San Francisco city supervisors have proposed an ordinance that will "prohibit tobacco retailers from selling flavored tobacco products, including menthol cigarettes." If approved, this ban would be the first of its kind in the nation, and the hope is that it will curb the rate at which teenagers and young adults are adopting tobacco. The city board will be voting on the ordinance this week.

Tobacco products without flavorings will still be allowed, but products with flavor additives will be banned — including flavored cigarettes, flavored cigars, flavored smokeless tobacco, flavored shisha and flavored nicotine solutions that are used in electronic nicotine delivery systems (ENDS). The protective move follows California's legislation in 2016 to raise the legal age for the purchase of tobacco from 18 to 21.

The ordinance expresses the concern about flavored products in general "flavored tobacco products promote youth initiation of tobacco use" and about menthol, specifically — "menthol, in particular, cools and numbs the throat to reduce throat irritation and make the smoke feel smoother."

Studies have shown the flavorings in inhaled products can be harmful by themselves. One of the ingredients in many ENDS products is benzaldehyde, which can create irritation in the airways and is associated with gastrointestinal disease and lung cancer in animal studies.

Menthol has been used for decades as a tobacco additive. Some of the dangers of this additive have been known for years, while others have been recently identified.

Surprisingly, the reports on cancer and menthol are conflicting.

Researchers in 2012 found a lower rate of lung cancer among smokers of menthol tobacco products compared to smokers of nonmenthol tobacco products. But there is also an indication that African-Americans have a higher rate of lung cancer than Caucasians, and that African-Americans also use menthol products at a higher rate than Caucasians. However, there is also evidence that both menthol and nicotine are metabolized differently across races.

Studies have demonstrated a role for menthol in the metabolism of nicotine in the body. There is an interaction between menthol and the nicotinic acetylcholine receptor cells in the neural system, particularly in the brain, and this has implications for the greater addictive properties of menthol tobacco products.

But if the ban on flavors and menthol go into effect, it may impact long-term menthol product tobacco users. The good news is going from menthol products to nonmenthol does not have an immediate downside.

A randomized, open-label, laboratory-based study looked at 32 adults over 35 days. The group used a menthol product for 15 days and a nonmenthol product for 15 days, and they were compared to a control group that used their own brand of cigarettes.

The study found that after ceasing the menthol product, there was a period of longer inhalation or total volume of puff, but no increase in the overall quantity of cigarettes used.

Flavor additives for cigarettes have been banned in the United States since 2009, with the exception of menthol. The tobacco industry has had large-scale efforts to move around this ban with flavored nicotine products in e-cigarettes and cigars.

"Each day, about 2,500 children in the United States try their first cigarette, and another 400 children under 18 years of age become new regular, daily smokers," the San Francisco ordinance reports. "81 percent of youth who have ever used a tobacco product report that the first tobacco product they used was flavored."

These products are appealing to the vulnerable youth market. The ordinance will protect youth in San Francisco and is a wise public health move.