Researchers Debunk Five Second Rule
“Bacteria can contaminate instantaneously.” ~Donald Schaffner, PhD
Many of us have heard someone grab food that dropped to the floor shouting, "Five second rule!" moments before shoving that food into their mouths. Most of us already knew that rule was never official, however now it's official in the most thorough debunking yet! Rutgers researchers have found that sometimes bacteria can transfer to food in less than a second. So no matter how fast you scoop up that dropped food and eat it there is no “safe” five-second window.
So why aren't lots of people sick that follow the rule? It's important to know that "covered in bacteria" doesn't necessarily mean unsafe. Most microbes are harmless, but good to be aware of the science. Especially if you happen to drop food in say a public bathroom.
Donald Schaffner, professor and extension specialist in food science, found that moisture, type of surface and contact time all contribute to cross-contamination. In some instances, the transfer begins in less than one second.
Their findings appear online in the American Society for Microbiology’s journal, Applied and Environmental Microbiology.
“The popular notion of the ‘five-second rule’ is that food dropped on the floor, but picked up quickly, is safe to eat because bacteria need time to transfer,” Schaffner said, adding that while the pop culture “rule” has been featured by at least two TV programs, research in peer-reviewed journals is limited.
“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 science,” said Schaffner, who conducted research with Robyn Miranda, a graduate student in his laboratory at the School of Environmental and Biological Sciences, Rutgers University-New Brunswick.
The researchers tested four surfaces – stainless steel, ceramic tile, wood and carpet – and four different foods (watermelon, bread, bread and butter, and gummy candy). They also looked at four different contact times – less than one second, five, 30 and 300 seconds. They used two media – tryptic soy broth or peptone buffer – to grow Enterobacter aerogenes, a nonpathogenic “cousin” of Salmonella naturally occurring in the human digestive system.
Transfer scenarios were evaluated for each surface type, food type, contact time and bacterial prep; surfaces were inoculated with bacteria and allowed to completely dry before food samples were dropped and left to remain for specified periods. All totaled 128 scenarios were replicated 20 times each, yielding 2,560 measurements. Post-transfer surface and food samples were analyzed for contamination.
Not surprisingly, watermelon had the most contamination, gummy candy the least. “Transfer of bacteria from surfaces to food appears to be affected most by moisture,” Schaffner said. “Bacteria don’t have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer. Also, longer food contact times usually result in the transfer of more bacteria from each surface to food.”
Perhaps unexpectedly, carpet has very low transfer rates compared with those of tile and stainless steel, whereas transfer from wood is more variable. “The topography of the surface and food seem to play an important role in bacterial transfer,” Schaffner said.
So while the researchers demonstrate that the five-second rule is “real” in the sense that longer contact time results in more bacterial transfer, it also shows other factors, including the nature of the food and the surface it falls on, are of equal or greater importance.
“The five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food,” Schaffner said. “Bacteria can contaminate instantaneously.”Source
Before It Was Official -MythBusters Busted The Five Second Rule
Lisa Geng got her start as a designer, patented inventor,and creator in the fashion, toy, and film industries, but after the early diagnosis of her young children she entered the world of nonprofit, pilot studies, and advocacy. As the mother of two “late talkers,” she is the founder and president of the nonprofit CHERAB Foundation,co-author of the acclaimed book, The Late Talker, (St Martin’s Press 2003), and is instrumental in the development of IQed, a whole food nutrition meal replacement. Lisa currently serves as a parent advocate on an AAN board for vaccines, and is a member of CUE through Cochrane US. Lisa is currently working on a second book, The Late Talker Grows Up and serves as a Late Talkers, Silent Voices executive producer. She lives on the Treasure Coast of Florida.