It's happened to all of us. Just as we grab a morsel of something mouthwatering, it slips from our fingers and lands on the floor. It's times like these when invoking the so-called 5-second rule is tempting. As the latest Berkeley Wellness Letter says, many people want to believe that "anything is fair game if you pick it up within that time frame."
But is there any evidence that a short stint on the floor is perfectly safe? The most definitive study was conducted in 2007 by a team led by food scientist Paul Dawson at Clemson University in South Carolina. What the researchers discovered may make you think twice about eating dropped food.
"No matter how quickly you pick it up, you're going to get significant transfer if there's bacteria there," Dawson told Squid Ink.
Published in the Journal of Applied Microbiology, the study found that five seconds is more than enough time for nasty microbes to latch on. Researchers coated wood, tile and carpet with Salmonella and then measured how long it took bologna and bread to become contaminated.
If you don't like bologna, you might assume there's no way it could be grosser, but it turns out that being plopped on the floor makes the lunchmeat even more unappetizing. Dropped food picked up 150 to 8,000 bacteria almost immediately, with the highest transfer on tile and the least on carpet. In case you're wondering: It takes only a few Salmonella spores to infect the digestive tract.
Dawson pointed out that some types of bacteria are harmless "and you're probably not going to get sick. On the other hand, food safety is a big issue and people die from food poisoning. So that's the other side of the coin."
In our home kitchens, countertops may actually be dirtier than the floor. Microbes from uncooked meat and unwashed produce can linger, posing a threat of illness. "The most likely place that you're going to have cross-contamination is where you've been handling raw food," Dawson warned.
Recently, his students proposed looking into the drinking game Beer Pong, which involves tossing Ping-Pong balls into beer that players drink. The researchers analyzed just how dirty those flying orbs are, and whether the germs they carry end up floating in the brew.
They found that Ping-Pong balls can be coated with anywhere from several hundred to 3 million pathogens. (We're guessing it depends on how many frat guys handle them.) "That's plenty of bacteria to make you sick, if it's the wrong ones," Dawson said. "We found almost all the bacteria were transferred to the drink."
This might explain why some players at tournaments have come down with what has been called "pong flu."
Clemson studies also have confirmed, as we suspected, that bacteria are transferred when you drink milk straight out of the carton (you know who you are) or when you double-dip with chips.
"It's kind of just common sense, but sometimes people forget about that," Dawson said. "I equate it to not wearing a seatbelt."
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