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		Five-second rule on trial Misstropolis.com View Web Version June 13, 2007 In the hands of a child, food finds itself magnetically drawn to the unwashed floor. Swan-diving sandwiches and cannon-balling cantaloupe – tasty, apparently clean – stare up at the hungry grade-schooler, begging to be eaten. Enter the Five-Second Rule, the legend that food dropped on the floor less than five seconds is perfectly safe to eat. While the Rule embraces the possibility that something dangerous and invisible may in fact be lurking on the kitchen tile, it really demonstrates that kids, with a kind of fearless invincibility, don’t much care. In the world of children, the Rule is a fine compromise. So a recent series of scientific experiments testing the validity of Five-Second Rule probably strikes youngsters as akin to testing whether gum actually sits in your stomach for seven years – do you really want to know? Parents kind of do. So does a team of researchers at Clemson University in South Carolina, who recently conducted the laboratory equivalent of dropping a bologna sandwich on the floor to find out how long it takes for bacteria to jump aboard. Turns out, five seconds is more than enough time. To simulate a dirty floor, the scientists squirted high concentrations of the bacteria Salmonella Typhimurium, which can cause food poisoning, onto three types of surfaces – ceramic tile, carpet or wood. They let the bacteria sit awhile, and then dropped a slice of bologna or white bread onto the floor. They found that bacteria could survive on tile for at least 28 days – even when bone-dry. Ninety-nine percent of the bacterial cells were transferred from the tile to the bologna after the lunchmeat sat there for just five seconds. Bacteria survived for even longer periods of time in carpet, and bread’s bacterial load was similar to bologna’s. The researchers did find that the shorter the time the food touched the bacteria, the lower the numbers of bacteria that stuck to it, yet the amount that did stick was still enough to cause illness in an adult. The experiment was fascinating, but a bit contrived. So two undergrads at Connecticut College decided to take the test into the dirty real world – their college dining hall and snack bar. They dropped either “wet” food (apple slices) or “dry” food (Skittles) onto the floors and picked them up after either five, 10, 30 or 60 seconds or five minutes (they made no mention of the percentage of college students who actually practice the Five-Second Rule). After swabbing the sacrificial foods and growing whatever bacteria had managed to wiggle onto them, the college students found no germs on either the apples or the Skittles after five, 10 or 30 seconds. Finally, after one minute, the apple slices became contaminated, and, after five minutes, the Skittles. The wet food, it seems here, was more prone to contamination than the dry (unlike the bologna experiment), though both wet and dry took a lot longer to get that way than did the bologna. It should be mentioned that this work, unlike the Clemson study, was not published in a peer-reviewed scientific journal, but the results indicate that perhaps the real world is safer than the lab. In the end, these disparate experiments don’t really tell us whether or not we should grab that fallen sandwich, give it a quick blow, and shove it back into our toddler’s mouth. The CDC does estimate that 76 million cases of food-borne illness occur each year in the US, causing 5,200 deaths. Most of this is probably not a result of picking Skittles off a cafeteria floor, but other lax kitchen, farming and processing practices. Keeping raw poultry and meats separate from salads and other raw fruits and vegetables in your kitchen and shopping cart, and washing fruits and vegetables thoroughly before eating are far more effective ways to reduce the risk of food-borne illness. Yet the findings still give parents pause. Perhaps it does make more sense to give the family dog a chance at that suicidal bologna instead of your eight-year-old. Dogs like licking off the floor, and, as far as we know, have no Five-Second Rule to speak of. < Back to Articles