Government drug abuse surveys appear to greatly overestimate the number of American teenage girls using anabolic steroids, experts told lawmakers Wednesday.

Scientists and athletes were called to Capitol Hill to testify on what federal figures say is a high number of teenage girls using anabolic steroids for cosmetic reasons. The human-made substances, related to the male sex hormones, can increase muscle mass and promote loss of body fat. Those qualities could make anabolic steroids tempting for teenage girls, experts say.

Read Web MD's "Lawmakers Upset Over Mixed Signals on Steroids."

Abuse of anabolic steroids can lead to many serious medical problems, including liver tumors, cancer, and high blood pressure. In women, anabolic steroid use can result in unwanted side effects including growth of facial hair, deepening of the voice, male pattern balding, and menstrual irregularities.

A 2003 CDC survey concluded that 7.3 percent of ninth-grade girls and 5.3 percent of all high school girls had taken steroids without a doctor's prescription.

But two experts disputed the agency's figures, warning that a faulty survey question in its biannual Youth Risk Behavior Survey may have grossly overstated the problem by creating confusion among survey participants.

The survey asked teens whether they had ever taken steroids in pill or injectable form without a doctor's prescription.

Harrison Pope, MD, a psychiatrist and steroid researcher from Harvard Medical School, told members of the House Government Reform Committee that most teenagers are unaware of the limited number of drugs classified as anabolic steroids and that they may include medications used to treat certain types of skin conditions.

The survey also did not exclude dietary supplements, often marketed to mimic steroids both in their claims and product names.

Read Web MD's "Teen Girls Turning to Body-Shaping Diet Pills."

Alternate Estimates of Steroids Abusers

Pope told lawmakers that the actual rate of anabolic steroid abuse among high school girls is "probably only a few tenths of one percent."

"The use of anabolic steroids by teenage women I believe has been exaggerated by these studies," he said. "Among teenage girls there is little evidence to support a serious problem."

Diane Elliot, MD, a professor of medicine at Oregon Health & Science University, told the committee that the CDC's 7.3 percent steroid-use rate among ninth-grade girls is so high because many girls mistake steroids for other medications. Surveys instructing girls to exclude other drugs as well as dietary supplements show that 1 to 2 percent of freshmen girls have ever taken anabolic steroids, Elliot says.

"Still, one to two percent is significant when applied to a population," she says.

Another expert defended the federal figures, noting that steroid use among high school boys and girls has been rising steadily since the 1990s. "It's available, and available equally to young boys and young girls. If you had to ask me where the bias is, it's in underreporting," says Charles Yesalis, MD, a professor of health policy at Penn State University.

CDC spokeswoman Karen Hunter tells WebMD that the Youth Risk Behavior Survey relies on self-reported drug use data from 15,000 teenagers and that "self-reported is always a little less reliable."

The agency provides the surveys to public health departments in all 50 states, which in turn collect the data. "If they wanted to make their questions more specific, they could certainly do that," she says.

Read Web MD's "Why Steroids Are Bad for You."

By Todd Zwillich, reviewed byBrunilda Nazario, MD

SOURCES: Youth Risk Behavior Survey, CDC, 2003. Harrison Pope, MD, professor of psychiatry, Harvard Medical School. Diane Elliot, MD, professor of medicine, Oregon Health & Science University. Charles Yesalis, MD, professor of health policy, Penn State University. Karen Hunter, CDC spokeswoman.