A decade ago, reports of widespread heroin use by U.S. troops in Vietnam spawned fears that servicemen would come home with their drug habits, leading to a generation of drug enslavement, crime and ruined lives.

A leading columnist said some observers estimated as many as 25 percent of all U.S. soldiers in Vietnam were regular users.

Estimates of the number of troops addicted to heroin and other opiates rose to the hundreds of thousands. In a speech, then Sen. Harold Hughes said the "massive influx of living death into our troops" was creating a U.S. drug addiction problem that threatened a generation of American youth.

Today, it's clear that these fears were grossly exaggerated.

According to the best study available, only 2.4 percent at most of the enlisted men ended up addicted to narcotics after coming home. Most of them who had regularly used heroin shed the habit when they reached the United States or shortly thereafter. The figure for officers and women personnel was probably lower, according to studies.

To be sure, 2.4 percent is well over the general population addiction rate in the United States -- but it's not the 10 percent or 20 percent many feared.

Ten years ago newspapers and television were full of stories of doped-up GIs in Vietnam openly buying "hits" of pure heroin for $2.50 a shot or less.

Although the Defense Department and White House protested that the heroin addiction rates among soldiers were'nt nearly as high as many were saying, the drug use image gradually took hold.

Probably the best study done to date, according to Dr. Stewart L. Baker, chief of the Alcohol and Drug Dependence Division of the Veterans Administration, was commissioned by the White House Special Action Office for Drug Abuse Prevention and conducted by Lee N. Robins, a researcher at Washington University, St. Louis.

It selected a representative sample of 451 enlisted men returning from Vietnam in September 1971. That was a month when narcotics use was thought heavy. The men were interviewed and tested 10 months later and three years after return. The survey involved use or opium, codeine, heroin, morphine and chemically related substances.

It found that narcotics use in Vietnam among these men -- a group more likely to use them than officers or women soldiers -- was pretty high.

All told, 44 percent had tried a narcotic at least once, and 20 percent considered themselves to have been addicted in Vietnam.

Initial interviews months after return showed the percentage of soldiers still considering themselves addicted had dropped to under 1 percent.

In the followup in 1974, according to Dr. John Helzer, who worked with Robins, there was evidence that during the three years after return, some had been readdicted.

Even so, Helzer said, only 2.4 percent of the whole sample wre addicted in 1974. This means that nearly nine-tenths of those who were addicts in Vietnam had stopped the habit.

Baker said that the best explanation for the falloff in narcotics addiction after soldiers left Vietnam was the difficulty and cost of obtaining narcotics at home.

In Vietnam, narcotics were cheap and accessible. In the United States, "it's not at your elbow, not easy, not cheap. Availability certainly determines prevalence" in many cases, he said.

He said that returning soldiers, facing a different way of life i the United States if they wished to continue their addiction -- enormous costs, perhaps criminal acts, avoiding being caught, leaving the mainstream of society -- in many cases simply dropped the habit.

According to the Robins study and other sources, many of those who had used narcotics in Vietnam weren't addicted, and simply stopped when they returned to a different environment. Of those who were addicts, some stopped or tapered off by themselves when it became difficult and expensive to obtain narcotics at home. In many cases, they suffered withdrawal symptoms.