The home of the San Francisco Giants may become the first city in the nation to outlaw chewing tobacco from its playing fields. Supervisors on Tuesday voted unanimously to prohibit the use of smokeless tobacco at athletic venues, specifically singling out baseball, which has a long history of players masticating and spitting tobacco juice in view of children who worship them. Kids shouldn't get the idea that they need to use tobacco to play ball, Farrell said. The San Francisco ordinance is part of an overall push by the Campaign for Tobacco-Free Kids, based in Washington, D.C., which targeted the city and California to promote its anti-smoking efforts.