

The Giants' Jake Peavy would have to pitch without his chewing tobacco next season if a city ordinance receives final approval. (Ben Margot/AP)

This post has been updated.

Chewing tobacco, as much a part of baseball tradition as popcorn and the seventh-inning stretch, would be banned from the San Francisco Giants' ballfield and all other athletic fields throughout the city under a plan that received tentative approval from city supervisors Tuesday night.

The city where Willie Mays, Barry Bonds and Buster Posey have starred would become the first in the nation to ban the on-field use of various forms of smokeless tobacco that some players shove into their cheeks or between their lips and gums. It would apply to home and visiting professional players at AT&T Park, in an effort to keep them from modeling the unhealthful practice for children and other fans.

Supervisor Mark Farrell, who sponsored the city-wide ban, said that "we're trying to de-couple the historic notion and the visuals we've had for decades that playing baseball and success in baseball has anything to do with chewing tobacco."

The ordinance received unanimous support from supervisors, who must approve it again next Tuesday. Then it would go to Mayor Ed Lee (D) for his signature. If approved, it would take effect Jan. 1, in time for the 2016 season. It would not apply to parks.

Jess Montejano, a legislative aide for Farrell, said next week's vote is a formality and that Lee has pledged to sign the ordinance.

"I think we're trying to send a strong public health message," Montejano said. "The effects of tobacco couldn't be more clear. We are trying to start a national dialogue that tobacco shouldn't have any place in our sports or [especially] in baseball."

A statewide bill that would apply to the rest of the state's major and minor league parks is working its way through the legislature, Montejano said. California is also home to the Oakland A's, the Los Angeles Dodgers, the Los Angeles Angels of Anaheim and the San Diego Padres.

Smokeless tobacco is already prohibited in the minor leagues. Major League players cannot chew it during interviews or carry it in their uniforms while fans are in the stadium. Violators can be fined.

Research has linked smokeless tobacco to numerous health problems, including oral and pancreatic cancer, gum disease and nicotine addiction, according to a 2015 paper by researchers at the University of California, San Francisco School of Dentistry. Superstar Tony Gwynn, who spent his entire career with the Padres, blamed the mouth cancer that ultimately killed him at age 54 on his smokeless tobacco habit, and other players have expressed regret about chewing tobacco's impact on their health.

[Curt Schilling talks about his battle with mouth cancer, says chewing tobacco was to blame]

The University of California study said that "male high school athletes are significantly more likely to use smokeless tobacco than their non-athlete counterparts" and that "modeling of smokeless tobacco use by family, friends, respected coaches and elite athletes is strongly associated with smokeless tobacco initiation among adolescent males."

The ordinance approved Tuesday night was promoted by the Campaign for Tobacco-Free Kids, which called the move "truly historic and a huge step toward eliminating tobacco from baseball for good."

[Ian Desmond tosses batting gloves to fan who sent him 12-pack of Big League Chew]

In January, a coalition of anti-tobacco activists approached Farrell, who chewed tobacco as a high school and college baseball player and said he became addicted to the substance before kicking the habit. Once the ordinance is signed, the 11-member board of supervisors expects the Giants, the city's recreation department and anyone else in charge of an athletic field to post signs warning that smokeless tobacco would be illegal as of Jan. 1.

He acknowledged that enforcement will be unlikely in the Giants' dugout and clubhouse, but that home and visiting players alike will be sanctioned if they chew on the field. Penalties have not yet been worked out, Farrell said.