Discarded testing materials litter a dioxin-contaminated field at the international airport in Da Nang, Vietnam. The airport served as a major U.S. base during the Vietnam War, and was a primary storage site for Agent Orange and other herbicides. From 1961 to 1971, the U.S. Air Force dumped more than 20 million gallons of the chemicals on southern Vietnam and along the borders of neighboring Laos and Cambodia. Used to defoliate the jungles that North Vietnamese and Viet Cong soldiers used for cover, Agent Orange and other herbicides were laced with dioxin, a deadly compound that has been linked to cancer, diabetes, birth defects and other illnesses. The Vietnam Red Cross estimates that 3 million Vietnamese suffer from illnesses related to dioxin exposure, including at least 150,000 people born with severe birth defects since the end of the war. The United States is paying to clean up contaminated soil at the airport, a $43 million project that started last August and is expected to take until the end of 2016 to complete. But there are at least 26 other known or potential dioxin "hotspots" in Vietnam, all of them around former U.S. bases. It is unclear at this point when these sites will be cleaned up and who will pay for it. May 30, 2012.