Wells: What made you want to write a book about cleanliness, and why is it coming out during a time of extreme fear over germs?
Hamblin: Well, I started working on this back in 2015 when there was some interesting new science coming out around the microbes that live on our skin. I wrote a story for The Atlantic that centered on a skin-probiotic company, for which I didn’t shower. I’d been leading up to it by minimizing my hygiene routine for a while, and for the story, I tried to see if I could just go with absolutely nothing. That got me into this idea of wondering why we do the things we do and how much of it is really associated with health. So I spent the last few years tracing those ideas and trying to break down the concept. I finished writing it at the end of last year and then this pandemic happened. Which, obviously, I did not anticipate. But I still think the book really holds up.
Wells: What does it mean to be clean today? Are we too clean? Not clean enough?
Hamblin: How would you describe “clean”?
Wells: Germ-free, I think, is usually the way I think of it. Post-soap.
Hamblin: It’s interesting that you think soap kills germs.
Wells: Doesn’t it?
Hamblin: No. Soap is a fatty acid that is combined with a base and heat and results in this product that you see as a bar of soap. It can become liquid depending on what kind of oils you use, but that’s all it is. Anything else that’s added to a soap makes it not a soap. For example, Dove is not a soap. It’s a beauty bar because there are emollients in it. Soap is just a collection of these molecules, called saponins, that will bind to an oil on one end and to water on the other. When you have, say, syrup on your hands and it’s really sticky and it’s not coming off with just water, you use soap and it miraculously washes the syrup off. One end of that molecule binds to the sticky, fatty syrup and the other binds to the water, and it washes away.
The idea that soap kills microbes on your hands is not accurate and potentially bad because the act of removing microbes from your hands comes from a combination of scrubbing water and soap. You know how people are asked to wash their hands for 20 seconds or to sing “Happy Birthday”?
Wells: Yes. I’ve heard that you should sing “Happy Birthday” twice.
Hamblin: Right. You wouldn’t have to do that if the soap was killing the virus like a hand sanitizer, which is killing microbes. The act of washing hands is really about scrubbing—that mechanical force of removing whatever is on your hands.
Wells: I thought the soap disintegrated the coronavirus cell walls?
Hamblin: It can, because the cell walls have some fats in them, but that is not the primary action. It’s really about scrubbing and about washing everything off that whole layer of skin.
Wells: Would you get the same result without soap?