In 2009 Prof. Dr. Uwe Wollina has published a scientific article on the beneficial properties of peat for the skin (Journal of Cutaneous and Aesthetic Surgery). In his introduction to the science article, the Professor mentions that the use of peat has a long tradition in spa medicine and rheumatology.
Whereas complete peat is mostly used under these circumstances, peat extracts and isolated humic substances are of greater interest in dermatology and cosmetology. Key words of this article were Fulvic acids, Humic substances and peat.
You are more than welcome to read and study Prof. Uwe Wollina article “Peat: A Natural Source for Dermatocosmetics and Dermatotherapeutics” in the Journal of Cutaneous and Aesthetic Surgery: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2840924/#CIT17