Metal Concentrations in E-Cigarette Aerosol Samples: A Comparison by Device Type and Flavor.

BACKGROUND: The rapid evolution of electronic cigarette (e-cigarette) products warrants surveillance of the differences in exposure across device types-modifiable devices (MODs), cartridge ("pod")-containing devices (PODs), disposable PODs (d-PODs)-and flavors of the products available on the market. OBJECTIVE: This study aimed to measure and compare metal aerosol concentrations by device type and common flavors. METHODS: We collected aerosol from 104 MODs, 67 PODs (four brands: JUUL, Bo, Suorin, PHIX), and 23 d-PODs (three brands: ZPOD, Bidi, Stig) via droplet deposition in a series of conical pipette tips. Metals and metalloids [aluminum (Al), arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), and zinc (Zn)] were measured using inductively coupled plasma mass spectrometry (ICP-MS), results were log-transformed for statistical analysis, and concentrations are reported in aerosol units (mg/m3). RESULTS: Of the 12 elements analyzed, concentrations were statistically significantly higher in MOD devices, except for Co and Ni, which were higher in PODs and d-PODs. Of the POD brands analyzed, PHIX had the highest median concentrations among four metals (Al, Ni, Pb, and Sn) compared to the rest of the POD brands. According to POD flavor, seven metals were three to seven orders of magnitude higher in tobacco-flavored aerosol compared to those in mint and mango flavors. Among the d-POD brands, concentrations of four metals (Al, Cu, Ni, and Pb) were higher in the ZPOD brand than in Bidi Stick and Stig devices. According to d-POD flavor, only Cr concentrations were found to be statistically significantly higher in mint than tobacco-flavored d-PODs. DISCUSSION: We observed wide variability in aerosol metal concentrations within and between the different e-cigarette device types, brands, and flavors. Overall, MOD devices generated aerosols with higher metal concentrations than PODs and d-PODs, and tobacco-flavored aerosols contained the highest metal concentrations. Continued research is needed to evaluate additional factors (i.e., nicotine type) that contribute to metal exposure from new and emerging e-cigarette devices in order to inform policy. https://doi.org/10.1289/EHP11921.

Mechanistic Studies of the TRIP-Catalyzed Allylation with Organozinc Reagents.

3,3-Bis(2,4,6-triisopropylphenyl)-1,1-binaphthyl-2,2-diyl hydrogenphosphate (TRIP) catalyzes the asymmetric allylation of aldehydes with organozinc compounds, leading to highly valuable structural motifs, like precursors to lignan natural products. Our previously reported mechanistic proposal relies on two reaction intermediates and requires further investigation to really understand the mode of action and the origins of stereoselectivity. Detailed ab initio calculations, supported by experimental data, render a substantially different mode of action to the allyl boronate congener. Instead of a Brønsted acid-based catalytic activation, the chiral phosphate acts as a counterion for the Lewis acidic zinc ion, which provides the activation of the aldehyde.

Occurrence, Seasonal Variation, and Size Resolved Distribution of Arsenic Species in Atmospheric Particulate Matter in an Urban Area in Southeastern Austria.

Extensive information is available on total arsenic in particulate matter (PM), but little is known about the relative contribution of each individual species. Recent studies often focus on inorganic arsenic as arsenite and arsenate, neglecting the organoarsenicals, i.e., methylarsine, dimethylarsine, and trimethylarsine or the corresponding oxidized forms methylarsonate, dimethylarsinate, and trimethylarsine oxide, although they were already first detected in PM in the mid-1970s. This work presents results from more than 300 daily PM10 and further size-resolved atmospheric PM samples in the size range from 15 nm to 10 µm collected in an urban environment in Austria during the course of a year. An ion-exchange-HPLC (with anion and cation exchange columns) and an ICPMS/MS system were used to study the seasonal variations of total arsenic and all species known to exist in PM. Inorganic arsenic was present in significant amounts in all samples with highest concentrations during winter, but also all organoarsenicals were detected throughout the year. We show that their contribution cannot be ignored, as particles smaller than <1 µm can contain up to 35% of the water+H2O2 extractable arsenic as methylated species, but only dimethylarsinate showed a clear seasonal trend throughout the year.

Recycling of scrap metal into artisanal cookware in the informal sector: A public health threat from multi metal exposure in South Africa.

Recycling of scrap metal into artisanal cookware is widespread in poorly resourced countries. The aim of the study was to determine the risk of metal exposure from the use of artisanal cookware available in South Africa. Twenty cookware samples were purchased from local manufacturers and informal traders across South Africa. Aluminum and silicon concentrations were determined using XRF and the total content of 18 elements (Ag, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn) were evaluated using ICPMS. Leaching of metals from cut pieces of cookware over a 2-h period of boiling in a 3% acetic acid solution was repeated 3 times and revealed multi-metal migration that was compared to EU maximum permissible levels. The mean Al migration of 509 mg L-1 was over 100 times the EU maximum permissible level allowed for cookware. Lead was detected in all samples with 11 (55%), 12 (60%) and 9 (45%) of samples being over the maximum EU permissible level (10 µg Pb L-1) for 1st, 2nd and 3rd migrations respectively. The mean As migration concentrations in the first leaching event ranged from 0.23 to 24.1 µg L-1 with four pots (20%) over the maximum EU permissible limit for As (2 µg L-1). Notably, all four pots were well below the maximum EU permissible As limit by the 3rd migration. Cadmium and mercury were detected in each pot across all three migrations however the levels were relatively low. Transmission electron microscopy revealed dramatic changes in surface structure after leaching of cookware.

Impact of New Year's Eve fireworks on the size resolved element distributions in airborne particles.

New Year's Eve fireworks represent one of the most unusual atmospheric pollution events in the course of a year. A majority of particles aerosolized by burning of fireworks consist of metals and their compounds used in firework displays. In this study, ambient particulate matter was sampled using a 14 stage cascade impactor in two European cities during turn of the years 2016/17 and 2017/18. Concentrations of 33 elements were determined by inductively coupled plasma mass spectrometry. To assess the impact of New Year's Eve fireworks on ambient air quality, chemically resolved size distributions of particles with diameters between 15 nm and 10 µm collected during fireworks episodes were compared to ones collected in normal winter weeks. For some metals a distinct shift of their concentration maximum related to fireworks could be observed, which is in between the maxima for accumulation and coarse mode particles. Concentrations of these elements (Sr, Ba, Mg, Bi, Al, Cu and K) were also higher during weeks with fireworks episodes than during control weeks. Although New Year's Eve fireworks only take place once a year, these results show that air pollution caused by fireworks can be a potential health risk, especially for people with pre-existing diseases.

Arsenic speciation in aerosols of a respiratory therapeutic cave: A first approach to study arsenicals in ultrafine particles.

Arsenic is ubiquitous in the environment and of special concern due to its varying toxicity depending on the chemical form present. Less is known about arsenic in air, especially about organoarsenicals, their sources and fate. There is also a lack of knowledge regarding arsenic in airborne nanoparticles that are critical for understanding with respect to human health effects due to their size. Here we show results from an arsenic speciation analysis in size-resolved airborne particles with aerodynamic diameters down to 15 nm. Analysis of aerosols from a respiratory therapeutic cave showed temporarily higher concentrations of trimethylarsine oxide than inorganic arsenic and substantial amounts of organoarsenicals, especially in smaller particles. Our method provides guidance for future studies investigating arsenicals in ultrafine particles and their health implications. Furthermore, the method developed can be used to widely monitor particle-bound organoarsenicals to fully understand the importance of As biovolatilization in the environment.

Metal Concentrations in e-Cigarette Liquid and Aerosol Samples: The Contribution of Metallic Coils.

BACKGROUND: Electronic cigarettes (e-cigarettes) generate an aerosol by heating a solution (e-liquid) with a metallic coil. Whether metals are transferred from the coil to the aerosol is unknown. OBJECTIVE: Our goal was to investigate the transfer of metals from the heating coil to the e-liquid in the e-cigarette tank and the generated aerosol. METHODS: We sampled 56 e-cigarette devices from daily e-cigarette users and obtained samples from the refilling dispenser, aerosol, and remaining e-liquid in the tank. Aerosol liquid was collected via deposition of aerosol droplets in a series of conical pipette tips. Metals were reported as mass fractions (µg/kg) in liquids and converted to mass concentrations (mg/m3) for aerosols. RESULTS: Median metal concentrations (µg/kg) were higher in samples from the aerosol and tank vs. the dispenser (all p<0.001): 16.3 and 31.2 vs. 10.9 for Al; 8.38 and 55.4 vs. <0.5 for Cr; 68.4 and 233 vs. 2.03 for Ni; 14.8 and 40.2 vs. 0.476 for Pb; and 515 and 426 vs. 13.1 for Zn. Mn, Fe, Cu, Sb, and Sn were detectable in most samples. Cd was detected in 0.0, 30.4, and 55.1% of the dispenser, aerosol, and tank samples respectively. Arsenic was detected in 10.7% of dispenser samples (median 26.7µg/kg) and these concentrations were similar in aerosol and tank samples. Aerosol mass concentrations (mg/m3) for the detected metals spanned several orders of magnitude and exceeded current health-based limits in close to 50% or more of the samples for Cr, Mn, Ni, and Pb. CONCLUSIONS: Our findings indicate that e-cigarettes are a potential source of exposure to toxic metals (Cr, Ni, and Pb), and to metals that are toxic when inhaled (Mn and Zn). Markedly higher concentrations in the aerosol and tank samples versus the dispenser demonstrate that coil contact induced e-liquid contamination. https://doi.org/10.1289/EHP2175.

The association of e-cigarette use with exposure to nickel and chromium: A preliminary study of non-invasive biomarkers.

BACKGROUND: Nickel (Ni) and chromium (Cr) are components of e-cigarette heating coils. Whether e-cigarettes increase metal internal dose, however, is unknown. We assessed the association of e-cigarette use patterns and of e-liquid and aerosol metal concentrations with Ni and Cr biomarker levels in e-cigarette users from Maryland. METHODS: We recruited 64 e-cigarette users from December 2015 to March 2016. We collected urine, saliva, and exhaled breath condensate (EBC), data on e-cigarette use, and samples from their e-cigarette device (dispenser e-liquid, aerosol, and tank e-liquid). RESULTS: Median Ni and Cr levels were 0.73 and 0.39µg/g creatinine in urine, 2.25 and 1.53µg/L in saliva, and 1.25 and 0.29µg/L in EBC. In adjusted models, tertiles 2 and 3 of aerosol Ni concentrations were associated with 16% and 72% higher urine Ni and 202% and 321% higher saliva Ni compared to the lowest tertile. Tertile 3 of aerosol Cr levels were associated with 193% higher saliva Cr. An earlier time to first vape in the morning and more frequent coil change were associated with higher urine Ni. Tertile 2 of e-liquid consumption per week and voltage were associated with higher saliva Ni levels than tertile 1. CONCLUSION: Positive associations of Ni and Cr aerosol concentrations with corresponding Ni and Cr biomarker levels indicate e-cigarette emissions increase metal internal dose. Increased e-cigarette use and consumption were also associated with higher Ni biomarker levels. Metal level standards are needed to prevent involuntary metal exposure among e-cigarette users.