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What is HAIR ANALYSIS? What does HAIR ANALYSIS mean? HAIR ANALYSIS meaning – HAIR ANALYSIS definition – HAIR ANALYSIS explanation.
Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license.
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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 and, increasingly, environmental toxicology. Several alternative medicine fields also use various hair analyses for environmental toxicology, 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.
Hair analysis is used for the detection of many therapeutic drugs and recreational drugs, including cocaine, heroin, benzodiazepines and amphetamines. 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. 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 three days; hair analysis can sometimes detect use as far as a month, 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.
Microscopic hair analysis is the science of comparing several strands of hair under a microscope and attempting to deduce if the strands ‘match’. 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…..