ORIGINAL ARTICLE Earwax: an innovative tool for assessment of tobacco use or exposure. A pilot study in young adults Engy Shokry 1 • Anselmo Elcana de Oliveira 2 • Melissa Ameloti Gomes Avelino 3 • Mariana Moreira de Deus 3 • Naiara Zedes Pereira 2 • Nelson Roberto Antoniosi Filho 1 Received: 4 April 2017 / Accepted: 25 May 2017 Ó Japanese Association of Forensic Toxicology and Springer Japan 2017 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 discrimi- nate 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 ana- basine) in the analyzed earwax samples were treated by data mining techniques. It was possible to discriminate the studied groups using the evolutionary tree (evtree) algo- rithm and support vector machine discriminant analysis as the statistical models with the best discrimination accura- cies 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. Keywords Earwax (cerumen) Á Alternative specimen Á Smoking status Á Cotinine Á Anabasine Á GC–MS Introduction According to the World Health Organization (WHO), tobacco kills around 6 million people each year, and more than 5 million of such deaths are the result of direct tobacco use. More than 600,000 non-smokers exposed to second-hand smoke are dying worldwide [1]. There is no safe level of exposure to second-hand tobacco smoke, because the effects of smoking are not restricted to the action of nicotine, but also related to various toxic sub- stances resulting from tobacco combustion. There are more than 4000 chemicals in tobacco smoke, at least 250 of which are known to be harmful and more than 50 of which are known to cause cancer [2]. In view of the damage to health, smoking is related to the incidence of lung, oral, and esophageal cancers, chronic bronchitis, and myocardial infarction [3]. Lately, there has been increasing demand for laboratory analysis to assess the exposure to tobacco, especially for patients undergoing smoking cessation or for children, pregnant women, and the elderly with suspected environ- mental exposure to cigarette smoke. These analyses are also applicable to workers involved in tobacco cultivation, since dermal absorption of nicotine may occur [4]. & Engy Shokry angeliqa26582@yahoo.com 1 Laborato ´rio de Me ´todos de Extrac ¸a ˜o e Separac ¸a ˜o (LAMES), Instituto de Quı ´mica (IQ), Universidade Federal de Goia ´s (UFG), Campus II, Samambaia, Goiania, GO CEP 74690-900, Brazil 2 Instituto de Quı ´mica (IQ), Universidade Federal de Goia ´s (UFG), Campus II, Samambaia, Goiania, GO CEP 74690-970, Brazil 3 Centro Clı ´nico Hospital da Crianc ¸a, Rua 107 Qd. F-32 Lt. 37 Setor Sul, Goias, GO CEP 74085-060, Brazil 123 Forensic Toxicol DOI 10.1007/s11419-017-0370-0