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Cannabis Drug Testing on Hair


Hair testing analyzes a hair sample for parent drugs and their metabolites.  A hair specimen, collected from a donor's head or body, is sent to the laboratory and is screened for illicit substances.

can be detected in a hair sample from the head for up to 90 days. Body hair samples are said to detect the substance even longer. Usually provided by persons with short or limited hair on their heads.
Because hair grows about 1.5 inches (3.8 cm) in 90 days, hairs with a length of about 1.5 inches (3.8 cm) are targeted for cutting.
Note: Because it can take up to a week for drug-affected hair to grow above the scalp, hair tests can miss very recent drug use.

also see Drug Testing for: Blood, Oral, Other, and Urine.

Medical Journals for Cannabis Drug Testing on Hair

2017 - Study ~ Drugs in hair. Part I. Metabolisms of major drug classes.
Forensic Science Review.
2016 - Study ~ Influence of thermal hair straightening on cannabis and cocaine content
in hair.
Forensic Science International.
2016 - Study ~ Endocannabinoid concentrations in hair are associated with PTSD symptom severity.
International Society of Psychoneuroendocrinology.
2016 - Study ~ Metabolites of synthetic cannabinoids in hair-proof of consumption or false friends for interpretation? Analytical and Bioanalytical Chemistry.
2016 - Study ~ Evidence based decontamination protocols for the removal of external Δ9-
tetrahydrocannabinol (THC) from contaminated hair.
Forensic Science International.
2016 - Study ~ Assessment of rates of recanting and hair testing as a biological measure of drug use in a general population sample of young people.
Society for the Study of Addiction.
2016 - Study ~  Comparison of cannabinoids in hair with self-reported cannabis consumption in heavy, light and non-cannabis users. Drug and Alcohol Review (APSAD)
2015 - Study ~ Determination of XLR-11 and its metabolites in hair by liquid chromatography-tandem mass spectrometry. Journal of Pharmaceutical and Biomedical Analysis.
2015 - Study ~ Finding cannabinoids in hair does not prove cannabis consumption.
Scientific Reports.
2015 - Study ~ Hair analysis for Δ(9) -tetrahydrocannabinolic acid A (THCA-A) and Δ(9)
-tetrahydrocannabinol (THC) after handling cannabis plant material.
Drug Testing and Analysis.
2015 - Study ~ Ultra-structural hair alterations of drug abusers: a scanning electron microscopic investigation. International Journal of Clinical and Experimental Medicine.
2014 - Study ~ Hair analysis as a tool to evaluate the prevalence of synthetic cannabinoids in different populations of drug consumers.
Drug Testing and Analysis.
2014 - Study ~ Contribution of in utero drug exposure when interpreting hair results in young children. Forensic Science International.
2014 - Study ~ Simultaneous determination of five naphthoylindole-based synthetic cannabinoids and metabolites and their deposition in human and rat hair.
Journal of Pharmaceutical and Biomedical Analysis.
2014 - Study ~ Workplace drug testing in Italy: Findings about second-stage testing.

Drug Testing and Analysis.
2014 - Study ~ Proof of cannabis administration by sensitive detection of 11-nor-Delta(9)-
tetrahydrocannabinol-9-carboxylic acid in hair using selective methylation and
application of liquid chromatography- tandem and multistage mass spectrometry.

Drug Testing and Analysis.
2014 - Study ~ Is urine an alternative to cosmetically treated hair for the detection of drugs and alcohol?
Drug Testing and Analysis.
2014 - Study ~ 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.
Drug Testing and Analysis.
2014 - Study ~ Hair-based rapid analyses for multiple drugs in forensics and doping: application of dynamic multiple reaction monitoring with LC-MS/MS.
Chemistry Central Journal.
2012 - Study ~ Simultaneous analysis of several synthetic cannabinoids, THC, CBD and CBN, in hair by ultra-high performance liquid chromatography tandem mass spectrometry. Method validation and application to real samples. Journal of Mass Spectrometry,
University of Turin, Italy.

2011 - Study ~ The standardization of results on hair testing for drugs of abuse: An interlaboratory exercise in Lombardy Region, Italy. Forensic Science International.

2010 - Study ~ Hair analysis for Delta9-tetrahydrocannabinolic acid A--new insights into the mechanism of drug incorporation of cannabinoids into hair. US National Library of Medicine.

2010 - Study ~ 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid ethyl ester (THC-COOEt): unsuccessful search for a marker of combined cannabis and alcohol consumption.
Prime Outbound Medicine.

2007 - Study ~ Cannabinoid Concentrations in Hair from Documented Cannabis Users.

National Institute of Health.

2007 - Study ~ Differentiation between drug use and environmental contamination when testing for drugs in hair. Forensic Science International.

2007 - Study ~ Evaluation of the IDS One-Step ELISA kits for the detection of illicit drugs in hair. US National Library of Medicine.

2006 - Study ~ Deposition of cannabinoids in hair after long-term use of cannabis.

Forensic Science International.

2004 - Study ~ Cannabinoids in hair: strategy to prove marijuana/hashish consumption.  Science Direct.

2003 - Study ~ Comparison of meconium and neonatal hair analysis for detection of gestational exposure to drugs of abuse. Archives of Disease in Childhood. Fetal and Neonatal.

2003 - Study ~ Weather-induced changes in cannabinoid content of hair.

German Archive of Criminology.

2003 - Study ~ Assessing the potential of a "color effect" for hair analysis of 11-nor-9-carboxy-delta(9)-tetrahydrocannabinol: analysis of a large sample of hair specimens. Life Sciences.

2000 - Study ~ Stability of Cannabinoids in Hair Samples Exposed to Sunlight.

Clinical Chemistry.

1999 - Study ~ Are cannabinoids detected in hair after washing with Cannabio shampoo? Journal of Analytical Toxicology.

1998 - Study ~ Drugs in Prehistory: Chemical Analysis of Ancient Human Hair.

Forensic Science International.

1995 - Study ~ Testing human hair for cannabis. Forensic Science International.

Cannabinoid concentrations in hair from documented cannabis users

.pdf studies available

Forensic Science International
Volume 176, Issue 1, 21 March 2008, Pages 19-22
Practical Aspects of Drug Testing in Hair

Copyright © 2007 Elsevier Ireland Ltd All rights reserved.

Lolita Tsanaclis, and John F.C. Wicks

TrichoTech, No. 1 Pentwyn Business Centre, Cardiff CF23 7HB, United Kingdom

Received 31 May 2007; 
accepted 20 August 2007. 
Available online 5 November 2007.


The differentiation between systemic exposure and external contamination for certain drug groups has been frequently referred to as one of the limitations of in drug testing in hair. When hair samples are used, three steps are usually employed in order to minimise the possibility of external contamination causing a misinterpretation.

The first consists of decontaminating hair samples by washing the hair before analysis, the second is the detection of the relevant metabolites in the hair samples and the third is the use of cut-off levels. Difficulty in the interpretation arises when metabolites are not detected either due to external contamination of the hair or low doses of the drugs used. A wash protocol needs to be practical and ideally remove any drug deposited on the external portion of the hair.

We propose an additional step that helps considerably in the interpretation of the results with the aim to establish a consensus: the analysis of the wash residue (W) and its comparison with the levels detected in hair (H).

The wash residue is the remainder of a quick wash with methanol which is dried and reconstituted in buffer before analysis.

The detection of small quantities of analytes that are not susceptible to external contamination in the wash residue, such as metabolites or drugs such as dihydrocodeine, indicates that the washing procedure is in fact able to remove drugs from the hair shaft. Where the W/H ratio is less then 0.1 or null, it would tend to indicate drug use as opposed to environmental contamination.

Where the W/H ratio is above 0.1 but less than 0.5, it is likely to indicate possible use possibly combined with a level of external contamination. A W/H ratio greater than 0.5 is likely to indicate that the source of most of the drug in the wash residue is from external contamination.

In this last case, the source of levels detected in the hair is questionable, as it is not possible to be absolutely sure that all external contamination was removed, and so use cannot be confirmed.

Two hundred and sixteen hair samples from a population where external contamination could be expected (Police Investigations on drug related cases) and their wash residue were analysed. The W/H ratios of 891 results were evaluated over 13 analytes.

Between 74 and 100% of the analytes studied produced W/H ratios less than 0.5, in particular in cannabis (93%) and cocaine (95%), where external contamination is more likely because of the way the drug is used.

The data do show that while it is very important to always be aware of alternative explanations for test results, the likelihood of external contamination confounding the interpretation of hair tests can be reduced to manageable proportions.

Evaluation of the IDS One-Step ELISA kits for the detection of illicit drugs in hair

Forensic Sci Int. 2007 Aug 6;170(2-3):189-92. Epub 2007 Jul 12

Pujol ML, Cirimele V, Tritsch PJ, Villain M, Kintz P.

Laboratoire ChemTox, Illkirch, France.


This work presents the validation of a new immunological assay, the One-Step enzyme-linked immunosorbent assay (ELISA) tests from International Diagnostic Systems Corp. for the screening of drugs of abuse (cannabis, amphetamines, opiates, and cocaine) in human hair, with subsequent GC-MS confirmation.

After decontamination and segmentation into small pieces, 50 mg of hair sample were incubated in 1 ml of methanol during 16 h at 40 degrees C. A 100 microL aliquot was collected and evaporated to dryness in presence of 100 microL of methanol/hydrochloric acid (99:1, v/v) to avoid amphetamines loss. The dried extract was dissolved in 100 microL of the "sample and standard diluent" solution included in the kit.

This solution was submitted to analysis according to the recommended instructions of the manufacturer. During the validation phase, GC-MS confirmations were conducted according to our fully validated and published methods for opiates, cocaine, cannabis, and amphetamines determinations in hair. In a last development step, these procedures were slightly modified to directly confirm ELISA results by GC-MS using the methanolic extract.

Ninety-three specimens were simultaneously screened by the ELISA tests (103 for tetrahydrocannabinol (THC)) and confirmed by GC-MS. Twenty were found positive for cannabis (THC: 0.10-6.50 ng/mg), 21 for cocaine (0.50-55.20 ng/mg), 24 for opiates (6-acetylmorphine (6-AM): 0.20-11.60 ng/mg, MOR: 0.20-8.90 ng/mg, codeine (COD): 0.20-5.90 ng/mg), and 13 for amphetamines (AP: 0.20 and 0.27 ng/mg, methamphetamine (MAP): 0.30 and 1.10 ng/mg, methylenedioxymethamphetamine (MDMA): 0.22-17.80 ng/mg). No false negative results were observed according to the Society of Hair Testing's (SoHT) cutoffs (0.5 ng/mg for cocaine, 0.2 ng/mg for opiates and amphetamines, and 0.1 ng/mg for THC).

The One-Step ELISA kits appear suitable due to their sensitivity and specificity for drug of abuse screening in hair.

This technology should find interest in workplace drug testing or driving license regranting, especially when many samples have to be tested with a high rate of negative samples, as ELISA is an easy and high-throughput method.

Deposition of cannabinoids in hair after long-term use of cannabis


Hair analysis has shown great potential in the detection and control of drug use. Whether an assay is of quantitative value roughly corresponding to the amount of drug consumed, is still a matter of debate.

The present investigation was aimed at a possible relationship between the cannabinoid concentration in hair and the cumulative dose in regular users of cannabis. Hair samples from the vertex region of the scalp were obtained from 12 male regular users of cannabis, and 10 male subjects with no experience of cannabis served as controls. None of the subjects had his hair permed, bleached or colored.

Cannabis users provided information on drug use such as the current cannabis dose per day, the cumulative cannabis dose of the last 3 months, as well as the frequency of cannabis use during the last year. The concentration of delta-9-tetrahydrocannabinol (THC), cannabinol (CBN) and cannabidiol (CBD) in hair was determined using gas chromatography–mass spectrometry. Cannabinoids were present in any hair sample of cannabis users, but were not detectable in control specimens.

An increase in the amount of cannabinoids in hair with increasing dose was evident. The concentration of major cannabinoids (sum of THC, CBD and CBN) was significantly correlated to either the reported cumulative cannabis dose during the last 3 months or to the cannabis use during the last 3 months estimated from the daily dose and the frequency per year (r=0.68 or 0.71, p=0.023 or 0.014).

A significant relationship between THC and the amount of cannabis used could not be established. As a conclusion, the sum of major cannabinoids in hair of regular users may provide a better measure of drug use than THC.

Comparison of meconium and neonatal hair analysis for detection of gestational exposure to drugs of abuse

Arch Dis Child Fetal Neonatal Ed. 2003 March; 88(2): F98–F100.
doi: 10.1136/fn.88.2.F98.
PMCID: PMC1721515

B Bar-Oz, J Klein, T Karaskov, and G Koren

Background: Meconium and hair are two biological markers of in utero exposure to illicit drugs.
Objective: To compare the sensitivity of the two tests for different drugs.
Setting: Motherisk laboratory which tests in utero drug exposure in Toronto.
Methods: Cocaine, benzoylecgonine, opiates, cannabis, benzodiazepines, methadone, and barbiturates were measured in pairs of hair and meconium samples from the same neonates.
Results: Meconium was marginally more sensitive than neonatal hair for detection of cocaine and cannabis, possibly because it may detect second trimester exposure whereas hair grows only during the third trimester of pregnancy. There was a significant correlation between hair and meconium concentrations of cocaine, cannabis, and opiates.
Conclusion: In cases of clinical suspicion and a negative neonatal urine test, both meconium and hair are effective biological markers of in utero illicit drug exposure. Meconium may be more sensitive, but neonatal hair is available for three months whereas meconium is available for only one or two days. In contrast, the use of meconium, being a discarded material, is more acceptable to some parents than hair testing, which entails cutting scalp hair from the newborn.
Full Text
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Selected References
These references are in PubMed. This may not be the complete list of references from this article.
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Articles from Archives of Disease in Childhood. Fetal and Neonatal Edition are provided here courtesy of
BMJ Group

Are cannabinoids detected in hair after washing with Cannabio shampoo?

 J Anal Toxicol. 1999 Sep;23(5):349-51.

Cirimele V, Kintz P, Jamey C, Ludes B.

Institut de Médecine Légale, Strasbourg, France.


Today, cannabis plants are used in shampoo preparations, in foodstuffs (e.g., oils, noodles, crackers, etc.), and in beverages (e.g., tea).

These products often contain < 1% delta9-tetrahydrocannabinol (THC) in order to eliminate psychoactive effects, but some of them can include 1 to 3% of THC.

Gas chromatography-mass spectrometry (GC-MS) analysis of Cannabio shampoo revealed the presence of THC (412 ng/mL) and two constituents of cannabis plants, cannabidiol (CBD, 4079 ng/mL) and cannabinol (CBN, 380 ng/mL).

In order to verify if normal hygiene practices with Cannabio shampoo can result in positive tests for cannabinoids in hair, three subjects washed their hair with this shampoo once daily for two weeks. After this period, hair specimens were collected.

In the three hair specimens, THC, CBD, and CBN were never detected within their limits of detection, 0.05, 0.02, and 0.01 ng/mg, respectively.

We concluded that the use of Cannabis shampoo during normal hygiene practices cannot be considered as a source of potential contamination of hair.

In a second experiment, drug-free hair specimens (200 mg) were incubated in 10 mL water/Cannabio shampoo (20:1, v/v) for 30 min, 2 h, and 5 h.

After incubation, hair strands were washed with water and separated into two portions. One portion was extracted directly; the second was decontaminated with methylene chloride and then extracted.

After an incubation period of 30 min, the analysis of hair by GC-MS did not reveal the presence of THC, CBD, and CBN in hair, regardless of whether the hair was decontaminated.

After an incubation period of 2 h, specimens tested positive for CBD (0.11 ng/mg without decontamination and 0.10 ng/mg with decontamination) and CBN (0.02 ng/mg without decontamination and 0.02 ng/mg after decontamination).

After an incubation period of 5 h, specimens tested positive for CBD (0.25 ng/mg without decontamination and 0.14 ng/mg after decontamination) and CBN (0.02 ng/mg without decontamination and 0.02 ng/mg after decontamination).

In all cases, THC was never detected. Extensive but unrealistic use of Cannabio shampoo can cause drug-free hair to test positive for CBD and CBN but not for the primary psychoactive drug THC.

Weather-induced changes in cannabinoid content of hair

Arch Kriminol. 2003 Jan-Feb;211(1-2):9-18.


Kury M, Skopp G, Mattern R.

Institut für Rechtsmedizin und Verkehrsmedizin, Universität Heidelberg.


Authentic hair samples from Cannabis users and a drug free hair sample which was separately spiked with tetrahydrocannabinol (THC), cannabidiol (CBD) or cannabinol (CBN) were exposed outside as well as to natural sunlight at prevailing and elevated humidity in quartz glass tubes during 8 weeks. In addition, authentic and spiked hair samples were exposed to xenon arc radiation in a light exposure cabinet for 24 hours.

Stability of THC, CBD and CBN in authentic samples differed from that of the spiked hair. The radiation experiment revealed that CBN could not be measured in hair which had been spiked with THC. Under all conditions chosen the concentrations of THC, CBD and CBN decreased.

At high humidity the concentrations declined more rapidly. In both authentic and spiked samples THC was most unstable compared to CBD and CBN. Therefore, in hair analysis determination of CBD and CBN seems promising to detect Cannabis exposure even under unfavorable conditions.

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