Cannabinoid findings in children hair – what do they really tell us? An assessment in the light of three different analytical methods with focus on interpretation of Δ9‐tetrahydrocannabinolic acid A concentrations

Abstract

Hair analysis for drugs and drugs of abuse is increasingly applied in child protection cases. To determine the potential risk to a child living in a household where drugs are consumed, not only can the hair of the parents be analyzed but also the hair of the child. In the case of hair analysis for cannabinoids, the differentiation between external contamination and systemic uptake is particularly difficult, since the drug is quite often handled extensively prior to consumption (e.g. when preparing a joint) and smoke causes a further risk for an external contamination. Δ9-tetrahydrocannabinolic acid A (THCA-A), the non-psychoactive biogenetic precursor of Δ9-tetrahydrocannabinol (THC), is a suitable marker for external contamination since it is not incorporated into the hair matrix through the bloodstream in relevant amounts. In the presented study, hair samples from 41 children, 4 teenagers, and 34 drug-consuming parents were analyzed for THCA-A, THC and cannabinol (CBN) applying methanolic extraction and a fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (Method 1). For comparison, a part of the samples was also analyzed applying alkaline hydrolysis followed by liquid/liquid extraction and gas chromatography-mass spectrometry (GC-M)S (Method 2), or by headspace-solid phase microextraction-gas chromatographymass spectrometry (HS-SPME-GC-MS) (Method 3). Furthermore, 458 seized marihuana samples and 180 seized hashish samples were analyzed for the same cannabinoids by gas-chromatography-flame ionization detector (GC-FID). In all but one of the hair samples, the concentration of THCA-A was higher than the concentration of THC and in 14 cases no THC could be detected despite the presence of THCA-A, suggesting that in almost all cases a significant external contamination had occurred. Within-family comparison showed a higher THCA-A/THC ratio in hair of children than of their consuming caregivers. Mean and median of this ratio of all hair samples (6.7 and 4.2) were between those of marihuana (11.0 and 8.3) and hashish (2.8 and 2.1) with a large variation in all samples. Comparison of the Methods 1 to 3 showed clearly that the choice of the analytical procedure has a strong influence on the quantitative results, mainly because of decarboxylation of THCA-A during hair hydrolysis by NaOH and other analytical steps, which lead to artifactually elevated THC concentrations. In conclusion, these findings suggest that the major part of the cannabinoids detected in the hair samples from children arose from an external contamination through 'passive' transfer by e.g. contaminated hands or surfaces and not from inhalation or deposition of side stream smoke.

Hair analysis for Δ9‐tetrahydrocannabinolic acid A (THCA‐A) and Δ9‐tetrahydrocannabinol (THC) after handling cannabis plant material

“…Even in the hair samples obtained four weeks after the first exposure the two cannabinoids were detected in hair samples of nine participants for THCA‐A and five participants for THC (Table ). When comparing the ratio of THCA‐A to THC ranging from 1.1 to 20 (median: 4.2) in the study samples with the ratios found in forensic samples (0.9 to 36, median: 4.2), the study findings strongly suggest that transfer through contaminated fingers is the main reason for the high concentrations of THCA‐A detected in routine samples and in the hair samples of children in a previous study . This hypothesis is supported not only by the absence of any relevant THCA‐A incorporation via the blood stream but also by the almost complete thermal decomposition of THCA‐A to THC and other products of thermolytic reactions during smoking …”

“…abstinence control). Given the instability of THCA‐A, high temperatures and/or alkaline conditions during the analytical process artifactually elevate the THC concentration thus creating a discriminatory treatment depending on the analytical method applied …”

“…rolling a joint, crumbling hashish). Furthermore, Δ 9 ‐tetrahydrocannabinolic acid A (THCA‐A), the non‐psychoactive biogenetic precursor of THC in Cannabis sativa , can be detected quite often in forensic hair samples alongside THC . Previous studies indicate that THCA‐A is not incorporated in relevant amounts into hair via the bloodstream .…”

Hair analysis for JWH-018, JWH-122, and JWH-210 after passive in vivo exposure to synthetic cannabinoid smoke

“…Subsequently, exhaled smoke and side-stream smoke may condense on any surfaces present, including furniture and the skin, hair, and clothes of people present. Moosmann et al [2] showed that large amounts of D 9 -tetrahydrocannabinol (THC) were incorporated into scalp hair after daily in vivo exposure to marijuana smoke over a 3-week period, supporting the hypothesis that findings of THC in the hair of cannabis users mainly derive from external contamination [3,4].…”

Experiences in Child Hair Analysis

“…Recently, Moosmann et al [24] analyzed 41 hair samples of children and 35 hair samples of drug consuming parents. For example, the differentiation between an active cannabis consumption and a passive drug exposure (i.e., through sidestream marijuana smoke, or transfer from contaminated hands) remains an unsolved problem in hair analysis.…”