Companies that allow their workers to access to Facebook during business hours lose an average of 1.5% in total employee productivity, according to a study by Nucleus Research.

Interviews with  237 randomly selected US office workers and a subsequent analysis found that 77% report having a Facebook account and 61% of them access Facebook during work hours. Moreover, one in every 33 employees has built their entire Facebook profile during work time, and roughly the same number of respondents use Facebook only when they are at work.

According to Nucleus Research’s calculations, these figures amount to a 1.47% loss in total productivity among workers.

Additional study findings:

• Of those using Facebook at work, 87% cannot define a clear business reason for accessing the site.
• Of the 13% of users who had a business reason to access Facebook, most were not using it for personal networking and it was one component of a largely unmeasured business stragtegy.
• While the average user spends 15 minutes or work time on Facebook each day, some employees report spending upwards of two hours.

The analysis also revealed potential security concerns relating to Facebook use as an email alternative, since most organizations do not monitor and manage Facebook as closely as email. This, Nucleus Research said, creates an opportunity for Facebook users to circumvent controls and violate corporate communications policies.