CSP deposition to the alveolar region of the lung: implications of cigarette design

Deposition of Smoke Particles in Human Airways with Realistic Waveform

Exposure to toxic particles from smoke generated either from bush fire, stable burning, or direct smoking is very harmful to our health. The tiny particles easily penetrate deep into the lungs after exposure and damage the airways. Tobacco smoking causes the direct emission of 2.6 million tons of CO2 and 5.2 million tons of methane annually into the atmosphere. Nevertheless, it is one of the significant contributors to various respiratory diseases leading to lung cancer. These particles’ deposition in the human airway is computed in the present article for refining our understanding of the adverse health effects due to smoke particle inhalation, especially cigarette smoke. Until recently, little work has been reported to account for the transient flow pattern of cigarette smoking. Consideration of transient flow may change the deposition pattern of the particle. A high-resolution CT scan image of the respiratory tract model consisting of the oral cavity, throat, trachea, and first to sixth generations of the lungs helps predict cigarette smoke particle (CSP) deposition. With the same scan, a realistic geometric model of the human airways of an adult subject is used to simulate the transport of air and particle. The CSP deposition is determined at different locations from the oral cavity to the sixth generation of the bronchi. In addition, an unsteady breathing curve indicative of realistic smoking behavior is utilized to represent the breathing conditions accurately. The discrete phase model (DPM) technique is used to determine smoke particle deposition in the human airways. It is found that the deposition increases with the size of the smoke particle. Particles tend to deposit in the oral cavity around the bifurcation junction of the airways. The deposition fraction of CSP with the realistic waveform of smoking is found to be smaller compared to that during the stable flow condition. It is also observed that the fine particles (0.1–1.0 micron) escape to lower generations, leading to higher deposition of fine particles in the deeper airways. The outcome of the study is helpful for understanding smoke-related pulmonary complications.

Feasibility of Using the Hexoskin Smart Garment for Natural Environment Observation of Respiration Topography

Background: Limited research has been done to measure ambulatory respiratory behavior, in particular those associated with tobacco use, in the natural environment due to a lack of monitoring techniques. Respiratory topography parameters provide useful information for modeling particle deposition in the lung and assessing exposure risk and health effects associated with tobacco use. Commercially available Wearable Respiratory Monitors (WRM), such as the Hexoskin Smart Garment, have embedded sensors that measure chest motion and may be adapted for measuring ambulatory lung volume. Methods: Self-reported “everyday” and “some days” Hookah and Cigarette smokers were recruited for a 3-day natural environment observation study. Participants wore the Hexoskin shirt while using their preferred tobacco product. The shirt was calibrated on them prior to, during, and after the observation period. A novel method for calculating the calibration parameters is presented. Results: N_H = 5 Hookah and N_C = 3 Cigarette participants were enrolled. Calibration parameters were obtained and applied to the observed chest motion waveform from each participant to obtain their lung volume waveform. Respiratory topography parameters were derived from the lung volume waveform. Conclusion: The feasibility of using the Hexoskin for measuring ambulatory respiratory topography parameters in the natural environment is demonstrated.

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

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.

Feasibility Assessment of Wearable Respiratory Monitors for Ambulatory Inhalation Topography

Background: Natural environment inhalation topography provides useful information for toxicant exposure, risk assessment and cardiopulmonary performance. Commercially available wearable respiratory monitors (WRMs), which are currently used to measure a variety of physiological parameters such as heart rate and breathing frequency, can be leveraged to obtain inhalation topography, yet little work has been done. This paper assesses the feasibility of adapting these WRMs for measuring inhalation topography. Methods: Commercially available WRMs were compiled and assessed for the ability to report chest motion, data analysis software features, ambulatory observation capabilities, participant acceptability, purchasing constraints and affordability. Results: The following WRMs were found: LifeShirt, Equivital EQ02 LifeMonitor, Smartex WWS, Hexoskin Smart Garment, Zephyr BioHarness, Nox T3&A1, BioRadio, SleepSense Inductance Band, and ezRIP & zRIP Durabelt. None of the WRMs satisfied all six assessment criteria in a manner enabling them to be used for inhalation topography without modification and development. Conclusions: The results indicate that there are WRMs with core technologies and characteristics that can be built upon for ambulatory inhalation topography measurement in the NE.

A Comparison between Cigarette Topography from a One-Week Natural Environment Study to FTC/ISO, Health Canada, and Massachusetts Department of Public Health Puff Profile Standards

Standardized topography protocols for testing cigarette emissions include the Federal Trade Commission/International Standard Organization (FTC/ISO), the Massachusetts Department of Health (MDPH), and Health Canada (HC). Data are lacking for how well these protocols represent actual use behavior. This study aims to compare puff protocol standards to actual use topography measured in natural environments across a range of cigarette brands. Current smokers between 18 and 65 years of age were recruited. Each participant was provided with a wPUM™ cigarette topography monitor and instructed to use the monitor with their usual brand cigarette ad libitum in their natural environment for one week. Monitors were tested for repeatability, and data were checked for quality and analyzed with the TAP™ topography analysis program. Data from n = 26 participants were analyzed. Puff flow rates ranged from 17.2 to 110.6 mL/s, with a mean (STD) of 40.4 (21.7) mL/s; durations from 0.7 to 3.1 s, with a mean (STD) of 1.5 ± 0.5 s; and volumes from 21.4 to 159.2 mL, with a mean (STD) of 54.9 (29.8) mL. Current topography standards were found to be insufficient to represent smoking across the wide range of real behaviors. These data suggest updated standards are needed such that emissions tests will provide meaningful risk assessments.

Behavior-based yield for electronic cigarette users of different strength eliquids based on natural environment topography

Introduction: The extent to which electronic cigarette users will compensate for lower nicotine eliquids has implications on the risk associated with regulating eliquid composition. This article elucidates topography as a compensatory mechanism by investigating the impact of nicotine strength on total particulate matter (TPM) and nicotine consumed per puff.Methods: Thirty-three experienced vape pen users were assigned an NJOY™ VapePen and AVAIL™ brand Tobacco Row eliquid with their usual nicotine strength (L = 6 mg/mL, M = 12 mg/mL, H = 18 mg/mL) and vaped through RIT's wPUM^TM vape pen monitor to record every puff during 1 week. Nicotine and TPM yield per puff was determined accounting for the impact of topography characteristics on emissions and used to compute participant-specific mean yield per puff.Results: Nicotine yields ranged from 0.01 to 0.05 mg/puff and varied widely within each group (L, M, and H nicotine strength). Group-wise mean flow rate was lower for L compared to M (p = 0.2) and duration was higher compared to M (p = 0.09). Larger TPM was consumed per puff for L compared to M (p = 0.07), yet nicotine per puff for L was less than M (p = 0.3). H users took smaller volumes than L (p = 0.1) or M (p = 0.17), and there was little difference between L and M (p = 0.47).Conclusions: Evidence was provided for topography as a compensatory mechanism. Use of low nicotine strength eliquids can increase TPM, which can lead to increase in HPHC. Regulatory review of new products should consider natural use topography and realistic use exposures to nicotine, TPM and HPHCs.

[Bronchial carcinoma and tobacco: An update]

Lung cancer remains the most lethal cancer. The most common cause is smoking, which is also preventable, unlike the causes of other types of cancer. A genetic characteristic has emerged over several years, which explains particular profiles of smokers, or highly dependent smokers. The emergence of new therapies for the treatment of lung cancer, and the impact of tobacco on reducing the effectiveness of these therapies must challenge practitioners to obtain a complete cessation of smoking regardless of the stage of the disease.

Cigarette Filter Ventilation and its Relationship to Increasing Rates of Lung Adenocarcinoma

The 2014 Surgeon General's Report on smoking and health concluded that changing cigarette designs have caused an increase in lung adenocarcinomas, implicating cigarette filter ventilation that lowers smoking machine tar yields. The Food and Drug Administration (FDA) now has the authority to regulate cigarette design if doing so would improve public health. To support a potential regulatory action, two weight-of-evidence reviews were applied for causally relating filter ventilation to lung adenocarcinoma. Published scientific literature (3284 citations) and internal tobacco company documents contributed to causation analysis evidence blocks and the identification of research gaps. Filter ventilation was adopted in the mid-1960s and was initially equated with making a cigarette safer. Since then, lung adenocarcinoma rates paradoxically increased relative to other lung cancer subtypes. Filter ventilation 1) alters tobacco combustion, increasing smoke toxicants; 2) allows for elasticity of use so that smokers inhale more smoke to maintain their nicotine intake; and 3) causes a false perception of lower health risk from "lighter" smoke. Seemingly not supportive of a causal relationship is that human exposure biomarker studies indicate no reduction in exposure, but these do not measure exposure in the lung or utilize known biomarkers of harm. Altered puffing and inhalation may make smoke available to lung cells prone to adenocarcinomas. The analysis strongly suggests that filter ventilation has contributed to the rise in lung adenocarcinomas among smokers. Thus, the FDA should consider regulating its use, up to and including a ban. Herein, we propose a research agenda to support such an effort.

The impact of commonly used air filters in eliminating the exposure to secondhand smoke constituents

Exposure to secondhand tobacco smoke (SHS) also known as environmental tobacco smoke (ETS) has been well established scientifically as a human health hazard. Despite this and warnings from health agencies, concerns over the economic impact of smoke-free bans have limited political resolve to enact these regulations. Arguments against smoke-free bans include the contention that air filters can eliminate the health risks from SHS exposure. In this study, we assessed the effectiveness of air filters (MERV 4 and MERV 8) commonly used in homes and businesses in reducing the concentrations of total suspended particulates, fine particles and carbon monoxide from SHS as a measure of their potential to reduce the toxicity associated with SHS exposure. Our results demonstrate that these filters are not effective at reducing carbon monoxide levels or PM 2.5, which have been correlated with human health toxicity/disease. Thus, our findings, from a public health perspective, do not support the use of common air filters as a viable alternative to smoke-free bans.

Cigarette smoke cadmium breakthrough from traditional filters: implications for exposure

Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found <1% cadmium passed through electrostatic precipitators. In contrast, cadmium that passed through 92 mm glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5 to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6 to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers.

Inter- and intra-subject variability of kinetics of airway exhalation and deposition of particulate matter in indoor polluted environments

PM(2.5) generated by indoor combustion activities can contribute significantly to personal PM exposure. The aims of this study were: (1) to validate a device specifically designed to study the kinetics of particle exhalation and the percentage of airway particle deposition (%DEP) in polluted indoor environments (welding fumes, environmental tobacco smoke - ETS) and (2) to assess the intra- and inter-subject variability of the signal. The device was tested on 14 subjects exposed to welding fumes and 10 subjects exposed to environmental tobacco smoke (ETS), performing repeated measures at different environmental PM concentrations. The intra-subject variability of the signal for particles with diameter 0.3-1.0 μm showed a geometric mean of %CV always below 6%, despite the values of %DEP. In the welding fume study, the increase in airborne 0.5-1.0 μm PM concentrations between the consulting room and production department was explainable in terms of increased density due to the metallic composition of particles. The %DEP of 0.3-1.0 μm ETS particles decreased with airborne PM concentration due to the technical limits of a laser particle counter and the perturbation induced by the physical characteristics of ETS PM. However, also at those extreme conditions, the signal remained repeatable and the individual susceptibility to PM remained substantially unaltered. In conclusion, the versatility and portability of our device, together with the repeatability of the signal, confirmed that the kinetics of exhaled particles and %DEP could be routinely measured in polluted environments and used to define individual susceptibility to airborne particles.

Has the lung cancer risk from smoking increased over the last fifty years?

BACKGROUND

We examine whether the lung cancer risk due to smoking has increased over time.

METHODS

Lung cancer risk equations based on prospective mortality data collected from 1960 to 1972 were applied to 5-year birth-cohort-specific estimates of smoking behaviors among white males to estimate lung cancer mortality rates for U.S. white males from 1960 to 2000. These estimated rates were compared to U.S. white male mortality rates for the same birth cohorts.

RESULTS

Observed birth-cohort-specific U.S. lung cancer mortality rates are substantially higher than those expected from changes in smoking behaviors, and the proportional difference increases with advancing calendar year. This trend persisted even when the duration term was increased in the risk equation. However, adjusting for changes in cigarette design over time by adding a term for the duration of smoking after 1972 resulted in the predicted rates closely approximating the observed U.S. mortality rates.

CONCLUSION

Lung cancer risk estimates observed during the 1960s under predict current lung cancer mortality rates in U.S. white males. Adjustment for the duration of smoking after 1972 results in estimates that reasonably approximate the observed U.S. lung cancer mortality, suggesting that lung cancer risks from smoking are increasing in the United States coincident with changes in cigarette design.

Do changes in cigarette design influence the rise in adenocarcinoma of the lung?

Background

Incidence rates for adenocarcinoma of the lung are increasing and are higher in the United States than in many other developed countries. We examine whether these trends may be associated with changes in cigarette design.

Methods

Lung cancer risk equations based on observations during 1960–1972 from the American Cancer Society Cancer Prevention Study I are applied to 5-year birth cohort–specific estimates of changes in smoking behaviors to predict birth cohort–specific rates of squamous cell carcinoma and adenocarcinoma of the lung among US White men for the period 1973–2000. These expected rates are compared to observed rates for the same birth cohorts of White men in the US Surveillance, Epidemiology and End Results (SEER) data.

Results

Changes in smoking behaviors over the past several decades adequately explain the changes in squamous cell carcinoma rates observed in the SEER data. However, predicted rates for adenocarcinoma do not match the observed SEER data without inclusion of a term increasing the risk for adenocarcinoma with the duration of smoking after 1965.

Conclusion

The risk of developing squamous cell carcinoma from smoking appears to have remained stable in the United States over the past several decades; however, the risk of adenocarcinoma has increased substantially in a pattern temporally associated with changes in cigarette design.