HANOI, Vietnam -- Researchers at the first U.S.-Vietnamese conference on Agent Orange, a defoliant used by U.S. forces during the Vietnam War, said they will report "extraordinarily" high levels of cancer-causing dioxin in people living in heavily sprayed areas.

The three-day conference that starts Sunday is the result of agreement reached last July to cooperate on Agent Orange research. American and Vietnamese scientists are also conducting a pilot study to test soil and sediment for dioxin.

"The key fact about this conference is that it's happening, that the Vietnamese government is backing it, and the U.S. government is backing it," said Rick Weidman, director of government relations for the Vietnam Veterans of America. "We think it's a tremendous step forward."

From 1962 to 1971, U.S. forces sprayed an estimated 11 million gallons of defoliants, mainly Agent Orange, on Vietnam to destroy jungle cover for Communist troops.

American veterans and many Vietnamese have blamed a variety of ailments, including birth defects, cancers and nervous disorders, on exposure to the defoliant.

Vietnamese victims

Vietnam's government says about 1 million Vietnamese are victims of Agent Orange, including veterans, civilians living in affected areas and their descendants. The U.S. government maintains that there is no proven direct link between dioxin and many of the illnesses.

A leading American researcher on Agent Orange, Arnold Schecter, said he will present results of a new study of people in Bien Hoa, a highly sprayed area near a former U.S. air base, that show "extraordinarily high levels" of dioxin in their blood more than 30 years after the spraying ended. One of the highest levels -- 206 times greater than average -- was in a person born in 1973, well after Agent Orange was halted, he said.

"It shows that dioxin persists and can even be introduced decades after initial exposure," Schecter said. "It also shows that American veterans who served in the area may have had high dioxin exposure."

Dioxin, one of the most poisonous chemicals created by man, is also one of the most persistent pollutants known.

Vietnam's cash-strapped government has not been able to clean up the dioxin pollution in Bien Hoa or resettle the area's 20,000 residents.

"We hope that this conference will result in much more research. But it's important not just to do research, but to solve the problems revealed by the research," said Le Cao Dai, a Vietnamese scientist who also participated in the study.

"I believe we are not able to do this ourselves. We have to ask the help of the international community, especially the companies that produced the chemicals and the U.S. government," he said.

Weidman said he hopes the conference will lead to more joint research projects in Vietnam to determine the health effects of the defoliants.

"We believe very strongly that part of the answer for U.S. veterans is here in Vietnam," he said.