Despite potentially serious health risks, an estimated 262,000 teenagers have illegally used body-building steroids in recent years, and use of the drugs among teens appears to be growing significantly, according to two Department of Health and Human Services reports released yesterday.

The studies also concluded that many teachers, high school coaches and parents are subtly encouraging use of the drugs or failing to admonish young people for taking them. Based on in-depth interviews with 72 current and former high school steroid users, the studies found that large numbers of students in grades 7 through 12 use the drugs, not only to boost their athletic performance, but also to improve their appearance and "enhance sexual capacity or enjoyment."

Health and Human Services Secretary Louis W. Sullivan called the findings "disturbing" and said he was forming an interagency task force to explore new approaches to combat the use of steroids. "I am very concerned that some adults who are charged with our young people's welfare might be passively accepting or even tacitly approving use of these dangerous drugs," he said.

The reports by the HHS inspector general's office were the federal government's most comprehensive to date on the spread of anabolic-androgenic steroids. The drugs, which are synthetic derivatives of the natural male hormone testosterone, are mostly sold on the black market and have been used for years by professional athletes to enhance muscle mass and strength. They are chemically different from steroids related to cortisol, a natural hormone produced by the adrenal gland, which is used to treat diseases such as asthma.

The use of anabolic steroids received most prominent attention in 1988 when Canadian sprinter Ben Johnson was stripped of his gold medal in the Seoul Olympics after testing positive for steroid use.

But in recent years the drugs also have filtered down to high schools and junior high schools, according to the HHS studies. The studies found, for example, that the average age at which students started taking the drugs was 16 and that some began as early as 13. Most of them are injecting the drugs, and 86 percent have no plans to stop.

Most significantly, researchers said these students differ markedly from the users of illegal street drugs, making the problem of combatting steroid use all the more difficult. "These are motivated kids. They want to be better, strong, faster; they want to achieve a goal," said Robert E. "Skip" Morris, executive director of the National High School Athletic Coaches Association. "This is not the group who want to lay on the couch and smoke dope that you're dealing with."

"The thing that is most scary . . . is the kids do it for what society would view as very positive values, winning and success," HHS deputy inspector general Michael F. Mangano added.

While there is no scientific consensus on the long-term health effects of taking steroids, most medical researchers believe steroids are linked to acne, fluid retention, breast development in males, baldness, liver damage and increased chance of muscle injury.

The National Institute on Drug Abuse's annual high school senior survey released earlier this year found that 4.7 percent of the males and 1.3 percent of the females in the class of 1989 -- or 3 percent overall, an estimated 83,000 students -- acknowledged having used steroids. This compares with 10 percent who said they had used cocaine.

The HHS studies extrapolate from these figures to estimate that at least 262,000 students in grades 7 to 12 use or have used the drugs, but then cite a number of researchers who have concluded that these numbers may be excessively conservative and that use may be growing at potentially alarming rates. In one recent study of high school football players in Portland, Ore., the percentage of self-reported steroid use had more than tripled, rising from 1.1 to 3.8 percent.

A key reason is the attitudes of parents. Of the 72 steroid users in the sample, 55 percent agreed with the statement, "My parents probably know I use {or used} steroids."

But HHS's conclusion of increasing steroid use contrasts with a National Collegiate Athletic Association survey of more than 2,000 college athletes, which found no evidence of growing use. The survey found that about 5 percent of college athletes reported using steroids, virtually the same figure as a similar survey four years earlier.