Elements including metals in the atomizer and aerosol of disposable electronic cigarettes and electronic hookahs

Abstract

ObjectiveOur purpose was to quantify 36 inorganic chemical elements in aerosols from disposable electronic cigarettes (ECs) and electronic hookahs (EHs), examine the effect of puffing topography on elements in aerosols, and identify the source of the elements.MethodsThirty-six inorganic chemical elements and their concentrations in EC/EH aerosols were determined using inductively coupled plasma optical emission spectroscopy, and their source was identified by analyzing disassembled atomizers using scanning electron microscopy and energy dispersive X-ray spectroscopy.ResultsOf 36 elements screened, 35 were detected in EC/EH aerosols, while only 15 were detected in conventional tobacco smoke. Some elements/metals were present in significantly higher concentrations in EC/EH aerosol than in cigarette smoke. Concentrations of particular elements/metals within EC/EH brands were sometimes variable. Aerosols generated at low and high air-flow rates produced the same pattern of elements, although the total element concentration decreased at the higher air flow rate. The relative amount of elements in the first and last 60 puffs was generally different. Silicon was the dominant element in aerosols from all EC/EH brands and in cigarette smoke. The elements appeared to come from the filament (nickel, chromium), thick wire (copper coated with silver), brass clamp (copper, zinc), solder joints (tin, lead), and wick and sheath (silicon, oxygen, calcium, magnesium, aluminum). Lead was identified in the solder and aerosol of two brands of EHs (up to 0.165 μg/10 puffs).ConclusionThese data show that EC/EH aerosols contain a mixture of elements, including heavy metals, with concentrations often significantly higher than in conventional cigarette smoke. While the health effects of inhaling mixtures of heated metals is currently not known, these data will be valuable in future risk assessments involving EC/EH elements/metals.

Metal/Metalloid Levels in Electronic Cigarette Liquids, Aerosols, and Human Biosamples: A Systematic Review

“…As indicated, most e-liquids sampled from cartridges or from tanks or open wicks that were in contact with the coil had higher metal/metalloid levels in comparison with levels in e-liquids sampled from the bottle. Numerous studies have shown that e-liquids in contact with heating coils like nichrome or kanthal (Olmedo et al 2018;Palazzolo et al 2017;Williams et al 2013Williams et al , 2015Williams et al , 2017Zhao et al 2018) facilitate leaching of metals/metalloids into the liquid present in the tank or cartomizer. A recently published study showed that metals (Cu, Ag, Ni, Si, Ca, Al, Mn, Zn, and Sn) were used in various device components, such as thick wires, wicks, sheaths, and joints (Williams et al 2019a).…”

“…The total SD was estimated because it accounts for the SD within the groups as well as among the groups (Sharma 2006). For some studies, there were insufficient data to estimate the SD because only means were reported, with no estimation of variability around those point estimates (Beauval et al 2017;Dunbar et al 2018;Margham et al 2016;Palazzolo et al 2017;Song et al 2018;Williams et al 2013;Williams et al 2017;Zhao et al 2018). The study by Olmedo et al (2018) reported medians instead of means (SDs) in the original publication, but we calculated them directly from the original data.…”

“…Most studies of aerosols reported metals/metalloids in ng per puff. For studies reporting aerosol metal/metalloid levels in other units (Beauval et al 2017;Goniewicz et al 2014;Mikheev et al 2016;Olmedo et al 2018;Palazzolo et al 2017;Williams et al 2013Williams et al , 2015Williams et al , 2017Zhao et al 2018), we converted them to ng per puff. For the study by Mikheev et al (2016) that reported aerosol metal/metalloid levels in nanograms per milligram of total PM (TPM), we used the average mass of TPM per puff of 2 mg to convert nanograms per milligram TPM to ng per puff.…”

“…The presence of metals and metalloids (e.g., arsenic, chromium, lead, nickel) in e-cigarette aerosols is a major concern, given their serious health effects, including cancer (García-Esquinas et al 2014;Kuo et al 2017), cardiovascular disease (Chowdhury et al 2018;Moon et al 2012), renal damage (Suwazono et al 2006), and neurotoxicity (Sankhla et al 2017). Metals/metalloids may originate from the coil (Farsalinos et al 2015;Olmedo et al 2018) and from soldered joints and other parts of the device (Williams et al 2017). Commonly used coils are made of alloys {e.g., kanthal [iron (Fe), chromium (Cr), and aluminum (Al)], nichrome [nickel (Ni) and Cr], or high-purity metals (e.g., Ni or titanium)} (Farsalinos et al 2015;Olmedo et al 2018).…”

The toxic potential of a fourth‐generation E‐cigarette on human lung cell lines and tissue explants

“…Although, here we have provided data on the chemical content of E‐cig aerosols, we mainly focused on the organic chemical constituents, with emphasis on those that are known to be present in cigarette smoke. E‐cig aerosols also contain metal nanoparticles that are a potential source of toxicity and oxidative potential (Williams, Bozhilov, Ghai, & Talbot, ). This is a factor that should be considered in future toxicological studies.…”