Why did the VA turn their backs on the Vietnam veterans that were clearly suffering from "Agent Orange"?

I lost a very close and dear friend from Agent Orange ( called a presumtive disease) he wasn't that bad in the late 70's but he deteriated slowly over the years. They struggled for money so I did what I could like pay a mortage payment here and there. He fought the VA for about 40 years. He gave me book to read about Agent Orange and it went somthing like this.

It was a program of chemical warfare codenamed "Operation Ranch Hand". From 1961 to 1971 the U.S. Military sprayed more than 20 million gallons across 4.5 milion acres of Vietnam, Laos, and Cambodia.

The herbicides used were in 55 gallon droms with different colored rings on them and were named Agent Pink, Agent Green, Agent Purple, Agent White, Agent Blue and of course the most popular and strongest Agent Orange! Agent Orange came in four different strengths known as AO-1 (agent orange), Agent Orange-2, AO-3 and "Super Orange".

13 Million gallons were used just in Vietnam most of it was "Super Orange". In the production of Agent Orange a bi-product was produced known as DIOXIN which is also produced in other chemical manufacturing including Cigarettes. And of all other forms of manufacturing the Dioxin in Agent Organe was the most danerous to humans. Because of the Dioxin in Agent Orange it had not only immediate effets to humans but it had long term effects. Includeing birth effects and spina bifina.

Short-term exposure to dioxin can cause darkening of the skin, Liver problems and a severe acne skin disease called "Chloracne". Dioxin has been linked to Ishemic Heart disease, hormone disruption, type 2 diabetes, nerve disorders and muscular atrophy (waste away).

I miss my friend everyday and I'n glad the even though he never knew that he won his case his wife and children will benifit from 40 years back pay. RIP "Jim"