EUROPEAN COMMISSION “Quality of Life and Management of Living Resources” Contract No. QLK4-2000-00196 Full Title EVALUATIONS AND PREDICTIONS OF DERMAL ABSORPTION OF TOXIC CHEMICALS Acronym EDETOX

In order to obtain better insight into the robustness of in vitro percutaneous absorption methodology, the intraand interlaboratory variation in this type of study was investigated in 10 European laboratories. To this purpose, the in vitro absorption of 3 compounds through human skin (9 laboratories) and rat skin (1 laboratory) was determined. The test materials were benzoic acid, caffeine and testosterone, representing a range of different physicochemical properties. All laboratories performed their studies according to a detailed protocol in which all experimental details were described and each laboratory performed at least three independent experiments for each test chemical. All laboratories assigned the absorption of benzoic acid through human skin the highest ranking of the three compounds (overall mean flux of 16.54 g/cm/h). The absorption of caffeine and testosterone through human skin was similar, having overall mean maximum absorption rates of 2.24 g/cm/h and 1.63 g/cm/h, respectively. In 7 out of 9 laboratories, the maximum absorption rates of caffeine were ranked higher than testosterone. No