A boy holds a page that he has colored at a center for children who have been affected by dioxin exposure in Da Nang, Vietnam. The Da Nang Association of Victims of Agent Orange/Dioxin says that more than 1,400 children around the city suffer mental and physical disabilities because of dioxin, a legacy of the U.S. military's use of Agent Orange and other herbicides during the Vietnam War more than 40 years ago. About 200 children attend three centers operated by the group. Because of their disabilities, it usually takes two to three years for the children to interact with others and to learn simple tasks, says Phan Than Tien, the association's president. 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 U.S. government is paying to clean up dioxin-contaminated soil at the Da Nang airport, which served as a major U.S. base during the conflict. But the U.S. government still denies that dioxin is to blame for widespread health problems in Vietnam and has never provided any money specifically to help the country's Agent Orange victims. May 28, 2012.