Hair analysis may refer to the chemical analysis of a
hair sample, but can also refer to microscopic analysis or comparison. Chemical hair analysis may be considered for retrospective purposes when blood and urine are no longer expected to contain a particular contaminant, typically three months or less.
Its most widely accepted use is in the fields of
forensic toxicology
Forensic toxicology is the use of toxicology and disciplines such as analytical chemistry, pharmacology and clinical chemistry to aid medical or legal investigation of death, poisoning, and drug use. The primary concern for forensic toxicology is ...
and, increasingly, environmental
toxicology
Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...
.
Several
alternative medicine fields also use various
hair analyses for environmental
toxicology
Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...
, but these uses are controversial, evolving, and not standardized.
Microscopic hair analysis has traditionally been used in forensics as well. Analysts examine a number of different characteristics of hairs under a microscope, usually comparing hair taken from a crime scene and hair taken from a suspect. It is still acknowledged as a useful technique for confirming that hairs do not match. But DNA testing of evidence has overturned many convictions that relied on hair analysis. Since 2012, the Department of Justice has conducted a study of cases in which hair analysis testimony was given by its agents, and found that a high proportion of testimony could not be supported by the state of science of hair analysis.
In forensic toxicology
Chemical hair analysis is used for the detection of many therapeutic drugs and
recreational drugs
Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasur ...
, including
cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Ameri ...
,
heroin,
benzodiazepines and
amphetamines
Substituted amphetamines are a class of compounds based upon the amphetamine structure; it includes all derivative compounds which are formed by replacing, or substituting, one or more hydrogen atoms in the amphetamine core structure with sub ...
.
Hair analysis is less invasive than a blood test, if not quite as universally applicable. In this context, it has been reliably used to determine compliance with therapeutic drug regimes or to check the accuracy of a witness statement that an illicit drug has not been taken. Hair testing is an increasingly common method of assessment in substance misuse, particularly in legal proceedings, or in any situation where a subject may have decided not to tell the entire truth about his or her substance-using history. Post-mortem hair sample analysis can also be performed, to allow for determination of long-term drug use or poisoning. It is also used by private employers who test their employees. Hair analysis has the virtue of showing a 'history' of drug use due to hair's slow growth.
Urine analysis might detect drugs taken in the past 2–3 days; hair analysis can sometimes detect use as far as 90 days, although certain cosmetic treatments (e.g. dyeing hair) can interfere with this.
Hair analysis has the ability to measure a large number of potentially interacting elements, although that trait is shared with many other drug tests.
Common instruments used in drug analysis of hair samples is
liquid chromatography–mass spectrometry
Liquid chromatography–mass spectrometry (LC–MS) is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS). Coupled ...
(LC-MS) and
gas chromatography–mass spectrometry
Gas chromatography–mass spectrometry (GC-MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, ...
(GC-MS).
These instruments are used because of the ability to positively detect trace concentrations of drugs.
The judicial admissibility of the test in the United States is guided by the
Daubert standard. A notable court case was ''United States v. Medina, 749 F.Supp. 59 (E.D.N.Y.1990)''.
Microscopic hair analysis in forensics
Microscopic hair analysis consists of the comparison of several strands of hair under a microscope and determining if the physical characteristics of each individual hairs are consistent with each other or not. It was accepted as a forensic science by the 1950s.
Researchers often monitored more than a dozen attributes, including pigment distribution and scale patterns. This technique has been used in criminal investigations to try to tie hair found at a crime scene, or other location of note, and confirm if the hair matches that of a suspect. While a simple hair color match might be ''consistent'' with a certain suspect having been at the scene – black hair at the scene when the suspect has black hair – microscopic hair analysis began to claim a stronger standard by the 1970s. Rather than merely "narrow the field" of possibilities, hair analysts claimed to be able to match a specific person, such that the hair could be 'proof' of a specific suspect's presence. While the typed reports often hedged the certainty of microscopic hair analysis, witnesses in court would not always be as modest. The manager of the Montana state crime lab testified there was a "1 in 10,000 chance" that hairs found at a crime scene did not come from the suspect in one case, for example.
Microscopic hair analysis has a long tradition of being used in crime fiction as well; it was originally popularized in the
Sherlock Holmes series before being widely used by the police.
Fictional TV programs involving police procedurals and detectives have continued to use it since, including ''
Columbo'', ''
Quincy, ME'', ''
Dexter'', and ''
CSI''.
![Microscopic Overview of Hair Properties](https://upload.wikimedia.org/wikipedia/commons/6/6d/Microscopic_Overview_of_Hair_Properties.png)
Skepticism about the stronger claims used by witnesses in the 1970s and 1980s existed at the time. Researchers said in 1974 that the whole process was inherently subjective, and the FBI wrote in 1984 that hair analysis cannot positively match one single person.
In the 1990s,
DNA profiling was introduced as a key new technique into forensics investigations; it introduced a new level of certainty about matching suspects to evidence. DNA analysis of old cases from the 1970s and 80s, however, contradicted conclusions about a number of earlier matches on the basis of hair analysis.
In 1994, the Justice Department created a task force which would eventually review 6,000 cases by 2004, focusing on the work of one particularly zealous examiner, Michael Malone.
These reviews came after reports that sloppy work by examiners at the FBI lab was producing unreliable forensic evidence in court trials. At first, these investigations were largely kept quiet; ''The Washington Post'' reported that "Instead of releasing those findings, they made them available only to the prosecutors in the affected cases."
A study of FBI Laboratory hair analysis cases between 1996 and 2000 was released in 2002 by Max M. Houck and Bruce Budowle. The study showed that 11% of hair analysis "matches" were contradicted by DNA analysis. As the set of cases analyzed was one which would be expected to favor matches strongly in any case – only hair of individuals the police already believed to be potential suspects was sent in – this error rate was considered to be extremely high.
Kirk L. Odom was convicted of rape in Washington, DC in 1982 by no physical evidence except microscopic hair analysis performed by the
FBI Crime Laboratory.
Combined with a witness's identification in a
line-up (another technique which modern research has shown to be much less reliable than previously thought), Odom was sentenced to twenty or more years in jail. DNA analysis, however, proved that Odom was entirely innocent.
While Odom had been released from prison in 2003, he was officially exonerated in 2012 and was paid a large settlement by the city.
In a similar case,
Santae Tribble was convicted in 1979 at the age of 17 in Washington, DC of murder due to FBI testimony in a hair analysis match of hair found at the scene. But he had three witnesses who gave him an
alibi
An alibi (from the Latin, '' alibī'', meaning "somewhere else") is a statement by a person, who is a possible perpetrator of a crime, of where they were at the time a particular offence was committed, which is somewhere other than where the crim ...
for the time when the crime was committed. The prosecutor overstated the reliability of hair analysis in identifying a single person, saying in his closing statement that "There is one chance, perhaps for all we know, in 10 million that it could
esomeone else's hair."
DNA testing in January 2012, however, showed that the prosecution's key piece of evidence, the hair, did not in fact match the defendant. Tribble was fully exonerated in December 2012, having served 28 years in prison that resulted in severe health problems.
The outcry from defense attorneys about the unreliability of hair analysis and overstatement by FBI experts has resulted in the FBI conducting a review of disputed hair analysis matches since 2012. Due to what it found, in July 2013 the Justice department began an "unprecedented" review of older cases involving hair analysis, examining more than 21,000 cases referred to the FBI Lab's hair unit from 1982 through 1999.
By 2015, these cases included as many as 32 death penalty convictions, in which FBI experts may have exaggerated the reliability of hair analysis in their testimony and affected the verdict. Of these, 14 persons have been executed or died in prison.
In 2015, DOJ released findings on 268 trials examined so far in which hair analysis was used (the review was still in progress). The review concluded that in 257 of these 268 trials (95 percent), the analysts gave flawed testimony in court that overstated the accuracy of the findings in favor of the prosecution. About 1200 cases remain to be examined. The department emphasized its commitment to following up on these cases to correct any wrongs, saying that they "are committed to ensuring that affected defendants are notified of past errors and that justice is done in every instance. The department and the FBI are also committed to ensuring the accuracy of future hair analysis, as well as the application of all disciplines of forensic science."
In 2017, new Attorney General
Jeff Sessions
Jefferson Beauregard Sessions III (born December 24, 1946) is an American politician and attorney who served as the 84th United States Attorney General from 2017 to 2018. A member of the Republican Party, he previously served as United States ...
, appointed by President
Donald Trump
Donald John Trump (born June 14, 1946) is an American politician, media personality, and businessman who served as the 45th president of the United States from 2017 to 2021.
Trump graduated from the Wharton School of the University of P ...
, announced that this investigation would be suspended, at the same time that he announced the end of a forensic science commission that had been working to establish standards on several tests and to improve accuracy; it was a "partnership with independent scientists to raise forensic science standards".
Independent scientists, prosecutors, defense counsel and judges criticized ending the commission, saying that the criminal justice system needed to rely on the best science.
As of late 2019, 75 people who were convicted of a crime based on microscopic hair comparison were subsequently exonerated. Another notable case that received media attention since was Anthony Broadwater, who had been convicted of raping
Alice Sebold
Alice Sebold (born September 6, 1963) is an American author. She is known for her novels ''The Lovely Bones'' and '' The Almost Moon'', and a memoir, '' Lucky''. ''The Lovely Bones'' was on ''The New York Times'' Best Seller list and was adapte ...
in 1982, and was formally exonerated in 2021 after finishing his time in 1998. The only physical evidence the prosecution offered in 1982 was a hair analysis that was "consistent" with Broadwater. More alarmingly, the only reason the case was re-examined was the unusual fact that Sebold had written an extensive memoir of her experiences (''
Lucky''), which allowed later investigators to uncover major problems with the case.
In environmental toxicology
Analysis of hair samples has many advantages as a preliminary screening method for the presence of toxic substances deleterious to health after exposures in air, dust, sediment, soil and water, food and toxins in the environment. The advantages of hair analysis include the non-invasiveness, low cost, and the ability to measure a large number of, potentially interacting, toxic and biologically essential elements. Hence, head hair analysis is increasingly being used as a preliminary test to see whether individuals have absorbed poisons linked to behavioral or health problems.
[
]
Detection of long-term elemental effects
The use of hair analysis appears to be valid for the measurement of lifelong, or long-term heavy metal burden, if not the measurement of general elemental analysis. Several studies, including the analysis of Ludwig van Beethoven
Ludwig van Beethoven (baptised 17 December 177026 March 1827) was a German composer and pianist. Beethoven remains one of the most admired composers in the history of Western music; his works rank amongst the most performed of the classic ...
's hair, have been conducted in conjunction with the National Institutes of Health
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
and Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
.
In a 1999 study on hair concentrations of calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
, iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
, and zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
in pregnant women and effects of supplementation, it was concluded that "From the analyses, it was clear that hair concentrations of Ca, Fe, and Zn could reflect the effects of supplementation... Finally, it could be concluded that mineral element deficiencies might be convalesced by adequate compensations of mineral element nutrients."
Occupational, environmental and alternative medicine
Hair analysis has been used in occupational, environmental
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
and some branches of alternative medicine as a method of investigation to assist screening and/or diagnosis
Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...
. The hair is sampled, processed and analyzed, studying the levels of mineral and metals in the hair sample. Using the results, as part of a proper examination or test protocol,[Bass DA, Hickok D, Quig D, Urek ]
Trace element analysis in hair: factors determining accuracy, precision, and reliability – Statistical Data Included.
Altern Med Review 2001;6(5):472–481. practitioners screen for toxic exposure and heavy metal poisoning
A toxic heavy metal is any relatively dense metal or metalloid that is noted for its potential toxicity, especially in environmental contexts. The term has particular application to cadmium, mercury and lead, all of which appear in the World H ...
. Some advocates claim that they can also diagnose mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
deficiencies and that people with autism have unusual hair mineral contents.[Lathe, Richard, and Michael Le Page. "Toxic metal clue to autism: a study has revealed startling differences in mercury levels in the hair of autistic and normal children. (This Week)." ''New Scientist'' 178.2400 (June 21, 2003): 4(2).] These uses are often controversial, and the American Medical Association states, "The AMA opposes chemical analysis of the hair as a determinant of the need for medical therapy and supports informing the American public and appropriate governmental agencies of this unproven practice and its potential for health care fraud."[Hair analysis: A potential for medical abuse. Policy number H-175.995,(Sub. Res. 67, I-84; Reaffirmed by CLRPD Rep. 3 – I-94)]
A recent review of scientific literature by Dr Kempson highlighted analysis of metals/minerals in hair can be applied in large population studies for researching epidemiology and groups of chronically exposed populations, however any attempt to provide a diagnosis based on hair for an individual is not possible. An exception to this can be in advanced analyses for acute poisoning.
Literature
* Pragst F., Balikova M.A.: State of the art in hair analysis for detection of drugs and alcohol abuse; Clinica Chimic Acta 370 2006 17–49.
* Auwärter V.: Fettsäureethylester als Marker exzessiven Alkoholkonsums – Analytische Bestimmung im Haar und in Hautoberflächenlipiden mittels Headspace-Festphasenmikroextraktion und Gaschromatographie-Massenspektrometrie. Dissertation Humboldt-Universität Berlin 2006.
*
References
Bibliography
*
* Henderson, G.L., Harkey, M.R., Jones, R.T.
"Analysis of Hair for Cocaine"
in (eds. Edward. J. Cone, Ph.D., Michael. J. Welch, Ph.D., and M. Beth Grigson Babecki, M.A.), "Hair Testing for Drugs of Abuse: International Research on Standards and Technology", 1995, pp. 91–120. NIH
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
Publication No. 95-3727.
*
*
*
*
External links
Cary T. Oien, Unit Chief, FBI Lab, "Forensic Hair Comparison: Background Information for Interpretation"
''Forensic Science Communications'', April 2009, Volume 11, Number 2
Society of Hair Testing
*
Criminology, Florida State University
{{DEFAULTSORT:Hair Analysis
Toxicology tests
Trichology
Forensic techniques