An undisclosed number of positive tests for the Class 3 drugs phenylpropanoloamine and norpseudoephedrine has prompted the California Horse Racing Board to urge trainers to scrutinize any herbal products or food supplements they feed their horses. Fifteen trainers were notified on Aug. 9 by the board, asking them to avoid a specific herbal product. The CHRB also sent memos to official veterinarians at California racetracks asking them to remind trainers to be aware of the contents of herbal products and food supplements.CHRB spokesman Mike Marten would confirm neither the positive tests nor the existence of an investigation. He did say the warnings sent to trainers involved a product sold by a vendor who was not licensed by the board but may have gained access to the stable area using an owner's license.Trainer Richard Mandella, who said he was not one of the 15 trainers notified by the CHRB, identified the product as "Herbal Advantage." Promotional material from its distributor, "Herbman Products" of Manhattan Beach, Calif., said it "promotes, healthy, happy horses," and has endorsements attributed to trainers Wallace and Craig Dollase and jockey Gary Stevens.The Internet site promoting "Herbal Advantage" could not be accessed and the telephone number listed in the product's promotional material has been disconnected."This guy kept trying to sell me this stuff and I finally bought a 25-pound container and tried it on a few horses," said Mandella, who learned on Aug. 11 that the product may be responsible for positive tests. "I heard about it and scratched my horses, including Lexicon in the stakes (the Aug. 12 Pat O'Brien Handicap, gr. II). I ran one before I knew about this and the test hasn't come back yet. I'm holding my breath on that one."According to Mandella, the product lists nine herbs in its contents, but Ephedra, which is believed to have caused the presence of the prohibited substances, is not among them. According to a fact sheet from Ohio State University, Ephedra refers to 40 related species of ancient plants, with the Chinese plant ma huang the most widely used. While Ephedra is often sold as a weight-loss supplement it is also used as a muscle builder and has been mentioned as a possible link in the deaths of human athletes, including a Northwestern University football player who died earlier this month during a conditioning test.