A ball and chewing tobacco before a Colorado Rockies at Milwaukee Brewers game in 2012. (Jeffrey Phelps/Getty Images)

THE CENTERS for Disease Control and Prevention released some dismaying findings last week. Though combustible tobacco use is down among high school students, smokeless tobacco use is up among high school athletes. If professional sports leagues don’t do more to stamp out this horrid addiction, local governments should step in and do it for them.

According to the CDC, combustible tobacco use among all high school students dropped from 31.5 percent in 2001 to 19.5 percent in 2013. But use of smokeless tobacco — chewing tobacco, snuff or dip — stayed flat at 5.9 percent among non-athletes during that period and rose from 10 percent to 11.1 percent among athletes. Moreover, the researchers found, students who participated in many sports teams used smokeless tobacco at higher rates than those who played fewer sports.

Government researchers speculated that, while athletes generally do a better job avoiding cigarettes than non-athletes, they might believe chewing tobacco or snuff is harmless — or even helpful for athletic performance. Whether they are operating on these misconceptions, or whether student athletes are just emulating older athletes, coaches and sports stars, one obvious and long-overdue reaction should be to eliminate smokeless tobacco in major league sports.

Smokeless tobacco is very far from harmless. It introduces a toxic mixture of carcinogens into the mouth, promoting several types of cancer. Even before the CDC’s findings, last year brought high-profile examples of its toll: First there was pitching legend Curt Schilling’s brutal battle with a carcinoma that began on his tonsil, then there was the tragic death of San Diego Padres great Tony Gwynn from salivary gland cancer at age 54. Besides, the habit is plain disgusting. ESPN reported that one NFL quarterback wears a gold grill on his lower teeth to cover up their telltale brownish tint.

Though baseball is not the only sport with a smokeless tobacco problem, its many chewing players are by far the most visible smokeless tobacco addicts in the United States. Major League Baseball’s brass tried to ban smokeless tobacco in its 2011 contract negotiations with players. But management had to settle for half-measures. While smokeless tobacco is forbidden in the minor leagues, major league players merely can’t do things such as carry it in their uniforms or conduct television interviews while chewing. Though many players now seem to draw their chewing medium from the giant buckets of bubble gum in major league dugouts, TV cameras still catch others expectorating substances that are far from pink. It’s bad for them, and it’s a bad example. The next round of players contract negotiations begin next year, so MLB policy can’t change until after the 2016 season.

City governments aren’t waiting. San Francisco banned smokeless tobacco from sports venues in May. Boston’s city council voted to do the same last week. Other states and cities, including Washington, should do the same, now.

One measure alone probably won’t root out a practice that has been ingrained in baseball culture for so long. But there’s no downside for cities to do what Major League Baseball hasn’t, and it could help both the stars and their fans.