HARTFORD — Eighty-seven percent of people have eaten food dropped on the floor and 81 percent of them do it based on the five-second rule. We all know the five second rule: if a food item falls on the floor it is OK to eat it if you retrieve it within 5 seconds. Well, is the five second rule fact, or fiction?
In an original study by Aston University, they found that when food sat on the floor for anywhere between 3-30 seconds that the longer the food remained on the floor, the greater the transfer of e coli and staph aureus. They also found that there was less transfer from carpeted surfaces than laminate or tiled surfaces and that dry foods like toast had less transfer than sticky ones like wet candy.
In the newest study by Rutgers University, they found that when food sat on the floor from 1 to 300 seconds that the longer the food remained on the floor the more Enterobacter contamination occurred. There was a dramatic linear rise in the amount of bacteria sticking to the food in the first 10 to 30 seconds before leveling off with a slower rise thereafter. Watermelon acquired more Enterobacter than bread with gummy bears having the least amount of bacterial transfer. Again, carpet transferred less bacteria to food than tile, stainless steel, or wood surfaces. So all in all, there is always a risk of bacterial contamination after food falls to the floor and is picked up and eaten, no matter how fast you do it. The faster you pick it up, the lower the amount of bacteria you will eat. The drier and less porous the food, like a gummy bear or toast, the less contamination and when food falls on carpet, the less contamination occurs.
What these studies cannot tell us is to what extent people get sick when they eat the food that fell to the floor. We know that the amount of bacteria you are exposed to be important in determining your risk of disease so a few bacterial colonies is less likely to harm you than a big exposure. We also know that over sterilizing your environment can lead to the development of more allergies since your immune system is not dealing with real threats and has time to be oversensitive.
– Dr. Michael White from the UConn School of Pharmacy