Story highlights Tony Gwynn died at age 54 after battling salivary gland cancer

He's not the only MLB player to battle oral cancer

MLB implemented rules in 2011 but hasn't banned tobacco use on the field

San Diego Padres fans remember Hall of Famer Tony Gwynn 's hitting prowess: 3,141 hits, a .338 batting average and an intense focus at the plate.

What they probably don't remember is Gwynn using smokeless tobacco throughout his career -- a habit, Gwynn told ESPN in 2010, that he believed gave him cancer . Gwynn's use doesn't specifically come to mind because so many of his fellow Major League Baseball players had the same habit.

But it wasn't until 2011 that MLB implemented rules related to smokeless tobacco products. Worried about the message it was sending to young fans, MLB collaborated with the Major League Baseball Players Association to prohibit teams from providing tobacco to players. Players cannot have tobacco tins in their uniforms or do interviews while using chewing tobacco.

Photos: Hall of Famer Tony Gwynn Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Tony Gwynn , a Hall of Fame baseball player known as one of the game's all-time best hitters, died Monday, June 16, after a multiyear battle with salivary gland cancer. He was 54. Hide Caption 1 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn, seen here in 1989, played his entire 20-year career with the San Diego Padres. Hide Caption 2 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn watches the flight of a ball against the New York Mets in 1993. Gwynn finished his career with 3,141 career hits and a .338 batting average. Hide Caption 3 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn bats during Game 1 of the 1998 World Series. Although the Padres lost the Series to the New York Yankees that year, Gwynn told the MLB Network that his opening game home run was "the highlight of my career." Hide Caption 4 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn signs a baseball for two police officers before the 1999 All-Star Game. Gwynn made the All-Star team in 15 of his 20 seasons. Hide Caption 5 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn gets his 3,000th hit during a game against the Montreal Expos in 1999. Hide Caption 6 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn celebrates his final game as he walks off the field with teammate Rickey Henderson in 2001. Hide Caption 7 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – A bronze statue of Gwynn is unveiled at San Diego's Petco Park in 2007. Hide Caption 8 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn poses with his Hall of Fame plaque during his induction in 2007. Hide Caption 9 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – Gwynn throws out the first pitch to his son, Tony Gwynn Jr., before a 2011 game between the Los Angeles Dodgers and the Houston Astros on Father's Day. Gwynn's son was playing for the Dodgers at the time. Hide Caption 10 of 11 Photos: Hall of Famer Tony Gwynn Hall of Famer Tony Gwynn – After retiring from baseball, Gwynn became head coach of the baseball team at his alma mater, San Diego State University. Here, he talks to the team during an NCAA tournament game in 2013. Hide Caption 11 of 11

Yet the players' union stopped short of banning tobacco use on the field.

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Smokeless tobacco is the general term for two products: chewing tobacco and snuff. Though snuff can be inhaled, most users place smokeless tobacco in their mouth and suck on it, periodically spitting out the juices.

Smokeless tobacco contains 28 carcinogens, according to the Centers for Disease Control and Prevention , and is a known cause of oral cancer.

Smokeless tobacco is primarily a male habit, the CDC says . In 2012, approximately 11% of high school boys used smokeless tobacco; only 1.5% of girls did. Nationally, an estimated 6% of adult men use smokeless tobacco, compared with just 1% of adult women.

"Current use of smokeless tobacco is about half of what it was in the mid-1990s," the CDC Youth and Tobacco use website states. "However, only a modest decline has occurred since 2010 and no change occurred between 2012 and 2013."

Gwynn was diagnosed with cancer in 2010. ESPN reported at the time that the then-50-year-old faced chemotherapy and radiation to fight the "slow-moving but aggressive" cancer in his salivary gland.

"The kind of chewing tobacco Gwynn used does have some risk of oral cancer, but not parotid (salivary) gland cancer, which is the kind that took his life at such a young age," said Dr. Gilbert Ross, the council's medical director.

Gwynn isn't the only former ballplayer to battle oral cancer. Most notably, Babe Ruth, Brett Butler and Bill Tuttle were all diagnosed after years of chewing tobacco use. Butler became a passionate advocate against tobacco after he returned to the field following treatment, according to the Oral Cancer Foundation

"I use it as a stimulator when I go to hit," Boston Red Sox star David Ortiz told the Boston Globe. "But the minute I finish my at-bat, I spit it out. It keeps me smooth and puts me in a good mood. I don't do it in the off season. I don't really like it that much, to be honest with you."

Nicotine, the addictive substance found in cigarettes, occurs naturally in all tobacco.

"Over time, a person becomes physically dependent on and emotionally addicted to nicotine," according to the American Cancer Society

Those who do try to quit experience withdrawal, often for weeks after their last spit or chew. Withdrawal symptoms can include irritability, dizziness, depression, headaches and weight gain, according to the American Cancer Society.