Via AmericanGut:

Skin, the largest and most exposed organ of the human body, harbors an incredible diversity of molecules that have a number of origins. Such origins include but are not limited to human cells, microbes that live on the skin, and the surrounding external environment. Our daily routine as well as all of the soaps, creams, and moisturizers that we apply on the skin also contribute to the chemical composition of human skin.

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In the Dorrestein lab at the University of California San Diego, we have decided to develop a mass spectrometry based approach in combination with computational tools to study the chemical composition of human skin surface.

See the study: Molecular cartography of the human skin surface in 3D