Five-second rule: Fact or fiction?

(PhysOrg.com) -- Are copper coins protected from bacteria? Are certain reusable bags cleaner than others?
Can you drop a cookie on the floor and still eat it if it falls within the five-second rule?

Three local elementary and high school students tested these hypotheses for the 51st annual Bay Area Science and Engineering Fair (BASEF) and were recognized by the Michael G. DeGroote Institute for Infectious Disease Research.

The first place winner of the M.G. DeGroote Institute for Infectious Disease Research Internship Award was Jessica Knight, a Grade 9 student from St. Jean de Brebeuf Catholic Secondary School, whose project was entitled, "Hey copper can you arrest these germs?"

Knight's project tested the effectiveness of copper as an antimicrobial agent. For her study she swabbed coins with various amounts of copper and innoculated petri dishes that contained tryptic soy agar and observed and recorded the growth of bacteria colonies. Her results showed that the coin with the highest amount of copper harboured the least bacteria and the coin with the least amount of copper harboured the most bacteria.

As winner of the award Knight will have the opportunity to work alongside some of McMaster's most promising researchers in the Institute for Infectious Disease Research. Details about the internship are to be determined.

Second place was awarded to Catharine Bowman, a Grade 7 student from St. Augustine Catholic Elementary School whose project was entitled "There's bugs in my bag!"

Bowman's project determined if there is harmful bacteria or fungi in reuseable grocery bags, what type of bag is more sterile and the most effective way to clean them. Bowman swabbed a cloth bag, canvas bag, disposable plastic bag, a pull cart, and a reuseable plastic bag, before and after sterilization and grew any present bacteria or fungi on agar plates. She repeated the process for eight days. Her results showed that the bags had high levels of contamination as indicated by the number of colonies that grew and also showed that anti-bacterial spray was effective in killing the bacteria.

Third place went to Evan Adcock, a Grade 7 student from Trinity Christian School, for his project "Busting the five-second rule." Edcock's project determined if the "five- second rule", which suggests it is okay to eat food that has fallen on the floor within five seconds, is fact or fiction.

For his project, Adcock took various food items and dropped them on the floor for five seconds and 60 seconds and then took a tool called an inoculation loop to spread the bacteria around so he could count them. His experiment found there was a noticeable difference in the amount of bacteria between five seconds and 60 seconds, concluding that they longer food is left on the floor the more bacteria it picks up.

The BASEF recognizes science projects of Grades 7 to 12 students from Hamilton, Halton, Brant, Haldimand and Norfolk. This year more than 300 students competed for trips, prizes, and scholarships worth almost $140,000, with almost half of the participants winning a prize.

A list of winners, including pictures, titles and abstracts of the students' projects is available on the BASEF website.

Provided by McMaster University