THURSDAY, March 11 (HealthDayNews) -- U.S. health officials said Thursday that they're cracking down on companies that manufacture, market or distribute the performance-enhancing steroid precursor androstenedione, better known as "andro." "We are sending letters to 23 companies telling them to stop selling these products as dietary supplements and warning them they could face enforcement options if they don't take appropriate steps," Department of Health and Human Services Secretary Tommy Thompson said at a news conference in Washington, D.C. 8th street latinas The warning letters state that the companies must stop selling any products containing andro unless they can offer proof the substances are safe. The use of andro took off dramatically after baseball slugger Mark McGwire said he used it in 1998 while hitting a then-record-setting 70 home runs for the St. Louis Cardinals. He has said he later quit the supplements. Mike in BrazilU.S. Food and Drug Administration Commissioner Dr. Mark McClellan added Thursday that if companies don't comply with the warning letters, the government would consider taking such actions such seizures or injunctions, as well as civil or criminal court action. Senators Joseph Biden (D-Del.) and Orrin Hatch (R-Utah) were also present at the news conference as sponsors of the Anabolic Steroid Control Act of 2003. The bill would add andro and other so-called "steroid precursors" to the category of controlled substances. This would give the U.S. Drug Enforcement Agency more flexibility to further crack down on companies that make or sell the substances. The senators said they hoped the legislation would pass both the House and the Senate by the end of the year. "I think it'll pass like a hot knife through butter," Biden said. The dual moves received the support of the supplement industry