A Pennsylvania legislator said he plans to call this fall for county referendums on the issue of slot machines at the state's four racetracks. Meanwhile, a resolution that seeks an economic impact study to develop ways the state "can help maintain fiscal soundness" of the horse racing and breeding industry has been introduced.Rep. Tom Petrone of Pittsburgh told the Associated Press he would introduce legislation this fall calling for referendum in the counties in which The Meadows, Penn National Race Course, Philadelphia Park, and The Downs at Pocono are located. No machines would be permitted at each of the racing association's off-track betting parlors.A lobbyist for the four tracks said Petrone, not the racing industry, came up with the idea.The resolution introduced June 13 in the Senate Agriculture and Rural Affairs Committee says Thoroughbred and Standardbred breeding and racing contribute $600 million to the state's economy each year, and that competition from neighboring states threatens the industry. It calls on the Joint State Government Committee to gather information in one year and report on its findings.