Toxic Metals in Liquid and Aerosol from Pod-Type Electronic Cigarettes

Abstract

High-quality, accurate data on liquid contents and aerosol emissions from electronic nicotine delivery systems (ENDS, e.g., e-cigarettes) are crucial to address potential health concerns as these devices evolve and mature. Metals are an important class of ENDS constituents that merit attention as they have various health implications. Proper sampling, handling and aerosol trapping materials are essential to generate accurate quantitative metal data and to reduce the likelihood of inaccurate results originating from inappropriate collection vessels and materials that contribute to high background levels. Published methods that meet these criteria were applied to the analyses of chromium, nickel, copper, zinc, cadmium, tin and lead in liquid and aerosol from mint/menthol and tobacco flavors of currently popular pod-based devices from three manufacturers. Metal concentrations from pods that had not been used for generating aerosol ranged from below our lowest reportable level to 0.164 µg/g for Cr, 61.3 µg/g for Ni, 927 µg/g for Cu, 14.9 µg/g for Zn, 58.2 µg/g for Sn and 2.56 µg/g for Pb. Cadmium was included in our analyte panel and was not present above detection limits in liquid or aerosol. Aerosol metal concentrations (using a 55-mL puff) ranged from below our lowest reportable level to 29.9 ng/10 puffs for Cr, 373 ng/10 puffs for Ni, 209 ng/10 puffs for Cu, 4,580 ng/10 puffs for Zn, 127 ng/10 puffs for Sn and 463 ng/10 puffs for Pb. Our results showed some metal delivery from all the products examined and highly variable metal levels between manufacturer, brand and package.

Analysis of Toxic Metals in Aerosols from Devices Associated with Electronic Cigarette, or Vaping, Product Use Associated Lung Injury

“…The wires connecting the heating block to the battery were composed of Ni and Cr and the holder was primarily composed of Ni. These materials in this cannabinoid delivery system were similar to those previously reported for nicotine delivery systems, although nickel was more prevalent than copper and brass [ 7 , 8 , 9 ].…”

“…Because available sample volume only permitted one analytical replicate, results that were slightly above our reportable level, could not be repeated. It should be noted that method LODs reported for this study were slightly higher than reported in a previous study [ 9 ] as a result of the analysis of only 15 puffs of aerosol due to limited availability of sample volume and possibly due to the additional tube rinse with an organic solvent.…”

“…The growing popularity of vaping as a means of delivery of both nicotine and cannabinoids has increased the need for the development of well validated methods for the analysis of potentially harmful substances such as toxic metals in EVP liquids [ 7 ]. Rigorous and validated analytical methods are also needed for measuring harmful substances including toxic metals in the aerosols generated by EVPs [ 8 , 9 ] so that inhaled exposure can be assessed. Furthermore, concurrent and/or dual use of both nicotine and cannabinoid EVP liquids is increasing, and thus robust methods are needed for diverse EVP liquids and aerosols [ 10 ].…”

“…The analysis of hydrophilic EVP aerosols for toxic metals can be challenging, since aerosols that contain very low metal concentrations must be trapped using materials that do not leach metals into the samples to avoid sample contamination [ 8 , 9 , 10 ]. Common solvents in nicotine containing EVP are propylene glycol and glycerol which make them hydrophilic [ 17 , 18 ].…”

“…Common solvents in nicotine containing EVP are propylene glycol and glycerol which make them hydrophilic [ 17 , 18 ]. Sample preparation for these hydrophilic aerosols may be as simple as dilution of the aerosol in high purity aqueous acids [ 8 , 9 ]. However, the analysis of EVPs with hydrophobic aerosols is more challenging.…”