Sweat dissolution of lead and other selected metals in traditional eyeliner (Tiro): A search for mechanism of dermal penetration

In our search for data on the mechanism of dermal penetration for some selected potentially toxic metals in face-cosmetics, we studied a popular traditional face cosmetic (Tiro) sold in Nigeria and several developing countries. The methods employed were acid digestion for total content and dissolution in synthetic sweat for bioaccessible dose of Cadmium (Cd), Chromium (Cr), lead (Pb) and zinc (Zn). The mean total concentrations of the five Tiro samples investigated varied between 26.7 – 2430 mg/Kg, 111 – 296 mg/Kg, 650 – 671000 mg/Kg and 296 – 2710 mg/Kg, for Cd, Cr, Pb and Zn, respectively. The mean % dissolutions in synthetic sweat were as follows: Cd (5.6 %), Cr (5.0 %), Pb (0.3 %) and Zn (6.6 %). Therefore, we conclude that, since potentially toxic metals in Tiro are soluble in sweat, inadvertent use of this traditional eye-liner cosmetic may be a vehicle for the uptake of the metals during sweat reabsorption.