If you’ve ever dropped a piece of food on the floor, the five-second rule has probably popped into your mind. The rule says that it takes five seconds for bacteria to transfer from the floor, or another surface, to your food. And if you pick up the food within that crucial five-second window, it’s safe to eat.

Usually, you’re just trying to rationalize the fact that you want to enjoy that tasty morsel. But is there any truth to this so-called rule?

Several studies have been conducted to find the answer. According to the research, there are several factors that are involved in the transfer of bacteria to food. In certain circumstances, bacteria can transfer instantaneously. In other words, the 5-second rule is an oversimplification of what actually happens.

“There are many different pathogens and disease-causing microbes that could live on a surface where you drop your food,” said Manish Doshi, M.D., an infectious disease physician at Geisinger Community Medical Center in Scranton. “Some of these can cause foodborne-illnesses and for certain bacteria, it only takes a small number to make you sick.”

Roughly one in six people gets a foodborne-illness each year, and 3,000 people die from these illnesses, according to the Centers for Disease Control and Prevention.

The amount of bacteria that transfers from the surface to the food has to do with how much bacteria is on the surface, the type of surface, the moisture level of the food that comes in contact with it, and the length of time the food touches that surface.

It is likely that more bacteria will transfer to wet or moist foods like a piece of raw meat, chicken or fish, or fruit like watermelon or an orange slice. Less bacteria transfers to foods like a cracker or a piece of hard candy.

The type of surface also affected how much bacteria transferred. Surfaces like tile, stainless steel, or wood transferred more bacteria than carpet.

"If food falls on the floor, even if there are trace amounts of harmful bacteria, there is the potential to cause illness,” said Dr. Doshi. “You should always throw out food that gets accidentally dropped on the floor. You could save yourself from some discomfort at the least or a trip to the hospital at the most.”

If you drop a piece of food on the floor and that surface contains harmful bacteria, there’s a good chance it has transferred to your food. If you pick up that food, there’s also a chance that bacteria has transfer to your hands, so it’s important to wash your hands, too.

So, the next time you drop that potato chip or carrot on the floor, put it in the trash can instead of in your mouth.