We’ve all heard a lot recently about hand washing as an important step in illness prevention. Effective hand washing starts with soap and clean, running water. Either bar soap or liquid soap will work. Wet hands with clean water and apply soap. When we place unclean hands in water, nothing really happens. Add soap and scubbing and…..Voila! Magic.
Why is soap the magic ‘ingredient’? Soap is a surfactant, it has a water-loving or hydrophilic part and a water-fearing or hydrophobic part. The dirt, grease, viruses, or bacteria that may be on our hands are hydrophobic, they like to stick to the natural oils on our skin and they don’t like water. Soap can mix with both water and oil, the ‘head’ of the soap molecule is hydrophilic and attracted to water; the ‘tail’ of the soap molecule is hydrophobic and attracted to the oil or germs on our skin.
How do we make the magic happen? We start by wetting our hands with clean water (warm water works best but any temperature will work). Add soap and start scrubbing for 20 seconds. As we scrub our hands, the hydrophobic (water-fearing) part of the soap molecule is reaching out and attaches to oils and germs on our skin that are also hydrophobic. Soap grabs and traps more and more oils and germs as we scrub. Research shows us that 20 seconds of good scrubbing will remove enough dirt that we can call our hands ‘clean.’ After 20 seconds, rinse under clean, running water. In the rinsing process, the hydrophilic (water-loving) part of soap is captured by the water and the soap and all those germs and skin oils and associated ‘dirt’ that the soap has trapped are washed away, down the drain. It’s like magic. Dry clean hands on a clean towel or, better yet, a disposable paper towel. It’s important that the drying process doesn’t re-contaminate your hands.
Here are the magic steps:
- Wet hands with running water and apply soap.
- Rub hands together to make a lather. Continue rubbing hands for at least 20 seconds.
- Rinse hands well under running water.
- Dry hands using a paper towel or a clean cloth.
Is antibacterial soap even better? It’s pretty clear that the answer is ‘no.’ Antibacterial soaps have added ingredients like triclosan or triclocarban, which are hydrophobic molecules that can penetrate bacterial cell membranes and kill the bacteria. Sounds impressive, but studies have shown that antibacterial soaps are no more effective than regular soaps at removing bacteria. And the proliferation of antibacterial soaps in the marketplace can actually make it harder for doctors to fight disease.
What about hand sanitizer? The CDC recommends cleaning hands with soap and water, but if that’s not an option, then hand sanitizer with at least 60% alcohol is a good backup.
Wanting to explore more about hand washing?
- See a video of how astronauts wash their hands in space!
- More space videos: How do you wash your hair in space?
- Thinking of space (and stars) Kate Winslet explains hand washing; an accurate explanation of why soap and water hand washing is so important.
Stay well and food-safe.
