What is lurking on your skin?

By Shakir Sayani

We almost undoubtedly look at ourselves in the mirror, each morning, as we step out of the shower and are about to carry on with our daily grooming and hygiene rituals. Most of us are concerned with the tone and complexion of our skin or the unfortunate occurrence of an unsightly blemish. However, it is unlikely and understandable, that beyond the thoughts of our tone, complexion and removal of blemishes, we do not give much thought to what else could be there. Could there be something else lurking on our skin? Although the prior statement may sound like something out of a science fiction novel or movie, it is nevertheless completely true.

Our skin is normally populated with a large number of different microbes called normal flora. Recent studies have revealed that our daily hygienic routines leave a lasting impression on our skin, literally. In order to gain a better understanding of the effects of various hygienic practices on our skin’s resident microbes, American and German researchers carefully studied the link between the microbial diversity of 850 kinds of skin-residing microbes with the distribution of chemical molecules present on the skin.

Researchers at the University of California, San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences were able to make a three-dimensional map of the skin surface, showing both the microbial and chemical makeup present. This is the first study ever to address both of these variables in parallel.

About 400 swabs were collected from different places on the body of a healthy male and female, abstained from bathing and using any hygienic or beauty product for 3 days. Using mass spectrometry and DNA sequencing, the chemical and molecular composition as well as the microbial species present on each swab was determined. Scientists found that over 8% of the chemical content from swabs was traceable to persistent residues from cosmetics and/or beauty products like sunscreen or shampoo.

For instance, after we are done shampooing our hair, we think that a good rinse with water removes the residual chemicals originating from the shampoo. Well, not quite so. The investigators discovered that even after rinsing, certain chemicals from the shampoo can become lodged onto our hair and scalp surface, almost serving as a memory of the shampooing event. “Personal care products we use every day really stay on the skin … for moisturizers this would be advantageous,” says co-author Pieter Dorrestein, PhD, professor of pharmacology in the UC San Diego Skaggs School of Pharmacy. Even though we shed millions of skin cells every day, these residues were still present.

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