The Current Level of Dioxin Pollution in the Area of Large-Scale Spraying of Agent Orange in Vietnam

摘要

Quang Tri is the province of central Vietnam located between 16°18' and 17°10' N and 106°32' and 107°24' E. Its population is 600 895 people; the area is 4745.74 km2. The demarcation line between Northern Vietnam and Southern Vietnam ran across this province until the end of the Second Indochina War (1975). There were intense battles there and, in addition, defoliants, including Agent Orange (AO), were sprayed. As it became known later, AO contained 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD) atppm level. Large-scale use of defoliants caused substantial destruction of ecosystems, including alteration of the plant and animal species composition [1]. It is interesting to estimate the current level of dioxin contamination of the environment and humans 40 years after the primary pollution. The half-life of dioxins in soils is assumed to be about ten years at temperature of 7°C [2]; therefore, the dioxin levels in soils must have considerably decreased after 40 years; however, accumulation of dioxins in food chains and their transmission to the next generations via blood during intrauterine development and via breast milk can have preserved a certain amount of those in living organisms [3].