One year into Philadelphia's 1.5-cents-per-ounce "soda tax," new findings show that the law had minimal to no influence on what Philadelphians are drinking. The results were published this month in the International Journal of Environmental Research and Public Health from researchers at Drexel University's Dornsife School of Public Health.

The team conducted a random phone survey of 515 adult residents of Philadelphia and neighboring cities of Camden and Trenton, New Jersey, and Wilmington, Delaware. Respondents shared how much and how frequently they drink soda, fruit drinks, energy drinks and bottled water during a 30-day period when the tax was first implemented, in Dec. 2016 -- Jan. 2017, and again reported their consumption over a 30-day period during a follow-up survey a year later in Dec. 2017-Feb. 2018.

Taking into account other health behaviors and socio-demographics, at the one-year mark, 39% of Philadelphians, and 34% of those in surrounding cities, reported drinking fewer sugar-sweetened beverages. This amounts to only three fewer sugary beverages for Philadelphians each month -- not a statistically significant difference.

Previous studies have looked at sales of sugary drinks after the tax was implemented, but did not evaluate consumption of the taxed drinks. A previous study looked at similar changes in consumption after the tax -- finding that one year after the tax, adults consumed fewer sugary beverages in Philadelphia relative to outside Philadelphia (about 10 fewer occasions per month) -- that study focused on lower-income Philadelphians who lived with children and, on average, consumed a sugary beverage every day. The current study differs from that one as it was population-based and thus reflects the response of a typical adult. In this sample, only 25% consumed sugary beverages every day.

"We have ample evidence that sugary beverages are connected to type 2 diabetes, obesity, cardiovascular disease, and other health issues, but we're seeing that raising the price of sugary-beverages may not impact consumers who don't drink a lot of soda," said study co-author Amy Auchincloss, PhD, an associate professor in the Dornsife School of Public Health.

"The availability of untaxed sugary beverages outside of Philadelphia, the still relatively lower price of these drinks compared to healthier ones and marketing and advertising may explain the low effect of the tax," said lead author Yichen Zhong, a doctoral student at the Dornsife School of Public Health.

Unlike other cities that enacted a similar beverage tax to increase general revenue, Philadelphia's tax, was enacted with the goal of financing universal pre-kindergarten and parks and recreation programs in the City.

"Although this law was not passed for health reasons, the tax has the potential to generate long- term health benefits for many Philadelphians because revenue from the tax is being directed toward expanding access to quality early childhood education for children in lower-income families -- and education has a positive effect on many health outcomes," said senior author Brent Langellier, PhD, an assistant professor in the Dornsife School of Public Health.