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Spot on Science: 5 Second Rule? Not So Fast!

Is it really okay to eat food that has fallen on the floor? Margaret dives into the science behind why the five second rule isn't a good one to follow. 

Class Discussion Questions:

1) Which food would collect more bacteria if dropped? Cantelope or pretzels? Why did you chose that food?

Read the Script:

Have you ever overloaded your plate and lost a cookie to the floor? Five second rule. You can eat it if it didn't touch the floor for more than five seconds, right? Maybe not. Some scientists at Rutgers University, took the five second rule to the lab to see if it really is okay to eat foods that have fallen on the floor. 

They dropped watermelon, buttered bread, plain bread, and gummy candies on different floor types, like tile, wood, and carpet. Then they tested the food for bacteria. Turns out contamination for some of the food was instant. Bacteria transferred the most to the watermelon and the least to the gummy candy. 

According to the researchers, this is because bacteria don't have legs to just hop on the food. They need moisture to help them hitch a ride. So the more watery the fallen food, the more bacteria it's going to pick up. And they did note the longer the food is on the ground, the dirtier it gets. But still, the five seconds is plenty of enough time to make you think twice about biting into that fallen cookie, especially if it's a gooey one.

Instructional Links

Website Article: Kids Health, 5-Second Rule http://kidshealth.org/en/kids/5-seconds.html

Magazine Article: Science News, Time to Retire the 5-second Rule, October 29, 2016 http://search.ebscohost.com/login.aspx?direct=true&db=mih&AN=118746355&site=src_ic-live&authtype=cookie,ip,custuid&custid=infohio

May Need Password

Game: Partnership for Food Safety Education, The Food Detectives Fight Bac! http://www.fooddetectives.com/welcome.html

PDFs: K-State Research and Extension, Kids a Cookin', Food Safety Tips http://www.kidsacookin.org/tips-and-techniques/food-safety-tips.html

Experiment: Science Bob: Experiments, Growing Bacteria for Science Fairs https://sciencebob.com/growing-bacteria-for-science-fairs/