Results of hair analyses for drugs of abuse and comparison with self-reports and urine tests

Urine as well as head and pubic hair samples from drug abusers were analysed for opiates, cocaine and its metabolites, amphetamines, methadone and cannabinoids. Urine immunoassay results and the results of hair tests by means of gas chromatography-mass spectrometry were compared to the self-reported data of the patients in an interview protocol. With regard to the study group, opiate abuse was claimed from the majority in self-reports (89%), followed by cannabinoids (55%), cocaine (38%), and methadone (32%). Except for opiates the comparison between self-reported drug use and urinalysis at admission showed a low correlation. In contrast to urinalysis, hair tests revealed consumption in more cases. There was also a good agreement between self-reports of patients taking part in an official methadone maintenance program and urine test results concerning methadone. However, hair test results demonstrated that methadone abuse in general was under-reported by people who did not participate in a substitution program. Comparing self-reports and the results of hair analyses drug use was dramatically under-reported, especially cocaine. Cocaine hair tests appeared to be highly sensitive and specific in identifying past cocaine use even in settings of negative urine tests. In contrast to cocaine, hair lacks sensitivity as a detection agent for cannabinoids and a proof of cannabis use by means of hair analysis should include the sensitive detection of the metabolite THC carboxylic acid in the lower picogram range.     

Disappearance of cocaine from human hair after abstinence

In this work the study of the disappearance of cocaine in hair is reported. The subject of the study is a woman who stopped the consumption of cocaine after a period of drug abuse of over 1 year. Hair samples were collected over a period of 10 months. During this time the absence of cocaine intake was monitored by the toxicological analysis of urine, performed every 2 days. After decontamination with methanol, the hair sample, cut in two segments (0-1.5 and 1.5-3 cm from the hair root) was added with cocaine-D(3) (internal standard), hydrolyzed and extracted with chloroform/isopropanol (9:1). The extract was evaporated to dryness, reconstituted in 25 microl of ethyl acetate and analyzed by GC-MS in SIM mode. The obtained results show that the incorporation of cocaine in hair decreased during the first 3 months after the last consumption and after this period of time no cocaine was found in the hair sections closest to the root.     

Correlation of the incidence of cocaine and cocaethylene in hair and postmortem biologic samples

Hair samples are useful as a matrix for drug testing because drugs can be detected in hair for longer periods than in blood or urine. The authors report a prospective comparison of the detection of cocaine and cocaethylene in routine postmortem biologic specimens to the detection of cocaine and cocaethylene in hair. The authors collected hair samples from various areas of the head in 53 autopsy cases, prepared them, and analyzed them by gas chromatography/mass spectrometry (GC/MS) for cocaine and cocaethylene. The authors compared the results of hair analysis with the results of toxicologic analysis performed on routine postmortem samples by enzyme multiplied immunoassay technique and GC/MS. Cocaine was found in either biologic fluids or in hair in 16 of 53 samples tested. Nine samples were positive for cocaine in both biologic fluids and hair. Five samples contained cocaine only in biologic fluids, and two contained cocaine only in hair. Cocaethylene was present in two cases. Drug screening of hair provides additional information in some autopsy cases, but the authors have not made hair analysis a routine practice. It may prove useful to save hair samples in all cases for later analysis if warranted by additional history or autopsy findings.     

Hair and urine analysis: relative distribution of drugs and their metabolites

This work studies the distribution of cocaine and heroin metabolites in hair and urine of living polidrug abusers. Cocaine, benzoylecgonine (BEG), ecgonine methyl ester (EME), morphine, codeine and 6-monoacetylmorphine (6-MAM) were simultaneously extracted and analyzed by GC/MS in SIM mode. The results obtained show a different distribution of heroin and cocaine metabolites in urine and hair. In urine, we generally find BEG and EME for cocaine abuse, and morphine for heroin abuse. In hair, we detect cocaine and MAM as major metabolites for cocaine and heroin abuse, respectively.     

Clinical applications of hair testing for drugs of abuse--the Canadian experience

During the last 2 decades there has been a substantial increase in illicit drug consumption in North America. It has been repeatedly shown that the personal history of drug use is far from being accurate. Fearing legal consequences and embarrassment of admitted illicit substance use, most users tend to deny or, to under-report illicit drug consumption. These facts have stressed an urgent need for a biological marker which does not lose its sensitivity within a few days after the end of exposure and which may yield a cumulative reflection of long term exposure to illicit drugs. Hair analysis has emerged as such a marker. A variety of illicit and medicinal compounds have been shown to be incorporated into hair including trace metals, barbiturates, amphetamines, opiates, phencyclidine, cocaine, nicotine and cannabis. Hair analysis for drugs of abuse provides long-term information on an individual's drug use; its window of detection is limited only by the length of the hair and typically, ranges from a week to several months. After establishing and validating several hair tests during the last decade, we have analyzed over 1000 hair samples for different drugs of abuse. We used RIA for screening and GC-MS for confirmation of positive results. The aim of this report is to illustrate the diagnostic usefulness of hair testing in different age groups (newborns, children, adults) and circumstances: (criminal cases, athletes, child custody cases, etc.).     

Levels of cocaine and its metabolites in washed hair of demonstrated cocaine users and workplace subjects

In a study of subjects in drug rehabilitation programs, cocaine and cocaine metabolite levels were determined in the hair of 75 subjects who had produced cocaine-positive urine results. The hair was analyzed after being washed with the 3.75 h wash procedure developed by this laboratory. In addition, results of testing 73 non-users are presented, as well as levels of cocaine, benzoylecgonine (BE), cocaethylene, and norcocaine from workplace population samples. The data support a recommendation of reporting as positive a sample with cocaine of 500 pg/mg hair and either a 5% ratio of benzoylecgonine (BE) to cocaine in samples, or the presence of cocaethylene at 50 pg/mg hair, or norcocaine at 50 pg/mg hair for samples < or =2000 pg cocaine/mg hair. For samples with cocaine present at >2000 pg/mg hair, the data indicate that a ratio of 5% BE may be an overly conservative approach. In appropriately washed hair samples, cocaine users can produce hair levels of <5% BE and thus a minimum BE cutoff in lieu of a ratio could be considered.     

Drugs in prehistory: chemical analysis of ancient human hair

Concern about drug abuse in modern populations has led to the development of specific methods for identification of cocaine, opiates and cannabis in human hair. Drug use in prehistory can provide indirect evidence of interpopulational contact and social stratification. This paper reports drug evaluation in nineteen ancient hair samples from archaeological sites in northern Chile. Each sample was tested for the presence of traces of cocaine, opiates and cannabis, in order to establish a standard methodology for studies of drug use among prehistoric groups. Although results are negative, this absence of evidence could be due to two main causes: (1) the individuals evaluated did not use any drugs, which does not mean that other members of their cultural group did, or (2) the wide range of known drugs studied did not consider some group specific drugs, derived from local or imported plants, thus meaning that a greater drug range must be tested. In any case, our study confirms that drug testing in prehistoric samples is viable. However, in order to determine what kind of substances were used in prehistoric times new patterns that incorporate all drugs which are not part of the western pharmacopeia must be created. Finally, a methodology for the study of drug use among prehistoric groups using ancient hair samples is described.     

Hair testing and self-report of cocaine use

Hair analysis is a useful tool in both clinical and forensic fields: it allows information about drugs of abuse (DOA) consumption to be obtained. However, in spite of analytical results, sometimes patients continue to deny using drugs or, on the contrary, insist on describing themselves as severe drug addicts; indeed there are often considerable difficulties in getting truthful statements about the real amount of drugs used. In this study we have tried to compare cocaine concentration in hair samples with self-reported drug intake. We enrolled 113 subjects (61 Africans, 52 Caucasians) who had been recently sent to jail. They were asked to tell about their use of illicit drugs during the last three months and then submitted to hair analysis. Hair segments (3 cm) were analyzed by GC-MS for amphetamines, cocaine and opiates. Useful data was obtained from 82 subjects, separated into two main groups on account of ethnic origin (African or Caucasian) and divided further into daily, weekly and monthly users. The results showed qualitative results and self-reported consumption to be in good agreement, although the correlation between frequency of consumption and concentration in hair revealed sometimes higher concentrations in contrast with the admission of low consumption. There was a definite separation between occasional and daily use (especially in Caucasian people), while concentrations found where weekly use was reported were more variable. Concentrations of cocaine measured in Africans' hair were much higher than in Caucasians'. Even if this study is exclusively based on self-report, it provides some interesting information in order to differentiate the frequency of consumption, and especially underlines the great importance of ethnic bias on hair analysis.     

Simultaneous hair testing for opiates, cocaine, and metabolites by GC-MS: a survey of applicants for driving licenses with a history of drug use

A sensitive GC-MS method for the simultaneous determination of opiates, cocaine, and metabolites in hair at a cut-off level of 0.1 ng/mg was adopted to assess past exposure to these drugs in applicants for driving licenses with a history of drug use. The sampling protocol consisted of collection of one hair (sample A, 5-cm length) and one urine sample. When hair and urine (EMIT Syva, cut-off levels: 0.3 mg/l for opiates, 0.15 mg/l for cocaine, GC-MS confirmation of positives) were both positive or negative the protocol was concluded. In the other cases, the assessment of 'current exposure' to drugs was carried out, in order to avoid seriated random urinalysis, by collecting a second hair sample (sample B) 6 weeks later and analysing the proximal 1-cm segment. Out of the 214 'A' hair samples analyzed, 14 (6.5%) tested positive for morphine and/or 6-acetylmorphine (6AM), and 26 (12%) for cocaine and/or benzoylecgonine (BE), whereas none of the samples tested positive for both drugs. Levels between 0.1 and 1 ng/mg of the single analytes were found in eight out of the 14 morphine-6AM positives (57%) and in 18 out of the 26 cocaine-BE positives (69%). The time course of positive cases showed a progressive decrease of morphine-6AM positives and a corresponding increase of cocaine-BE positives within the study period September 1995-February 1999. No cases with positive urine and negative hair were observed. Among the 40 positive cases, seven (four and three for opiates and cocaine, respectively) were found to be 'currently exposed to drug', four by urinalysis (three and one) and three by analysis of the hair sample B (1 and 2).     

Evidence for bias in hair testing and procedures to correct bias

A number of in vitro experiments show that different hair samples incorporate differing amounts of drugs under identical conditions. Incorporation of cocaine and morphine tends to be correlated with race, in that the hair of African American females incorporates higher concentrations of cocaine than does the hair of Caucasian males or females. Extrapolation of these data into populations has been fraught with difficulties because the dosages of drugs and their use patterns are unknown. Cosmetic treatments and hygiene alter drug binding, which must be considered in comparing populations because cosmetic treatments are often group dependent. Four reasons are proposed that account for the uptake and retention of drugs by hair and that may differ among groups: (1) permeability and other characteristics of the hair due to genetic influences, (2) cosmetic hair treatments and hair care habits (which may be culturally influenced), (3) drug removal during personal hygiene, and (4) manner and route of drug administration which can affect passive exposure to residual drugs in the environment. The data supporting bias in hair testing are reviewed and methods are proposed that use either the uptake of dyes or the incorporation of drug homologs to reduce bias.     

Hair analysis for drugs of abuse. Hair color and race differentials or systematic differences in drug preferences?

There is currently a debate in the literature on chemical drug analysis concerning the contribution of biophysical attributes associated with specimens and specimen donors to assay outcome. In recent years this debate has focused on hair analysis, but has in the past also been raised in urinalysis interpretation. In this article we examine several aspects of that controversy. First, we present data regarding the effects of hair color on the distribution of positive hair testing results for three drug classes. We compare these results to negative hair samples from comparable donors. This data is derived from head hair from preemployment donors that was classified according to seven visual color categories. We determined the distribution of colors for hair samples devoid of any of three assayed drugs (amphetamines, cocaine, and cannabinoids). Subsequently, this distribution was compared with the distributions for hairs that had tested positive for amphetamines, cocaine or cannabinoids. We examined a total of 2000 randomly selected samples; 500 negative hair samples and 500 positive samples for each of three drugs: cannabinoids, cocaine, and amphetamine. We also evaluated ethnic/racial factors in relation to positive urinalyses for various ethnic/racial groups. We examined approximately 4000 urine specimens from two different groups, each constituting around 2000 specimens. In addition to ethnicity/race and urinalysis outcome, we also examined the relationship between the hair color distributions of urine donors and the corresponding urinalysis results for the three drug classes. We also compared them to drug-negative samples. Our summary impression is that the observed outcome patterns were largely consistent with differences in drug preferences among the various societal groups. There was little evidence of a pattern attributable to hair color bias alone or selective binding of drugs to hair of a particular color. Likewise, there was no discernible pattern associated with race or ethnicity that would lend support to a "race effect" in drug analysis.     

Evaluation of the catalytic decomposition of H2O2 through use of organo-metallic complexes--a potential link to the luminol presumptive blood test

Hair testing for drugs of abuse is performed in Lombardy by eleven analytical laboratories accredited for forensic purposes, the most frequent purposes being driving license regranting and workplace drug testing. Individuals undergoing hair testing for these purposes can choose the laboratory in which the analyses have to be carried out. The aim of our study was to perform an interlaboratory exercise in order to verify the level of standardization of hair testing for drugs of abuse in these accredited laboratories; nine out of the eleven laboratories participated in this exercise. Sixteen hair strands coming from different subjects were longitudinally divided in 3-4 aliquots and distributed to participating laboratories, which were requested to apply their routine methods. All the participants analyzed opiates (morphine and 6-acetylmorphine) and cocainics (cocaine and benzoylecgonine) while only six analyzed methadone and amphetamines (amphetamine, methamphetamine, MDMA, MDA and MDEA) and five Δ(9)-tetrahydrocannabinol (THC). The majority of the participants (seven labs) performed acidic hydrolysis to extract the drugs from the hair and analysis by GC-MS, while two labs used LC-MS/MS. Eight laboratories performed initial screening tests by Enzyme Multiplied Immunoassay Technique (EMIT), Enzyme-linked Immunosorbent Assay (ELISA) or Cloned Enzyme Donor Immunoassay (CEDIA). Results demonstrated a good qualitative performance for all the participants, since no false positive results were reported by any of them. Quantitative data were quite scattered, but less in samples with low concentrations of analytes than in those with higher concentrations. Results from this first regional interlaboratory exercise show that, on the one hand, individuals undergoing hair testing would have obtained the same qualitative results in any of the nine laboratories. On the other hand, the scatter in quantitative results could cause some inequalities if any interpretation of the data is required.     

Driving under the influence of drugs -- evaluation of analytical data of drugs in oral fluid, serum and urine, and correlation with impairment symptoms

A study was performed to acquire urine, serum and oral fluid samples in cases of suspected driving under the influence of drugs of abuse. Oral fluid was collected using a novel sampling/testing device (Dr?ger DrugTest System). The aim of the study was to evaluate oral fluid and urine as a predictor of blood samples positive for drugs and impairment symptoms. Analysis for cannabinoids, amphetamine and its derivatives, opiates and cocaine was performed in urine using the Mahsan Kombi/DOA4-test, in serum using immunoassay and gas chromatography-mass spectrometry (GC-MS) confirmation and in oral fluid by GC-MS. Police and medical officer observations of impairment symptoms were rated and evaluated using a threshold value for the classification of driving inability. Accuracy in correlating drug detection in oral fluid and serum were >90% for all substances and also >90% in urine and serum except for THC (71.0%). Of the cases with oral fluid positive for any drug 97.1% of corresponding serum samples were also positive for at least one drug; of drug-positive urine samples this were only 82.4%. In 119 of 146 cases, impairment symptoms above threshold were observed (81.5%). Of the cases with drugs detected in serum, 19.1% appeared not impaired which were the same with drug-positive oral fluid while more persons with drug-positive urine samples appeared uninfluenced (32.7%). The data demonstrate that oral fluid is superior to urine in correlating with serum analytical data and impairment symptoms of drivers under the influence of drugs of abuse.     

Patterns in drug use in the United Kingdom as revealed through analysis of hair in a large population sample

This paper presents an overview of the most common sectioning patterns utilised in the analysis of hair for drug use; report on the major user groups (sectors) that currently make use of hair analysis in the United Kingdom (UK); present the results for the different drug groups analysed in samples of hair samples analysed at TrichoTech between 2001 and 2005.A total of 186,084 tests on 34,626 hair samples were performed for the commonly requested drug groups. There were 145,799 enzyme-linked Immunosorbent positive screening tests (ELISA), which were subsequently confirmed by gas chromatography equipped with mass spectrometry detection (GC–MS). The two major sectors were the Medico-Legal sector (65%) and Workplace (20%). Police (Forensics), Clinical Monitoring, Schools, Research and Insurance accounted together for the remaining 15% of the samples. Combinations of several sections patterns were requested covering periods from the most recent month up to 24 months. The most common sectioning pattern was one single section measuring 3 cm, to cover the most recent 3 months (44%), which in some cases was complemented by a further 3 cm to cover together 6 months (13%). The second most common sectioning pattern was the analysis of three sections of 1 cm each to cover the most recent 3 months (28%), when a more detailed evaluation of drug use pattern was relevant. Samples collected from other areas of the body such as axilla, pubic, chest, beard and leg, constituted 6% of the samples. The analysis of monthly sections plays an important role in the evaluation and interpretation of drug use, particularly in certain Medico-Legal cases. The sectors with the highest rates of positive results were Police (Forensics) (78%), Medico-Legal (62%) and Clinical (54%). The common drugs in each group were cannabinol (27%), cocaine (25%), morphine (17%), amphetamine (13%) and diazepam (15%). The positive rate for the Workplace sector was 10%. The most common drugs detected in the Workplace samples in each group were: THC (4%), codeine (2%), cocaine (2%), MDMA (0.5%) and diazepam (0.1%). The concentration levels of drugs found in samples from the workplace were lower than in the other sectors (95% of cases). The exceptions were for dihydrocodeine and MDMA, where levels were 170 and 143% higher, respectively. However, the maximum levels detected in the Workplace samples were lower. The Medico-Legal sector is the most prevalent sector using hair analysis in the UK but the rate of Workplace sector use of hair testing is increasing. One in 10 workplace hair tests detected the presence of at least one drug, which is twice the rate of detection using urine, which is a 1 in 20 urine sample. This means that the chances of identifying people on drugs in the workplace by testing hair samples are twice as likely than urine samples.     

A 6-year experience with urine drug testing by family service agencies in Nova Scotia, Canada

The objective of this study is to describe a urine drug-testing program implemented for parents with a history of substance abuse by family service agencies in the province of Nova Scotia, Canada. Nurse collectors went to the parents' home to obtain urine specimens under direct observation and then delivered the specimens to the toxicology laboratory or arranged shipment by courier under chain of custody. Each urine specimen was screened for cannabinoids, cocaine metabolite, opiates, amphetamines and benzodiazepines, ethyl alcohol and creatinine. All positive screening tests were confirmed by another method such as gas chromatography-mass spectrometry (GC-MS). In 15,979 urine specimens collected from 1994 to 1999, the percent positive rate for one (or more) drugs/metabolites ranged from 45.6% (1994-1996) to 30.0% (1998, 1999). A total of 575 specimens (3.7%) were dilute (urine creatinine <25mg/dl). Positive rates in 15,404 non-dilute specimens from 1994 to 1999 were as follows: cannabinoids - 11.7%, benzodiazepines - 11.3%, cocaine metabolite - 3.7%, and ethyl alcohol - 2.6%. Most clients provided less than 20 urine specimens for testing but some individuals submitted urine specimens more than 100 times in a 12-15-month period. Urine drug screening in parents with a history of substance abuse provided an objective and reliable indication of recent drug use in this population.     

Simultaneous Quantitative Determination of Amphetamines,Opiates, Ketamine,Cocaine and Metabolites in Human Hair: Application to Forensic Cases of Drug Abuse

A method using liquid chromatography–tandem mass spectrometry (LC–MS/MS) to simultaneously quantify amphetamines, opiates, ketamine, cocaine, and metabolites in human hair is described. Hair samples (50 mg) were extracted with methanol utilizing cryogenic grinding. Calibration curves for all the analytes were established in the concentration range 0.05–10 ng/mg. The recoveries were above 72%, except for AMP at the limit of quantification (LOQ), which was 48%. The accuracies were within ±20% at the LOQ (0.05 ng/mg) and between −11% and 13.3% at 0.3 and 9.5 ng/mg, respectively. The intraday and interday precisions were within 19.6% and 19.8%, respectively. A proficiency test was applied to the validated method with z-scores within ±2, demonstrating the accuracy of the method for the determination of drugs of abuse in the hair of individuals suspected of abusing drugs. The hair concentration ranges, means, and medians are summarized for abused drugs in 158 authentic cases.     

The detection of cocaine in hair specimens using micro-plate enzyme immunoassay.

The analysis of hair for drugs of abuse is becoming increasingly popular and is under consideration by the Division of Health and Human Services as a possible alternative or adjunct to urinalysis in workplace programs. The detection of cocaine in human hair using a commercially available micro-plate enzyme immunoassay is described for the first time. Sample size and incubation time were the major variables in the optimization of the method. In order to validate the procedure, the method was applied to 105 consecutive hair samples routinely received into our laboratory. The samples were simultaneously analyzed by the Micro-Plate immunoassay (EIA), as well as our current fluorescence polarization immunoassay (FPIA) procedure and gas chromatography-mass spectrometry (GC/MS). The sensitivity of the EIA and FPIA assays were 75% and 67.8% respectively; specificity 97.4% and 80.5% respectively; and efficiency 91.4 and 77.1% respectively. The Micro-Plate EIA was shown to be a valid alternative to other immunoassay screening methods for the detection of cocaine in hair by demonstrating increased sensitivity, specificity and efficiency over our current technique.     

Value of the concept of minimal detectable dosage in human hair

The influence on drug incorporation of melanin affinity, lipophilicity, and membrane permeability is of paramount importance. Despite their high lipophilicity, some drugs have quite low incorporation rate into hair, suggesting that the higher incorporation rates of basic drugs (cocaine, amphetamines.) than neutral (steroids, benzodiazepines, cannabinoids…) or acidic ones are strongly related to the penetrating ability of the drug to break through the membrane based on the pH gradient between blood and the acidic hair matrix. When using hair analysis as a matrix during investigative analysis, e.g. workplace drug testing, doping, driving under the influence, drug-facilitated crime, the question of importance is to know whether the analytical procedure was sensitive enough to identify traces of drugs; this is particularly important when the urine sample(s) of the subject was positive and the hair sample(s) was negative. It has been accepted in the forensic community that a negative hair result cannot exclude the administration of a particular drug, or one of its precursors and the negative findings should not overrule a positive urine result. Nevertheless, the negative hair findings can, on occasion, cast doubt on the positive urine analysis, resulting in substantial legal debate and various consequences for the subject. The concept of minimal detectable dosage in hair is of interest to document the negative findings, but limited data is currently available in the scientific literature. Such data includes cocaine, codeine, ketamine, some benzodiazepines and some unusual compounds. Until laboratories will have sensitive enough methodologies to detect a single use of drug, care should be taken to compare urine and hair findings.     

Hair analysis for driving licence in cocaine and heroin users. An epidemiological study

Diagnosis of drug exposure is strongly supported by analysis of hair samples. In the province of Brescia, Italy, for regranting driving license to drug addicts or occasional abusers, a control programme was adopted including analysis of illicit drugs in two hair segments (0-3 and 3-6 cm) and in urine. From January 1998 to April 1999, upon request of the Local Medical Commission, 697 hair samples were tested in our laboratory. One hundred and eighty subjects resulted positive in hair for one or two of the controlled drug classes (73.3% for cocaine, 10% for opiates, 16.7% for both). Positive subjects were classified by residence, age, sex and license category. Seventy-two subjects were called back after 6-12 months and submitted to a second hair and urine analysis: in 34 cases the result of the first analysis was confirmed (19 negatives, 15 positives for one or both drug classes). Another 37 cases tested positive at the first control and negative at the second, suggesting the hypothesis that a strict control may have a significant deterrent function. The high percentage of negative results at the second control may be explained by the prevalence of cocaine users in the examined population. Our results allow us to conclude that the strict application of control rules lead to a decrease of social risk behaviours.     

Hair analysis by using radioimmunoassay, high-performance liquid chromatography and capillary electrophoresis to investigate chronic exposure to heroin, cocaine and/or ecstasy in applicants for driving licences

The present paper describes an integrated diagnostic strategy to check the physical fitness of subjects, formerly users of illicit drugs, to obtain a driving license, after having quit their addiction. According to the Italian law, applicants for a driving license with a history of drug abuse must give evidence to have quit this behaviour and to show no risk of relapse in the future. To prove this, at our institute, they undergo medical examination, hair analysis and a urinalysis program on eight seriate samples, collected over about 40 days. About 700 subjects per year are investigated with this strategy. The hair samples are screened for opiates (morphine), cocaine and ecstasy, the most abused illicit substances in our region, by using commercial radioimmunoassays adopting cut-off levels of 0.1 ng/mg. All positive samples and about 10% of negatives are confirmed by high-performance liquid chromatography. Further confirmation of results can be carried out by capillary electrophoresis (and/or GC/MS or MS/MS). In 1998, the prevalence of positives for morphine, cocaine and ecstasy was 4.8, 11.3 and 2.6%, respectively. In this year, for the first time, the percentage of hair samples positive for cocaine was greater than that for opiates. The results of this integrated diagnostic strategy are presented and discussed, with particular emphasis on the comparison between hair analysis on a single sample and seriate urinalyses (on eight samples).