With the City of Philadelphia last week passing its so-called “soda tax,” or a tax on sweetened beverages, it becomes the first big U.S. city and the second in the country to do so after Berkeley, Calif. Philadelphia’s move is expected to embolden other U.S. cities contemplating such a tax as they battle concerns about the adverse health effects of sugary sodas on their residents. A handful of U.S. cities are planning to put such a tax on the ballot in coming months, and they are encouraged also by the prospect of the tax dollars it would bring in. The likely impact of such a tax on reducing beverage consumption and the consequent health benefits are uncertain, but the road to those goals will be long, according to experts at Wharton and the University of Pennsylvania. A difference in consumption would be visible in a year or two after the soda tax kicks in, predicted Karen Glanz , professor at the Perelman School of Medicine and also director of the University of Pennsylvania Prevention Research Center .…