La Thanh Nghia, 18, grimaces slightly as he does physical therapy with his mother at their home near Da Nang, Vietnam. Nghia, and his brother Toan, 21, are third generation victims of dioxin exposure, the result of the U.S. military's use of Agent Orange and other herbicides during the Vietnam War more than 40 years ago. The brothers were born healthy, but began to suffer from muscular dystrophy and other problems as they grew older. They are now confined at home as their bodies and lives waste away. Jan. 5, 2013.