With the Summer Olympic Games about to get under way, some of the best-known U.S. track and field stars are being investigated for allegedly using illegal performance-enhancing drugs. If the charges are proven, some could be banned from competition for life. The growing scandal over pharmaceutically pumped-up athletes also embraces other professional and collegiate athletes. Major League Baseball is under pressure to crack down on players who use steroids or other banned substances. Anti-doping advocates say the drugs hurt sports and risk players' health. A handful of dissidents disagree and call for lifting the anti-doping bans. A new international anti-doping code prescribes a two-year ban for a first offense, but drug testing is often circumvented, and some newly designed drugs cannot be detected. Meanwhile, the baseball players' association is resisting more rigorous testing, even though dozens of players tested positive in 2003.