Amphetamines and cannabinoids testing in hair: Evaluation of results from a two-year period

Abstract

This paper presents an overview of a set of amphetamines and cannabinoids tests performed on head hair samples from the Medico-Legal sector at the Madrid Department of the Spanish National Institute of Toxicology and Forensic Sciences during the years 2013 and 2014.The hair samples were tested for five stimulant phenylalkylamine derivatives -amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxy-amphetamine (MDA), and 3,4-methylenedioxy-N-ethylamphetamine (MDEA)- and/or two cannabinoids-Δ9-tetrahydrocannabinol (THC) and cannabinol (CBN)- by gas chromatography equipped with mass spectrometry detection in selected-ion monitoring mode, applying a method accredited to ISO/IEC 17025 standards. The test results were interpreted according to the confirmation cut-offs proposed by the Society of Hair Testing (SoHT) to identify chronic drug use. The ratios of positive results were studied in relation to gender, age, hair colour, dyeing and length of the tested samples to assess the independence from these variables or the association with them. Low, medium and high ranges of concentration were also estimated for each drug.21.94% of the 2954 hair samples tested for phenylalkylamine derivatives were positive for one or more substances. 16.38% of the samples were positive for AP, 12.09% for MDMA and only 0.44% for MA. 6.60% of the tested samples were positive for AP/MDMA combination. A total of 3178 samples were tested for cannabinoids, resulting in 53.40% positive for THC and CBN. Simultaneous tests for phenylalkylamine derivatives and cannabinoids were performed in 2931 of the samples; 14.94% of them were positive for THC, CBN, and one or more amphetamines.According to the results from the statistical analysis, the use of THC and MDMA vary with age and gender among the Medico-Legal sector in an extended area of Spain, while the use of AP appears to be independent of these variables. On the other hand, the results of THC in hair could be influenced by the length of the tested segment; therefore, a consensus regarding the hair length between 3.0 and 5.5cm for THC testing should be reached.