If you stop showering, three days later, you might still be coated in chemicals from your shampoo, soap, deodorant, or sunscreen. At least that’s what a new map of human skin suggests.

In a new experiment, researchers from University of California-San Diego created a 3D topographical map of the chemistry and microbiology of the skin, swabbing 400 spots on each volunteer. While scientists have mapped out microorganisms before, this is the first time that anyone has looked at how the trillions of bacteria and other tiny organisms on the skin relate to chemistry.





It’s something that’s only possible now because of better technology in the lab. “We now have the computers to deal with the volume of data that is mapped in this study,” says Pieter Dorrestein, lead author of the study. “We also have more sensitive mass spectrometers that can detect molecules with much smaller samples.”

Most of the molecules they found couldn’t be identified–not surprising, since something similar happened when scientists originally tried to sequence the human genome. What was surprising: Out of the chemicals that could be identified, most came from cosmetics or personal care products.





The researchers also found correlations between the microorganisms on the skin and the chemicals present, something that they hope to study further. “One key question we want to answer is: Do personal care products alter the microbial communities?” says Dorrestein.

Ultimately, the new method of mapping could be used to better understand the effects of everyday products we use. Eventually, once thousands of people are sampled, the researchers may also discover new ways to test for diseases like skin cancer by swabbing skin, rather than taking a biopsy.





“It is an incredible powerful way to manage big data generated in the life sciences,” says Dorrestein. “For the molecules, mapping this way makes sense because one can now see the distribution. Because of this ability we can now readily ask questions about the chemistries we see.”