This project was initially inspired by the COVID-19 pandemic. Handwashing with soap and water proves to be the most effective hand washing method regarding pathogen removal. Soap is able to dissolve the fat membrane of numerous viruses, rendering them inactive. Soap and water washing also involves the physical hand scrubbing act as well as a rinsing step that can help remove additional pathogens/dirt/contaminants. However, water is not readily available for handwashing throughout the world. Hand sanitizers, such as alcohol-based sanitizers (ABHS) similar to Purell, seem like a great first step in developing a waterless hand cleanser. ABHS work well against many pathogens, including COVID-19. However, literature review shows that ABHS do not perform well against spore-forming bacteria that can result in detrimental diarrheal and respiratory illnesses. This project aims to identify factors that make a cleanser more viable for water-minimal hand washing and spore removal.
- Experiment design
- Project planning
- Technical writing
- Literature review
- Data analysis and summary
- Microbiology
The seemingly simple act of soap and water hand washing is not possible in all communities throughout the world since millions lack consistent access to clean water. As a result, deadly diarrheal and respiratory illnesses can be more easily spread throughout these communities. Many of these illnesses come from spore forming pathogens. Spores have a very robust structure that makes them difficult to kill. Alcohol-based hand sanitizers (ABHS) are often used as a solution to waterless hand washing, however, ABHS are unable to kill spores. To develop a water-minimal cleanser more suitable, factors that make a cleanser more effective for spore removal need to be determined. Various hand cleanser compositions and textures were tested to determine to what degree the cleanser composition contributes to spore removal versus to what degree the scrubbing and rinsing step contributes to spore removal. Hand cleansers studied included Dove bar soap, Purell, Betadine, Purell coupled with pumice, and wood ash paste. Zone of Inhibition tests and simulated hand wash experiments were performed to determine how hand wash composition and texture impact spore removal effectiveness. No cleanser composition alone was effective in killing the bacteria post growth. Cleansers that acted more as a scrub, such as the Purell with pumice, were the most effective in removing the bacterial spores in a simulated hand wash. In the future, waterless hand cleansers can be further optimized to assist in spore removal. Wet wipes with embedded particulate may be a good solution. The corresponding waste, cost, ingredients, ability to locally manufacture, ease of use, and more will all need to be considered before a final hand cleanser recommendation is determined.