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Finding cannabinoids in hair does not prove cannabis consumption
Bjoern Moosmann1, Nadine Roth1, Volker Auwärter1
1Institute of Forensic Medicine, Forensic Toxicology, Medical Center - University of Freiburg, Albertstr. 9, 79104 Freiburg, Germany.
Scientific Reports
|October 8, 2015
Summary
Cannabinoids like THC are not reliably incorporated into hair after use. Even THC-COOH, a supposed proof of intake, can appear in hair from external contact, not just consumption. This challenges drug testing accuracy.
Area of Science:
- Forensic Toxicology
- Cannabinoid Science
- Hair Analysis
Background:
- Hair analysis for cannabinoids (THC, THC-COOH) is common in drug testing and child protection.
- Limited data exists on how cannabinoids incorporate into human hair.
- THCA-A, a cannabis precursor, is found in hair of handlers, raising questions about incorporation mechanisms.
Purpose of the Study:
- To investigate the incorporation mechanisms of THC, THCA-A, and THC-COOH into human hair.
- To evaluate the validity of current hair analysis interpretations for cannabinoids.
- To assess the potential for external cannabinoid transfer to hair.
Main Methods:
- Analysis of cannabinoids (THC, THCA-A, THC-COOH) in hair segments and sebum/sweat samples.
- Controlled studies on cannabinoid uptake and transfer.
- Comparison of cannabinoid presence in hair before and after known oral THC intake.
Main Results:
- THC and THCA-A were not significantly incorporated into hair after systemic uptake.
- THC-COOH was detected in hair, including segments grown before intake, and in sebum/sweat.
- Cannabinoids were found in the hair of non-consumers due to external transfer from consumers (handling, sweat, smoke).
Conclusions:
- Current assumptions about THC-COOH as definitive proof of intake are questionable.
- External cannabinoid transfer can lead to positive hair tests in non-consumers.
- Findings have significant implications for drug testing and child custody cases, requiring re-evaluation of interpretation standards.
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