Human scalp permeability to the chemical warfare agent VX

► Human scalp is significantly more permeable to VX than abdominal skin. ► Pig-ear skin is the most relevant model to predict the in vitro human scalp permeability to VX. ► The follicular pathway significantly contributes to the skin absorption of VX through human scalp. ► The hair follicles and the stratum corneum significantly contribute to the formation of a skin reservoir for VX. The use of chemical warfare agents such as VX in terrorism act might lead to contamination of the civilian population. Human scalp decontamination may require appropriate products and procedures. Due to ethical reasons, skin decontamination studies usually involve in vitro skin models, but human scalp skin samples are uncommon and expensive. The purpose of this study was to characterize the in vitro permeability to VX of human scalp, and to compare it with (a) human abdominal skin, and (b) pig skin from two different anatomic sites: ear and skull roof, in order to design a relevant model. Based on the VX skin permeation kinetics and distribution, we demonstrated that (a) human scalp was significantly more permeable to VX than abdominal skin and (b) pig-ear skin was the most relevant model to predict the in vitro human scalp permeability. Our results indicated that the follicular pathway significantly contributed to the skin absorption of VX through human scalp. In addition, the hair follicles and the stratum corneum significantly contributed to the formation of a skin reservoir for VX.