ONE OF THE BITTEREST legacies of the Vietnam War has been the generally shoddy treatment accorded its veterans by the government they served and by the general public to whom the veterans -- some jobless, drug-addicted, maimed -- are a painful reminder of a time they would rather forget. High among the veterans' continuing troubles is the uncertainty over what health damage they may have suffered from exposure to the wartime defoliant Agent Orange.

Agent Orange was a mixture of two herbicides known to have been contaminated by dioxin -- a highly toxic but still mysterious chemical. In laboratory animals, dioxin is among the most lethal chemicals ever tested, but its effects on people are still unknown, despite several industrial accidents and the extensive exposure in Vietnam. Among the possible effects suggested by either laboratory tests or the results of many conflicting studies are liver damage, kidney and other cancers, damage to the nervous system and damage to the reproductive system, which could cause birth defects in the exposed man's children. Not one of these effects has been proven, but all are possibilities.

Considering these potentially tragic consequences, you might have expected that the Veterans Administration would have aggressively tried to find all those who might have been exposed and offered them thorough medical tests. Instead, for more than two years the VA has offered only steady resistance and the confident assertion that Agent Orange led to nothing more serious than a skin rash. Every one of the limited steps that have been taken was the result of fierce pressure from veterans groups and, more recently, from Congress. Not only did the VA not begin epidemiological studies; it still maintains that it does not even have a list of the names of those who served in Vietnam.

The Air Force has announced a six-year study, but the first step -- publication of the study design -- is already eight months late, and six years is too long for the veterans to wait for an answer. HEW has begun basic research into dioxin's effects, but it is not studying the veterans. Finally, last December, Congress resorted to writing a law requiring the VA to do a study that would produce results in about two years. But that effort is already three months behind schedule.

Having understandably lost hope that the VA would either prove or disprove the charges, veterans groups are now trying to raise money from foundations for an independent epidemiological study. This is a sorry spectacle: veterans turning to private philanthropy for help when the responsiblity is, without doubt, the government's. This entire episode -- whatever the final answers about dioxin -- should be a source of deep embarrassment to the VA, the military services, HEW and the entire government. It is still not too late to turn things around.