Toxic Metal-Containing Particles in Aerosols from Pod-Type Electronic Cigarettes

Abstract

The popularity of electronic cigarettes (electronic nicotine delivery systems or ENDS) has grown rapidly over the past decade. With the continued evolution of ENDS, and the arrival of newer replaceable pod devices on the market, it is prudent to examine their emissions to help determine potential health risks to the user. Metal containing particles were examined in aerosol from several pod-based devices from three manufacturers that offer flavored liquids in their respective products. Previous ENDS metal emissions studies focused on the total toxic metal concentrations in aerosols and have suggested that the principal sources are oxidized internal metal components that are in contact with the liquid. Most metal oxides have limited solubility and it is likely that some metal content in ENDS aerosol may present as particles rather than dissolved forms. Examining the composition and number of particles in the ENDS aerosols is important because inhaled metal oxide particles cause pulmonary inflammation. Chronic inhalation of ENDS aerosol may lead to inflammatory cell activation in the lungs. Therefore, this study was designed to measure metal oxide particle concentrations and sizes in ENDS aerosols from select pod-based systems. Aerosol samples were generated with pod liquids (tobacco, mint or menthol) from devices produced by three manufacturers using CORESTA Recommended Method 81 parameters with a high purity fluoropolymer aerosol trap. Particle sizes for chromium, iron, nickel, copper, zinc, tin, and lead oxides were measured in triplicate using single particle inductively coupled plasma-mass spectrometry and dynamic light scattering. A novel aspect of these measurements included using dual element particle analysis to infer particle source component material. Particle concentrations in aerosols from the devices were variable between devices and from pod to pod, ranging from no detectable chromium and zinc containing particles in aerosol from some pods to 222,000 lead containing particles per 10 puffs from individual pods.

Effects of E-Cigarette Refill Liquid Flavorings with and without Nicotine on Human Retinal Pigment Epithelial Cells: A Preliminary Study

“…RPE cells in vivo are known to contain melanin pigment while ARPE-19 cells lack any visible pigmentation. It would be necessary to evaluate the effects of e-liquids on pigmented RPE, especially as melanin is known to have affinity for metals [ 83 ] and it has been reported that several trace metals, such as nickel, chromium, lead, and copper are present in e-liquids [ 84 , 85 , 86 , 87 ]. Hence, the cytotoxicity profile of the flavors with and without nicotine will need to be determined in the physiological environment utilizing primary RPE cells for the future.…”

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

“…Studies using methods with well determined limits of detection also indicated that the corrosive nature of the liquid toward metal device components in contact with the liquids as well as the ages of the devices were important factors that contributed to liquid and aerosol metal concentrations [ 7 , 8 ]. Studies of aerosols using single particle and dual element single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) provided evidence that electrical connectors and other device components, other than the heating element, were the more likely sources of chromium or nickel containing particles [ 13 ].…”

The Impact of the Storage Conditions and Type of Clearomizers on the Increase of Heavy Metal Levels in Electronic Cigarette Liquids Retailed in Romania

“…Other data support that the nichrome from the heating elements is resistant to oxidation (even at high temperatures) and suggest other alloys as possible sources of chromium, iron, and nickel oxide. However, the authors cannot exclude a limited degree of degradation of nichrome heating elements caused by extensive use periods [ 21 ].…”

“…E-cigarette aerosols contain nanoparticles (11–25 nm median diameter) and submicron particles (96–175 nm median diameter) [ 20 ]. The size of the inhaled particles is important for the depth of airway penetration, and the toxic potential can be enhanced by the high penetration of small-sized particles in tissues and organs [ 21 , 22 ]. Re et al found a connection between chronic e-cigarette aerosol exposure and endogen metal dyshomeostasis, which has been linked to the onset of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s [ 19 ].…”