With the advent of social media, many people have blurred the lines between their personal and professional lives. And according to a new survey, it could be causing problems.

Staffing company Kelly Services, which surveyed 170,000 people in 30 countries for its Kelly Global Workforce Index, found that more than half of respondents feel social media has a negative impact on workplace productivity, and also that mixing personal and professional connections is a dicey thing to do.

What’s more, nearly 15 percent of employees surveyed have no qualms posting their opinions about work on social media sites where both friends and colleagues can see them.

“The reality is that the spread of social media in the workplace is occurring faster than any rules designed to manage it,” said Steve Armstrong, senior vice president and general manager for Kelly Services. “While many employees are quick to see the benefits, employers and managers are still grappling with a host of complex issues relating to privacy, monitoring, and access to sensitive business information.”