Bacteria Be Gone! Do Non-Toxic Disinfectants Really Work?

Overview

Objectives/Goals The objective of my experiment was to determine if non-toxic disinfectants work as well as those which contain toxic materials in eliminating bacteria from a wooden cutting board. Methods/Materials I chose 5 household disinfectants that were developed to kill bacteria, three that contained toxic materials: bleach (10% Clorox ), ammonia and petroleum based (409), and sodium hydroxide (Mr. Clean), and two that contained less toxic ingredients: thymol from thyme oil, (7th Generation) and a homemade combination of white vinegar and hydrogen peroxide. I divided a wooden cutting board into six sections, one for each of the 5 different disinfectants, and one for a control. I contaminated the cutting board with raw chicken, then applied a different disinfectant to each of the 5 squares. I waited 10 minutes, wiped each surface with a sterilized sponge, and swabbed each square. I rubbed each swab on a labeled Petri dish, and allowed the bacteria to grow for 5 days at 62 degrees F. I measured the bacterial growth in each Petri dish to determine antimicrobial effectiveness. I conducted my experiment three times. Results Averaging the results from my three trials, the non-toxic mixture of hydrogen peroxide and vinegar eliminated the most bacteria from the cutting board. The other non-toxic disinfectant, 7th Generation, tied for 3rd place with Chlorox Bleach. The more toxic 409 came in 2nd, while Mr. Clean consistently failed to eliminate bacteria. Conclusions/Discussion The results of my experiment supported my hypothesis that the hydrogen peroxide and vinegar combination would eliminate more bacteria from a wooden cutting board than more toxic disinfectants. I believe vinegar and hydrogen peroxide, sprayed one right after the other, worked the best because, from my research, I learned that this combination oxidizes the surface of bacteria, causing their cell walls to split open, killing the bacteria. This method of killing bacteria seems to work better than more more toxic disinfectants which poison bacteria. This is important because it shows that people can use relatively non-toxic disinfectants to effectively clean cutting boards while avoiding the environmental and health problems that more toxic disinfectants can cause.

Competition history

• CSEF 2012 Product Science (Biological) (Junior Division Only) · Entry J2019

Resources

• CSEF project summary ↗

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