Comparison of cannabinoids in hair with self-reported cannabis consumption in heavy, light and non-cannabis users.
Biological tests of drug use can be used to inform clinical and legal decisions and hold potential to provide evidence for epidemiological studies where self-reported behaviour may be unavailable or unreliable. We test whether hair can be considered as a reliable marker of cannabis exposure.



Hair samples were collected from 136 subjects who were self-reported heavy, light or non-users of cannabis and tested using GC-MS/MS. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for five cannabinoids (tetrahydrocannabinol [THC], THC-OH, THC-COOH, cannabinol and cannabidiol). Samples also were segmented in 1 cm sections representing 1 month exposure and the correlation between amount of cannabinoid detected and self-reported cannabis consumption tested.



All five cannabinoids were detected. Seventy-seven percent of heavy users, 39% of light users and 0% of non-users tested positive for THC. The sensitivity of detection of THC was 0.77 (0.56-0.91) comparing heavy cannabis smokers with light and non-users, whereas the sensitivity of other cannabinoids generally was considerably lower. The positive and negative predictive value of detection of THC were 0.57 (0.39-0.74) and 0.91 (0.82-0.97), respectively. A correlation of 0.52 (P < 0.001) was observed between self-reported monthly cannabis use and THC.



Hair analysis can be used as a qualitative indicator of heavy (daily or near daily) cannabis consumption within the past 3 months. However, this approach is unable to reliably detect light cannabis consumption or determine the quantity of cannabis used by the individual. [Taylor M, Lees R, Henderson G, Lingford-Hughes A, Macleod J, Sullivan J, Hickman M. Comparison of cannabinoids in hair with self-reported cannabis consumption in heavy, light and non-cannabis users. Drug Alcohol Rev 2017;36:220-226].
MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, UK.|School of Social and Community Medicine, University of Bristol, Bristol, UK.
Michelle
0000-0002-1849-8543
M
Taylor
School of Social and Community Medicine, University of Bristol, Bristol, UK.
Rosie
R
Lees
School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.
Graeme
G
Henderson
Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK.
Anne
A
Lingford-Hughes
School of Social and Community Medicine, University of Bristol, Bristol, UK.
John
J
Macleod
Alere Toxicology PLc, Oxford, UK.
John
J
Sullivan
School of Social and Community Medicine, University of Bristol, Bristol, UK.
Matthew
M
Hickman
D002186:Cannabinoids / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006197:Hair / Q000737:chemistry*; D006801:Humans; D002189:Marijuana Abuse / Q000175:diagnosis*; D008385:Marijuana Smoking / Q000378:metabolism; D011237:Predictive Value of Tests; D057566:Self Report; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D013997:Time Factors
D002186:Cannabinoids
cannabinoid; cannabis; hair testing; sensitivity; specificity