If your family has lived, or at least survived, by the 5-second rule, researchers at San Diego State University say you may be living on borrowed time.

You know the rule: If food falls to the floor and you grab it back within 5 seconds, you can still eat it. Without, you know, dying.

Granted, the study was funded by Clorox Co., which is all about disinfecting surfaces. But experiments in dropping carrots and sippy cups on a typical floor found that germs do indeed attach themselves within 5 seconds.

You gotta love this research: Three baby carrots were dropped into a kitchen sink, onto a tiled floor, a carpeted floor, a table and a countertop. There also was a control carrot, which remained undropped. In each case, germs glommed on to the veggie in 5 seconds. The germiest culprit? The countertop, followed by carpeted floor and the tiled floor. The wet sippy cup actually picked up the most germs when, gulp, dropped onto a highchair tray.

The university also surveyed 500 parents, finding that 65 percent admitted to following the 5-second rule in their home. The bleach folks would like everyone to think about disinfecting surfaces more often. But there also may be an argument that ingesting a certain amount of germs helps build up our tolerance levels.

Or we could just step up our game.

A 3-second rule, anyone?