The Food and Drug Administration took the unusual step of issuing a "recall" notice yesterday for a black-market drug by warning athletes against a counterfeit hormone that is contaminated and dangerous.

The hormone is the black-market version of gonadotropin; it is used to counteract the effects of steroids, which athletes often acquire on the black market.

Steroids are used to increase muscle bulk faster than is usually possible. But they can cause breast enlargement, withering of the testicles, sterility, cancer, heart problems and other side effects. In young people, they arrest bone growth and so can prematurely halt growth and limit height.

To stop breast development and other sexual effects, steroid-using athletes use gonadotropin. It is not clear whether gonadotropin is effective.

Black-market gonadotropin has been found to be contaminated and to lack the main ingredient -- human chorionic gonadotropin. These characteristics make the black-market version dangerous and ineffective, an FDA spokesman said.

The black-market substance is not sterile and causes infections and fever. It is unknown how much of the substance is being sold on the black market or how many athletes are using it, but it is believed to be commonly used in combination with steroids.

More than a million athletes are estimated to have used steroids, at least briefly. The estimated value of black-market steroid sales exceeds $100 million a year. The last drug seizure netted about $70 million in steroids, said the FDA's William M. Grigg.

Steroid use is believed to have reached beyond professional athletes and into high school athletics.

The FDA and the Justice Department have seized a supply of black market gonadotropin, but spokesmen refused to say how much or where because they say the makers are being pursued.

The FDA said that coaches, physicians and athletes should watch out for the drug, which is labeled "Pregnyl Chorionic Gonadotropin for injection, 10,000 units/vial, xxx 10ml Multiple Dose Co-Vial Organon Laboratories, Cambridge, England."

The FDA said it has determined that Organon, the company with U.S. approval to make the drug, did not produce the product, here or in Britain.