(Bloomberg) -- San Francisco Mayor London Breed said she supports a citywide ban on the sale of e-cigarettes, signaling her intention to sign an ordinance recently passed by the city’s board of supervisors into law.

With the mayor’s backing, San Francisco is set to become the first U.S. city to implement a ban on nicotine vaporizer products. Breed is expected to sign the law in the next week. After that, stores will have seven months before they must remove all e-cigarettes from shelves. Cigarettes, other tobacco products and recreational marijuana will remain legal.

The city will outlaw e-cigarette sales in stores and through online orders to San Francisco addresses until the U.S. Food and Drug Administration gives the products a stamp of approval. In an onstage interview at Bloomberg’s Players Technology Summit in San Francisco, Breed said her biggest concern is use of the products by young people.

“We don’t understand the impacts of this product,” Breed said on Thursday. “Until the FDA provides the facts and the appropriate regulations of this product, then we should not allow those things to be sold on the market. I’m not suggesting that we don’t allow it in the future, but we need to understand the health impacts.”

Juul Labs Inc., the biggest e-cigarette brand in the country, is based in San Francisco. The company has said the prohibition would drive adults back to cigarettes and create a black market for the products.

To contact the reporters on this story: Romy Varghese in San Francisco at rvarghese8@bloomberg.net;Brad Stone in San Francisco at bstone12@bloomberg.net

To contact the editors responsible for this story: Mark Milian at mmilian@bloomberg.net, Anne VanderMey

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