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Statistical examination of hair color as a potential biasing factor in hair analysis

Department of Criminology, University of South Florida 33701-5016, USA.
Forensic Science International (Impact Factor: 2.12). 02/2000; 107(1-3):13-38. DOI: 10.1016/S0379-0738(99)00147-4
Source: PubMed

ABSTRACT We review eight different data sets in this paper for the purposes of assessing the possibility that reported color of hair can produce a systematic bias in the interpretation of hair assays. We review studies or data sets that include heroin and its metabolites, cocaine and its metabolites, MDMA and its analogs, and amphetamine and methamphetamine. The studies have utilized a variety of different degrees of color categorization, ranging from the simple dichotomy of brown and black, to a high of 12 categories. The mean number of categories reported approaches 6 (mean = 5.875). There are a total of 2791 data points in this analysis. We utilize two major statistical techniques for assessing significance; one-way analysis of variance, and Tukey's Honestly Significant Difference procedure. In circumstances were only dichotomous contrasts are possible, one-way analysis of variance is used. In contrasts involving three or more categorical groups, Tukey's procedure is used. In circumstances where the homogeneity of group variances is not sustained by the Levene statistic, we use the Tamahane procedure, allowing an assessment that assumes unequal variances. The analysis of this data fails to discern a significant color effect. We speculate that it may be that variance is large in many domains affecting analyte recovery from hair. In large groups these variations tend to regress towards a typical or mean value. Thus the data here show that while there are group or aggregate differences in these 'typical' values, they are not great when considered in relation to the within-group variations which exist for those values. It is our view that color may play a role in the accumulation of drugs in hair, however it is likely to account for only a very small part of the complex process of drug accumulation.

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    • "Dokonując oceny barwy, trzeba pamiętać, iŜ pod wpływem niektórych czynników (np. narkotyki) we włosach następują procesy, które mogą wpłynąć na odcień lub całkowicie zmienić barwę włosa (Mieczkowski, Newel, 2000, s. 13–38). NaleŜy takŜe uwzględnić działanie wysokiej temperatury (przyciemnienie), promieniowania UV (rozjaśnienie) czy róŜnego rodzaju substancji chemicznych (środowisko kwaśne – brązowienie, obecność rudy miedzi – odcień zielony, a rudy kobaltu – niebieskawy) oraz niektóre procesy chorobowe (przebycie szkarlatyny – rozjaśnienie, a duru brzusznego – przyciemnienie ). "
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    ABSTRACT: This study deals with human hair ultrastructure examinations performed for crime detection purposes. A researches and microscopic analyses of various damages to hair resulting from mechanical, thermal, and/or chemical exposure of hair during a criminal event have been conducted, and resulting changes in hair structure have been examined. Tests performed using an electron microscope and hair damage analysis are deemed capable of contributing to obtaining significant information on crime progress, crime scene, perpetrator’s methods of action, or perpetrator him/herself.
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    ABSTRACT: To elucidate the role of drug basicity in the preferential incorporation of certain drugs into dark hair rather than light hair, Long-Evans rats were dosed with amphetamine or its non-basic analogue N-acetylamphetamine (N-AcAp) and their hair evaluated for drug content. Rats were shaved prior to dosing. On the 14th day after dosing, hair from the same area that was shaved prior to dosing was shaved and collected. After the addition of amphetamine-d3 or N-AcAp-d3 as an internal standard, hair samples (20 mg) were digested in 1M NaOH at 37 degrees C. Digested solutions were then extracted with n-butyl chloride/chloroform (4:1, v/v). After drying and reconstituting, samples were injected onto a ThermoQuest TSQ liquid chromatography-tandem mass spectrometry instrument for analysis. Black hair from rats dosed with amphetamine (n = 8) was found to contain 6.44 +/- 1.31 (SD) ng amphetamine/mg hair. White hair from the same rats contained 2.04 +/- 0.58 ng amphetamine/mg hair. In contrast, no difference in N-AcAp content was found between black hair (0.87 +/- 0.08 ng N-AcAp/mg hair) and white hair (0.83 +/- 0.15 ng N-AcAp/mg hair) from rats dosed with N-AcAp (n = 8).
    Journal of analytical toxicology 05/2001; 25(4):221-7. DOI:10.1093/jat/25.4.221 · 2.63 Impact Factor
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