Nancy Brown is the CEO of the American Heart Association. John Maa MD is the president of the San Francisco Marin Medical Society. The opinions expressed in this commentary are theirs.

(CNN) San Francisco, long a leader in fighting the addiction, misery and death caused by tobacco, is now the site of a fierce battle. In the summer of 2017, the city's Board of Supervisors unanimously supported a law to protect youth and adults from candy-flavored tobacco products and menthol cigarettes. San Francisco's visionary restriction on the sale of all flavored tobacco products was the first in the country .

But, due to a lavishly funded effort to oppose the ordinance, largely spearheaded by tobacco company R.J. Reynolds, the fate of the ban will be determined in a referendum on the June 5 ballot, where it is known as Proposition E. The campaign is now inundating voters with misguided advertising . So far, spending to oppose the local ordinance totals over $11 million

R.J. Reynolds' desperate need to continue targeting youth with candy-flavored products is palpable as the company faces the realities of selling products that cause addiction and kill users. But why are these flavored products so important to a company that sells other, more-traditional, tobacco products?

Turns out tobacco, like many poisons, is bitter. Menthol is a soothing agent that creates a cooling sensation, and flavorings mask the irritating nature of tobacco smoke on the airway. Candy-flavored cigarettes have been banned since 2009 , and the movement to ban menthol (mint flavoring) is gaining ground around the US and the globe. But sickly-sweet e-cigarette liquids still fill the actual and virtual shelves of e-cigarette vendors.

It's no accident that flavored vape liquids are made to taste like popular kids' treats. Many smokers get hooked as teens, and flavored tobacco products consumed through e-cigarettes -- electronic devices that vaporize a liquid chemical brew -- are an enticing, trendy source of addictive nicotine

The array of kid-friendly flavors is a blatant and sickening reminder that tobacco companies have a direct economic incentive to appeal to new, young customers. In a 1970's tobacco industry document, Claude Teague of R.J. Reynolds once wrote : "if our company is to survive and prosper, over the long term we must get our share of the youth market."

Given this reality, the real question is whether inhaling bubble gum-, gummi-, or lollipop-flavored vapor from an e-cigarette is dangerous. In short, the answer is yes. A recent medical study published in the journal Pediatrics found that vaping exposes teens to toxic, cancer-causing chemicals. Further research suggests that flavor additives may pose unique harm to lung cells. And a study funded by the National Institutes of Health suggests that teens who use e-cigarettes are more likely to smoke conventional cigarettes.

What's more, young people of color have been historically targeted by Big Tobacco through advertisements for addictive products like menthol cigarettes, resulting in disproportionately higher rates of tobacco-related diseases among minorities.

Proponents of e-cigarettes claim the dangers of their products are minimal . Conversely, there is evidence that using e-cigarettes harms hearts , adversely increasing aortic stiffness and blood pressure.

The American Heart Association is proud to support the growing movement to end the sale of all candy flavored and menthol tobacco products in America. Decades of research shows that smoking can ruin and end lives; it's one of the leading preventable causes of death in the United States, claiming around 500,000 lives annually . To curb this statistic, we must do all we can to stop the alarming popularity of menthol cigarettes and youth e-cigarette use.

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San Francisco's elected officials have stepped up, and the voters who put them in office should vote to uphold the visionary flavored tobacco products ban. The American Heart Association, American Medical Association, American Cancer Society and American Lung Association stand united in support of this lifesaving legislation.

If our experiences with cigarettes and other tobacco products have taught us anything, it is this: Nothing good comes from nicotine addiction. If we can keep our kids from getting addicted now, Big Tobacco won't have a new generation of life-long users.