Human Hair in Personal Identification and Documenting Drug and Substance Abuse

Jaydip Sen

Department of Anthropology, University of North Bengal, P.O.: N.B.U., Raja Rammohunpur 734 013, District Darjeeling, West Bengal, India E-mail: [email protected]

KEYWORDS Human Hair, Hair Structure and Formation. Hair Types. Forensic. Drugs. Problems. Future Directions

ABSTRACT Human hair has played a significant role in forensic anthropology for decades. The morphological characteristics of human hair have long been utilized for personal identification in forensic investigations. With the development of better analytical techniques, hairs samples are also being used to understand and solve instances of poisoning, drug and substance abuse. This communication presents a brief outline of the structure of various types of hair, its formation and growth, along with its various types. The issues of hair as an evidence, its transfer, utility and significance of its morphological variables are discussed. The importance of hair in documenting exposure to drug and substance abuse is also highlighted. The main advantages and disadvantages of using hair as evidence are also discussed.

INTRODUCTION on the head, pubic region, arms, legs, and other body areas. Human hair has a significant potential in forensic anthropology and has been extensively HAIR STRUCTURE used in forensic investigations. Investigators believe that their presence can associate a Hair is a biological polymer with over ninety suspect to a victim or a suspect/victim to a crime percent of its dry weight being made up of keratin scene primarily because hairs can be transferred protein. Keratins are cystine-containing proteins, from the suspect to the victim and/or vice-versa which forms two large groups called Intermediate during physical contact. The types of hair filament proteins and Intermediate filament- recovered, the condition and number of hairs associated proteins (Powell et al. 1991) that are found in the scene of crime all have great almost equally abundant in most hairs. Of the relevance as evidences in criminal investigations. several types of bonds that stabilize the keratin The forensic anthropologist routinely compares molecule, the most unique is –S-S-. This –S-S- the morphological characteristics of the hair linkage is formed by two cystine residues samples in question to known hair samples to contained in adjacent polypeptide chains and it determine a transfer. Human hair has also been is this disulfide bond that is mainly responsible successfully used to assess drug and substance for keratin’s resistance to destruction. Research abuse as drugs of abuse cannot be often detected work on the elucidation of genes encoding in body fluids. Using very sophisticated analytical structural proteins of the human hair follicle has techniques such as immunoassay and gas advanced rapidly during the last decade and chromatography, investigators are now exten- significant developments were made in both the sively using human hair to solve cases of characterization of human hair keratins, as well poisoning and drug and substance abuse. as the hair keratin associated proteins. Rogers et Hairs may be defined as slender filamentous al. (2006) provides a pertinent review of the keratin outgrowths of the skin and are primarily composed proteins found in human hair. of keratin. It differs from one animal species to The human hair follicle is a structure, which is another in the basis of length, color, shape, root formed as a result of epithelio-mesenchymal appearance and morphological characteristics. interactions initiated around the third month of There is also a considerable deal of variability in fetal development. It is very complex, consisting the types of hairs that are found on the body of a of more than twenty different cell types particular animal. In humans, hairs are distributed distributed into six main areas. These areas are 48 JAYDIP SEN the connective tissue sheath, the dermal papilla, called anagen, catagen and telogen. Anagen is the outer root sheath, the inner root sheath, the the period of active follicle differentiation and hair shaft and the sebaceous gland. This complex growth. At the end of this phase, there is a short appendage behaves in a unique pattern in mam- transitionary phase called the catagen which then mals as, after a hair production phase, it involutes leads to the dormant stage referred to as telogen. in situ before entering a resting phase after which During the telogen phase, the fully formed hair is it renews in a cyclical but stochastic fashion. The retained in the follicle as club hair. In humans, the hair follicle thus is a fully auto-nomous skin anagen phase lasts for three to five years, the append-age with its own hormonal control, its catagen phase for a few weeks and the telogen own autocrine and paracrine network and its own phase for two months (Stene 2004). However, cycle, appearing as an incredibly complex and although the structure and histology of hair are stable structure that summarizes the main rules well known, the molecular events controlling the of tissue homeostasis (Bernard 2005). As a result, hair cycle remain unclear (Bernard 1994). studies on the histo-physiology of the hair follicle Nevertheless, a great deal of research work is are now gaining a great importance (Barinov and currently being undertaken in the various aspects Sulaeva 2004). of the hair cycle (e.g. Bayer-Garner et al. 2002; Structurally, hair consists of: a) an inner cortex Paus and Foitzik 2004). comprising spindle-shaped cells, and b) an outer The morphological study of the root area of sheath called the cuticle. Each cortical cell the hair determines the growth phase. About consists of many fibrils. In between the fibrils a eighty to ninety percent of the hair follicles of the softer material called the matrix is present which head hair of a healthy individual are in the anagen grows from a hair follicle. The fibrils run to form phase, while only two percent are in the catagen the fiber axis. The cuticle consists of scale- phase and the rest ten to eighteen percent are in shaped layers and is responsible for much of the the telogen phase. The anagen phase of a new mechanical strength of the hair fiber. The cuticle hair starts at the moment it begins to grow. During is made up of a number of layers, which varies this time there is very active growth in the hair from one species to another. Typical human hair bulb and materials are deposited in the hair shaft has six to eight layers of cuticle. by cells found in the follicle. The medulla, cortex, cuticle, and accompanying root sheath are formed HAIR FORMATION AND GROWTH by the metabolically active dividing cells above and around the dermal papilla of the follicle that Hair formation begins in the third month of fetal grow upward during this phase. Hair melanin is life. Each hair grows through a follicle and is made produced in the hair bulb throughout this phase up of epidermal cells that grow under the dermis. of the hair cycle. A short resting phase known as Initially the epidermis thickens and cells begin to the catagen phase follows the anagen phase. No grow down into the dermis. This down growth forms pigment is made during this phase and the follicle a cap over some of the connective tissue to create stops producing hair. In the telogen phase, the papillae whose cells multiply to form the hair. As follicle is dormant. This is the time when a new these cells are pushed up the central canal of the hair begins to grow from the hair follicle. As it hair shaft and away from their source of nourishment, grows upwards the old hair will be shed naturally they become impregnated with keratin. The or may be pulled out, which happens easily and morphogenesis of most hairs follow a cyclic pattern painlessly. These old hairs are the ones that come of cell proliferation and differentiation initiated in out when an individual combs the hair. At any mid to late embryonic development and repeated one time, around one in ten of the follicles on an throughout life (Orwin 1979). As hairs undergo a individual’s head are in the shedding phase. Once cyclical growth, intermediate and resting phases, the hair reaches the telogen phase, the follicles the visible morphological characteristics under the have achieved a mature, stable stage of quie- microscope are sufficient to determine the phases scence and are anchored in the follicle only by of growth of the hair. the club-shaped root. The next generation of an anagen hair is formed by the germ cells below The Various Stages of the Hair Cycle this root. The replacement of human head hair does not have any apparent seasonal pattern, Each hair passes through three distinct stages rather it occurs in a scattered mosaic fashion. The HUMAN HAIR IN PERSONAL IDENTIFICATION AND DOCUMENTING DRUG ABUSE 49 average time period of growth for scalp hair is they grow all over the baby’s body and its main approximately one thousand days with the resting function is to retain body heat. They all grow at phase lasting for about hundred days. Around the same rate and so are of the same length. ten percent of the head hairs of a human are, Around the eighth month of development this therefore, in the quiescent telogen phase, and a hair is usually shed and often a second generation minimal amount of force—such as that from of lanugo hairs then starts growing and lasts until combing—is required to dislodge the hairs from the first three or four months of extra uterine life the dormant follicle. The new hair emerges from are completed. These are then replaced by vellus the same opening at the surface of the skin as the hair. Sometimes incorrectly referred to as lanugo old one, and the hair cycle begins afresh. hair, vellus hair is short, fine, “peach fuzz” unpigmented hair. It is very soft, much softer than Factors Controlling Hair Growth lanugo and grows in most places on the human body in both sexes. It is usually less than two Hair grows roughly at an average speed of 10 centimeters long and the follicles are not cm/yr (0.3 mm/day). A general good health and connected to sebaceous glands. Vellus hair is also nutrition are important for healthy hair growth. present among pre-adolescents (Tanner stage 1). Malnutrition, under-nutrition and anemia have Terminal hair is developed hair, which is generally strong influences on hair growth. Certain minerals, longer, coarser, thicker, and darker than vellus vitamins, hormones and trace elements are also hair. The phases of growth in terminal hair are particularly important for normal hair growth. The more apparent than in vellus hair and the former levels of androgens are another important factor generally has a longer anagen phase. Terminal regulating hair growth (Itami and Inui 2005). hair contains a large hair follicle and sometimes, a Estrogens, on the other hand, slow down hair medulla. During puberty many hair follicles in the growth during the growing period. A current pubic region, armpits, legs, chest and face, the review by Conrad and Paus (2004) provides an latter two in case of males, transform from vellus insight to the effects of estrogens on hair follicle hair to terminal hair under the influence of hor- cycling, cutaneous expression of estrogen mones. Terminal hairs can be further subdivided receptors, and potential functions of estrogens into different types depending on their nature in hair biology. At the onset of puberty the and/or position of growth on the body. The immature vellus hairs on the bodies change to different types of terminal hair types include hair terminal hairs. This change is due to both adrenal of the eyebrows, eyelashes, head hair, beard hair, and gonadal androgens that exert their biological pubic hair and peri-anal hair. effects via the androgen receptor, a nuclear transcription factor modulating a specific Types of Terminal Hair transcription regulation of largely unknown genes (Hiort 2002). Eyebrow hair is a protective patch of hair above the eye. It keeps the eyes free from sweat TYPES OF HAIR and other fluids and helps reduce any excessive glare from sunlight entering the eyes. The hair The hair follicle present in humans is quite fiber contains a medulla and is curved and coarse. distinct from hair types found in animals. However, Eyebrow hair is considered to have one of the even though the basic human hair follicle structure slowest growth rates of any hair follicle type remains the same, the type of hair that is produced found on the human body. Eyelash hair is very can be quite different. Humans have several similar to eyebrow hair. Its growth rate is about different types of hair that can be classified the same as for eyebrows. Eyelashes are very depending on their body position and form. important in protecting the eye from dust and Generally three different hair types are debris. Head hair is generally comprised of described. They are based on the length and terminal hair which grows in a clockwise whorl diameter of the hair follicles in the skin and called pattern on the top of the head and merging of lanugo, vellus and terminal. Lanugo is the hair this pattern into hair angled downwards and away type produced in the very first cycle of hair growth from the face around the ears and lower back of when a hair follicle enters shortly after it develops the scalp. Growth rates are possibly slightly faster in the embryo. These hairs are fine and soft, and in females than males. Head hairs are usually the 50 JAYDIP SEN longest hairs on the human body and are environment can easily cause a secondary characterized as having a uniform diameter. The transfer of hair. Hairs that are found on the beard develops in response to testosterone/ clothing of suspects or victims and appear to have steroidal hormones during puberty in males and fallen out naturally may be the result of primary is thick, coarse with a triangular cross section. or secondary transfer. Hairs that have been Heavy shouldering or troughs in the hair are forcibly removed may suggest a violent observed under magnification. Other charac- confrontation and this can often happen in cases teristics include a wide medulla and a razor-cut of sexual assault. A study has reported higher tip. The hair follicles of the beard are some of the transfer of pubic hair from females to males than fastest producers of hair. Limb hairs are shorter from males to females during sexual intercourse in length, arc-like in shape, and often abraded or (Exline et al. 1998). This prevalence of female-to- tapered at the tips. The pigment in limb hair is male pubic hair transfers suggests the importance generally granular in appearance, and the medulla of collecting pubic hair combings from the male is trace to discontinuous. Pubic hair is a kind of suspects as well as from female victims, provided terminal hair that is usually pigmented, short, the time interval is not extreme. The type of fabric thick, coarse and kinky. Pubic hair is quite different also has a major role in hair transfer (Dachs et al. from head hair as instead of forming a round 2003). It is recognized that generally, hairs persist shape, the hair is oval. They possess a consi- longer on rougher fabrics. Moreover, wool gives derable diameter variation or buckling and often the best chance of recovering samples of hair as have a continuous to discontinuous medulla. The the speed at which hair was lost from fabrics growth period for pubic hair is short and within decreased in the order polyester, cotton/acrylic, six months, the hair follicle dies and the hair falls polycotton, cotton, smooth wool, rough wool. In out. Hence, pubic hair never gets a chance to their study on fibre transfer, Palmer and Banks grow longer. Though not much is known about (2005) observed that the greatest degree of peri-anal hairs, it is generally agreed that these secondary transfer occurred with cotton, then are terminal hairs surrounding the anus. Peri-anal acrylic, then wool. The very importance on hair hairs are distinguished from other hair types in transfer can be gauged from the fact that there the vicinity by their size and their unusually large have been scientific papers published based on associated sebaceous glands. specific individual investigations (e.g. Taupin 1996)

HAIR AS EVIDENCE Hair Morphological Studies

It has been recognized for a number of The examination of human hairs in the forensic decades that the presence of hairs can associate laboratory is typically conducted through the use a suspect to a victim or a suspect/victim to a crime of light microscopy. The forensic anthropologist scene. The types of hair recovered, their condition compares the various morphological charac- and number of hairs all have a great impact as teristics of the hair samples such as medullation, evidence in a criminal investigation. Comparisons diameter, form and cross-section. Methods of of the morphological characteristics of analyzing these characteristic features were questioned hairs to known hair samples are developed decades ago. The initial methodology usually done to ascertain whether a transfer may for understanding hair morphology was develop- have occurred. ed by Hausman in the 1920s. Subsequently a number of notable studies on hair morphological Hair Transfer characteristics were initiated. Such studies include those of Wynkoop (1929) on hair diameter, Physical contact may result in the transfer of Fiala (1930) on hair cross-section, Trotter et al. hairs. The transfer can directly be from the region (1956) on hair form, Hrdy (1973) on hair medulla of the body where they are growing (primary and Das Chaudhuri (1977) on hair cross-section. transfer) or they can transfer from the clothing of With some modifications, these methods are still individuals (secondary transfer). An individual being used today. For instance, Kempson et al. sheds approximately hundred head hairs each day (2002) developed a simple technique is presented on clothing and on items in the environment. for the longitudinal sectioning of hair samples Contact between a victim and a suspect’s without the need for any embedding medium. HUMAN HAIR IN PERSONAL IDENTIFICATION AND DOCUMENTING DRUG ABUSE 51

The morphological examination routinely hairs required for a meaningful comparison may involves a two-step process involving a vary depending on the uniformity of charac- comparison microscope — (i) the identification teristics present in the hairs from an individual of questioned hairs and (ii) the comparison of but it is recommended that at least twenty-five questioned and known hairs. During comparison, full-length hairs be obtained, including both full length of the hairs as well as a maximum number plucked and combed hairs, packaged separately. of microscopic features must be considered. The Pubic hairs are not subject to as much change as purpose for conducting this examination is to head hairs over time, as a result of which, a sample ascertain whether two or more individuals could can still be collected months after a crime for the have come into contact or whether one or more purpose of suitable and meaningful comparisons. individuals could have come into contact with an However, it is recommended that a known pubic object. This associative evidence is particularly hair sample be obtained as soon as possible after useful in crimes of violence where physical a crime and should contain at least twenty-five contact may have occurred, such as homicide and full-length hairs taken from different areas of the sexual assault. Crimes such as burglary and armed pubic region. Pubic hairs commonly may possess robbery typically involve the recovery of articles tapered tip, but they also be cut with scissors and clothing, which may contain hairs that are and razors. Presence of facial hairs, more useful for the identification of suspects. However, commonly called beard hairs or moustache hairs, the value and reliability of this evidence is closely on the clothing of a suspect or victim may help related to the variability of hair characteristics establish contact between these individuals. between individuals in the population. While these hairs may be compared morpho- The main steps used by the forensic anthro- logically with the help of a microscope, the pologist in the morphological study of human significance of the association may not be as great hair are outlined below: as head hair and pubic hair associations. While limb hairs are not routinely compared in a forensic a) Body Area Determination laboratory, they can differ in appearance between individuals. However, these differences are not The body area from which a hair originated considered sufficient to allow limb hairs to be of can be determined by general morphology. value for meaningful comparison purposes. The Length, shape, size, color, stiffness, medullar presence of leg or arm hairs on certain items of appearance, curliness, and microscopic appear- evidence only corroborates other investigative ance all contribute to the determination of body information. area. There is a wide range of interpersonal variation in head and pubic hairs as a result of b) Racial Determination which, the majority of work in forensic anthropology has been in comparing and differentiating Forensic anthropologists routinely try to hairs from the head and pubic regions. establish the racial affinities of the head hair Head hairs can appear uncut, with tapered samples. However, it must be cautioned here that tips but are more often cut with scissors and it is difficult to assess the racial affinities of head razors. In general these hairs are subject to more hairs of infants. Moreover, hair samples from alteration than hairs from other body areas. individuals of mixed racial affinities may yield Alterations can be attributed to the use of chemi- microscopic features attributed to more than one cals (hair dyes, rinses, permanents and frosts) racial group. and also to the environment (exposure to exce- The main features of hair that are studied are ssive sunlight, wind and dryness). As such, it is shape of the longitudinal cross section, hair recommended that head hair samples be obtained pigmentation, shape of the cuticle, hair texture, as soon as possible from suspects, victims of medullation and hair form. In case of Caucasoids, crime and possibly from other individuals the cross section varies from round to oval, with (elimination samples). Head hair samples obtained an evenly distributed pigment granules, a colour years after a crime are generally not suitable for ranging from blonde to brown to black, medium meaningful comparison purposes. The known cuticle, fine to medium coarseness, dicontinuous sample usually contain a random sampling of hair medulla and a wavy hair form. The Negroids from different areas of the scalp. The number of exhibit a flat cross section, a dense pigment, a 52 JAYDIP SEN thin cuticle, an absence of medulla and a curly/ growth rate of head hairs is known, the woolly/kinky hair form. Negroid hair pigment investigator can assess the approximate time of granules are larger than those found in other racial this treatment by measuring the length of groups and the shaft exhibits variation or apparent untreated area of the hair. This is done by a direct, variation in diameter as it is often flattened nature side-by-side comparison of the color of the and the manner in which it lies on the microscope questioned and known artificially treated hairs. A slide. Twisting of the hair shaft (buckling) may be microscopical study of the hair root determines present, and the hair shaft may be frequently split whether the hair was forcibly removed from the along its length. The hairs of Mongoloids show a body or shed naturally. Hairs that fall out naturally round cross section and a straight hair form, having exhibit a club-shaped root, while a forcibly a characteristic reddish appearance or tinge. These removed hair will be stretched and may have tissue hairs are often coarse having a wider diameter than attached to it. The manner in which a hair was those of the other racial groups. The cuticle is removed has considerable forensic value, espe- usually thicker than that of Negroid and Caucasian cially when there is a possibility of violent contact hairs, and the medulla is continuous. The hair shaft between a suspect and a victim. Microscopic or cortex of Mongoloid hair contains pigment examination can also be used to establish whether granules that are generally larger in size than the the hair was burned, cut or crushed. The micro- pigment granules of Caucasian hairs. scopic study of changes in hair roots has been often utilized to solve murder cases (Tafaro 2000). c) Age and Sex Determination Conclusions and Significance of the The age of an individual is difficult to determine Morphological Study of Human Hair by a microscopic examination. But the microscopic characteristics hair of infants and elderly Forensic anthropologists provide a range of individuals may provide a general indication of opinions regarding the importance of hair age. It may be mentioned here that hairs of infants examinations. Some believe that hair cannot be are generally finer and less distinctive in comparable to the specificity of dermatoglyphics microscopic appearance. With the advancement and opine that the probability of establishing of age, hair may lose pigments, turn gray and also personal identification from hair is the same as the become much finer and more variable in diameter. probability of determining identification using the In many cases, instances of gray hair in head and ABO blood group system. Others believe that hair pubic hair samples were utilized for a general from two individuals is distinguishable and that no assessment of age. In a significant study, Haga et accidental or coincidental matches can take place. If al. (1995) investigated the appearance age and such accidental or coincidental matches occur, these possible appearance age of gray hair in pubic hair would be referred to as only a relatively rare event. in an attempt to ascertain age of individuals and Lamb and Tucker (1994) pointed out that the formulated a five-stage classification. interpretation of human hair comparisons is highly However, the sex of an individual is difficult to subjective and there tends to be some caution when determine from microscopic examination of hair. evaluating positive evidence. This, they opined was Women generally possess longer, treated hairs mainly due to a lack of background information than men. Sex can be determined from a forcibly relating to the interpretation of the results obtained. removed hair (with tissue), but this is not routinely Their study was significant because they concluded done. The staining of sex chromatin in the cells that comparisons of Afro-Caribbean hairs were found in the follicular tissue is a better option. possible and a significant proportion of individuals With the advent of better techniques, DNA tests can be excluded by such tests. can also provide more specific information. There are three possible conclusions that can be reached from the microscopic examination and d) Determination of Hair Treatment and comparison of human hairs. It may be concluded Forceful Removal of Hair that: a) The questioned hair and the hairs in the Morphological examination can identify known hair sample exhibits the same whether a hair sample had undergone artificial characteristics and, accordingly, is associated treatment such as use of dyes. Moreover, as the with the same source of the known hairs. HUMAN HAIR IN PERSONAL IDENTIFICATION AND DOCUMENTING DRUG ABUSE 53 b) There are differences between the questioned ed the collection of forensic evidence when sexual hair and the known hair sample and, abuse has occurred within three days or when accordingly, the questioned hair cannot be there is bleeding or acute injury (Christian et al. associated to the same source of the known 2000). hairs. c) Similarities exist between the questioned hair Present Day Problems of Hair Microscopic and hairs in the known hair sample, along with Features as Material of Evidence some differences. Hence, it is not definitely possible to determine whether the questioned These days there is a lot of debate in the hair and the known hairs originated from the judicial and forensic fields concerning the same source. In such cases, the forensic admissibility and reliability of forensic comparison anthropologist may make a general statement sciences such as handwriting, tool mark analyses concluding that since it is unusual to find hairs and hair analysis. In particular, there has been an from two different individuals sharing same increasing controversy over the use and characteristics, such a microscopic associa- interpretation of hair comparison evidence and it tion or match is the basis for a strong associa- has been often held partly responsible for tion. miscarriages of justice. It will not be wrong to While trying to establish a particular asso- mention here that although the morphological ciation between the hair sample and the victim/ comparison of human hairs has been accepted in accused, the probability that the association (or courts of law for over a century, recent advances elimination) was due to coincidence or the proba- in DNA technology have questioned this type of bility that the association (or elimination) was due forensic examination. As a matter of fact, in a to examiner error and the probability that there is number of cases, post-conviction DNA testing an alternative explanation for the evidence can has exonerated defendants who were convicted both be influencing factors. This alternative in part on the results of morphological hair explanation can be secondary transfer, conta- comparisons. It is pertinent to mention here that mination, or deliberate planting. changes in the acceptance of hair test results in Specific case situations can also play an the United States courts have resulted from two important role. In investigations dealing with factors: i) the rapid advancement of under- sexual offences and rape, it is always important standing of hair test data and ii) modification of to put a patient at ease prior to making an the admissibility standards for forensic evidence examination for the collection of seminal stains, in United States courts (Huestis 1996). It is now hair samples and a general gynaecological being opined that morphological hair compa- examination (Huntington 1976). The broad risons should be regarded by law enforcement protocol goals are to minimize the physical and agencies and courts of law as merely presumptive psychological trauma to the victim while in nature, and all morphological hair comparisons maximizing the probability of collecting and should be confirmed by nuclear DNA profiling or preserving physical evidence for potential use in mitochondrial DNA sequencing (Rowe 2001). the legal system. Furthermore, there are also The method of hair collection at the scene of established procedures that the hospital staff the crime, its preservation, the evidence needs to follow in cases of sexual assault. The processing techniques employed, the examination procedure followed by the Sexual Assault Nurse of the victim and the accused, the methodology Clinician (SANC) in Emergency Departments in used in the hair morphological examination Minneapolis, Minnesota (Ledray 1992) may be process and the experience of the hair examiner mentioned here. Similar national hospital/ all play important roles in the final judgment of community model protocols for the forensic and hair examination results. Keating and Allard (1994) medical examination of victims of sexual assault stresses upon the need for a precise sampling exist in various cities and hospitals in the United without contamination as the interpretation of the States (Young et al. 1992; Sievers et al. 2003). results depend a lot on these two factors. Other However, in case of sexual assault of children, factors that impede the reliability of hair evidence the guidelines for collection of forensic include experience, training, suitability of known specimens like hair are not suited, even though hair standards, and equipment. Wickenheiser and the American Academy of Pediatrics recommend- Hepworth (1991) have observed that, due lack of 54 JAYDIP SEN consistency in examiner discrimination, routine exposure to pollutants and adulterants. Moreover, hair classification is not feasible. They have also as hair growth is uniform, segmental hair analysis shown that that with the application of rigid can provide the information about the time course selection criteria, the frequency of coincidental of the substance use or exposure. Advantages of matches in forensic science hair comparisons is analyzing hair samples also include their easy, low. non-invasive collection, the small sample size The importance of hair evidence is also greatly required for analysis, and their easy storage at dependent upon its association with a number of room temperature (Daniel et al. 2004). Hair samples compared characteristics, length of compared hair, have also been collected from dead bodies at the hair treatment, racial group and most importantly, time of postmortem and analyzed for drug content the number of known hairs with which the sample (Drummer 2004). Among the drugs involved, was matched. A positive hair comparison is heroin, cocaine, amphetamine, and cannabis are strengthened by the presence of two or more the ones that are most frequently involved in mutually dissimilar hairs that are similar to a known judicial inquiries. The detection of cocaine in hair sample or by hairs with unusual characteristics has been the Federal Bureau of Investigation’s or by two-way transfers. Additional examinations first priority in hair testing for drugs of abuse of confirmation, such as DNA and sex typing also because of its prevalence. lay credence to a positive hair comparison. A hair comparison is weakened if the known sample Techniques and Advantages of Using Hair in has too few hairs, unrepresentative hairs, Documenting Drug and Substance Abuse incomplete hairs, and a significant temporal difference between the offense and the collection The analysis of hair for drugs of abuse is a of the known sample. Negative hair comparison powerful tool that can be very useful here in conclusions are also weakened by the presence solving such cases (Moeller 1996). In recent years, of incomplete questioned hairs and by similarities remarkable advances in sensitive analytical and differences within the hair sample. techniques have enabled the analysis of drugs in hair. The main analytical methods that are used HAIR ANALYSIS IN DOCUMENTING to analyze drugs in hair are immunoassay, gas DRUG AND SUBSTANCE ABUSE chromatography and mass spectrometry. Improv- ed chromatographic-mass spectrometric techni- Background ques with increased selectivity and sensitivity and new methods of sample preparation have now It is generally accepted that chemical testing improved detection limits from the ng/mg range of body fluids is the most objective means of to below pg/mg (Pragst and Balikova 2005). diagnosis and documenting exposure to drug and Moreover, as hair growth is continuous, the substance use. However, it has often reported window of drug detection is dramatically extended that drugs of abuse cannot be detected in body to weeks, months or even years. A lock of hair the fluids and as such hair becomes important as a width of a pen tied at the root end is all that is tissue material for analysis of the same. With the required for a comprehensive drug test and profile development of different analytical methods in (Flanagan et al. 2005). There is a recent review on recent years, hair began to be utilized in solving the current status of hair analysis in drug abuse poisoning cases and cases of drug and substance (Kintz 2004). This review by Kintz (2004) is worth abuse. In a very recent review on this subject, mentioning as in an earlier paper Kintz and Balikova (2005) has pointed out that for over the Mangin (1995) pointed out that hair was still a last twenty years hair analysis for drugs abuse seldom used specimen in most laboratories for has been gaining increasing attention and documenting drug abuse mainly because the recognition in forensic identification, doping scientific community still had reservations about control of banned substances and clinical the validity of hair analysis. They had further diagnostics in health problems. Hair is also a argued that the areas of agreement and consensus unique material for the retrospective investigation needed to be worked out. Miller et al. (1997) also of chronic drug consumption, intentional or reported that the Federal Bureau of Investigation unintentional chronic poisoning in criminal cases, only resorts to hair analysis when other gestational drug exposure or environmental information pointed towards drug use and also HUMAN HAIR IN PERSONAL IDENTIFICATION AND DOCUMENTING DRUG ABUSE 55 when hair analysis could remove a person from fully investigated and needs further research. suspicion or associate them with criminal activity. Harkey (1993) pointed out that a basic understanding of hair biology is important necessary Kinds of Drugs and Substance Analyzed so as to interpret the results of hair analysis tests in cases of drug abuse. It is well recognized that The use of hair for analyzing exposure to hair grows from follicles present within the skin, substance abuse started in the 1990s. Many which has multiple layers of tissue, glands whose employers in the United States started programs to secretions bathe hair, and multiple vascular deter drug use by their employees and these systems. All these he opined are capable of programs included the collection and analysis of transferring drugs to hair at many levels along hair samples (Bost 1993). It may be mentioned here the length of the hair shaft. that in Greece, hair analysis for drug abuse has been Moreover, it is difficult to interpret to what in use since 1993 and this was in addition to the extent test results from different laboratories are psychiatric or other forensic clinical examinations comparable and how far their results are consistent. necessary for the confirmation of a person’s use of For this, in the United States, proficiency testing drugs (Tsatsakis 1998). The importance of hair of crime laboratories began in the mid-1970s and analysis towards the understanding of drug and presently assumes an important role in quality substance abuse can be gauged from the fact that assurance programs within most forensic there have been also a number of research publi- laboratories. Peterson and Markham (1995a) cations on specific cases of such abuse that had reviewed the origins and early results of this testing been solved by hair analysis. In this context, the program and also highlighted the progress of studies of Strano Rossi et al. (1998) on heroin abuse, proficiency testing. They also reviewed the Selavka et al. (1995) on fentanyl consumption, success of laboratories in the identification and Tagliaro et al. (1998) on morphine abuse, classification of some common forensic evidences Tassiopoulos et al. (2004) on cocaine abuse, Klys et and concluded that laboratories have more success in determining the origin of finger and al. (2004a) on levomepromazine poisoning, Villain et palm prints, metals, firearms and footwear and only al. (2004) on bromazepam cases, Berankova et al. moderate success in determining the source of (2005) on methamphetamine abuse and De Giovanni bloodstains and hair. In yet another review, et al. (2005) on buprenorphine intake may be referred Peterson and Markham (1995b) highlighted to. Cases related to complex and multiple drug laboratory proficiency in determining if two or more poisoning has been reported by Klys et al. (2004b) evidences shared a common source. Furthermore, and Musshoff et al. (2006). hair reference materials containing recommended concentrations of drugs that are generally used Disadvantages of Using Hair in Documenting during the process of determination are also lacking. Drug and Substance Abuse Very few laboratories have developed such reference materials (Welch et al. 1993). Similarly, In a review, Wennig (2000) pointed out that it there also has to be consensus on the establishment is rather difficult to interpret parent drug or/and of cut-off values. The cut-off values proposed by metabolite concentrations in hair. This is mainly Kintz and Mangin (1995) using 30-mg hair samples due to differences in hair growth rate, anatomical may be cited here - 0.5 ng/mg in the case of heroin region, age, gender, ethnicity and inter-individual abuse and 1 ng/mg of cocaine in the case of cocaine variability, Furthermore, as drug incorporation abuse, which can be decreased to 0.5 ng/mg when mechanisms into hair matrix is not yet fully use is supported by other evidence of drug intake. understood, it is difficult to extrapolate details on time and dose from hair segment analysis. CONCLUSION AND FUTURE DIRECTIONS Cosmetic hair treatment, natural and artificial hair colour, differences in hair structure and specificity Hair consists of an inner cortex and a cuticle, of analytical methodology may represent other and is basically made up of cystine containing bias sources affecting concentrations of drugs keratin protein. Within this protein many bonds in hair. It is also opined that the frequency of are present, the most important of which is a drug consumption and time intervals between disulfide bond. This disulfide bond that is mainly multiple consumption or lag time between con- responsible for keratin’s resistance. The hair sumption and appearance in the hair has not been follicle is a very complex structure and has its 56 JAYDIP SEN own sebaceous network and cycle. Hair formation analysis of the same. Hair analysis for the begins in the third month of fetal life and follows documentation of drug and substance abuse a cyclic pattern of growth. This hair growth is started only in the decade of the nineties. influenced by a number of factors such as nutri- Moreover, as hair growth is continuous, it is easy tion and hormones. There are three types of hair to document the exposure over a period of time. in humans - lanugo, vellus and terminal. All these This time can by extended to weeks, months or types have their own characteristic features. even years Heroin, cocaine, amphetamine, Hair has a great role in forensic anthropology cannabis and levomepromazine are some of the as its presence can associate a suspect to a victim substances most frequently involved in judicial or a suspect/victim to scene of crime. One of the inquiries and hair is being used to document main aspects of this investigation is to understand exposure to these. There are a number of problems whether any transfer (primary or secondary) had as drug incorporation mechanisms into hair matrix occurred. Then comes the process of comparing which are yet to be fully understood. There exist the microscopic features of the known and considerable individual variations in hair growth unknown hair samples. The hairs that are rate, anatomical region, age, gender, ethnicity routinely compared are head and pubic hairs the which are also the areas of concern. Moreover, hairs. The purpose for conducting this exami- variation in the results between the laboratories nation is to ascertain whether two or more poses questions regarding the reliability individuals could have come into contact or consistency of the results. Reference materials whether one or more individuals could have come and cut-off values of the discussed variables into contact with an object. For this a maximum required with respect to the specific outcomes. number of microscopic features need to be There is the need to develop universally considered. The forensic anthropologist also tries accepted methods of hair collection from the scene to ascertain the body area of the unknown of the crime and the evidence processing sample, along with the racial type and age and techniques employed. Similarly the methodology sex. It is also determined whether the hair sample used to study hair morphological features should had undergone artificial treatment and whether also need to be looked into. Hair treatment is the hair had been forcefully pulled out. Forensic another area which needs to be addressed. As anthropologists give a wide range of opinions recent advances in DNA technology have with regards to hair microscopic examinations. questioned hair examinations, future studies need For some, the probability of identification is the to use both hair and DNA technology to arrive at same as that obtained by ABO blood groups, while a conviction or exoneration. The utility of hair for others it is almost certain. analysis for drugs and substances of abuse has However, method of hair collection, the been well-established. Future studies need to be evidence processing techniques employed for the done to understand the process of incorporation examination of the victim and the accused, the of drug and substances into the hair matrix. The methodology used to study hair morphological areas of individual variations in hair growth rate, features and the experiences of the hair examiner anatomical region, age, gender and ethnicity also are all confounding factors in the final analysis. need to be addressed. There need to be close The other conflicting parameters are the number cooperation and linkage between different of compared characteristics, length of compared laboratories as questions are often raised hair, hair treatment, racial group and the number regarding the reliability consistency of the results. of known hairs with which the sample was Reference materials and cut-off values of the matched. Moreover, recent advances in DNA discussed variables need to be developed. technology have questioned hair examinations and it has been reported that post-conviction ACKNOWLEDGEMENT DNA testing has exonerated many defendants who were convicted in part on the results of The author acknowledges the co-operation morphological hair comparisons. of the Department of Anthropology, University It has now been reported that drugs and of North Bengal while preparing this paper. substances of abuse cannot be detected in body fluids. 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