No abstract

E-cigarette aerosol is a complex mixture of gases and particles with a composition that is dependent on the e-liquid formulation, puffing regimen, and device operational parameters. This work investigated mainstream aerosols from a 3 rd generation device, as a function of coil temperature (315 -510 °F, correspond to 157 -266 °C), puff duration (2 -4 s), and the ratio of propylene glycol (PG) to vegetable glycerin (VG) in e-liquid (100:0 -0:100). Targeted and untargeted analyses using liquid chromatography high-resolution mass spectrometry, gas chromatography, in-situ chemical ionization mass spectrometry, and gravimetry was used for chemical characterizations. PG and VG were found to be the major constituents (> 99%) in both phases of the aerosol. Most e-cigarette components were observed to be volatile or semivolatile under the conditions tested. PG was found almost entirely in the gas phase, while VG had a sizable particle component. Nicotine was only observed in the particle phase. The production of aerosol mass and carbonyl degradation products dramatically increased with higher coil temperature and puff duration, but decreased with increasing VG fraction in the e-liquid. An exception is acrolein, which increased with increasing VG. The formation of carbonyls was dominated by the heatinduced dehydration mechanism in the temperature range studied, yet radical reactions also played an important role. The findings from this study identified open questions regarding both pathways.The vaping process consumed PG significantly faster than VG under all tested conditions, suggesting that e-liquids become more enriched in VG and the exposure to acrolein significantly increases as vaping continues. It can be estimated that a 30:70 initial ratio of PG:VG in the e-liquid becomes almost entirely VG when 60-70% of e-liquid remains during the vaping process at 375 °F (191 °C). This work underscores the need for further research on the puffing lifecycle of ecigarettes.

Engineered nanoscale materials provide tremendous promise for technological advancements; however, concerns have been raised about whether research of the possible health risks of these nanomaterials is keeping pace with products going to market. Research on nanomaterials, including carbon nanotubes, semiconductor crystals, and other ultrafine particles (i.e., titanium dioxide, quantum dots, iridium) will be examined to illustrate what is currently known or unknown about how particle characteristics (e.g., size, agglomeration, morphology, solubility, surface chemistry) and exposure/dose metrics (e.g., mass, size, surface area) influence the biological fate and toxicity of inhaled nanosized particles. The fact that nanosized particles (1) have a potentially high efficiency for deposition; (2) target both the upper and lower regions of the respiratory tract; (3) are retained in the lungs for a long period of time, and (4) induce more oxidative stress and cause greater inflammatory effects than their fine-sized equivalents suggest a need to study the impact of these particles on the body. Achieving a better understanding of the dynamics at play between particle physicochemistry, transport patterns, and cellular responses in the lungs and other organs will provide a future basis for establishing predictive measures of toxicity or biocompatibility and a framework for assessing potential human health risks.

The emergence of engineered nanoscale materials has provided significant advancements in electronic, biomedical, and material science applications. Both engineered nanoparticles and nanoparticles derived from combustion or incidental processes exhibit a range of physical and chemical properties, which have been shown to induce inflammation and oxidative stress in biologic systems. Oxidative stress reflects the imbalance between the generation of reaction oxygen species (ROS) and the biochemical mechanisms to detoxify and repair resulting damage of reactive intermediates. This review examines current research incidental and engineered nanoparticles in terms of their health effects on the lungs and mechanisms by which oxidative stress via physicochemical characteristics influence toxicity or biocompatibility. Although oxidative stress has generally been thought of as an adverse biological outcome, this review will also briefly discuss some of the potential emerging technologies to use nanoparticle-induced oxidative stress to treat disease in a site specific fashion.

Cases of chronic beryllium disease (CBD) and beryllium (Be) sensitization continue to be identified among Be industry workers. The currently accepted method for measuring exposure, which involves measuring the total mass of airborne Be per cubic meter, shows an inconsistent dose-response relationship with the prevalence of CBD. This study was conducted to evaluate which Be aerosol characteristics other than total mass may be more informative in understanding the dose-response relationship between exposure to Be and disease. Personal (n = 53) and general (n = 55) area airborne Be samples were collected in five furnace areas at a Be manufacturing facility where prevalence rates of CBD and Be sensitization had been previously studied among 535 employees with significant Be exposure. In the five furnace areas, particle-size specific personal samples and area samples were collected using an Andersen impactor and a microorifice uniform deposit impactor (MOUDI), respectively. The calculated concentrations were expressed in terms of total mass per cubic meter, and in forms of mass, number, and surface area of particles less than 10 microm or less than 3.5 microm mass median aerodynamic diameter per cubic meter that are predicted to deposit in the alveolar region of the lung. Tests for linear trend of the relationships of the various exposure metrics to prevalence of CBD and sensitization demonstrated highly significant associations between mass concentration (MOUDI) of particles less than 10 microm, and less than 3.5 microm, predicted to deposit in the alveolar region of the lung and CBD (p = 0.0004 and 0.000003, respectively) and sensitization (p = 0.025 and 0.003, respectively). However, no statistically significant association was found between these two exposure metrics and personal (Andersen) samples. The number and surface area concentration (MOUDI) of alveolar-deposited particles (less than 10 microm) also showed significant relationships with CBD (p = 0.03 and 0.03, respectively). No other exposure parameters showed significant relationships with CBD or Be sensitization. These results suggest that the concentration of alveolar-deposited particles less than 10 microm or, more particularly, the concentration of alveolar-deposited particles less than 3.5 microm may be a more relevant exposure metric for predicting the incidence of CBD or sensitization than the total mass concentration of airborne Be.