Figure 1.

Distribution of some relevant minerals in human epidermis (relative quantities, gradients) mg/g range: Na, S, K, P; µg/g range: Ca, Zn, Fe, (Mg: quantitative data not found; Cu, below the method’s sensitivity limit). Based on data found in the literature. Due to the differences in methodological approaches, this “skyline” graph shows only a relative abundance of various elements, as they are distributed throughout various epidermal layers (SB = stratum basale; SS = stratum spinosum; SG = stratum granulosum; SC = stratum corneum). Most of the minerals are not detected or in very low quantities in the horny layer. No consensus has been reached concerning calcium; depending on the method of detection, some groups continue to see it in the SC, the others claim its complete absence at this location in case of persistence of the functional permeability barrier.