The incorporation of methamphetamine into hair through the external environment, such as sweat containing the drug (liquid), smoke (vapour) and direct contact with drugs (solid), as well as the effectiveness of the decontamination procedures in removing the drug is investigated and presented in this paper.

ABSTRACT

This study evaluates the methamphetamine contamination routes through exposure to sweat, smoke in the environment and direct contact, as well as the effectiveness of decontamination procedures. For sweat exposure, drug-free hair samples (n = 10) were sprayed with artificial sweat containing amphetamine and methamphetamine at either ‘low’ (2.6 and 6.5 ng/mL, respectively) or ‘high’ concentration (3.1 and 25.2 ng/mL, respectively), 5 times (2 mL each time) per day for 5 days. In the smoke exposure, 2 mg of methamphetamine hydrochloride powder was heated and vapourised on one side of an enclosed cardboard box containing hair (n = 10) on the other side. In the direct contact with methamphetamine powder, 0.6 mg of methamphetamine hydrochloride was rubbed gently by hand onto hair (n = 5) for 1 min. Each contaminated hair sample was then subjected to either one of the 3 wash methods, namely, (1) sequential wash using dichloromethane, water, and methanol; (2) sequential wash by hexane and acetone; and (3) methanol wash only. All solvents and hair samples were analysed. The results show that it was relatively difficult to remove methamphetamine from the hair that was exposed to methamphetamine in artificial sweat, followed by methamphetamine smoke and then direct contact with the methamphetamine powder. None of the wash methods was able to completely remove amphetamine and methamphetamine from the contaminated hair. Overall, methods (1) and (3) show better decontamination efficacy than method (2), probably due to the polar protic nature of the solvents.