(4) organic catalysts
The job of catalysts in chemical reactions is to make the reaction go faster by lowering the amount of energy needed to activate the reaction. If less energy is needed for the reaction to occur, then the reaction can go faster because a large energy build-up is not needed.
This would directly affect the epidermis because blisters will develop within the surface of the skin. Having blisters on the epidermis will decrease the function of the skin to be an effective barrier to disease. This is because blisters are open wounds that are prone to infection. As infection passes through these openings, it will affect the dermis and the other layers of the skin. Bullae is actually an auto-immune skin disease.
Phosphorus. It's not abundant, but it's important. There are traces of it in our bones and in the "phospho-lipid bilayer" of the membrane.
Hope that helps!