Dermal exposure to methamphetamine hydrochloride contaminated residential surfaces II. Skin surface contact and...

This in vitro investigation evaluated [(14)C] - d-methamphetamine hydrochloride ([(14)C]-meth HCl) transfer from contaminated vinyl tile (non-porous and smooth) and upholstery fabric (rough and loose) to human skin. (14)C-Meth HCl transfer rate from vinyl to skin was rapid; a contact duration as brief as 15s resulted in measurable radioactivity in the skin and receptor fluid samples. In contrast, the transfer from fabric occurred more slowly: the amount of [(14)C]-meth HCl that was transferred from dry fabric after 2-h skin contact was one-fifth the amount transferred from vinyl after 5-min contact time. With moistened fabric, the transfer efficiency to skin after 2-h contact was seven times greater than that of dry fabric. While the duration of surface-skin contact appeared to affect the total dermal absorption of [(14)C]-meth HCl, it had little effect on the time point of maximum transdermal absorption. [(14)C]-meth HCl retained in skin continued to be absorbed after the contaminated material was removed. Mass balance in these studies was approximately 96%. In conclusion, [(14)C]-meth HCl penetrates into/through human skin quickly following skin contact with contaminated materials. The porosity of the contact surface and the moisture content appears to alter the degree of transfer and dermal penetration.