Study says five-second rule for dropped food isn't actually a thing

Studies on this rule have been done for years. Rutgers University is only the latest to say that bacteria on the floor can almost immediately contaminate food as soon as it hits the ground.

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Rutgers Today reported that food science professor Donald Schaffner conducted research that found cross-contamination of food can occur in less than a second.

"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 told Rutgers Today. "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."

Related: 5-second rule backed up by science

The Associated Press reported that the findings were published in September's American Society for Microbiology journal, "Applied and Environmental Microbiology."

To test the rule, researchers tested four surfaces and four different foods: stainless steel, ceramic tile, wood and carpet, and watermelon, bread, bread and butter and gummy candy, respectively. They also used contact times of less than one second, five seconds, 30 seconds and 300 seconds.

Findings said that moisture contributes most to bacteria transfer. The gummy candy had the least amount of contamination and watermelon had the most.

The study also found that the longer food is on the ground, the more time it has to collect more bacteria, so if you must eat that piece of candy that fell on the floor, be quick about it.

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