WASHINGTON >> U.S. senators and health officials are taking on a baseball tradition older than the World Series itself: chewing tobacco on the diamond.

With the Series set to begin Wednesday between the St. Louis Cardinals and Texas Rangers — a team that started life as the Washington Senators 50 years ago — the senators, along with health officials from the teams’ cities, want the players union to agree to a ban on chewing tobacco at games and on camera. They made the pleas in separate letters, obtained Tuesday by The Associated Press.

"When players use smokeless tobacco, they endanger not only their own health, but also the health of millions of children who follow their example," the senators wrote to union head Michael Weiner. The letter was signed by Dick Durbin of Illinois, the No. 2 Democrat in the Senate, and fellow Democrats Frank Lautenberg of New Jersey, Richard Blumenthal of Connecticut and Senate Health Committee Chairman Tom Harkin of Iowa.

The senators noted that millions of people will tune in to watch the World Series, including children.

"Unfortunately, as these young fans root for their favorite team and players, they also will watch their on-field heroes use smokeless tobacco products," they wrote. Smokeless tobacco includes chewing tobacco and dip.

With baseball’s current collective bargaining agreement expiring in December, the senators, some government officials and public health groups want the players to agree to a tobacco ban in the next contract. A coalition including the Campaign for Tobacco-Free Kids, the American Academy of Pediatrics, the American Cancer Society and the American Medical Association has been pushing for one since last year.

"Such an agreement would protect the health of players and be a great gift to your young fans," the senators wrote. Durbin also sent copies of the letter to the player representatives for his home state teams, the Chicago White Sox and Chicago Cubs, as well as the representative for the Cardinals, a team that draws Illinois fans from across the river in Missouri.

Commissioner Bud Selig endorsed the ban in March, but the players union hasn’t committed to one.

Weiner said in June that a "sincere effort" will be made to address the issue. Union spokesman Greg Bouris said Tuesday that since the issue is subject to collective bargaining which is currently taking place, it would be inappropriate to comment.

In Senate speech Tuesday, Durbin said, "Let’s not let the health and safety of young baseball fans across America be a bargaining chip between the major league players and the owners. Let’s win one for the kids across America."

The first World Series took place in 1903, but chewing tobacco in the sport dates well back into the previous century, when the habit was a popular pastime in American culture, not just on baseball diamonds. Players used tobacco juice to soften gloves, keep their mouths wet on dusty fields and doctor baseballs (the juice was part of the spitballer’s arsenal until baseball banned the spitter in 1920).

Some baseball players interviewed by The Associated Press last month were receptive to the idea, but others viewed a ban as an infringement on their freedom. Baseball banned smokeless tobacco in the non-unionized minor leagues in the 1990s, and recent call-ups from the minors spoke of "Dip Police" who would come through clubhouses and cite players if they saw tobacco at their lockers, subjecting violators to fines.

The health officials from St. Louis and Arlington, Texas, asked that players in the World Series voluntarily abstain from using tobacco, in addition to calling for a permanent ban.

"The use of tobacco by big league ballplayers at a single World Series game provides millions of dollars worth of free television advertising for an addictive and deadly product," wrote Dr. Cynthia Simmons, the public health authority for Arlington, Texas, and Pamela Walker, the St. Louis interim health director. They said that with tobacco companies banned from advertising on TV, they "literally could not buy the ads that are effectively created by celebrity ballplayers using tobacco at games."

The federal Centers for Disease Control and Prevention says smokeless tobacco can cause cancer, oral health problems and nicotine addiction, and stresses it is not a safe alternative to smoking. Despite the risks, the CDC’s most recent survey found that in 2009, 15 percent of high school boys used smokeless tobacco — a more than one-third increase over 2003, when 11 percent did.

Prior to last year’s World Series between the Rangers and San Francisco Giants, Rep. Frank Pallone, D-N.J., called on the teams to tell their players not to use tobacco on the field or in the dugout.