Rutgers Professor who Debunked Five Second Rule Learned By Teaching Students

by Noa Halff


Photo courtesy of The University of  New Mexico


The Rutgers professor who recently debunked the “five second rule”, learned from his students by guiding and teaching them through his research process.

Schnaffner worked with Robyn Miranda, a graduate student in his laboratory at the School of Environmental and Biological Sciences, to carry out the research. Together, they debunked the widely-known assumption that it is safe to consume food after it has dropped on the floor within a five-second window,

The recent study was the first ever to scientifically investigate the ‘five-second rule’ and published in the American Society for Microbiology’s journal.

A large part of the process for Schaffner was to supervise Miranda, he said.

Schaffner and Miranda tested four surfaces, four foods and four contact times to gather their results.

The surfaces included stainless steel, wood, carpet and ceramic tile, and the food included watermelon, bread, butter and candy. The times ranged from less than one second, five seconds, 30 and 300 seconds. The transfer of bacteria were examined for each combination, totaling 128 combinations which were repeated 20 times each.

The composition of the food and the surface on which it fell matter as much if not more than the length of time it remained on the floor, according to the New York Times.

Bacteria can transfer to food that has fallen on the floor regardless of how much time has passed, Schaffner’s two-year study concluded. In some cases, it may take less than one second.

Both Schaffner and Miranda expected the results. But what Schaffner focused most throughout his research was guiding graduate students like Maranda.

It was a series of meetings on a regular basis where, Miranda would explain the experiments she had run and the problems she was having. Then Schaffner and Miranda would decide together what the next step in the research project would be.

Once Miranda finished the research, Schaffner gave her advice on how to analyze the data, make figures and tables, write her thesis and the peer-reviewed draft manuscript, he said.

“I like teaching my graduate students how to work in the laboratory, how to think about the results, how to analyze the results, and how to write up their findings in an appropriate way for a thesis or a scientific article,” Schaffner said.

But all research involves some issues, he said.

“As the graduate student tries to develop the appropriate scientific methods and the skills and techniques needed to get meaningful results,” Schaffner said.

Nonetheless, Schaffner would not do anything differently in the future. All in all, the experience was positive., he said.

“My graduate student successfully defended her master’s thesis, we got the research article published in a really good journal, and we got a wide variety of attention from the news media,” he said.

In regards to the impact of his research, Schaffner said he is not “naïve” to think that one article will change behavior of people.

But Schaffner is more concerned about the future of his students.

“Hopefully our research will make them think about the risks, and perhaps think a little bit deeper about our world and the microorganisms that we shared with,” Schaffner said. “It would be great if our research inspired some kids to consider a career in science.”