Anabolic steroids are synthetic substances related to male sex hormones (androgens). Although it is illegal in the United States to possess or distribute anabolic steroids for nonmedical use, a "black market" for them exists, and many amateur and professional athletes take them to enhance performance. In many cases, the athletes take doses that are extremely high—perhaps 100 times the doses that might be prescribed for medical use. As a result, they put themselves in real danger of short-term and long-term health problems. Blood testing, as has been used in the Olympic Games, can detect, identify, and quantify the presence of anabolic steroids in the blood of athletes, which can lead to the disqualification of an athlete.