In order for Berkeley's penny-an-ounce soda tax to work, advocates say, retailers have to pass it through to customers. That way, the shoppers will see the higher price on the shelf, and some will choose lower priced (i.e. non-sugary) drinks.
In an analysis, UC Berkeley researchers say many retailers are doing just that. They sampled prices in Berkeley, Oakland and San Francisco, just before last November's election when Berkeley voters overwhelmingly passed the first-in-the-country soda tax.
Then they sampled prices again last summer, after the tax had gone into effect March 1. They found that retailers were passing through 69 percent of the tax on sodas and 47 percent of the tax on average for all sugar-sweetened beverages.
For a 20-ounce soda that had cost $1.75 now would cost $1.89, a 14-cent increase.
Lead author Jennifer Falbe, a post-doctoral researcher in the UC Berkeley School of Public Health, said she was encouraged by these findings.