Scientists from the United States and Vietnam gathered in Hanoi on Sunday for their first joint conference on the lingering health effects of the defoliant Agent Orange.

More than 30 years after the United States stopped spraying the herbicide Agent Orange during the Vietnam War, researchers are finding levels of cancer-causing dioxins in young children.

Agent Orange is one of the touchiest issues in relations between the former enemies. Last year the United States and Vietnam agreed to work together to study the long-term effects on the Vietnamese people.

U.S. Ambassador Raymond Burghardt said in the conference's opening ceremonies Sunday that there are no simple answers to how much damage Agent Orange has done to Vietnam. But he said it is a good sign that American and Vietnamese government scientists are studying the issue together.

From 1962 to 1971, the United States sprayed some 68 million liters of Agent Orange over southern Vietnam, trying to kill off the jungle growth hiding North Vietnamese forces.

Agent Orange contains dioxin, which can cause cancer and a host of other problems, including birth defects.

Vietnam's government claims more than one million people are victims of Agent Orange. For years, Hanoi demanded reparations from the United States, but dropped that demand when it established diplomatic relations with Washington

Washington has ruled out paying compensation to Vietnam. It pays compensation to a limited number of U.S. war veterans exposed to Agent Orange. The makers of Agent Orange - Dow Chemical and Monsanto Cos. - also paid damages to some veterans after losing a $180 million lawsuit.

Before the conference, the head of the Vietnam Red Cross said that victims associations are preparing to file their own lawsuit in American courts. Findings from this week's conference could end up helping their case.