Air Force Maj. Alvin L. Young, better known to some of his colleagues as "Dr. Orange," has spent his entire military career assigned to one task: studying Agent Orange, a controversial herbicide that was widely used in Vietnam and has been blamed by Vietnam veterans for numerous health problems.

For 15 years, Young, now on loan from the military to the Veterans Administration, has been involved in nearly every aspect of the Agent Orange saga, starting shortly after the Pentagon first began spraying it in Vietnam to clear jungle and kill crops.

His first assignment was to develop better methods for spraying Agent Orange from airplanes. ("The goal," he said, "was to dispense three gallons per acre at 150 feet above the ground at 150 mph.")

Later, Young conducted the Air Force's first study of animals exposed to dioxin, the ingredient in Agent Orange that has been shown to cause cancer and birth defects in test animals. ("Through the years we have looked at 100 generations of the beach mouse.")

He also supervised the ocean burning of 2.3 million gallons of Agent Orange after public pressure forced the Pentagon to stop spraying it in April, 1970. ("We destroyed more than $60 million worth of herbicide . . . and then held a 'Goodbye to Herbie' party.")

Now Young is supervising more than a dozen studies that the VA is conducting to determine if exposure to Agent Orange harmed Vietnam veterans. He admits to having a vested interest. Recently, VA surgeons found that fat tissues taken from Young as part of a test contained five parts per trillion of dioxin. Government tests have shown that 2.5 parts per trillion of dioxin can cause birth defects in some animals.

Through the years an estimated 40,000 studies of dioxin have been issued, and Young has collected nearly all of them. He frequently jumps from his chair to a nearby bookcase where he grabs a blue-bound folder and searches for a diagram to illustrate his point.

He keeps a vial of Agent Orange--a gift from co-workers--near his desk and maintains a detailed notebook, complete with photographs, that lists every time he has sprayed, taken samples or otherwise handled Agent Orange since the 1960s in laboratories and the field.

"It's our feeling that when it comes to really knowing the science of Agent Orange, no one knows it better than Al Young," said a spokesman for George A. Keyworth Jr., science adviser to President Reagan.

But there is not universal agreement with that assessment. In 1981, Young drew the wrath of some Vietnam veterans when he said "a few" who blamed Agent Orange for health problems might simply have been looking for "public recognition for their sacrifices in Vietnam" and for "financial compensation during economically depressed times."

A staff member of the Senate Veterans' Affairs Committee recently derided Young as "a glorified weed-killer" who is "not qualified to discuss the health effects of exposure to Agent Orange."

Young traces his interest in herbicides to his father's farm in Wyoming. He recalls standing under crop dusters as they coated his father's fields with the chemical 2,4,5-T, one of the ingredients in Agent Orange.

Deferred from military service until he could obtain a doctorate in herbicides from Kansas State University in 1968, Young then went directly to the Air Force's herbicide testing range in Florida.

He chronicled the Agent Orange history:

"At first no one worried about the human effects.

"In 1964, the Air Force was accused of engaging in chemical warfare.

"In '66 through '68 there were charges of ecological damage.

"Then in 1969, the first charges about birth defects came out of North Vietnam, and the whole emphasis shifted."

Young pushed forward with a score of tests and quickly began publishing his findings--too quickly, as it turned out. He and his colleagues had taken soil samples from a test area that had been sprayed heavily with dioxin-contaminated herbicides. Their tests showed that no dioxin remained in the soil, and they concluded that dioxin decomposed rapidly in the soil.

"We were wrong," Young recalled. A short while later, a Harvard professor perfected a way to measure dioxin accurately in concentrations as small as a few parts per trillion. When Young used those procedures, he discovered that all of the soil samples were contaminated and that dioxin was extremely persistent.

Young said he is now more cautious about what he prints, and he questions what he reads.

But so far, he said, he shares the official view of the VA: there is no conclusive scientific proof linking dioxin to serious health problems in humans.

Within the next decade, he said, the government will have completed enough tests to resolve the scientific questions about Agent Orange. But the controversy could remain, he said, because Agent Orange has become an emotional issue, in many ways a symbol for the Vietnam veteran and for other Americans still struggling with their feelings about the war.

As the Agent Orange debate moves from the laboratory to the courtroom, "the next step for people like me will be as witnesses," he said. A civil suit against Agent Orange manufacturers, filed in 1979 on behalf of 20,000 veterans, is expected to go to trial in 1985.

"In 1970, my colleagues and I put a big sign on our laboratory wall that said 'Orange is Eternal,' " Young said. "I'm afraid that it's proven to be correct."