Hair analysis for Δ9‐tetrahydrocannabinolic acid A (THCA‐A) and Δ9‐tetrahydrocannabinol (THC) after handling cannabis plant material. Issue 1 (21st June 2015)

• Record Type: Journal Article
• Authors: Moosmann, Bjoern; Roth, Nadine; Auwärter, Volker
• Is Part Of: Drug testing and analysis. Volume 8:Issue 1(2016:Jan.)
• Page Start: 129
• Page End: 133
• Publication Date: 2015-06-21
• Subjects: child protection -- external contamination -- hair analysis -- tetrahydrocannabinol -- tetrahydrocannabinolic acid A; Drugs -- Analysis -- Periodicals; Drug testing -- Periodicals; Chemistry, Forensic -- Periodicals; 615.1901
• DOI: 10.1002/dta.1830
• Languages: English
• ISSNs: 1942-7603

Abstract

Abstract : A previous study has shown that Δ 9 ‐tetrahydrocannabinolic acid A (THCA‐A), the non‐psychoactive precursor of Δ 9 ‐tetrahydrocannabinol (THC) in the cannabis plant does not get incorporated in relevant amounts into the hair through the bloodstream after repeated oral intake. However, THCA‐A can be measured in forensic hair samples in concentrations often exceeding the detected THC concentrations. To investigate whether the handling of cannabis plant material prior to consumption is a contributing factor for THC‐positive hair results and also the source for THCA‐A findings in hair, a study comprising ten participants was conducted. In this study, the participants rolled a marijuana joint on five consecutive days and hair samples of each participant were obtained. Urine samples were taken to exclude cannabis consumption prior to and during the study. THCA‐A and THC could be detected in the hair samples from all participants taken at the end of the exposure period (concentration range: 15–1800 pg/mg for THCA‐A and < 10–93 pg/mg for THC). Four weeks after the first exposure, THCA‐A could still be detected in the hair samples of nine participants (concentration range: 4–57 pg/mg). Furthermore, THC could be detected in the hair samples of five participants (concentration range: < 10–17 pg/mg). Based on these results, it can be concluded that at least parts of the THC as well as the major part of THCA‐A found in routine hair analysis derives from external contamination caused by direct transfer through contaminated fingers. This finding is of particular interest in interpreting THC‐positive hair results of children or partners of cannabis users, where such a transfer can occur due to close body contact. Analytical findings may be wrongly interpreted as a proof of consumption or at least passive exposure to cannabis smoke. Such misinterpretation could lead to severe consequences for the people concerned. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : Handling cannabis plant material leads to a relevant and persistent contamination of hair with Δ 9 ‐tetrahydrocannabinolic acid A (THCA‐A) and Δ 9 ‐tetrahydrocannabinol (THC). Concentrations and pattern of distribution along the hair shaft are not distinguishable from typical results in hair samples of known cannabis users. In the light of the results of this study, any use of THC cut‐off concentrations in hair to evaluate consumption habits or frequency is strongly discouraged.