Is the five-second rule for dropped food real?

The five-second rule says food picked up quickly from the floor is safe because bacteria need time to transfer. Researchers and food safety bodies reject it as a safety guide. A 2016 Rutgers study found that transfer can begin in less than one second. Longer contact does tend to move more bacteria, so the rule is real only in that narrow sense, and other factors count for as much or more. [1] [2]

Donald Schaffner and graduate student Robyn Miranda tested four surfaces (stainless steel, ceramic tile, wood and carpet) and four foods (watermelon, bread, bread and butter, and gummy candy). They used four contact times: under one second, five seconds, 30 seconds and 300 seconds. The bacterium was Enterobacter aerogenes, a nonpathogenic relative of Salmonella. In all, 128 scenarios were each repeated 20 times, giving 2,560 measurements. The results were published in Applied and Environmental Microbiology. [1]

According to National Geographic, only one other rigorous study had examined the idea before 2016, a 2007 peer-reviewed paper by Paul Dawson of Clemson University. It also found that food can pick up bacteria immediately on contact. Schaffner says that amateur studies and television investigations have muddied the picture with experiments that do not meet scientific standards. [3]

Schaffner said transfer is affected most by moisture, because bacteria move with the moisture. Watermelon picked up the most contamination and gummy candy the least. Carpet transferred far fewer bacteria than tile or stainless steel, and wood was more variable. National Geographic notes that carpet soaked up the bacterial solution the scientists applied, and that this does not make carpet a better place to drop food. Consumer Reports cites a 2006 study in the Journal of Applied Microbiology that also found carpet transfers less than ceramic tile. [1] [3] [4]

Sources agree that dropped food picks up bacteria, but they differ in emphasis on the practical risk. Consumer Reports food safety director James Rogers says he would not eat anything off the floor, noting that you cannot see how contaminated a floor is, and that young children, older adults and immunocompromised people face greater risk. Safefood calls the rule definitely a myth because some bacteria can cause serious illness. [4] [2]

Dawson, speaking to National Geographic, takes a more moderate view. He says that in most cases a cookie with a little dust and floor bacteria is unlikely to harm someone with a healthy immune system, and that it is probably safe 99 percent of the time. He would avoid it in a hospital or on a kitchen floor covered in chicken juice. Consumer Reports also says the chance of getting sick from dropped food is not very high, that washable or peelable foods such as apples or potatoes are less of a concern, and that food to be cooked afterward carries less risk than ready-to-eat food. [3] [4]