San Francisco has become the first city in the nation to ban chewing tobacco from its playing fields, including the home to the San Francisco Giants, AT&T Park. 

Players and managers of the team all expressed support for the new ordinance that was signed into law my Ed Lee, mayor of San Francisco, on Friday but also expressed concerns about breaking the chewing habit.

The new ordinance takes effect on January 1 and prohibits the use of smokeless tobacco products at all athletic venues but specifically singles out baseball, which has a long history of players chewing tobacco and spitting the juice in front of children who idolize the baseball stars.

"It's a step in the right direction," said Giants manager Bruce Bochy, who has chewed tobacco on and off for decades.  "It's a tough deal for some of these players who have grown up playing with it and there are so many triggers in the game," Bochy added. "I certainly don't endorse it. With my two sons, the one thing I asked them is don't ever start dipping."

This new ordinance is part of an overall push by the Campaign for Tobacco-Free Kids based in Washington, D.C.  An even more expansive bill that bans all use of tobacco, including electronic cigarettes and smokeless tobacco wherever an organized game of baseball is played in California is now making its way through the state's Assembly.

"Today, San Francisco entered the history books as the first city to take tobacco out of baseball. The home of the world champion Giants has set an example that all of Major League Baseball and the rest of the country should quickly follow," said Matthew L. Myers, president of the Campaign for Tobacco-Free Kids.

Use of smokeless tobacco has been banned by the minor leagues since 1993, but because Major League Baseball is unionized, smokeless tobacco cannot be banned by the League without an agreement with the Major League Baseball Players Association.  Under the current contract, coaches, managers and players cannot chew tobacco during interviews and they can't carry tobacco while wearing a uniform when fans are in the ballpark.

Almost 15 percent of boys in the United States currently use smokeless tobacco, and use is even higher among students who play organized sports, according to a report by researchers at the University of California, San Francisco.  The use of smokeless tobacco increases the risk of cancer, gum disease and addiction to nicotine.

Matt Cain, player rep and pitcher who does not chew, said he expects multiple discussions with the team to prepare players for the ban.

"The hard part is going to be policing it," Cain said. "It'll be interesting to see what they do about making it a policy."