摘要：Objectives. We assessed the short-term ability to increase retail prices of the first US 1-cent-per-ounce excise tax on the distribution of sugar-sweetened beverages (SSBs), which was implemented in March 2015 by Berkeley, California. Methods . In 2014 and 2015, we examined pre- to posttax price changes of SSBs and non-SSBs in a variety of retailers in Berkeley and in the comparison cities Oakland and San Francisco, California. We examined price changes by beverage, brand, size, and retailer type. Results . For smaller beverages (≤ 33.8 oz), price increases (cents/oz) in Berkeley relative to those in comparison cities were 0.69 (95% confidence interval [CI] = 0.36, 1.03) for soda, 0.47 (95% CI = 0.08, 0.87) for fruit-flavored beverages, and 0.47 (95% CI = 0.25, 0.69) for SSBs overall. For 2-liter bottles and multipacks of soda, relative price increases were 0.46 (95% CI = 0.03, 0.89) and 0.49 (95% CI = 0.21, 0.77). We observed no relative price increases for nontaxed beverages overall. Conclusions. Approximately 3 months after the tax was implemented, SSB retail prices increased more in Berkeley than in nearby cities, marking a step in the causal pathway between the tax and reduced SSB consumption. Consuming sugar-sweetened beverages (SSBs) increases the risk of obesity, diabetes, heart disease, and dental caries 1–4 and has been linked to approximately 184 000 deaths per year worldwide. 5 SSBs are also the largest source of added sugar in the US diet. 6,7 Thus, reducing SSB consumption has been identified as important in preventing obesity and chronic disease. 8–10 Because of the success of tobacco taxation in reducing smoking prevalence and related diseases, 11 public health experts, including the Institute of Medicine, have recommended taxing SSBs as a means to reduce SSB consumption. 12–15 In 2013 and 2014, more than a dozen states and several cities proposed SSB tax legislation—so called soda taxes. 16 Only 1 proposal passed. On November 4, 2014, Berkeley, California, passed a 1-cent-per-ounce specific excise tax on the distribution of SSBs (Measure D), becoming the first US city to levy such a tax. 17 Measure D is consistent with the type of tax public health experts have called for—an excise tax on SSBs. 12 Unlike a sales tax, which is added at the register and paid directly by the consumer, an excise tax is levied before the point of purchase (e.g., on distributors). Specific excise taxes are levied per volume of a product, whereas, ad valorem excise taxes are levied as a proportion of product price. 18 In response to an excise tax, distributors are expected to increase SSB prices for retailers, who, in turn, are expected to increase the shelf prices of SSBs paid by consumers. Excise taxes are thought to be more salient to consumers than are sales taxes because they result in higher shelf prices at the point of decision, thus deterring purchase. 12 The effectiveness of an excise tax in reducing SSB consumption hinges partly on its “pass-through rate,” or the extent to which the tax is passed on to consumers through higher shelf prices. In perfectly competitive markets with perfectly inelastic demand (i.e., changing price does not change demand), economic theory predicts perfect pass-through (i.e., a 1-cent excise tax leads to a 1-cent retail price increase). 19,20 However, research suggests that demand for SSBs is elastic 21 ; thus, distributors or retailers may undershift the tax (increase prices by < 1 cent/oz), either by absorbing the costs or distributing costs across untaxed products (e.g., food or diet soda). In fact, concerns have been raised that businesses might undershift the tax and lower their profit margins to sustain sales (known as “strategic pricing”). 22 Undershifting results in lower than expected price increases, potentially undermining the public health benefit of a tax. 23 However, taxes may also be overshifted in monopolistic or oligopolistic markets. 20 Empirically, there is evidence of both over- and undershifting of taxes on cigarettes, 24–29 alcohol, 30,31 and saturated fat. 32 The few empirical studies on SSB excise taxes in other countries have found pass-through rates ranging from about 63% to more than 300%, depending on beverage type, brand, and retailer. 33–35 Because Berkeley’s excise tax is the first of its kind in the nation, there is no empirical evidence on how such a tax will be passed-through to consumers in the United States. We have provided the first early details of the pass-through of Berkeley’s excise tax on SSBs. Using neighboring San Francisco and Oakland, California, as comparison cities, we estimated the effect of Berkeley’s tax on retail prices of SSBs. Additionally, we examined price changes by beverage, brand, size, and retailer type because research in other countries has found varying pass-through across these variables.
