A subset of Facebook (NASDAQ:FB) users are deleting their accounts over privacy concerns, reflecting a counter-trend to the past decade’s global dash onto the social networking site.

A study of 600 former and current Facebook users conducted by the University of Vienna found that 48 percent of those committing “virtual identity suicide” cited privacy concerns as their motivation. Another 13.5 percent said they quit over general dissatisfaction, 12.6 percent quit over various negative aspects of maintaining relationships online, like shallow conversations, and 6 percent quit out of fear of addiction. Other reasons listed were loss of interest in the site and social pressure to add friends.

The data is from 2010 but was released in the monthly journal Cyberpsychology, Behavior, and Social Networking on Sept. 12. Many of the study’s participants were recruited from quitfacebookday.com, an online community of more than 40,000 committed Facebook quitters.

Since its creation, Facebook has lost 9 million monthly users in the U.S. and 2 million users in Britain, according to the Daily Mail and a report in April from Social Bakers. Monthly active users log into their account at least once during a 30-day period. As of June 2013, Facebook reports that they have 1.15 billion active monthly users, and 80 percent of these users live outside the U.S. and Canada.

Stefan Steiger, the professor who oversaw the study, wrote in the report that personality traits may “influence the likelihood of quitting one’s Facebook account indirectly via privacy concerns and Internet addiction.”

“In this case, the concern about one’s privacy and Internet addiction propensity would not be directly in charge for quitting one’s Facebook account, but would function as mediators of the underlying personality traits,” Steiger wrote.

The quitters in the study were older and more likely to be male than those who continued to use Facebook.

But the study also admits the people they surveyed “only represent a small and probably not representative (i.e., self-selected) fraction of the intended target groups,” groups of Facebook users and quitters.