Luong Hoai Thuong does her homework. She was born without her left hand, a birth defect caused by Agent Orange remaining from the U.S. war against Vietnam. During the Vietnam War, US forces sprayed Agent Orange over forests and farmland in an attempt to deprive Viet Cong guerrillas of cover and food. The dioxin compound used in the defoliant is a long-acting toxin that can be passed down genetically, so it is still having an impact forty years on. The Vietnam Red Cross estimates that some 150,000 Vietnamese children are disabled owing to their parents' exposure to the dioxin. Symptoms range from diabetes and heart disease to physical and learning disabilities.