Metal and Silicate Particles Including Nanoparticles Are Present in Electronic Cigarette Cartomizer Fluid and Aerosol

Metal and Silicate Particles Including Nanoparticles Are Present in Electronic Cigarette Cartomizer Fluid and Aerosol Monique Williams 1 , Amanda Villarreal 1 , Krassimir Bozhilov 2 , Sabrina Lin 1 , Prue Talbot 1 * 1 Department of Cell Biology and Neuroscience, University of California Riverside, Riverside, California, United States of America, 2 Central Facility for Advanced Microscopy and Microanalysis, University of California Riverside, Riverside, California, United States of America Abstract Background: Electronic cigarettes (EC) deliver aerosol by heating fluid containing nicotine. Cartomizer EC combine the fluid chamber and heating element in a single unit. Because EC do not burn tobacco, they may be safer than conventional cigarettes. Their use is rapidly increasing worldwide with little prior testing of their aerosol. Objectives: We tested the hypothesis that EC aerosol contains metals derived from various components in EC. Methods: Cartomizer contents and aerosols were analyzed using light and electron microscopy, cytotoxicity testing, x-ray microanalysis, particle counting, and inductively coupled plasma optical emission spectrometry. Results: The filament, a nickel-chromium wire, was coupled to a thicker copper wire coated with silver. The silver coating was sometimes missing. Four tin solder joints attached the wires to each other and coupled the copper/silver wire to the air tube and mouthpiece. All cartomizers had evidence of use before packaging (burn spots on the fibers and electrophoretic movement of fluid in the fibers). Fibers in two cartomizers had green deposits that contained copper. Centrifugation of the fibers produced large pellets containing tin. Tin particles and tin whiskers were identified in cartridge fluid and outer fibers. Cartomizer fluid with tin particles was cytotoxic in assays using human pulmonary fibroblasts. The aerosol contained particles .1 m m comprised of tin, silver, iron, nickel, aluminum, and silicate and nanoparticles (,100 nm) of tin, chromium and nickel. The concentrations of nine of eleven elements in EC aerosol were higher than or equal to the corresponding concentrations in conventional cigarette smoke. Many of the elements identified in EC aerosol are known to cause respiratory distress and disease. Conclusions: The presence of metal and silicate particles in cartomizer aerosol demonstrates the need for improved quality control in EC design and manufacture and studies on how EC aerosol impacts the health of users and bystanders. Citation: Williams M, Villarreal A, Bozhilov K, Lin S, Talbot P (2013) Metal and Silicate Particles Including Nanoparticles Are Present in Electronic Cigarette Cartomizer Fluid and Aerosol. PLoS ONE 8(3): e57987. doi:10.1371/journal.pone.0057987 Editor: Stephen J. Johnson, University of Kansas, United States of America Received August 31, 2012; Accepted January 30, 2013; Published March 20, 2013 Copyright: s 2013 Willliams et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by grants from the Tobacco-Related Disease Research Program (TRDRP) to PT, a Cornelius Hopper Award to MW, a MARC National Institutes of Health (NIH) fellowship to AV, and a TRDRP Postdoctoral Fellowship to SL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: talbot@ucr.edu As EC have evolved, the atomizer and cartridge have often been combined into a single unit called a ‘‘cartomizer’’ [6]. Recent studies have shown that EC can deliver nicotine to users, although not always as effectively as conventional cigarettes [7,8]. EC may help smokers overcome nicotine addiction and/or serve as nicotine delivery devices that are safer than tobacco burning cigarettes [9,10]. EC have helped some smokers stop using conventional brands and either quit smoking entirely or switch to the presumably safer EC [11,12]. Their effectiveness in this regard may be aided by the hand-mouth motion that the EC provides, unlike nicotine patches and gum. Some users have reported to us that EC have helped them break nicotine addiction, but not the hand-mouth addiction associated with smoking. Because EC do not burn tobacco, they do not produce the numerous chemicals found in conventional tobacco smoke. For Introduction Electronic cigarettes (EC) are generally manufactured in China and are rapidly gaining acceptance in many countries [1,2]. In the United States, EC are available on the Internet, in malls, and in local shops. They have become an integral part of the environment without much information regarding the quality control used in their manufacture or their health effects [3]. EC deliver aerosolized nicotine to users and may serve as a surrogate for conventional tobacco-containing cigarettes [4,5]. Puffing an EC activates a battery that in turn heats liquid containing flavoring, a humectant(s) such as propylene glycol or vegetable glycerin, and nicotine. Some models, such as the one used in this study, do not contain nicotine. Early models of EC had separate atomizers for heating and cartridges for holding fluid [3]. PLOS ONE | www.plosone.org March 2013 | Volume 8 | Issue 3 | e57987