Legislation being sponsored by Iowa Congressman Jim Leach seeks to ban the use of credit cards for on-line gambling. While Internet gambling hasn’t yet created droves of addicts in Iowa, cases are starting to appear, and one expert fears many more people are quietly becoming hooked.Tom Fennelly is director of the Eastern Iowa Center for Problem Gambling, based in Davenport. He says he recently met with a young man who owed 12-thousand dollars from betting on-line.Some gambling supporters dislike Leach’s legislation, saying it could hurt legal wagering on horse racing in Iowa. Fennelly supports the measure being sponsored by Leach, a republican from Davenport. Fennelly says without credit cards, there’d be virtually no way to gamble over the Internet.Fennelly says it’s impossible to tell how many people from any given state are gambling on-line due to the anonymity of computers. Internet gambling generated about one-point-two billion dollars last year through more than 600 websites.