital officials in Los Angeles said it did not appear the mother and daughter had ingested anything radioactive.
There was no indication the women had business or political interests in Russia that could have made them a target for poisoning.
"She (Marina) didn't have enemies. Everybody loved her. She's a great doctor," Stern said.
Powdered or crystallized thallium is used to poison someone. The toxin works by knocking out the body's supply of potassium, essential for healthy cells, and attacking the nervous system, the stomach and kidneys.
Its effects are not immediately noticeable and can take weeks to kick in. Symptoms include hair loss and a burning sensation in extremities.
In the past, thallium has been used in rat poison and continues to be used industrially to manufacture products including glass lenses, semiconductors, dyes and pigments.
Iraqi dictator Saddam Hussein used thallium to poison several opposition members. The CIA also reportedly considered using thallium against Fidel Castro to prompt the loss of his trademark beard.