In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin.

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption.