You might want to think twice before you let your children play in those ball pits found at many popular restaurants and amusement parks.

A new study shows they're often dirty and filled with bacteria.

Researchers at the University of North Georgia inspected six ball pits in the U.S. and found 31 different types of bacteria, according to Kidspot.

One of the pits had an astounding average of 170,818 bacteria per ball.

Many of the pits had not been cleaned in days or even weeks, Kidspot says.

The bacteria found can reportedly cause a variety of medical problems, including bladder infections, meningitis, pneumonia, sepsis and skin rashes, among others. 

The University of North Georgia study was first published in the American Journal of Infection Control.