Citation

Meier U, Colledge F, Imfeld S, Briellmann T, Mercer-Chalmers-Bender K, Scheurer E, Dussy F. Drug Test. Anal. 2019; ePub(ePub): ePub.

Affiliation

Forensic Chemistry and Toxicology, University of Basel Institute of Forensic Medicine.

Copyright

(Copyright © 2019, John Wiley and Sons)

DOI

10.1002/dta.2679

PMID

31407516

Abstract

While hair analysis is important and accepted in forensic applications, fundamental knowledge gaps still exist, exacerbated by lacking knowledge of the incorporation mechanisms of substances into hair. The influence of the hair sampling location on the head on EtG and cocaine concentrations was investigated by measuring the complete scalp hair of 14 (2 EtG, 4 cocaine, 8 both EtG and cocaine) study participants in a grid pattern for EtG, drugs of abuse and benzodiazepines. Head skin perfusion and sweating rates were investigated to rationalize the concentration differences. For EtG, differences between minimum and maximum concentrations on the scalp ranged from factor 2.5 to 7.1 (mean 4.4). For cocaine, the differences ranged from factors of 2.8 to 105 (mean 17.6). EtG concentrations were often highest at the vertex, but the distribution was strongly participant dependent. Cocaine and its metabolites showed the lowest concentrations at the vertex and highest on the periphery, especially at the forehead. These differences lead to hair from some head parts being clearly above conventional cut-offs and others clearly below. In addition to EtG and cocaine, the distributions of 24 other drugs of abuse and benzodiazepines/z-substances and metabolites are described. No clear pattern was observed for the head skin perfusion. Sweating rate measurements revealed higher sweating rates on the periphery of the haircut. Therefore, sweat could be a main incorporation route for cocaine. Concentration differences can lead to different interpretations depending on sampling site. Therefore, the results are highly relevant for routine forensic hair analysis.

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Language: en

Keywords

Distribution; Drugs of abuse; Hair analysis; Perfusion rates; Sweating rates