THCCOOH concentrations in whole blood: Are they useful in discriminating occasional from heavy smokers?
Article first published online: 31 OCT 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Drug Testing and Analysis
Special Issue: Cannabinoids part II: The current situation with cannabinoids
Volume 6, Issue 1-2, pages 155–163, January-February 2014
How to Cite
Fabritius, M., Favrat, B., Chtioui, H., Battistella, G., Annoni, J.-M., Appenzeller, M., Dao, K., Fornari, E., Lauer, E., Mall, J.-F., Maeder, P., Mangin, P., Staub, C. and Giroud, C. (2014), THCCOOH concentrations in whole blood: Are they useful in discriminating occasional from heavy smokers?. Drug Test Analysis, 6: 155–163. doi: 10.1002/dta.1581
- Issue published online: 14 JAN 2014
- Article first published online: 31 OCT 2013
- Manuscript Revised: 10 OCT 2013
- Manuscript Accepted: 10 OCT 2013
- Manuscript Received: 29 JUL 2013
- whole blood;
- heavy use;
- occasional use
Some forensic and clinical circumstances require knowledge of the frequency of drug use. Care of the patient, administrative, and legal consequences will be different if the subject is a regular or an occasional cannabis smoker. To this end, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) has been proposed as a criterion to help to distinguish between these two groups of users. However, to date this indicator has not been adequately assessed under experimental conditions. We carried out a controlled administration study of smoked cannabis with a placebo. Cannabinoid levels were determined in whole blood using tandem mass spectrometry. Significantly high differences in THCCOOH concentrations were found between the two groups when measured during the screening visit, prior to the smoking session, and throughout the day of the experiment. Receiver operating characteristic (ROC) curves were determined and two threshold criteria were proposed in order to distinguish between these groups: a free THCCOOH concentration below 3 µg/L suggested an occasional consumption (≤ 1 joint/week) while a concentration higher than 40 µg/L corresponded to a heavy use (≥ 10 joints/month). These thresholds were tested and found to be consistent with previously published experimental data. The decision threshold of 40 µg/L could be a cut-off for possible disqualification for driving while under the influence of cannabis. A further medical assessment and follow-up would be necessary for the reissuing of a driving license once abstinence from cannabis has been demonstrated. A THCCOOH level below 3 µg/L would indicate that no medical assessment is required. Copyright © 2013 John Wiley & Sons, Ltd.