A plane taxis on the runway near the former herbicide storage and loading ramp at the international airport in Da Nang, Vietnam. The airport served as a major U.S. base and storage site for Agent Orange and other herbicides during the Vietnam War more than 40 years ago, and is still heavily contaminated with dioxin, a deadly compound that has been linked to cancer, diabetes, birth defects and other serious illnesses. 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 how or when these sites will be cleaned up and who will pay for it. May 30, 2012.