This video shows how Agent Orange (nearly 20 million gallons of defoliant) left negative effects in a central highland of Vietnam. The most toxic component: dioxin, has been accumulated in the food chain of this area because dioxin is fat soluble. The botanist Phung Tuu Boi tried to build up "green fence" to protect people and their life-stocks entering the hot zones of dioxin, but failed because the soil was too acidic.