Philadelphia’s tax on soda and other sweetened beverages has not reduced residents’ consumption of such drinks, according to a new study.

Philadelphians reported a slight but not statistically significant decrease in sugary beverage consumption compared with residents of nearby cities without a tax, Drexel University researchers found in surveys taken before and after the tax took effect.

“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,” Amy Auchincloss, an associate professor at Drexel’s Dornsife School of Public Health, said in a statement about the research.

Philadelphia became the first large U.S. city to pass a tax on soda in 2016. Mayor Jim Kenney championed the tax as a means of funding pre-K, community schools, and improvements to parks, recreation centers, and libraries. Public health advocates praised Philadelphia’s levy and have pointed to taxes on soda as a means of reducing consumption and improving residents’ health.

» READ MORE: A timeline of Philadelphia's soda tax

Drexel researchers surveyed Philadelphia residents during a 30-day period when the tax was first implemented, and followed up a year later. They also included residents of Camden, Trenton, and Wilmington in the random telephone survey of 515 adults.

A year after the 1.5-cents-per-ounce tax took effect, researchers said, 39% of Philadelphians reported drinking fewer sugar-sweetened beverages, compared with 34% of adults in other cities. But the researchers said that difference was not statistically significant.

The Drexel study was published this month in the International Journal of Environmental Research and Public Health.

Other studies of Philadelphia’s tax have focused on the impact on beverage sales and overall store sales. City Council voted to complete its own economic study of the tax last year. It has not been released.

Lauren Cox, a Kenney administration spokesperson, said that reducing consumption was not the city’s primary goal in implementing the tax. But she noted that the study’s sample size was small and included many people who rarely drink sweetened beverages.

“This study didn’t look specifically at the consumption of heavy-soda consumers whose health would benefit the most from cutting their soda consumption, and who in other studies have been more inclined to reduce consumption as a result of a tax," Cox said.

Anthony Campisi, a spokesperson for the beverage-association funded Ax the Philly Bev Tax Coalition, said “the better way to help people reduce the sugar they consume from beverages is to offer more choices with less sugar or zero sugar and smaller portion sizes.”

A study published in September — by researchers at Cornell University, the University of Iowa, and Mathematica Policy Research — found that the tax had reduced adult consumption of soda by 31%, and that Philadelphians drank about 10 fewer taxed beverages per month compared with residents outside the city.

But Drexel researchers noted that the previous study focused on lower-income residents who lived with children and drank an average of one sweetened beverage per day. Their study, they said, was more reflective of typical adults; just 25% of participants reported drinking sugary beverages every day.

Doctoral student Yichen Zhong, the lead author, said the lack of reduction in consumption found among residents could be explained by “the availability of untaxed beverages outside the city limits, the still relatively lower price of these drinks compared to healthier ones and marketing and advertising.”