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Clinical Chemistry 50: 596-602, 2004. First published January 15, 2004; 10.1373/clinchem.2003.026120
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(Clinical Chemistry. 2004;50:596-602.)
© 2004 American Association for Clinical Chemistry, Inc.

Drug Monitoring and Toxicology

In Vitro Contamination of Hair by Marijuana Smoke

Jana Thorspecken1, Gisela Skopp1,a and Lucia Pötsch2

1 Institut für Rechtsmedizin und Verkehrsmedizin der Universität Heidelberg, Heidelberg, Germany. 2 Institut für Rechtsmedizin der Universität Mainz, Mainz, Germany

aAddress correspondence to this author at: Institute of Legal Medicine, Voss-Strasse 2, 69115 Heidelberg, Germany. Fax 49-6221-565252; e-mail gisela_skopp{at}med.uni-heidelberg.de.


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Abstract
 
Background: The deposition of cannabinoids on/into hair from environmental smoke can be considered as a potential source of drug findings in hair. We studied external uptake of cannabinoids from marijuana smoke, investigating possible influencing factors on drug uptake and the efficiency of decontamination procedures.

Methods: Strands of a natural hair sample were moistened with water, greased with sebum or sebum/sweat, or bleached or permed. Treated and untreated samples were exposed to marijuana smoke for 60 min. Aliquots of each hair strand were either kept unwashed or were washed with methanol, dichloromethane, or 5 g/L dodecyl sulfate in water. Cannabinoid concentrations in unwashed and washed hair samples, as well as in air samples collected from the exposure chamber and in the marijuana sample being combusted, were quantified by gas chromatography–mass spectrometry or gas chromatography.

Results: Cannabinoids were deposited on the hair fibers from marijuana smoke. Cannabinoid concentrations were dependent on air concentration and hair pretreatment. Uptake was less in untreated than in pretreated hair. Concentrations were increased in damp hair, but were even higher in greased hair. There was no significant difference in concentration between bleached and permed strands. External contaminants were completely removed by washing with methanol and dichloromethane in untreated hair only. Washing with dodecyl sulfate in water was insufficient in all cases.

Conclusions: Exposures of hair to marijuana smoke yields detectable cannabinoids depending on concentrations in the air, hair care habits, and cosmetic treatment. Environmental marijuana smoke exposure may produce false-positive or falsely increased test results in hair.


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Introduction
 
Hair analysis has shown great potential in the detection and control of drug use (1)(2)(3)(4)(5) because drugs become entrapped during hair fiber formation and stabilized in the keratin matrix. The accurate interpretation of analytical results continues to be difficult because many questions concerning drug incorporation into hair remain unanswered. This applies particularly to cannabinoid findings in hair. Incorporation of cannabinoids into hair is weak compared with basic substances such as cocaine or methylenedioxymethamphetamine (6)(7)(8). The concentration of {Delta}9-tetrahydrocannabinol (THC) 1 that can be detected in hair after active drug use is typically far less than 5 µg THC/g of hair (7). The analysis of hair to identify cannabis use is often restricted to the identification of THC, because 11-nor-9-carboxy-{Delta}9-THC concentrations, reported to be <0.1 µg/g of hair, cannot be determined by routine gas chromatography–mass spectrometry (GC/MS) procedures (9)(10). Consequently, for cannabinoids, the use of the metabolite-to-parent drug ratio, proposed to differentiate active use from passive exposure, cannot be applied to routine cases (11)(12).

Although detectable amounts of THC in the blood of nonsmokers have been demonstrated after exposure to marijuana smoke, the low concentrations in blood in these circumstances make it unlikely that the amounts of THC in hair would be measurable (13). In addition to inhalation of smoke, the deposition of a drug on/into the keratin matrix of hair from the environment has been proposed as a further source of drug findings in hair. Romano and coworkers (14)(15) showed that manual contamination with powdered cocaine or heroin hydrochloride and hashish or marijuana produced positive drug findings and that decontamination procedures were not sufficient to remove drugs that had penetrated into hair fibers. Several authors (16)(17)(18) have investigated the deposition of cocaine from the vapor produced by crack smoking, but similar results for cannabis are not yet available.

The objective of the present study was to answer the question of whether marijuana smoke can produce positive cannabinoid findings in hair. Possible influencing factors of drug deposition on the keratin matrix, such as moisture, sebum, and bleaching or perming procedures, were investigated. In addition, commonly used washing procedures were applied to determine whether they are sufficient to remove drugs attributable to environmental uptake.


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Materials and Methods
 
study design
A sample of natural dark blonde hair was divided into several strands. One set of samples was not treated (control samples), whereas the others were moistened with tap water (series 1), greased with artificial sebum or a mixture of sebum and artificial sweat (series 2), or bleached or permed (series 3). Before exposure to smoke, the cut ends of all hair fibers were sealed with nail polish to avoid drug uptake by the cross-sections. The proximal sites of untreated (control samples) and treated hair strands of series 1–3 were fixed with a hairgrip, which was attached on a grid at the bottom of a vacuum desiccator. The loose ends of the hairs in each sample did not touch each other, the walls of the desiccator, or the grid. The desiccator was evacuated, and marijuana smoke was delivered by a beekeeper pipe (0.5 g of marijuana mixed with ~1 g of tobacco; Bienen-Meier) through a tubing (50 cm) that was inserted into the desiccator (6.11 L). The samples were kept in the closed chamber for 60 min. The tubing was replaced, and the desiccator was cleaned between uses.

Both ends of the exposed hair fibers were cut (~3 mm), and hair samples were further divided into eight strands and weighed (~250 mg/strand). In a particular series, two samples of each hair strand were kept unwashed, whereas two samples at a time were treated with 5 mL of one of the following wash solutions at room temperature for 10 min: (a) methanol (three times), (b) dichloromethane (three times), or (c) aqueous dodecyl sulfate (5 g/L) followed by distilled water (three times). The dried samples were pulverized in a ball mill (Retsch) for 4 min.

For the determination of air cannabinoid concentrations in the exposure chamber, we collected 4 mL of air directly after combustion of the marijuana/tobacco mixture with a gas-tight syringe (Hamilton) through a GC septum for autosampler use, which was attached to the desiccator by a three-way stopcock. The gas was then passed through 2 mL of n-hexane containing 100 ng of deuterated THC as internal standard in a head space vial. The n-hexane phase was taken to dryness under nitrogen, and the residue was further processed as reported for the hair samples. In each series, four air samples were collected.

In addition, two aliquots of each wash solution (0.1 or 1.0 mL) were analyzed for cannabinoids.

Determination of THC, cannabinol (CBN), and cannabidiol (CBD) in the marijuana sample being combusted involved extraction with methanol (50 mg of ground plant material/5 mL of methanol; duplicate measurement) and analysis by GC with a nitrogen–phosphorous detector (Shimadzu).

materials
Kerling International Haarfabrik supplied the hair sample. It had been pooled from natural hair strands of Caucasian origin and mixed to homogeneity as far as possible. This hair sample was used for the experiments as well as for preparation of calibrators. All chemicals were of the highest purity available. NaCl, NaOH, HCl, NH4Cl, acetic acid, lactic acid, squalene, and cholesterol were from Merck, and n-hexane, methanol, and dichloromethane were purchased from Roth. CBN and CBD were obtained from Lipomed, and THC and THC-d3 were from Cerilliant. For derivatization, N,O-bis(trimethylsilyl)trifluoroacetamide containing 10 g/L trimethyltrichlorosilane (Fluka) was used. Cacao butter, purified wool wax, and Vaseline were obtained from a local pharmacy.

Artificial sweat was made according to the formula proposed in the 3160/2 ISO standard (19), and sebum was prepared as reported previously (20). Two parts of artificial sweat were thoroughly mixed with one part of sebum at 40 °C. Approximately 200 mg of sebum or sebum/sweat was applied to 1 g of hair fibers.

For bleaching and perming, commercially available formulas for home use (Poly Blonde; Poly Lock) were applied to the hair strands according to the manufacturer’s instruction.

gc/ms analysis
The cannabinoid concentrations in unwashed and washed hair samples of series 1–3, in wash solutions, and air samples were determined by GC/MS. Approximately 50 mg of the hair powder was weighed, 250 ng of THC-d3 was added as internal standard, and the sample was dissolved in 1 mL of 0.1 mol/L NaOH (100 °C for 30 min). The solution was adjusted to a pH of 5.5 with 1.0 mol/L HCl, and THC, CBN, and CBD were extracted into n-hexane and quantified by GC/MS after silylation, as described elsewhere (21). Measurements were performed in duplicate for each hair sample, and values are presented as the mean.

THC-d3 was added as internal standard to the wash solutions, and aqueous wash solutions were extracted into n-hexane at pH 5.5 (0.1 mol/L HCl), whereas methanol and dichloromethane washings were taken directly to dryness (nitrogen and 40 °C). All residues were processed as reported for hair extracts.

The GC/MS system consisted of a HP 6890 gas chromatograph and a HP 5973 mass spectrometer (Agilent), and the compounds were eluted from a CP-Sil 5 column [12.5 m x 0.53 mm (i.d.); Chrompack]. Detection was by ionization in the electron impact mode (70 eV), with the scan mode set at single-ion monitoring (THC, m/z 299, 314, and 271; THC-d3, m/z 302, 317, and 274; CBN, m/z 295, 310, and 298; CBD, m/z 231, 246, and 314). For quantification, the peak-area ratio for THC (m/z 299) and its internal standard (m/z 302) was determined; for CBN and CBD, the response factors were calculated against THC-d3 (m/z 302:231 for CBD and m/z 302:295 for CBN) and referenced to the particular calibration curves. A separate calibration curve constructed with a stock solution of the analytes in n-hexane was prepared for the air samples. The seven-point calibration curves covered a concentration range of 0.5–50 µg/g of hair, 0.5–50 µg/L of air, and 1–250 µg/L of wash solution. The limits of detection and quantification were determined from the calibration curves according to DIN 32645 (22).

The within-run imprecision (CV) was determined by extracting and assaying five aliquots of hair to which the cannabinoids had been added at the lowest and highest calibrator concentrations in a single batch. Between-run imprecision was determined by testing two single aliquots (lowest and highest calibrator concentrations) in five consecutive assays. The recovery of analytes from n-hexane was calculated from samples to which cannabinoids had been added (10 µg/L) with the internal standard added before evaporation (n = 5) of the solvent or directly to the residue (n = 5). A similar procedure was applied to estimate the recovery of the analytes from aqueous wash solutions (n = 5).


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Results
 
The marijuana sample used for the experiments contained 86 mg/g THC and 0.4 mg/g CBN. CBD was not detectable at a detection limit of 0.01 mg/g and could not be identified in any air or hair sample. The mean air concentrations of THC and CBN (n = 4) determined in series 1–3 are given in Table 1 . Mean (SD) recovery of the analytes in air samples from n-hexane was 93 (8)% for THC, and 71 (8)% for CBN (n = 5). In air samples that were collected near the end of smoke exposure, THC and CBN concentrations had decreased to as little as 20% of the initial values (data not shown). The concentration of CBN relative to THC was considerably higher in air specimens than in the marijuana sample, whereas the ratio of CBN to THC in smoke was similar to that deposited on hair fibers.


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  		Table 1. THC and CBN concentrations in untreated and treated hair samples without and after washing.

Substantial amounts of both compounds were detectable in hair fibers; amounts were dependent on air concentrations as well as on the pretreatment of the hair sample (Table 1Up ). Duplicate measurements agreed within 5% of the mean. Intraassay CV ranged from 2.6 (3.3)% to 7.9 (8.2)%, whereas interassay CV were between 4.1 (3.9)% and 8.3 (8.4)% at the highest and lowest THC (CBN) calibrator concentrations, respectively. In all series, the concentrations of THC and CBN were always less in untreated hair than in pretreated hair. Cannabinoid concentrations were higher in hair moistened with tap water or a mixture of sebum and sweat than in apparently dry hair, and were still higher in greased, dry hair. We found no significant difference in THC or CBN uptake from marijuana smoke among bleached and permed hair samples.

The efficiency of the various wash procedures for removal of cannabinoids was dependent on hair pretreatment as well as on the particular wash solution. Methanol and dichloromethane removed both THC and CBN completely from untreated hair. Methanol was superior to dichloromethane when applied to damp hair, whereas dichloromethane completely removed cannabinoid residues from bleached hair strands or hair treated with sebum or sebum/sweat. After shampooing (dodecyl sulfate) and three wash cycles with water, significant amounts of THC and CBN remained regardless of whether the hair was pretreated. As for methanol and dichloromethane, this wash procedure was more effective when applied to untreated hair.

The highest concentrations of THC and CBN were always observed in the first wash for procedures a through c, and concentrations in wash solutions from procedure c were generally lower than in procedures a or b. Mean (SD) recoveries of THC and CBN from aqueous wash solutions were 87.2 (3.6)% and 86.8 (5.8)%, respectively. In series 1 (individual data not shown), total concentrations of THC and CBN did not differ significantly between methanol and dichloromethane washes 1–3. In apparently dry hair, total cannabinoid concentrations in the methanol washes were 1634 µg/L THC and 131 µg/L CBN, and the total concentrations in the dichloromethane washes were 1689 µg/L THC and 286 µg/L CBN. For damp hair, the total concentrations in the methanol washes were 1657 µg/L THC and 132 µg/L CBN, and the total concentrations in the dichloromethane washes were 1641 µg/L THC and 256 µg/L CBN. However, concentrations were considerably lower in the wash solutions of procedure c. In solutions from apparently dry hair, the THC and CBN concentrations were 424 and 44 µg/L, respectively, and in solutions from damp hair, the concentrations were 475 and 45 µg/L, respectively.

The cannabinoid concentrations found in wash solutions from series 2 and 3 are shown in Tables 2 and 3 . In series 2, cannabinoid concentrations in washings from hair samples always decreased in the following order: untreated hair > hair treated with sebum/sweat > hair treated with sebum. We observed very rapid decreases in the amounts of THC and CBN after the first wash for procedures a and b compared with washes from series 1 or 3. The highest analyte concentrations in wash solutions from series 3 resulted from bleached hair for procedures a–c. There was no difference between the methanol and dichloromethane washings from untreated and bleached hair.


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  		Table 2. THC and CBN concentrations in wash solutions in series 2.


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  		Table 3. THC and CBN concentrations in wash solutions in series 3.


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Discussion
 
Although cannabis is widely used and smoking is the most popular route of drug administration, contamination of hair from external marijuana smoke has been minimally investigated. Strano-Rossi and Chiarotti (23) exposed a hair sample to marijuana smoke for evaluation of sample decontamination procedures. Data for cannabinoid concentrations of exposed hair and/or in wash solutions were not reported. Hair samples from individuals exposed to marijuana or hashish smoke for 15 min in a small room tested negative for THC after four to five successive washings with dichloromethane (24).

The present study showed that a single exposure to marijuana smoke may produce a positive cannabinoid finding in hair. The THC concentration in the desiccator was close to the concentrations in air reported in a study of passive exposure by Cone et al. (25), in which individuals had been exposed to the smoke of 16 marijuana cigarettes and air concentrations of THC were up to 10.9 µg/L. In the present study, the deposition of cannabinoids was found to be influenced by hair care habits and cosmetic treatments.

A sufficient amount of a fairly homogeneous hair sample was necessary to perform the experiments. Dark blonde is the most common hair color in Germany; we therefore chose a pooled, dark blonde hair sample to avoid possible effects attributable to interindividual differences in hair morphology, as indicated by the study of Zahlsen et al. (26) on environmental tobacco smoke exposure. The influence of melanin on the drug content of hair has been hypothesized to be much lower for environmental contamination than for systemic incorporation via the hair follicle. On the basis of the findings of Zahlsen et al. (26), that uptake of air nicotine was not influenced by hair pigmentation, in our study, hair color should not affect the results. After diffusion into the keratin fiber, a drug–melanin association can occur only on the surface of the pigment granules for basic drugs such as nicotine. As already shown for various acidic drugs (4)(7), THC is not presumed to exhibit a high melanin affinity. We also found no reports in the literature that indicated that the cannabinoid content in hair of cannabis users might be influenced by hair color. For environmental contamination by acidic drugs, factors that affect diffusion into the keratin fiber are believed to be more important than the melanin content of the particular hair sample.

CBD present in plant material is also detectable in marijuana smoke and hair samples (27)(28)(29); however, some plants have been found to contain no detectable amounts of CBD (30). The marijuana sample used for the present experiments was derived from highly bred cannabis plants, which explains the negative CBD finding (27). A considerably higher concentration of CBN relative to THC could be measured from air and hair samples, although the proportion of CBN in the plant material used was very low compared with the THC concentration. This observation can be explained by formation of CBN from THC during smoking. Mikes and Waser (31) concluded from GC/MS analysis of smoke constituents from cigarettes impregnated with THC that CBN was formed during combustion by dehydrogenation of THC to CBN.

The ratio of THC and CBN deposited on hair was related to the ratio of both compounds in environmental smoke. Similar observations have been reported from controlled 72-h exposure of hair samples to environmental nicotine smoke (32). In this investigation, the chamber experiments revealed a linear increase in hair nicotine concentration with increasing chamber exposure up to 4.8 µg nicotine/L of air, suggesting the uptake was governed by an equilibrium between nicotine in air and on the hair surface. For chemicals such as polychlorinated dibenzofurans, rapid adsorption equilibrium with hair occurred within <1 h (33).

At present, the detailed mechanisms and major influences governing drug uptake from environmental gaseous or particulate matter are largely unknown. For cocaine, concentrations in hair samples soaked in aqueous solutions of cocaine were far higher than those measured in hair samples exposed to crack smoke (18). A 5-min exposure of hair to an aqueous solution containing 1 mg/L cocaine hydrochloride was sufficient to produce measurable cocaine concentrations of 0.2 µg/g of hair (34). From experiments involving dyestuffs (35)(36)(37) and drugs such as opiates(38), it can be assumed that, in intact hair, diffusion via the cuticle cell edges along the endocuticle and the cell membrane complex proceeds rapidly. From there, solutes are probably further distributed throughout the other morphologic components of hair by a slower process. Diffusion is largely promoted by water molecules, which allows the swelling of nonkeratins in hair, thus enlarging the "gaps" on the hair surface and facilitating drug entry into hair. This may explain the higher cannabinoid concentrations in hair samples moistened with tap water or treated with sweat/sebum compared with untreated, apparently dry hair specimens. In series 2, trapping of cannabinoids by the greasy film on the hair surface can be hypothesized because THC and CBN are highly lipophilic and essentially water insoluble (27). Indeed, a higher concentration was found in hair treated solely with sebum.

From experiments on diffusion of dyestuffs and drugs, there is also evidence that adsorption and diffusion of foreign matter is strongly influenced by the hair morphology (35)(36)(37)(38). Scalp hair plays an important role in individual appearance and, therefore, is frequently subjected to cosmetic treatments such as perming or bleaching. Both treatments lead to degradation of hair proteins and lipids and damage the nonkeratin layers of the cuticle, which represent the regions most vulnerable to these chemical interactions (39). Accordingly, as we expected, cannabinoid adsorption onto, or diffusion into, hair was increased in cosmetically treated hair compared with the untreated specimen (series 3).

Hair samples are generally cleaned before analysis to remove foreign matter from the hair surface. For cannabinoids, various wash procedures have been proposed, such as washing with dichloromethane, methanol, Tween 80, phosphate buffer, or petroleum ether (9)(10)(21)(23)(24)(28)(40). In the present study, dichloromethane and methanol were chosen because cannabinoids are slightly soluble in short-chain alcohols and chlorinated hydrocarbons. Methanol allows swelling of the hair, whereas dichloromethane does not. Typical hygienic practices were mimicked by wash procedure c, which used dodecyl sulfate in water. Water promotes swelling of the hair but poorly solubilizes cannabinoids. This wash procedure was insufficient to remove cannabinoids completely from any hair sample. Both methanol and dichloromethane successfully removed cannabinoids from untreated hair, suggesting that diffusion of THC and CBN into hair had not occurred. In the case of hair strands moistened with tap water, penetration of drugs into the fiber probably occurred during smoke exposure and/or washing with dichloromethane was insufficient. Although on gross inspection methanol appeared to successfully remove sebum or sebum/sweat, small amounts of THC and CBN were still detectable in hair after the three washes. These results demonstrate that it is important to choose the most favorable solvent for decontamination, with consideration of both the solubility of a particular compound and the swelling behavior of hair. In "wash" procedures used to the clean the surface of the hair before sample processing, it should be noted that although drugs may be removed from the outside, they may have also penetrated into the keratin matrix. Interestingly, in the present study a positive cannabinoid finding in the last wash solution did not imply a positive cannabinoid finding in hair. In contrast, a negative result in the last wash solution did not always entail a negative result in hair. Therefore, the criterion often used in hair analysis, that a negative wash solution assures complete removal of external contamination, does not seem universally valid.

Although cannabinoids initially were higher in bleached hair, there was no difference in total removal of cannabinoids from untreated and bleached hair strands by dichloromethane washes. Removal of THC and CBN from permed hair by methanol was more effective, which could be attributable to less damage of the keratin matrix from permanent waving. Overall, dichloromethane seemed superior to methanol when applied to apparently dry hair. However, it should be noted that dichloromethane reduced the measured concentration of THC in hair from cannabis users, whereas methanol washes did not appear to affect quantitative results compared with unwashed samples (41).

In conclusion, our study has demonstrated that short-term exposure to marijuana smoke may lead to detectable amounts of THC and CBN in hair. A positive finding may result from major cannabis components in vapor and may also be influenced by hair care habits and cosmetic treatment of hair. The measured cannabinoid concentration was also influenced by the decontamination procedure. These findings should be considered when the frequency of cannabinoid consumption is estimated by hair analysis. Certainly the scalp hair of a marijuana smoker is exposed to environmental smoke and may be contaminated. It is therefore very likely that the same process that occurred in the in vitro experiments could occur in real life. High concentrations of cannabinoids in a hair sample do not unequivocally indicate frequent or heavy smoking habits. At present, there is growing consensus that identification of 11-nor-9-carboxy-{Delta}9-THC is a requirement for reporting a positive hair test result. We appreciate that the analytical requirements for identification of this metabolite are beyond the capability of the instrumentation used in this study (41)(42), but identification of this metabolite is considered a solution to the problems posed by the results of this study.


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Acknowledgments
 
We thank Dr. E. Schneider (Chem. Dir., Landeskriminalamt Baden-Württemberg, Stuttgart, Germany) for supplying the marijuana sample, and I. Härle and S. Rostock-Wolf for technical assistance.


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Footnotes
 
1 Nonstandard abbreviations: THC, {Delta}9-tetrahydrocannabinol; GC/MS, gas chromatography–mass spectrometry; CBN, cannabinol; and CBD, cannabidiol.


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References
 
  1. Koren G, Chan D, Klein J, Karaskov T. Estimation of fetal exposure to drugs of abuse, environmental tobacco smoke, and ethanol. Ther Drug Monit 2002;24:23-25.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  2. Nakahara Y. Hair analysis for abused and therapeutic drugs. J Chromatogr B Biomed Sci Appl 1999;733:161-180.[CrossRef][Medline] [Order article via Infotrieve]
  3. Gaillard Y, Pepin G. Testing hair for pharmaceuticals. J Chromatogr B Biomed Sci Appl 1999;733:231-246.[CrossRef][Medline] [Order article via Infotrieve]
  4. Pragst F, Rothe M, Spiegel K, Sporkert F. Illegal and therapeutic drug concentrations in hair segments—a timetable of drug exposure?. Forensic Sci Rev 1998;10:81-111.
  5. Miller ML, Donelly B, Martz RM. The forensic application of testing hair for drugs of abuse. NIDA Res Monogr 1997;167:146-160.[Medline] [Order article via Infotrieve]
  6. Clauwaert KM, Van Bocxlaer JF, Lambert WE, De Leenheer AP. Segmental analysis for cocaine and metabolites by HPLC in hair of suspected drug overdose cases. Forensic Sci Int 2000;110:157-166.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  7. Sachs H, Kintz P. Testing for drugs in hair. Critical review of chromatographic procedures since 1992. J Chromatogr B 1998;713:147-161.[CrossRef]
  8. Rothe M, Pragst F, Spiegel K, Harrach T, Fischer K, Kunkel J. Hair concentrations and self-reported history of 20 amphetamine and ecstasy users. Forensic Sci Int 1997;89:111-128.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  9. Baptista MJ, Monsanto PV, Pinho Marques EG, Bermejo A, Avila S, Castanheira AM, et al. Hair analysis for {Delta}9-THC, {Delta}9-THC-COOH, CBN, and CBD, by GC/MS-EI. Comparison with GC/MS-NCI for {Delta}9-THC-COOH. Forensic Sci Int 2002;128:66-78.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  10. Cairns T, Kippenberger DJ, Scholtz H, Baumgartner W. Determination of carboxy-THC in hair by mass spectrometry/mass spectrometry. In: De Zeeuw R, Al Hosani I, Al Munthiri S, Maqbool A, eds. Hair analysis in forensic toxicology. Abu Dhabi: Proceedings of the 1995 International Conference and Workshop, 1995:185–93..
  11. . Society of Hair Testing. Forensic Sci Int 1997;84:3-6.[CrossRef]
  12. Kintz P, Mangin P. What constitutes a positive result in hair analysis: proposal for the establishment of cut-off values. Forensic Sci Int 1995;70:3-11.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  13. Skopp G, Pötsch L. Passive exposure and interpretation of low concentrations of cannabinoids in blood and urine. Arch Kriminol 2001;207:137-147.[Medline] [Order article via Infotrieve]
  14. Romano G, Barbera N, Lombardo I. Hair testing for drugs of abuse: evaluation of external cocaine contamination and risk of false positives. Forensic Sci Int 2001;123:119-129.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  15. Romano G, Barbera N, Spadaro G, Valenti V. Determination of drugs of abuse in hair: evaluation of external heroin contamination and risk of false positives. Forensic Sci Int 2003;131:98-102.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  16. Wang WL, Cone EJ. Testing human hair for drugs of abuse. IV: Environmental cocaine contamination and washing effects. Forensic Sci Int 1995;70:39-51.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  17. Koren G, Klein J, Forman R, Graham K. Hair analysis of cocaine: differentiation between systemic exposure and external contamination. J Clin Pharmacol 1992;32:671-675.[Abstract]
  18. Cone EJ, Yousefnejad D, Darwin WD, Maguire T. Testing human hair for drugs of abuse. II. Identification of unique cocaine metabolites in hair of drug abusers and evaluation of decontamination procedures. J Anal Toxicol 1991;15:250-255.[Web of Science][Medline] [Order article via Infotrieve]
  19. Randin JP. Corrosion behavior of nickel-containing alloys in artificial sweat. J Biomed Materials Res 1988;22:649-666.[CrossRef]
  20. Skopp G, Pötsch L, Moeller MR. On cosmetically treated hair—aspects and pitfalls of interpretation. Forensic Sci Int 1997;84:43-52.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  21. Skopp G, Pötsch L, Mauden M. Stability of cannabinoids in hair samples exposed to sunlight. Clin Chem 2000;46:1846-1848.[Free Full Text]
  22. . Deutsches Institut für Normung. DIN 32645 Chemische Analytik - Nachweis-, Erfassungs- und Bestimmungsgrenze 1994:3-10 Beuth Berlin. .
  23. Strano-Rossi S, Chiarotti M. Solid-phase microextraction for cannabinoids analysis in hair and its possible application to other drugs. J Anal Toxicol 1999;23:7-10.[Web of Science][Medline] [Order article via Infotrieve]
  24. Barbera N, Barbera S, Lombardo I, Sgarlata M, Romano G. Determinazione dei cannabinoidi nei capelli contaminazione esterna e rischio di falsi positivi. Riv It Med Legal 2000;22:1039-1056.
  25. Cone EJ, Johnson RE, Darwin WD, Yousefnejad D, Mell LD, Paul BD, et al. Passive inhalation of marijuana smoke: urinalysis and room air levels of {Delta}-9-tetrahydrocannabinol. J Anal Toxicol 1987;11:89-96.[Web of Science][Medline] [Order article via Infotrieve]
  26. Zahlsen K, Nilsen T, Nilsen OG. Interindividual differences in hair uptake of nicotine and significance of cigarette counting for estimation of environmental tobacco smoke exposure. Pharmacol Toxicol 1996;79:183-190.[Web of Science][Medline] [Order article via Infotrieve]
  27. Clarke RC, Watson DP. Die Botanik natürlicher Cannabismedikamente. Grotenhermen F eds. Cannabis und Cannabinoide 2001:21-32 Hans Huber Bern. .
  28. Cirimele V, Sachs H, Kintz P, Mangin P. Testing human hair for cannabis. III. Rapid screening procedure for the simultaneous identification of {Delta}9-tetrahydrocannabinol, cannabinol, and cannabidiol. J Anal Toxicol 1996;20:13-16.[Web of Science][Medline] [Order article via Infotrieve]
  29. Tjerdeema RS. The pyrolysis of cannabinoids. Rev Environ Contam Toxicol 1987;99:61-81.[Web of Science][Medline] [Order article via Infotrieve]
  30. Baker PB, Gough TA, Taylor BJ. Illicitly imported Cannabis products: some physical and chemical features indicative of their origin. Bull Narc 1980;32:31-40.[Web of Science][Medline] [Order article via Infotrieve]
  31. Mikes F, Waser PG. Marihuana components: effects of smoking on {Delta}9-tetrahydrocannabinol and cannabidiol. Science 1971;172:1158-1159.[Abstract/Free Full Text]
  32. Nilsen T, Zahlsen K, Nilsen OG. Uptake of nicotine in hair during controlled environmental air exposure to nicotine vapour: evidence for a major contribution of environmental nicotine to the overall nicotine found in hair from smokers and non-smokers. Pharmacol Toxicol 1994;75:136-142.[Web of Science][Medline] [Order article via Infotrieve]
  33. Schramm KW. Hair: a matrix for non-invasive biomonitoring of organic chemicals in man. Bull Environ Contam Toxicol 1997;59:396-402.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  34. Kidwell DA, Blank DL. Environmental exposure—the stumbling block of hair testing. Kintz P eds. Drug testing in hair 1996:17-68 CRC Press Boca Raton, FL. .
  35. Wortmann FJ, Wortmann G, Zahn H. Pathways for dye diffusion in wool fibers. Textile Res J 1997;67:720-724.
  36. Pötsch L, Moeller MR. On pathways for small molecules into and out of human hair fibers. J Forensic Sci 1996;41:121-125.[Web of Science][Medline] [Order article via Infotrieve]
  37. Schäfer K. Microscopical investigation of the diffusion of dyestuffs into keratin fibres. Wool Tech Sheep Bred 1994;42:59-82.
  38. Skopp G, Pötsch L, Aderjan R. Experimental investigations on hair fibers as diffusion bridges and opiates as solutes in solution. J Forensic Sci 1996;41:117-120.[Web of Science][Medline] [Order article via Infotrieve]
  39. Robbins CR. Chemical and physical behavior of human hair, 2nd ed 2002:25-51 Springer New York. .
  40. Wilkins D, Haughey H, Cone J, Huestis M, Foltz R, Rollins D. Quantitative analysis of THC, 11-OH-THC, and THCCOOH in human hair by negative ion chemical ionization mass spectrometry. J Anal Toxicol 1995;19:483-491.[Web of Science][Medline] [Order article via Infotrieve]
  41. Chiarotti M, Costamagna L. Analysis of 11-nor-9-carboxy-delta(9)-tetrahydrocannabinol in biological samples by gas chromatography tandem mass spectrometry (GC/MS-MS). Forensic Sci Int 2000;114:1-6.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
  42. Moore C, Guzaldo F, Donahue T. The determination of 11-nor-{Delta}9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in hair using negative ion gas chromatography-mass spectrometry and high-volume injection. J Anal Toxicol 2001;25:555-558.[Web of Science][Medline] [Order article via Infotrieve]




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