New tests reveal the level of dioxin (search) in the blood of Ukrainian presidential candidate Viktor Yushchenko (search) is more than 6,000 times higher than normal, according to the expert analyzing the samples.

The concentration, about 100,000 units per gram of blood fat, is the second highest ever recorded, said Abraham Brouwer, professor of environmental toxicology at the Free University in Amsterdam, where blood samples taken last weekend in Vienna were sent for analysis.

A normal level of dioxin is between 15 and 45 units. Almost everyone has some level of dioxins because the toxic chemical is widespread in the environment — mainly from its industrial usages — and accumulates in the food chain.

In the case of Yushchenko, Brouwer's team has narrowed the search from more than 400 dioxins to about 29 and is confident they will identify the poison by week's end. That, in turn, could provide clues for the investigation of the alleged poisoning.

"From a (chemical) fingerprint, at least you can deduce what kind of sources might have been involved," Brouwer told The Associated Press. "The labs will ... try to find out whether it matches any of the batches of dioxins that are around, so that maybe you can trace it back to where it was ordered or where it came from."

Experts say Yushchenko, whose face has been pockmarked and disfigured, has probably experienced the worst effects already and should gradually recover, with no impairment to his working ability.

The reformist candidate, who faces Kremlin-backed Viktor Yanukovych (search) in a repeat runoff on Dec. 26, first fell ill after having dinner with Ukrainian Security Service chief Ihor Smeshko and his deputy Volodymyr Satsyuk on Sept. 5. He reported having a headache about three hours after the dinner, and by the next day had developed an acute stomachache.

He later reported pancreatitis and gastrointestinal pain, as well as backache. He also suffered partial nerve paralysis in his face and an inflammation of one inner ear.

About three weeks after his first symptoms, he developed the rough, acne-like rash on his face which is the hallmark of dioxin poisoning.

"It was very late before the rash started to develop, so if he had died it would have been a mystery illness of his pancreas, his liver or his gut and they would have said maybe it's some rare bug thing," said John Henry, a toxicologist at London's Imperial College. "He would have died within a few days and nobody would ever, ever have thought of dioxins."

Brouwer said the highest dioxin dose recorded so far was in a woman in Vienna, who was poisoned intentionally with dioxin in the mid-1990s. Tests showed her blood had 140,000 units per gram of fat and that didn't kill her.

"We don't actually know what the lethal dose is. The only thing we do know is there's a woman who had an even higher dose, who didn't die, so it must be higher than that," Brouwer said.

Most of what is known about the health effects of acute dioxin poisoning comes from experiments on animals. Most animals would die from the levels found in Yushchenko.

Evidence of the hazards of dioxin also comes from studies of long-term exposure, such as those who work in chemical factories, or from people involved in industrial accidents.

Studies suggest Yushchenko faces an increased risk of heart attack, cancer, diabetes, muscle aches and other less severe symptoms, but it is unclear how high that risk has risen from a single poisoning.

The disfiguring acne, while not harmful to his health, may persist for decades, experts say.

"It'll be a couple of years, and he will always be a bit pockmarked. After damage as heavy as that, I think he will not return to his film star looks," said Henry.

Dioxin, which settles in the body fat, lasts a long time in the body. Eliminating it quickly from Yushchenko's body would likely reduce his chances of long-term ill health. One possibility is a couple of courses of liposuction, a procedure that sucks the fat out of the body.

Another option being discussed by scientists is the use of olestra, a fake fat substance used in diet food that could act as a magnet to draw the poison out of the body fat into the gut for elimination. The technique has been proposed before for the elimination of other fat-soluble pollutants.