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. May 28, 2012.