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Earwax: an innovative tool for assessment of tobacco use or exposure. A pilot study in young adults

Abstract

The present work represents a novel approach using earwax (cerumen) for the evaluation of the smoking status with regards to tobacco use/exposure. The method utilizes the difference in the concentration profiles of nicotine and its related compounds in earwax to discriminate among non-, passive, and active smokers. Earwax samples were collected from three study groups (non-, passive, and active smokers) and subjected to analysis by headspace gas chromatography–mass spectrometry. The nicotine levels in earwax were much lower than cotinine levels, even for active smokers; however, it was reported that the nicotine levels in scalp hair were much higher than the cotinine levels. Therefore, it is obviously correct that earwax is protected from external contamination to a larger extent than expected. The concentration profiles of nicotine and its related compounds (o-nicotine, cotinine, and anabasine) in the analyzed earwax samples were treated by data mining techniques. It was possible to discriminate the studied groups using the evolutionary tree (evtree) algorithm and support vector machine discriminant analysis as the statistical models with the best discrimination accuracies of 96.7 and 95.0%, respectively. The analytical method applied requires no sample pretreatment which makes it easy, fast, and a low-cost alternative method to those employing other biological matrices, such as blood, urine, and hair. The earwax, which is considered a neglected body secretion, is a useful tool to determine the exposure to tobacco smoke noninvasively and without the influence of external contamination.

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Acknowledgements

We wish to acknowledge Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), for the research fund provided within the postdoctoral program (PNPD) (Grant Number 1516965) for the first author, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for a research productivity Grant to Nelson Roberto Antoniosi Filho and ‘‘Fundação de Apoio à Pesquisa (FUNAPE) for management of financial resources. We also wish to acknowledge the contribution of the study participants. This work is a part of the research project “Chemical analysis composition of earwax in human and other animals” fully funded by CAPES.

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Correspondence to Engy Shokry.

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The authors declare that they have no conflict of interest.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

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Shokry, E., de Oliveira, A.E., Avelino, M.A.G. et al. Earwax: an innovative tool for assessment of tobacco use or exposure. A pilot study in young adults. Forensic Toxicol 35, 389–398 (2017). https://doi.org/10.1007/s11419-017-0370-0

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Keywords

  • Earwax (cerumen)
  • Alternative specimen
  • Smoking status
  • Cotinine
  • Anabasine
  • GC–MS