Dermal exposure to methamphetamine hydrochloride contaminated residential surfaces: surface pH values, volatility, and in vitro human skin.

This study evaluated pH effects on [(14)C] d-methamphetamine hydrochloride ([(14)C]-meth HCl) percutaneous penetration in vitro and volatility and stability in aqueous solution, on solid surface, or human skin using the finite dose technique and flow through diffusion cells. Results show that when the pH level exceeds 4 or 5, the nonvolatile [(14)C]-meth HCl salt becomes unstable, likely converting to its volatile freebase form. Additionally, contaminated smooth, dense surfaces retain and transfer more [(14)C]-meth HCl than those with rough, loose surfaces, especially under acidic conditions. Skin surface pH is a critical factor affecting the rate and magnitude of dermal absorption. [(14)C]-Meth HCl penetrates into and through the human cadaver skin quickly following exposure. [(14)C]-Meth HCl retained in the skin layer is released into the receptor fluid even if the contact material has been removed. Future exploration of decontaminant and removal procedure efficacies and their effect on dermal penetration of [(14)C]-meth HCl is recommended.