The women, who fell ill Feb. 24, were listed in moderately serious condition but were released from the hospital in "satisfactory" condition and were set to leave for the United States. This incident raises questions about how the women came into contact with thallium and speculation about Russian intelligence's possible involvement.



Two American women on March 7 checked out of the Moscow hospital where they were being treated for possible thallium poisoning and reportedly have left Russia for the United States in "satisfactory" health. The women -- Los Angeles residents Marina Kovalevsky and her daughter, Yana -- fell ill Feb. 24 and at one point were listed in moderately serious condition.

Their illness, which was confirmed by the U.S. Embassy in Moscow on March 7, has raised numerous questions and intense media interest -- particularly given that thallium, a poison the KGB frequently used against the Soviet government's enemies during the Cold War, has been confirmed as a factor.

The Soviets used thallium in 1957 in an attempt to kill Nikolai Khokhlov, a KGB assassin who had defected in 1954. Many suspect that Yuri Shchekochikhin, a Russian journalist and politician critical of Moscow's policies who died in 2003, was killed by thallium poisoning. Most recently, thallium was suspected to be the poison that led former KGB officer and defector Alexander Litvinenko to become fatally ill in London in November 2006, until polonium-210 was found to be the culprit. Russian journalist Anna Politkovskaya was also supposedly poisoned with thallium in 2004.

Thallium is a tasteless, odorless, but highly toxic heavy metal that is readily available; trace amounts can be found in the earth's crust. Ingesting as little as 0.00035- 0.00053 ounces (10-15 milligrams) of thallium for every 2.2 pounds of body weight can be lethal to humans. Industrial applications include manufacturing lenses, semiconductors, low-temperature thermometers, certain alloys and fireworks. One of its most common uses was as a rat poison, but because of its toxicity to humans, thallium is no longer used in this capacity in most countries. However, many poor countries that have vermin problems and few alternative poisons regularly use thallium.

Thallium can be ingested through food and drink or absorbed through the skin. When it is swallowed, thallium spreads rapidly to various parts of the body, especially the liver and kidneys. It can also affect the heart, lungs and nervous system. Hair loss, vomiting and diarrhea are signs of thallium poisoning.

Since the end of the Soviet era, many KGB members have gone into business for themselves in the private sector, including the Russian mafia, bringing with them their training and knowledge of dealing with enemies. This would include the use of poisons.

There is a long list of unknowns about how and why the Kovalevskys came into contact with thallium. They emigrated from Russia to the United States in 1989 and have visited relatives in Russia since the collapse of the Soviet Union. Business dealings in Russia could have brought them unknowingly into contact with criminal elements, which could have resulted in their poisoning as part of a business dispute or grudge. A personal relationship either in Russia or the United States could also have resulted in the poisoning. There is also speculation in Russian media reports that the women could have been poisoned as part of a robbery.

Without more information about the circumstances surrounding the Kovalevskys' poisoning, little more than speculation can be done. What is known is that they were made sick from thallium. What is not known is who would want them dead, if that was in fact the goal, or even if the poisoning was deliberate. What clouds the issue further is the use of poison to hurt people in Russia, where high crime rates provide plenty of opportunity for someone to "arrange" a shooting or stabbing.

The speculation around the Kovalevskys could fall into two broad categories. One is that the poisoning was done by or on behalf of the Russian government, since government enemies were killed by poisoning both during and after the Soviet period. Another possibility is that the government had nothing to do with the poisoning, but the actual culprit wanted it to appear that way. Until more facts are known, one theory is as good as another on what happened to the Kovalevskys in Moscow.