The persistent nature of dioxins, erosion caused by loss of tree cover, and loss of seedling forest stock meant that reforestation was difficult (or impossible) in many areas.Many defoliated forest areas were quickly invaded by aggressive pioneer species (such as bamboo and cogon grass), making forest regeneration difficult and unlikely.Over 3,100,000 hectares (31,000 km) of forest were defoliated.Defoliants eroded tree cover and seedling forest stock, making reforestation difficult in numerous areas.Agent Orange dries quickly after spraying and breaks down within hours to days when exposed to sunlight (if not bound chemically to a biological surface such as soil, leaves and grass) and is no longer harmful. Dioxin enters the body by attaching to a protein called the aryl hydrocarbon receptor (Ah R), a transcription factor.When TCDD binds to Ah R, the protein moves to the nucleus, where it influences gene expression. began a full-scale production of 2,4-D and 2,4,5-T and would have used it against Japan in 1946 during Operation Downfall if the war had continued. tested 1,100 compounds, and field trials of the more promising ones were done at British stations in India and Australia, in order to establish their effects in tropical conditions, as well as at the U. Between 19, trials were conducted in Tanganyika, at Kikore and Stunyansa, to test arboricides and defoliants under tropical conditions. considered the British precedent in deciding that the use of defoliants was a legal tactic of warfare.
Veterans began to file claims in 1977 to the Department of Veterans Affairs for disability payments for health care for conditions they believed were associated with exposure to Agent Orange, or more specifically, dioxin, but their claims were denied unless they could prove the condition began when they were in the service or within one year of their discharge.
By April 1993, the Department of Veterans Affairs had compensated only 486 victims, although it had received disability claims from 39,419 soldiers who had been exposed to Agent Orange while serving in Vietnam.
About 17.8 percent—3,100,000 hectares (12,000 sq mi)—of the total forested area of Vietnam was sprayed during the war, which disrupted the ecological equilibrium.
Several publications published by the Public Health Service have shown that veterans have increased rates of cancer, and nerve, digestive, skin, and respiratory disorders.
The Center for Disease Control and Prevention notes that in particular, there are higher rates of acute/chronic leukemia, Hodgkin's lymphoma and non-Hodgkin's lymphoma, throat cancer, prostate cancer, lung cancer, colon cancer, Ischemic heart disease, soft tissue sarcoma and liver cancer.
Animal species diversity sharply reduced in contrast with unsprayed areas.