“…Venier, Larese, and Filon's studies show that metallic ions can easily permeate the skin (nickel, cobalt, and chromium) [ 33 ]. Human skin is permeable to Mg, Ca, K, Cu, Br, Rb, Ca, Fe, Pb, Cd, and Zn ions [ 34 – 37 ] and sulfates and nitrate anions [ 35 ]. Factors influencing percutaneous absorption through the skin include (1) physicochemical properties of the test compound, (2) skin properties and metabolism, (3) dose and volume of test substance, and (4) duration of exposure [ 38 ].…”