The “Five-Second Rule” is a Myth

All of us have surely dropped food on the floor, scooped it up and have eaten it without thought. After all, for years it was believed that if you retrieved food dropped on the floor within five seconds, it was still safe to eat. According to scientists from Rutgers University in New Jersey, this rule has been proven wrong and is merely a myth.

Donald Schaffner, a professor in food science at Rutgers University and an author of the recent study says,

The popular notion of the “five-second rule” is that food dropped on the floor, if picked up quickly, is safe to eat because bacteria need time to transfer.

We decided to look into this because the practice is so widespread. The topic might appear “light” but we wanted our results backed by solid evidence.

The research has proven that in reality, it takes only one second for bacteria to migrate from floor to food. This is significant when you consider that there are 31 known pathogens for an estimated nine million cases of food-borne illness a year, according to the Centers for Disease Control and Prevention (CDC). Actually, the CDC sates that one in six people in the United States get sick each year from food-borne illness. That’s 48 million people.

Schaffner adds,

The “five-second rule” is a significant oversimplification of what actually happens when bacteria transfers from a surface to food. Bacteria can contaminate instantaneously.

The scientists tested the theory by coating stainless steel, ceramic tile, wood and carpeted surfaces with the microorganism Enterobacter aerogenes, similar to Salmonella. They proceeded to drop cubed watermelon, Haribo strawberry gummies, plain white bread (purchased at ShopRite) and buttered bread from a height of five inches onto each surface. They performed each drop on each surface 20 time apiece, taking 2,560 measurements. They observed contact times of less than one second, five seconds, thirty seconds and 300 seconds.

It was discovered that the amount of moisture present, the type of surface and how long the food was on the surface contributed to the contamination.

Watermelon contracted the most contamination, the gummies the least. Buttered and plain bread had the same contamination rate. Thus, it doesn’t matter if your buttered toast falls face-up or face-down, it is still contaminated. Also, carpet had a lower bacteria transfer rate than stainless steel.

Schaffner says,

Transfer of bacteria from surfaces to food appears to be affected most by moisture. Bacteria don’t have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer.

The longer the food remains on the surface, the more bacteria transferred.

You may think twice about picking food off the floor and eating it.