Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards

Facing an un-met need in lung cancer screening: The never smokers

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide and the second most common cancer in both men and women. In addition to smoking, other risk factors, such as environmental tobacco smoke, air pollution, biomass combustion, radon gas, occupational exposure, lung disease, family history of cancer, geographic variability, and genetic factors, play an essential role in developing LC. Current screening guidelines and eligibility criteria have limited efficacy in identifying LC cases (50 %), as most screening programs primarily target subjects with a smoking history as the leading risk factor. Implementing LC screening programs in people who have never smoked (PNS) can significantly impact cancer-specific survival and early disease detection. However, the available evidence regarding the feasibility and effectiveness of such programs is limited. Therefore, further research on LC screening in PNS is warranted to determine the necessary techniques for accurately identifying individuals who should be included in screening programs.

Sex-Dependent Occlusive Cardiovascular Disease Effects of Short-Term Thirdhand Smoke Exposure

INTRODUCTION

Thirdhand smoke (THS) is associated with many public health and disease concerns, such as respiratory illness, cancer, lipidemia, and cardiovascular disease (CVD). We have previously shown that a moderate to long-term exposure to THS increases the risk of thrombosis. However, whether short-term exposure to THS would produce any effects remains to be discovered. Therefore, this study investigated the impact of 1-month THS exposure on platelet function, in vivo and in vitro, and on cytokine response, in a sex-dependent manner.

AIMS AND METHODS

Secondhand smoke or clean air (CA) exposed upholstery materials for 1 week were kept in cages housed with 5-6 mice, and the procedure was repeated for 4 weeks. These THS-exposed mice were evaluated for thrombogenesis and platelet function assays. In addition, cytokines expression was evaluated from pooled serum.

RESULTS

Compared to the CA group, THS exposure significantly shortened the tail bleeding time and carotid artery thrombus formation. Moreover, the female mice appeared more sensitive to THS exposure than males. Furthermore, platelet aggregation, dense granule secretion, and P-selectin activation markers were significantly elevated due to THS exposure. In addition, high-throughput screening showed at least 30 cytokines differentially modulated by THS in females relative to 26 in male mice.

CONCLUSIONS

Collectively, these results demonstrate that 1 month of THS exposure represents a high health risk, in part, by triggering a prothrombotic phenotype that appears to be more significant in females, who are at a much higher risk for occlusive CVD. Additionally, changes in cytokine levels mediate some of the THS-induced occlusive effects.

IMPLICATIONS

This study revealed that THS exposure for 1 month is detrimental to the cardiovascular health of both sexes; however, females could be more aggressively affected than males. In addition, interleukins and chemokines could be critical factors for initiating prothrombotic activity due to THS exposure.

The chemical assessment of surfaces and air (CASA) study: using chemical and physical perturbations in a test house to investigate indoor processes

The Chemical Assessment of Surfaces and Air (CASA) study aimed to understand how chemicals transform in the indoor environment using perturbations (e.g., cooking, cleaning) or additions of indoor and outdoor pollutants in a well-controlled test house. Chemical additions ranged from individual compounds (e.g., gaseous ammonia or ozone) to more complex mixtures (e.g., a wildfire smoke proxy and a commercial pesticide). Physical perturbations included varying temperature, ventilation rates, and relative humidity. The objectives for CASA included understanding (i) how outdoor air pollution impacts indoor air chemistry, (ii) how wildfire smoke transports and transforms indoors, (iii) how gases and particles interact with building surfaces, and (iv) how indoor environmental conditions impact indoor chemistry. Further, the combined measurements under unperturbed and experimental conditions enable investigation of mitigation strategies following outdoor and indoor air pollution events. A comprehensive suite of instruments measured different chemical components in the gas, particle, and surface phases throughout the study. We provide an overview of the test house, instrumentation, experimental design, and initial observations - including the role of humidity in controlling the air concentrations of many semi-volatile organic compounds, the potential for ozone to generate indoor nitrogen pentoxide (N2O5), the differences in microbial composition between the test house and other occupied buildings, and the complexity of deposited particles and gases on different indoor surfaces.

Contamination of surfaces in children's homes with nicotine and the potent carcinogenic tobacco-specific nitrosamine NNK

BACKGROUND

Tobacco smoke exposure (TSE) through secondhand and thirdhand smoke is a modifiable risk factor that contributes to childhood morbidity. Limited research has assessed surface TSE pollution in children's environments as a potential source of thirdhand smoke exposure, and none have examined levels of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on surfaces.

OBJECTIVE

This study measured surface NNK and nicotine in children's homes and associations with sociodemographics and parent-reported TSE behaviors. We assessed correlations of surface NNK and nicotine with dust NNK, dust nicotine, and child cotinine.

METHODS

Home surface wipe NNK and nicotine data from 84 children who lived with smokers were analyzed. Tobit and simple linear regression analyses were conducted to assess associations of surface NNK and nicotine with child characteristics. Spearman's (ρ) correlations assessed the strength of associations between environmental markers and child cotinine.

RESULTS

Nearly half (48.8%) of children's home surfaces had detectable NNK and 100% had detectable nicotine. The respective geometric means (GMs) of surface NNK and nicotine loadings were 14.0 ng/m2 and 16.4 µg/m2. Surface NNK positively correlated with surface nicotine (ρ = 0.54, p < 0.001) and dust NNK (ρ = 0.30, p = 0.020). Surface nicotine positively correlated with dust NNK (ρ = 0.42, p < 0.001) and dust nicotine (ρ = 0.24, p = 0.041). Children with household incomes ≤$15,000 had higher surface NNK levels (GM = 18.7 ng/m2, p = 0.017) compared to children with household incomes >$15,000 (GM = 7.1 ng/m2). Children with no home smoking bans had higher surface NNK (GM = 18.1 ng/m2, p = 0.020) and surface nicotine (GM = 17.7 µg/m2, p = 0.019) levels compared to children with smoking bans (GM = 7.5 ng/m2, 4.8 µg/m2, respectively).

IMPACT

Although nicotine on surfaces is an established marker of thirdhand smoke pollution, other thirdhand smoke contaminants have not been measured on surfaces in the homes of children living with smokers. We provide evidence that the potent carcinogenic tobacco-specific nitrosamine NNK was detectable on surfaces in nearly half of children's homes, and nicotine was detectable on all surfaces. Surface NNK was positively correlated with surface nicotine and dust NNK. Detectable surface NNK levels were found in homes with indoor smoking bans, indicating the role of NNK as a persistent thirdhand smoke pollutant accumulating on surfaces as well as in dust.

Determining the prevalence of people's knowledge that third-hand smoke is harmful to health: A meta-analysis study

INTRODUCTION

Although the health effects of first-hand smoke and second-hand smoke are well known, third-hand smoke (THS) is a relatively new concept. We estimated the prevalence of people's knowledge that THS is harmful to health, including for some subgroups, in a meta-analysis.

METHODS

We searched PubMed, Web of Science, Scopus, EBSCO Host, ProQuest, and YOKTEZ databases for the prevalence of people's knowledge that THS is harmful to health using specified search words. A total of 12 publications (n = 8549 people) were included in the meta-analysis. The random effect model was used for meta-analysis, and Cochran's Q test and I2 values were used to determine heterogeneity. Subgroup analyzes and meta-regression were also performed.

RESULTS

The prevalence of people's knowledge that THS is harmful was 80.1%. The prevalence of people's knowledge that THS is harmful for children was 82%, and the prevalence of people's knowledge that THS is harmful for adults was 70.4%. For health professionals, the prevalence of people's knowledge that THS is harmful for children was 89.8%, the highest prevalence value calculated in this meta-analysis. Cochran's Q test and I2 values indicated that the included studies were heterogeneous.

CONCLUSIONS

In this meta-analysis, the overall prevalence of people's knowledge that THS is harmful was 80.1%, but large variations were found between samples.

Thirdhand Smoke Exposure Ignored by Pediatricians: A Cross-sectional Study

Thirdhand smoke (THS) is defined as the harmful substances in cigarette smoke that are absorbed into objects, people, and surfaces after smoking. This study aimed to determine the level of awareness of pediatricians working in a tertiary healthcare institution about THS exposure. In this cross-sectional study, participants were asked to fill out an information form in which we questioned the participant's age, sex, occupation in the institution, the exposure of pediatric patients to cigarette smoke during daily healthcare, tobacco product use status, smoking status in their home and car, behavior in case of smoking in closed areas where smoking is prohibited, and whether they knew the term of THS. Also, the Turkish version of The Beliefs About Third-Hand Smoke was used. Eighty-one participants, with a mean age of 34.2 ± 7.6 years, were included in the study. Fifty-six (69.1%) participants said they had never used tobacco products. Participants who had never used tobacco products (P = .005), never allowed smoking in their homes (P = .017) and cars (P = .001), had heard the definition of THS before (P = .013), and thought they knew it (P = .005) had higher total scale scores. There was no significant difference between the THS awareness levels of pediatricians who questioned children's exposure to cigarette smoke in their daily practice and those who did not (P = .491). Determining the awareness levels of pediatricians about THS will be an important step in preventing THS exposure in children.

A review of indoor nitrous acid (HONO) pollution: Measurement techniques, pollution characteristics, sources, and sinks

Indoor air quality is of major concern for human health and well-being. Nitrous acid (HONO) is an emerging indoor pollutant, and its indoor mixing ratios are usually higher than outdoor levels, ranging from a few to tens of parts per billion (ppb). HONO exhibits adverse effects to human health due to its respiratory toxicity and mutagenicity. Additionally, HONO can easily undergo photodissociation by ultraviolet light to produce hydroxyl radicals (OH•), which in turn trigger a series of further photochemical oxidation reactions of primary or secondary pollutants. The accumulation of indoor HONO can be attributed to both direct emissions from combustion sources, such as cooking, and secondary formation resulting from enhanced heterogeneous reactions of NOx on indoor surfaces. During the day, the primary sink of indoor HONO is photolysis to OH• and NO. Moreover, adsorption and/or reaction on indoor surfaces, and diffusion to the outside atmosphere contribute to HONO loss both during the day and at night. The level of indoor HONO is also affected by human occupancy, which can influence household factors such as temperature, humidity, light irradiation, and indoor surfaces. This comprehensive review article summarized the research progress on indoor HONO pollution based on indoor air measurements, laboratory studies, and model simulations. The environmental and health effects were highlighted, measurement techniques were summarized, pollution levels, sources and sinks, and household influencing factors were discussed, and the prospects in the future were proposed.

Investigation of the impact of thirdhand e-cigarette exposure on platelet function: A pre-clinical study

INTRODUCTION

The use of e-cigarettes (ECs) has reached unprecedented levels, due to a variety of reasons, including the misconception regarding their safety. Thus, there have been efforts to characterize the effects of EC exposure, including in the context of thirdhand EC (THEC) on a host of disorders, such as cardiovascular disease (CVD).

METHODS

To address this issue, we sought to characterize the effects of THEC on platelet function and thrombus formation, using a novel mouse exposure protocol that resembles real life scenarios. To assess these effects, a host of related in vivo (i.e. tail bleeding time, and ferric chloride injury induced thrombosis model) assays and in vitro platelet specific (e.g. aggregation, and dense granule secretion) investigative assays were conducted.

RESULTS

Our in vivo characterization demonstrated that THEC exposed mice exhibited a prothrombotic phenotype reflected by their shortened tail bleeding (THEC: 37 ± 15 seconds, versus clean air: 183 ± 56 s) and occlusion times (THEC: 188 ± 39 s, versus clean air: 519 ± 70 s), relative to those exposed to clean air. Importantly, we found no difference in the platelet counts between the THEC and clean air mice. As for the underlying mechanism, separate experiments revealed significantly enhanced platelet aggregation, dense and alpha granule secretion, as well as integrin/GPIIb-IIIa activation and phosphatidylserine exposure in response to thrombin and ADP agonist stimulation.

CONCLUSIONS

Taken together, these results provide evidence that THEC does have the capacity to increase the risk of thrombotic disease, which should increase awareness regarding its underappreciated negative health effects.

When Does Multiphase Chemistry Influence Indoor Chemical Fate?

Human chemical exposure often occurs indoors, where large variability in contaminant concentrations and indoor chemical dynamics make assessments of these exposures challenging. A major source of uncertainty lies in the rates of chemical transformations which, due to high surface-to-volume ratios and rapid air change rates relative to rates of gas-phase reactions indoors, are largely gas-surface multiphase processes. It remains unclear how important such chemistry is in controlling indoor chemical lifetimes and, therefore, human exposure to both parent compounds and transformation products. We present a multimedia steady-state fugacity-based model to assess the importance of multiphase chemistry relative to cleaning and mass transfer losses, examine how the physicochemical properties of compounds and features of the indoor environment affect these processes, and investigate uncertainties pertaining to indoor multiphase chemistry and chemical lifetimes. We find that multiphase reactions can play an important role in chemical fate indoors for reactive compounds with low volatility, i.e., octanol-air equilibrium partitioning ratios (Koa) above 108, with the impact of this chemistry dependent on chemical identity, oxidant type and concentration, and other parameters. This work highlights the need for further research into indoor chemical dynamics and multiphase chemistry to constrain human exposure to chemicals in the built environment.

Novel chemical contaminants associated with thirdhand smoke in settled house dust

Thirdhand smoke (THS) is the persistent and toxic residue from tobacco smoke in indoor environments. A comprehensive understanding of the chemical constituents of THS is necessary to assess the risks of long-term exposure and to establish reliable THS tracers. The objective of this study was to investigate compounds associated with THS through nontargeted analysis (NTA) of settled house dust samples from smokers' and non-smokers' homes, using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS). Compounds that were either only present in dust from smokers' homes or that had significantly larger abundance than in non-smokers' homes were termed qualified compounds. We identified 140 qualified compounds, and of these, 42 compounds were tentatively identified by searching matching mass spectra in NIST electron impact (EI) mass spectral library including 20 compounds confirmed with their authentic standards. Among the 42 compounds, 26 compounds were statistically more abundant (p < 0.10) in dust from homes of smokers; seven were tobacco-specific compounds, two of which (nornicotyrine, 3-ethenylpyridine) have not been reported before in house dust. Two compounds, tris (2-chloroethyl) phosphate (a toxic compound used as a flame retardant and reported in tobacco) and propanoic acid, 2-methyl-, 1-(1,1-dimethylethyl)-2-methyl-1,3-propanediyl ester (highly abundant and reported in exhaled air of smokers), were found in dust from all smokers' homes and in zero non-smokers' homes, making these potential THS tracers, possibly associated with recent smoking. Benzyl methyl ketone was significantly higher in dust in smokers' homes, and was previously reported not as a product of tobacco but rather as a form of methamphetamine. This compound was recently reported in mainstream tobacco smoke condensate through NTA as well. These identified potential tracers and chemical components of THS in this study can be further investigated for use in developing THS contamination and exposure assessments.

Updates in Air Pollution: Current Research and Future Challenges

Background

The United Nations has declared that humans have a right to clean air. Despite this, many deaths and disability-adjusted life years are attributed to air pollution exposure each year. We face both challenges to air quality and opportunities to improve, but several areas need to be addressed with urgency.

Objective

This paper summarises the recent research presented at the Pacific Basin Consortium for Environment and Health Symposium and focuses on three key areas of air pollution that are important to human health and require more research.

Findings and conclusion

Indoor spaces are commonly places of exposure to poor air quality and are difficult to monitor and regulate. Global climate change risks worsening air quality in a bi-directional fashion. The rising use of electric vehicles may offer opportunities to improve air quality, but it also presents new challenges. Government policies and initiatives could lead to improved air and environmental justice. Several populations, such as older people and children, face increased harm from air pollution and should become priority groups for action.

Status of home-based secondhand smoke exposure among children and its association with health risks in Japan

Objectives

In Japan, secondhand smoke (SHS) exposure in children has changed with increased heated tobacco products (HTPs) and electronic cigarettes (e-cigs) use. We clarified the status of home-based SHS exposure among children, including HTPs and e-cigs, as well as maternal perceptions on SHS avoidance and examined its association with health risks.

Methods

This cross-sectional questionnaire-survey-based study included 379 mothers who were raising children aged < 5 years.

Results

We found that 31.1 % of the children had home-based SHS exposure, with widespread HTP and e-cig use among smoking mothers and family members (74.2 % and 67.0 %, respectively). Significantly (p < 0.05), HTP and cigarettes were used in the kitchen and gardens/balconies, and maternal perceptions of child SHS-exposure avoidance were lower among smokers than non-smokers. Non-smoking mothers also had low perceptions of smoking on balconies and having immediate post-smoking contact with their children (27.6 % and 27.9 %, respectively). Most non-smoking mothers (76.4 %) reported that they do not encourage family members to quit smoking. The structural equation model showed that the presence of smoking at home and low maternal perceptions was correlated with SHS-related child health risks, including respiratory diseases, otitis media, and dental caries.

Conclusions

HTP and e-cig use in the household has been rapidly increasing even among mothers and family members, and the presence of smokers at home and low maternal perceptions may be associated with child health risks. Increasing the maternal awareness of the child health risks of home-based SHS, including HTPs and e-cigs, along with continued smoking-cessation support involving mothers and families, is indispensable.

Association between cigarette smoke exposure and urinary bladder cancer in Scottish terriers in a cohort study

Canine urothelial carcinoma (UC) initially responds favorably to treatment, but is ultimately lethal in most cases. Research to identify modifiable risk factors to prevent the cancer is essential. The high breed-associated risk for UC, e.g. 20-fold higher in Scottish terriers, can facilitate this research. The objective was to identify environmental and host factors associated with UC in a cohort of Scottish terriers. Information was obtained through dog owner questionnaires for 120 Scottish terriers ≥ 6 years old participating in a bladder cancer screening study, with comparisons made between dogs that did or did not develop UC during the 3 years of screening. Univariable models were constructed, and variables with P < 0.20 were included when building the multivariable model, and then removed using a backward stepwise procedure. P < 0.05 was considered statistically significant. Urine cotinine concentrations were measured by liquid chromatography-mass spectrometry to further investigate potential cigarette smoke exposure. Biopsy-confirmed UC which was found in 32 of 120 dogs, was significantly associated with the dogs living in a household with cigarette smokers (odds ratio [OR], 6.34; 95 % confidence intervals [CI], 1.16-34.69; P = 0.033), living within a mile of a marsh or wetland (OR, 21.23; 95 % CI, 3.64-123.69; P = 0.001), and history of previous bladder infections (OR, 3.87; 95 % CI, 1.0-14.98; P = 0.050). UC was diagnosed in 18 of 51 dogs (35.3 %) with quantifiable cotinine concentrations, and six of 40 dogs (15.0 %) without quantifiable cotinine concentrations in their urine (P = 0.0165). In conclusion, the main modifiable risk factor for UC in this cohort of dogs was exposure to second-hand tobacco smoke.

Gas-Phase and Surface-Initiated Reactions of Household Bleach and Terpene-Containing Cleaning Products Yield Chlorination and Oxidation Products Adsorbed onto Indoor Relevant Surfaces

The use of household bleach cleaning products results in emissions of highly oxidative gaseous species, such as hypochlorous acid (HOCl) and chlorine (Cl2). These species readily react with volatile organic compounds (VOCs), such as limonene, one of the most abundant compounds found in indoor enviroments. In this study, reactions of HOCl/Cl2 with limonene in the gas phase and on indoor relevant surfaces were investigated. Using an environmental Teflon chamber, we show that silica (SiO2), a proxy for window glass, and rutile (TiO2), a component of paint and self-cleaning surfaces, act as a reservoir for adsorption of gas-phase products formed between HOCl/Cl2 and limonene. Furthermore, high-resolution mass spectrometry (HRMS) shows that the gas-phase reaction products of HOCl/Cl2 and limonene readily adsorb on both SiO2 and TiO2. Surface-mediated reactions can also occur, leading to the formation of new chlorine- and oxygen-containing products. Transmission Fourier-transform infrared (FTIR) spectroscopy of adsorption and desorption of bleach and terpene oxidation products indicates that these chlorine- and oxygen-containing products strongly adsorb on both SiO2 and TiO2 surfaces for days, providing potential sources of human exposure and sinks for additional heterogeneous reactions.

Quantifying the Nitrogen Sources and Secondary Formation of Ambient HONO with a Stable Isotopic Method

Nitrous acid (HONO) is a reactive gas that plays an important role in atmospheric chemistry. However, accurately quantifying its direct emissions and secondary formation in the atmosphere as well as attributing it to specific nitrogen sources remains a significant challenge. In this study, we developed a novel method using stable nitrogen and oxygen isotopes (δ15N; δ18O) for apportioning ambient HONO in an urban area in North China. The results show that secondary formation was the dominant HONO formation processes during both day and night, with the NO2 heterogeneous reaction contributing 59.0 ± 14.6% in daytime and 64.4 ± 10.8% at nighttime. A Bayesian simulation demonstrated that the average contributions of coal combustion, biomass burning, vehicle exhaust, and soil emissions to HONO were 22.2 ± 13.1, 26.0 ± 5.7, 28.6 ± 6.7, and 23.2 ± 8.1%, respectively. We propose that the isotopic method presents a promising approach for identifying nitrogen sources and the secondary formation of HONO, which could contribute to mitigating HONO and its adverse effects on air quality.

Exposure to secondhand and thirdhand smoke in private vehicles: Measurements in air and dust samples

BACKGROUND

This study aimed to estimate airborne nicotine concentrations and nicotine, cotinine, and tobacco-specific nitrosamines (TSNAs) in settled dust from private cars in Spain and the UK.

METHODS

We measured vapor-phase nicotine concentrations in a convenience sample of 45 private cars from Spain (N = 30) and the UK (N = 15) in 2017-2018. We recruited non-smoking drivers (n = 20), smoking drivers who do not smoke inside the car (n = 15), and smoking drivers who smoke inside (n = 10). Nicotine, cotinine, and three TSNAs (NNK, NNN, NNA) were also measured in settled dust in a random subsample (n = 20). We computed medians and interquartile ranges (IQR) of secondhand smoke (SHS) and thirdhand smoke (THS) compounds according to the drivers' profile.

RESULTS

24-h samples yielded median airborne nicotine concentrations below the limit of quantification (LOQ) (IQR:

CONCLUSIONS

All cars of smokers had measurable SHS and THS pollution, the exposure levels markedly higher in vehicles of drivers where smoking took place. Our results evidence the need for policies to prohibit smoking in vehicles, but also urge for more comprehensive strategies aiming towards the elimination of tobacco consumption.

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Key Words

• Airborne nicotine
• Automobile
• Dust
• Thirdhand smoke
• Tobacco smoke pollution
• Tobacco-specific nitrosamines

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MESH Headings

• Nicotine/analysis
• Cotinine
• Tobacco Smoke Pollution/analysis
• Dust
• Nitrosamines/analysis
• Tobacco

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Affiliation(s)

Xavier Continente Agència de Salut Pública de Barcelona, Pl. Lesseps, 1, 08023, Barcelona, Spain; Centre for Biomedical Research in Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain; Sant Pau Institute of Biomedical Research (IIB Sant Pau), Sant Antoni Maria Claret, 167, 08025, Barcelona, Spain.
Elisabet Henderson Agència de Salut Pública de Barcelona, Pl. Lesseps, 1, 08023, Barcelona, Spain; Sant Pau Institute of Biomedical Research (IIB Sant Pau), Sant Antoni Maria Claret, 167, 08025, Barcelona, Spain.
Laura López-González Agència de Salut Pública de Barcelona, Pl. Lesseps, 1, 08023, Barcelona, Spain.
Esteve Fernández Unitat de Control de Tabac, Institut Català d'Oncologia, Av. Granvia de l'Hospitalet 199-203, 08908, L'Hospitalet de Llobregat, Spain; Institut D'Investigació Biomèdica de Bellvitge, Av. Granvia de l'Hospitalet 199, 08908, L'Hospitalet de Llobregat, Spain; Department of Clinical Sciences, Campus de Bellvitge, School of Medicine and Health Sciences, University of Barcelona, Feixa Llarga, S/n, 08907, L'Hospitalet de Llobregat, Spain; Centre for Biomedical Research in Respiratory Diseases (CIBERES), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain.
Olena Tigova Unitat de Control de Tabac, Institut Català d'Oncologia, Av. Granvia de l'Hospitalet 199-203, 08908, L'Hospitalet de Llobregat, Spain; Institut D'Investigació Biomèdica de Bellvitge, Av. Granvia de l'Hospitalet 199, 08908, L'Hospitalet de Llobregat, Spain; Department of Clinical Sciences, Campus de Bellvitge, School of Medicine and Health Sciences, University of Barcelona, Feixa Llarga, S/n, 08907, L'Hospitalet de Llobregat, Spain; Centre for Biomedical Research in Respiratory Diseases (CIBERES), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain.
Sean Semple Institute for Social Marketing, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
Rachel O'Donnell Institute for Social Marketing, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
Ana Navas-Acién Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, 722 W 168th St, New York, NY, 10032, United States.
Núria Cortés-Francisco Agència de Salut Pública de Barcelona, Pl. Lesseps, 1, 08023, Barcelona, Spain; Centre for Biomedical Research in Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain; Sant Pau Institute of Biomedical Research (IIB Sant Pau), Sant Antoni Maria Claret, 167, 08025, Barcelona, Spain.
Noelia Ramírez Institut d'Investigació Sanitària Pere Virgili, Dr. Mallafré Guasch, 4, 43007, Tarragona, Spain; Universitat Rovira i Virgili, Department of Electronic Engineering, Escorxador, s/n, 43003, Tarragona, Spain; Centre for Biomedical Research in Diabetes and Associated Metabolic Diseases (CIBERDEM), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain.
Ruaraidh Dobson Institute for Social Marketing, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
Maria José López Agència de Salut Pública de Barcelona, Pl. Lesseps, 1, 08023, Barcelona, Spain; Centre for Biomedical Research in Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos, 3-5, Pabellón 11, Planta 0, 28029, Madrid, Spain; Sant Pau Institute of Biomedical Research (IIB Sant Pau), Sant Antoni Maria Claret, 167, 08025, Barcelona, Spain; Departament de Ciències Experimentals i de la Salut (DCEXS), Universitat Pompeu Fabra, Doctor Aiguader, 88, 08003, Barcelona, Spain.

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Remediation of Thirdhand Tobacco Smoke with Ozone: Probing Deep Reservoirs in Carpets

We assessed the efficacy of ozonation as an indoor remediation strategy by evaluating how a carpet serves as a sink and long-term source of thirdhand tobacco smoke (THS) while protecting contaminants absorbed in deep reservoirs by scavenging ozone. Specimens from unused carpet that was exposed to smoke in the lab ("fresh THS") and contaminated carpets retrieved from smokers' homes ("aged THS") were treated with 1000 ppb ozone in bench-scale tests. Nicotine was partially removed from fresh THS specimens by volatilization and oxidation, but it was not significantly eliminated from aged THS samples. By contrast, most of the 24 polycyclic aromatic hydrocarbons detected in both samples were partially removed by ozone. One of the home-aged carpets was installed in an 18 m³ room-sized chamber, where its nicotine emission rate was 950 ng day^-1 m^-2. In a typical home, such daily emissions could amount to a non-negligible fraction of the nicotine released by smoking one cigarette. The operation of a commercial ozone generator for a total duration of 156 min, reaching concentrations up to 10,000 ppb, did not significantly reduce the carpet nicotine loading (26-122 mg m^-2). Ozone reacted primarily with carpet fibers, rather than with THS, leading to short-term emissions of aldehydes and aerosol particles. Hence, by being absorbed deeply into carpet fibers, THS constituents can be partially shielded from ozonation.

Policy-relevant differences between secondhand and thirdhand smoke: strengthening protections from involuntary exposure to tobacco smoke pollutants

Starting in the 1970s, individuals, businesses and the public have increasingly benefited from policies prohibiting smoking indoors, saving thousands of lives and billions of dollars in healthcare expenditures. Smokefree policies to protect against secondhand smoke exposure, however, do not fully protect the public from the persistent and toxic chemical residues from tobacco smoke (also known as thirdhand smoke) that linger in indoor environments for years after smoking stops. Nor do these policies address the economic costs that individuals, businesses and the public bear in their attempts to remediate this toxic residue. We discuss policy-relevant differences between secondhand smoke and thirdhand smoke exposure: persistent pollutant reservoirs, pollutant transport, routes of exposure, the time gap between initial cause and effect, and remediation and disposal. We examine four policy considerations to better protect the public from involuntary exposure to tobacco smoke pollutants from all sources. We call for (a) redefining smokefree as free of tobacco smoke pollutants from secondhand and thirdhand smoke; (b) eliminating exemptions to comprehensive smoking bans; (c) identifying indoor environments with significant thirdhand smoke reservoirs; and (d) remediating thirdhand smoke. We use the case of California as an example of how secondhand smoke-protective laws may be strengthened to encompass thirdhand smoke protections. The health risks and economic costs of thirdhand smoke require that smokefree policies, environmental protections, real estate and rental disclosure policies, tenant protections, and consumer protection laws be strengthened to ensure that the public is fully protected from and informed about the risks of thirdhand smoke exposure.

Thirdhand tobacco smoke exposure increases the genetic background-dependent risk of pan-tumor development in Collaborative Cross mice

Increasing evidence has shown that thirdhand smoke (THS) exposure is likely to induce adverse health effects. An important knowledge gap remains in our understanding of THS exposure related to cancer risk in the human population. Population-based animal models are useful and powerful in investigating the interplay between host genetics and THS exposure on cancer risk. Here, we used the Collaborative Cross (CC) mouse population-based model system, which recapitulates the genetic and phenotypic diversity observed in the human population, to assess cancer risk after a short period of exposure, between 4 and 9 weeks of age. Eight CC strains (CC001, CC019, CC026, CC036, CC037, CC041, CC042 and CC051) were included in our study. We quantified pan-tumor incidence, tumor burden per mouse, organ tumor spectrum and tumor-free survival until 18 months of age. At the population level, we observed a significantly increased pan-tumor incidence and tumor burden per mouse in THS-treated mice as compared to the control (p = 3.04E-06). Lung and liver tissues exhibited the largest risk of undergoing tumorigenesis after THS exposure. Tumor-free survival was significantly reduced in THS-treated mice compared to control (p = 0.044). At the individual strain level, we observed a large variation in tumor incidence across the 8 CC strains. CC036 and CC041 exhibited a significant increase in pan-tumor incidence (p = 0.0084 and p = 0.000066, respectively) after THS exposure compared to control. We conclude that early-life THS exposure increases tumor development in CC mice and that host genetic background plays an important role in individual susceptibility to THS-induced tumorigenesis. Genetic background is an important factor that should be taken into account when determining human cancer risk of THS exposure.

Exposure, Retention, Exhalation, Symptoms, and Environmental Accumulation of Chemicals During JUUL Vaping

Little is known about the chemical exposures that electronic cigarette (EC) users receive and emit during JUUL vaping and if exposures produce symptoms dose dependently. This study examined chemical exposure (dose), retention, symptoms during vaping, and the environmental accumulation of exhaled propylene glycol (PG), glycerol (G), nicotine, and menthol in a cohort of human participants who vaped JUUL "Menthol" ECs. We refer to this environmental accumulation as "EC exhaled aerosol residue" (ECEAR). Chemicals were quantified using gas chromatography/mass spectrometry in JUUL pods before and after use, lab-generated aerosols, human exhaled aerosols, and in ECEAR. Unvaped JUUL "Menthol" pods contained ∼621.3 mg/mL of G, ∼264.9 mg/mL of PG, ∼59.3 mg/mL of nicotine, ∼13.3 mg/mL of menthol, and ∼0.1 mg/mL of the coolant WS-23. Eleven experienced male EC users (aged 21-26) provided exhaled aerosol and residue samples before and after vaping JUUL pods. Participants vaped ad libitum for 20 min, while their average puff count (22 ± 6.4) and puff duration (4.4 ± 2.0) were recorded. The transfer efficiency of nicotine, menthol, and WS-23 from the pod fluid into the aerosol varied with each chemical and was generally similar across flow rates (9-47 mL/s). At 21 mL/s, the average mass of each chemical retained by the participants who vaped 20 min was 53.2 ± 40.3 mg for G, 18.9 ± 14.3 mg for PG, 3.3 ± 2.7 mg for nicotine, and 0.5 ± 0.4 mg for menthol, with retention deduced to be ∼90-100% for each chemical. There was a significant positive relationship between the number of symptoms during vaping and total chemical mass retained. ECEAR accumulated on enclosed surfaces where it could contribute to passive exposure. These data will be valuable to researchers studying human exposure to EC aerosols and agencies that regulate EC products.

Distinguishing Exposure to Secondhand and Thirdhand Tobacco Smoke among U.S. Children Using Machine Learning: NHANES 2013-2016

While the thirdhand smoke (THS) residue from tobacco smoke has been recognized as a distinct public health hazard, there are currently no gold standard biomarkers to differentiate THS from secondhand smoke (SHS) exposure. This study used machine learning algorithms to assess which combinations of biomarkers and reported tobacco smoke exposure measures best differentiate children into three groups: no/minimal tobacco smoke exposure (NEG); predominant THS exposure (TEG); and mixed SHS and THS exposure (MEG). Participants were 4485 nonsmoking 3-17-year-olds from the National Health and Nutrition Examination Survey 2013-2016. We fitted and tested random forest models, and the majority (76%) of children were classified in NEG, 16% were classified in TEG, and 8% were classified in MEG. The final classification model based on reported exposure, biomarker, and biomarker ratio variables had a prediction accuracy of 95%. This final model had prediction accuracies of 100% for NEG, 88% for TEG, followed by 71% for MEG. The most important predictors were the reported number of household smokers, serum cotinine, serum hydroxycotinine, and urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). In the absence of validated biomarkers specific to THS, comprehensive biomarker and questionnaire data for tobacco smoke exposure can distinguish children exposed to SHS and THS with high accuracy.

The beliefs of medical faculty students about thirdhand smoke

INTRODUCTION

Thirdhand smoke is the toxic remnant, including pollutants and by-products, of tobacco smoke that remains in the environment after the use of tobacco products. This study aimed to evaluate the relationships between the demographic characteristics and the beliefs about thirdhand smoke of medical faculty students.

METHODS

This descriptive cross-sectional study was conducted with 392 medical faculty students at Afyonkarahisar Health Sciences University. All the participants completed the Beliefs About ThirdHand Smoke (BATHS) questionnaire. Demographic data such as age, gender, year of study, family income level, and place of residence were recorded and evaluated together with tobacco product usage status. Factors (demographic data such as gender) affecting the BATHS scale and sub-scales were analyzed using SPSS software.

RESULTS

The study included 392 medical students. The students comprised 59.7% females and 40.3% males. The students had never used tobacco products (68.1%), 13% were previous users, and 18.9% were active users. The majority of the students stated that thirdhand smoke was harmful to the health of children (90%) and adults (85%) and that thirdhand smoke could remain in a room for days (79%). When the relationships were evaluated between the BATHS scale overall and the health and permanence subscales, and the demographic characteristics of the students, no statistically significant difference was determined according to gender, place of residence, family income level, and tobacco use status.

CONCLUSIONS

This study has provided information for the first time about the beliefs of medical faculty students about thirdhand smoke, and the relationships were investigated between these beliefs and gender, place of residence, family income level, and tobacco use status. The results of the study demonstrated that the students had a strong awareness of the harm of thirdhand smoke and of environmental permanence, and these beliefs did not change according to their own tobacco use status.

Carcinogenic and tobacco smoke-derived particulate matter biomarker uptake and associated healthcare patterns among children

BACKGROUND

The objective was to assess the associations of child tobacco smoke exposure (TSE) biomarkers (urinary cotinine, NNAL, and nicotelline N-oxides) and parent-reported smoking and child TSE patterns with total hospital visits, pediatric emergency department (PED) visits, urgent care (UC), revisits, and hospital admissions among 0-9-year-olds.

METHODS

A convenience sample of PED/UC patients (N = 242) who presented to a large, US children's hospital who had baseline urine samples assayed for the TSE biomarkers of interest were included. Biomarker levels were log-transformed, and linear and Poisson regression models were built.

RESULTS

The geometric means of child cotinine, creatinine-adjusted NNAL, and N-oxide levels were 11.2 ng/ml, 30.9 pg/mg creatinine, and 24.1 pg/ml, respectively. The mean (SD) number of daily cigarettes smoked by parents was 10.2 (6.1) cigarettes. Each one-unit increase in log-NNAL levels was associated with an increase in total UC visits (aRR = 1.68, 95% CI = 1.18-2.39) among 0-9-year-olds, while controlling for the covariates. Each one-unit increase in child log-NNAL/cotinine ratio (×103) values was associated with an increase in total hospital visits (aRR = 1.39, 95% CI = 1.10-1.75) and UC visits (aRR = 1.56, 95% CI = 1.14-2.13) over 6 months.

CONCLUSION

Systematic screening for child TSE should be conducted during all hospital visits. The comprehensive assessment of TSE biomarkers should be considered to objectively measure young children's exposure.

IMPACT

Higher levels of cotinine, a widely used tobacco smoke exposure biomarker, have been associated with higher healthcare utilization patterns among children. Less is known on the associations of carcinogenic and tobacco smoke-derived particulate matter biomarker uptake with child healthcare utilization patterns. This study assessed the associations of several biomarkers with healthcare utilization patterns among pediatric emergency department patients ages 0-9 years who lived with tobacco smokers. Higher urinary NNAL biomarker levels, in individual and ratio form with cotinine, increased children's risk for urgent care visits over 6 months. Higher parent-reported cumulative child tobacco smoke exposure increased children's risk for hospital admissions.

Urinary cotinine and exposure to passive smoke in children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V)

Passive smoking is a preventable and significant cause of many serious health problems, with children being particularly at risk. In the fifth German Environmental Survey (GerES V), conducted from 2014 to 2017, information reflecting the extent of passive smoke exposure in children and adolescents was collected by interview-based questionnaires and human biomonitoring (HBM) analyses of cotinine in urine from 2260 participants, aged 3-17 years. Based on these population-representative data, we describe current passive smoke exposure stratified by different subgroups and identify specific exposure determinants using multivariate logistic regression. The questionnaire data revealed that 42% of children and adolescents lived with at least one smoker in the household. Quantifiable concentrations of cotinine could be detected in 56% of the participants. The overall median concentration of cotinine was 0.2 μg/L, with children and adolescents of low socioeconomic status found to be a group particularly affected by passive smoke with higher cotinine concentrations (median = 1.2 μg/L). In the multiple analysis, the most significant predictor of cotinine levels derived from the questionnaire was passive smoking at home (odds ratio (OR) 13.07 [95CI: 4.65, 36.70]). However, parental smoking and passive smoking among friends and relatives could also be identified as independent factors influencing elevated cotinine levels. The comparison between the previous cycle GerES IV (2003-2006) on 3-14-year-olds and GerES V shows that tobacco smoke exposure of children decreased significantly. This decrease is likely an effect of extensive non-smoker protection laws being enforced 2007-2008 on federal and state level. This is reflected by a halving of urinary cotinine concentrations. Nevertheless, our results indicate that passive smoke is still a relevant source of harmful pollutants for many children and adolescents in Germany, and thus support the need for further efforts to reduce passive smoke exposure, especially in the private environment.

Widespread formation of toxic nitrated bisphenols indoors by heterogeneous reactions with HONO

With numerous structurally diverse indoor contaminants, indoor transformation chemistry has been largely unexplored. Here, by integrating protein affinity purification and nontargeted mass spectrometry analysis (PUCA), we identified a substantial class of previously unrecognized indoor transformation products formed through gas-surface reactions with nitrous acid (HONO). Through the PUCA, we identified a noncommercial compound, nitrated bisphenol A (BPA), from house dust extracts strongly binding to estrogen-related receptor γ. The compound was detected in 28 of 31 house dust samples with comparable concentrations (ND to 0.30 μg/g) to BPA. Via exposing gaseous HONO to surface-bound BPA, we demonstrated it likely forms via a heterogeneous indoor chemical transformation that is highly selective toward bisphenols with electron-rich aromatic rings. We used 15N-nitrite for in situ labeling and found 110 nitration products formed from indoor contaminants with distinct aromatic moieties. This study demonstrates a previously unidentified class of chemical reactions involving indoor HONO, which should be incorporated into the risk evaluation of indoor contaminants, particularly bisphenols.

A review of indoor Gaseous organic compounds and human chemical Exposure: Insights from Real-time measurements

Gaseous organic compounds, mainly volatile organic compounds (VOCs), have become a wide concern in various indoor environments where we spend the majority of our daily time. The sources, compositions, variations, and sinks of indoor VOCs are extremely complex, and their potential impacts on human health are less understood. Owing to the deployment of the state-of-the-art real-time mass spectrometry during the last two decades, our understanding of the sources, dynamic changes and chemical transformations of VOCs indoors has been significantly improved. This review aims to summarize the key findings from mass spectrometry measurements in recent indoor studies including residence, classroom, office, sports center, etc. The sources and sinks, compositions and distributions of indoor VOCs, and the factors (e.g., human activities, air exchange rate, temperature and humidity) driving the changes in indoor VOCs are discussed. The physical and chemical processes of gas-particle partitioning and secondary oxidation processes of VOCs, and their impacts on human health are summarized. Finally, the recommendations for future research directions on indoor VOCs measurements and indoor chemistry are proposed.

The Effect of Human Occupancy on Indoor Air Quality through Real-Time Measurements of Key Pollutants

The primarily emitted compounds by human presence, e.g., skin and volatile organic compounds (VOCs) in breath, can react with typical indoor air oxidants, ozone (O₃), and hydroxyl radicals (OH), leading to secondary organic compounds. Nevertheless, our understanding about the formation processes of the compounds through reactions of indoor air oxidants with primary emitted pollutants is still incomplete. In this study we performed real-time measurements of nitrous acid (HONO), nitrogen oxides (NO_x = NO + NO₂), O₃, and VOCs to investigate the contribution of human presence and human activity, e.g., mopping the floor, to secondary organic compounds. During human occupancy a significant increase was observed of 1-butene, isoprene, and d-limonene exhaled by the four adults in the room and an increase of methyl vinyl ketone/methacrolein, methylglyoxal, and 3-methylfuran, formed as secondary compounds through reactions of OH radicals with isoprene. Intriguingly, the level of some compounds (e.g., m/z 126, 6-methyl-5-hepten-2-one, m/z 152, dihydrocarvone, and m/z 194, geranyl acetone) formed through reactions of O₃ with the primary compounds was higher in the presence of four adults than during the period of mopping the floor with commercial detergent. These results indicate that human presence can additionally degrade the indoor air quality.

Dermal thirdhand smoke exposure induces oxidative damage, initiates skin inflammatory markers, and adversely alters the human plasma proteome

Background

Thirdhand smoke (THS) exposure correlated with significant metabolism of carcinogenic chemicals and the potential to cause detrimental health effects. Human harm research of THS exposure is limited to one other study and overall, there is a general lack of knowledge of the human health responses to THS exposure.

Methods

This was a clinical investigation to evaluate the health effects of 3-h dermal THS exposure from urine and plasma. 10 healthy, non-smoking subjects were recruited for dermal exposure for 3 h exposed to clothing impregnated with filtered clean air or THS. Exposures to clean air or THS occurred 20-30 days apart.

Findings

In THS-exposed group, there was a significant elevation of urinary 8-OHdG, 8-isoprostane, protein carbonyls. The THS 3-h exposure identified proteomics pathways of inflammatory response (p=2.18 × 10⁻⁸), adhesion of blood cells (p=2.23 × 10⁻⁸), atherosclerosis (p=2.78 × 10⁻⁹), and lichen planus (p=1.77 × 10⁻⁸). Nine canonical pathways were significantly activated including leukocyte extravasation signaling (z-score=3.0), and production of nitric oxide and reactive oxygen in macrophages (z-score=2.1). The THS 22-h proteomics pathways revealed inflammation of organ (p=3.09 × 10⁻⁸), keratinization of the epidermis (p=4.0 × 10⁻⁷), plaque psoriasis (p=5.31 × 10⁻⁷), and dermatitis (p=6.0 × 10⁻⁷). Two activated canonical pathways were production of nitric oxide and reactive oxygen in macrophages (z-score=2.646), and IL-8 signaling (z-score=2.0).

Interpretation

This is a clinical study demonstrating that acute dermal exposure to THS mimics the harmful effects of cigarette smoking, alters the human plasma proteome, initiates mechanisms of skin inflammatory disease, and elevates urinary biomarkers of oxidative harm.

Funding

Funding was provided by the Tobacco Related Disease Research Program (TRDRP) 24RT-0037 TRDRP, 24RT-0039 TRDRP, and 28PT-0081 TRDRP.

Rapid Gas-Phase Autoxidation of Nicotine in the Atmosphere

Nicotine is the most abundant alkaloid chemical in smoke emission. In this work, we investigated the gas-phase oxidation mechanism of nicotine initiated by its reactions with the OH radical and ozone. Both initiation reactions start dominantly by hydrogen atom abstractions from the C1, C3, and -CH₃ groups of the methylpyrrolidinyl group and form radicals nicotinyl-1, nicotinyl-3, and nicotinyl-6, respectively. The nicotinyl radicals would recombine rapidly with O₂, forming RO₂ with rapid intramolecular hydrogen-atom transfers (HATs) with rate coefficients from 4 s^-1 to greater than 10⁴ s^-1. The rapid HATs in peroxy radicals suggest rapid autoxidation of nicotine in the gas phase. Formation of HCNO and HC(O)NH₂, being observed in previous studies, arises likely from secondary reactions or photolysis of intermediate products.

Thirdhand Exposures to Tobacco-Specific Nitrosamines through Inhalation, Dust Ingestion, Dermal Uptake, and Epidermal Chemistry

Tobacco-specific nitrosamines (TSNAs) are emitted during smoking and form indoors by nitrosation of nicotine. Two of them, N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are human carcinogens with No Significant Risk Levels (NSRLs) of 500 and 14 ng day^-1, respectively. Another TSNA, 4-(methylnitrosamino)-4-(3-pyridyl) butanal (NNA), shows genotoxic and mutagenic activity in vitro. Here, we present additional evidence of genotoxicity of NNA, an assessment of TSNA dermal uptake, and predicted exposure risks through different pathways. Dermal uptake was investigated by evaluating the penetration of NNK and nicotine through mice skin. Comparable mouse urine metabolite profiles suggested that both compounds were absorbed and metabolized via similar mechanisms. We then investigated the effects of skin constituents on the reaction of adsorbed nicotine with nitrous acid (epidermal chemistry). Higher TSNA concentrations were formed on cellulose and cotton substrates that were precoated with human skin oils and sweat compared to clean substrates. These results were combined with reported air, dust, and surface concentrations to assess NNK intake. Five different exposure pathways exceeded the NSRL under realistic scenarios, including inhalation, dust ingestion, direct dermal contact, gas-to-skin deposition, and epidermal nitrosation of nicotine. These results illustrate potential long-term health risks for nonsmokers in homes contaminated with thirdhand tobacco smoke.

Gas-Phase Nitrous Acid (HONO) Is Controlled by Surface Interactions of Adsorbed Nitrite (NO2-) on Common Indoor Material Surfaces

Nitrous acid (HONO) is a household pollutant exhibiting adverse health effects and a major source of indoor OH radicals under a variety of lighting conditions. The present study focuses on gas-phase HONO and condensed-phase nitrite and nitrate formation on indoor surface thin films following heterogeneous hydrolysis of NO₂, in the presence and absence of light, and nitrate (NO₃^-) photochemistry. These thin films are composed of common building materials including zeolite, kaolinite, painted walls, and cement. Gas-phase HONO is measured using an incoherent broadband cavity-enhanced ultraviolet absorption spectrometer (IBBCEAS), whereby condensed-phase products, adsorbed nitrite and nitrate, are quantified using ion chromatography. All of the surface materials used in this study can store nitrogen oxides as nitrate, but only thin films of zeolite and cement can act as condensed-phase nitrite reservoirs. For both the photo-enhanced heterogeneous hydrolysis of NO₂ and nitrate photochemistry, the amount of HONO produced depends on the material surface. For zeolite and cement, little HONO is produced, whereas HONO is the major product from kaolinite and painted wall surfaces. An important result of this study is that surface interactions of adsorbed nitrite are key to HONO formation, and the stronger the interaction of nitrite with the surface, the less gas-phase HONO produced.

Association between involuntary smoking and risk of cervical cancer in Chinese female never smokers: A prospective cohort study

Involuntary smoking was a major public health problem for women in China. Previous studies mainly focused on secondhand smoke (SHS), which referred to direct exposure to smoke from burning cigarettes. Little evidence existed about the relationship between thirdhand smoke (THS), the residual tobacco smoke remaining in the environment after tobacco had been smoked, and cervical cancer. The China Kadoorie Biobank (CKB) study recruited 0.3 million female participants from 10 areas across China during 2004-2008. After an 11.2-year median follow-up, we documented 1094 cervical cancer cases. Multivariable Cox regression yielded adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of SHS and THS with cervical cancer incidence, respectively and jointly. Overall, 60.3% reported weekly SHS exposure, and 83.2% had been exposed to THS. Daily SHS exposure and THS exposure at the enrollment were associated with elevated risks of cervical cancer incidence, with adjusted HRs (95% CI) of 1.22 (1.06,1.42) and 1.24 (1.03,1.49), respectively. The longer the exposure duration, the higher the risks (P for trend = 0.006, 0.035, respectively). Compared with those who were neither exposed to SHS nor THS, those exposed to both SHS and THS had the highest risk, with adjusted HRs (95% CI) of 1.29 (1.05,1.58). Area of residence, breastfeeding duration and heating fuel types are potential effect modifiers. Among Chinese females, both SHS and THS were associated with higher risks of cervical cancer incidence, and a dose-response relationship was found between the exposure duration and cervical cancer risk. Our findings reinforce the need for proactive strategies for tobacco control, to protect women health.

Passive smoking and urinary oxidative biomarkers: A pilot study of healthy travelers from Los Angeles to Beijing

There is a great heterogeneity in smoking prevalence and tobacco control policy across different countries. However, it is unknown whether this heterogeneity could cause increased passive smoking and adverse health effects among international travelers. In this pilot study, we collected 190 urine samples from 26 Los Angeles residents before (LA-before), during (Beijing), and after (LA-after) a 10-week visit to Beijing to measure biomarkers of passive smoking (cotinine), exposure to polycyclic aromatic hydrocarbons (OH-PAHs), and oxidative stress (malondialdehyde, 8-isoprostane, and uric acid). The geometric mean concentrations of urinary cotinine were 0.14, 1.52, and 0.22 μg/g creatinine in LA-before, Beijing, and LA-after, respectively. Likewise, OH-PAH levels were significantly higher in Beijing as compared to LA-before or LA-after, in association with the urinary cotinine levels. One-fold increase in urinary cotinine levels was associated with 10.1% (95% CI: 5.53-14.8%), 8.75% (95% CI: 2.33-15.6%), and 25.4% (95%CI: 13.1-39.1%) increases in urinary levels of malondialdehyde, 8-isoprotane, and uric acid, respectively. OH-PAHs mediated 9.1-23.3% of the pro-oxidative effects associated with passive smoking. Taken together, our findings indicate that traveling to a city with higher smoking prevalence may increase passive smoking exposure, in association with pro-oxidative effects partially mediated by PAHs.

Indoor Secondary Pollutants Cannot Be Ignored: Third-Hand Smoke

Smoking has been recognized by the World Health Organization (WHO) as the fifth highest threat to humanity. Smoking, a leading disease promoter, is a major risk factor for non-communicable diseases (NCDs) such as cancer, cardiovascular disease, diabetes, and chronic respiratory diseases. NCDs account for 63% of all deaths worldwide. Passive smoking is also a health risk. Globally, more than a third of all people are regularly exposed to harmful smoke. Air pollution is a common global problem in which pollutants emitted into the atmosphere undergo a series of physical or chemical reactions to produce various oxidation products, which are often referred to as secondary pollutants. Secondary pollutants include ozone (O₃), sulfur trioxide (SO₃), nitrogen dioxide (NO₂), and respirable particulate matter (PM). It is worth mentioning that third-hand smoke (THS), formed by the reaction of nicotine with second-hand smoke (SHS) caused by indoor O₃ or nitrous acid (HONO), is a major indoor secondary pollutant that cannot be ignored. As a form of indoor air pollution that is relatively difficult to avoid, THS exists in any corner of the environment where smokers live. In this paper, we summarize the important research progress on the main components, detection, and toxicity of THS and look forward to future research directions. Scientific understanding of THS and its hazards will facilitate smoking bans in indoor and public places and raise public concern for how to prevent and remove THS.

Identification and determination of the volatile organics of third-hand smoke from different cigarettes and clothing fabrics

Third-hand smoke (THS) is a persistent mixture generated from aged second-hand smoke (SHS) that accumulates in indoor environments and reemits into the air. This work evaluates the tobacco-derived volatile organics of cigarette THS from various clothing fabrics that were exposed to side-stream smoke of several brands of cigarettes in a controlled experimental scale. The qualitative and quantitative determination of the chemicals off-gassed was performed using solid phase micro-extraction coupled with GC/MS. Sixty-six components of side-stream smoke were identified in third-hand cigarette smoke. In this study, toluene-reference concentration (TRC) was calculated for volatile compounds and estimated based on the basic response characteristics of GC/MS. Among the identified analytes, 16 compounds were quantified presenting high toxicity and/or abundance in smoke, such as: benzene, toluene, xylene, pyridine, limonene, naphthalene, furfural and nicotine. The results showed that the total quantified volatile organics released for cotton, wool, polyester and filament fabrics were 92.37, 93.09, 87.88, and 50.22 μg/l fabric, respectively. Fabric structure significantly affects chemical off-gassing. Natural fibers were more capable of holding and emitting THS than synthetic fibers. Besides, various desorption times from 15 to 45 min after exposure to cigarette smoke in the study were evaluated. With increasing desorption time, no significant decrease in the concentration of organic compounds in THS was observed. Therefore, it is necessary to pay attention to the fact that it will be difficult to clean the pollutants from the environment contaminated with cigarette smoke and it will take more hours to reduce the concentration of organic compounds.

Tobacco-specific nitrosamine 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA) causes DNA damage and impaired replication/transcription in human lung cells

Thirdhand smoke (THS) is a newly described health hazard composed of toxicants, mutagens and carcinogens, including nicotine-derived tobacco specific nitrosamines (TSNAs), one of which is 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA). Although TSNAs are generally potent carcinogens, the risk of NNA, which is specific to THS, is poorly understood. We recently reported that THS exposure-induced adverse impact on DNA replication and transcription with implications in the development of cancer and other diseases. Here, we investigated the role of NNA in THS exposure-induced harmful effects on fundamental cellular processes. We exposed cultured human lung epithelial BEAS-2B cells to NNA. The formation of DNA base damages was assessed by Long Amplicon QPCR (LA-QPCR); DNA double-strand breaks (DSBs) and NNA effects on replication and transcription by immunofluorescence (IF); and genomic instability by micronuclei (MN) formation. We found increased accumulation of oxidative DNA damage and DSBs as well as activation of DNA damage response pathway, after exposure of cells to NNA. Impaired S phase progression was also evident. Consistent with these results, we found increased MN formation, a marker of genomic instability, in NNA-exposed cells. Furthermore, ongoing RNA synthesis was significantly reduced by NNA exposure, however, RNA synthesis resumed fully after a 24h recovery period only in wild-type cells but not in those deficient in transcription-coupled nucleotide excision repair (TC-NER). Importantly, these cellular effects are common with the THS-exposure induced effects. Our findings suggest that NNA in THS could be a contributing factor for THS exposure-induced adverse health effect.

Toxicity of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in early development: A wide-scope metabolomics assay in zebrafish embryos

The tobacco-specific nitrosamine 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a carcinogenic and ubiquitous environmental pollutant for which toxic activity has been thoroughly investigated in murine models and human tissues. However, its potential deleterious effects on vertebrate early development are yet poorly understood. In this work, we characterized the impact of NNK exposure during early developmental stages of zebrafish embryos, a known alternative model for mammalian toxicity studies. Embryos exposed to different NNK concentrations were monitored for lethality and for the appearance of malformations during the first five days after fertilization. LC-MS based untargeted metabolomics was subsequently performed for a wide-scope assay of NNK-related metabolic alterations. Our results revealed the presence of not only the parental compound, but also of two known NNK metabolites, 4-Hydroxy-4-(3-pyridyl)-butyric acid (HPBA) and 4-(Methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanol (NNAL-N-oxide) in exposed embryos likely resulting from active CYP450-mediated α-hydroxylation and NNK detoxification pathways, respectively. This was paralleled by a disruption in purine and pyrimidine metabolisms and the activation of the base excision repair pathway. Our results confirm NNK as a harmful embryonic agent and demonstrate zebrafish embryos to be a suitable early development model to monitor NNK toxicity.

Content of toxic components of cigarette, cigarette smoke vs cigarette butts: A comprehensive systematic review

The commercially sold cigarettes contain more than 7000 chemicals, and their combustion produces potential toxicants in mainstream smoke (MS), sidestream smoke (SS), secondhand smoke (SHS), thirdhand smoke (THS), and discarded cigarette butts (CBs). We conducted a systematic review of published literature to compare the toxicants produced in each of these phases of tobacco combustion (MS, SS, and CBs). The initial search included 12,301 articles, but after screening and final restrictions considering the aims of this review, 159 published studies were selected for inclusion. Additionally, SHS and THS are briefly discussed here. Overall, polycyclic aromatic hydrocarbons (PAHs) and other aromatic hydrocarbons have been represented in more studies than other compounds. However, metals and nitrosamines were detected in higher concentrations than other components in SS. The concentrations of most PAHs and other aromatic hydrocarbons in MS and SS are higher compared to concentrations found in CBs. Also, the concentrations of all the studied carbonyl compounds, aldehydes and ketones in SS and MS were higher than in CBs. The mean levels of alcohols and phenols in SS were higher than those reported for both MS and CBs. Tobacco toxicants are inhaled by smokers and transmitted to the environment through SS, SHS, THS, and discarded CBs. However, further studies are necessary to assess adverse effects of toxicants found in CBs and THS not only on human health, but also on the environment and ecosystems. The results of this review provide updated information on the chemical contents of MS, SS, SHS, THS, and CBs. It adds to the growing understanding that smoking creates major health problems for smokers and passive smokers, but also that it generates environmental hazards with consequences to the ecosystems and human health through discarded CBs, SHS, and THS exposure.

Secondhand smoke exposure in school children in Malta assessed through urinary biomarkers

School children may be exposed to secondhand smoke (SHS) either at home, in transit or in social gatherings permitting smoking in their presence. Questionnaires about SHS often underestimate prevalence and extent of exposure. A more accurate tool is the use of biomarkers such as cotinine (COT) and trans-3'-hydrocycotinine (3HC) as biomarkers of SHS exposure, alongside 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a reduction product in the body of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), both potent carcinogens. We measured urinary COT, 3HC and total NNAL using sensitive and specific high-performance LC-MS/MS methods. The limit of quantification (LOQ) for each assay were 0.05 ng/mL, 0.1 ng/mL and 0.25 pg/mL respectively. The aim of this study was to evaluate the exposure to SHS of school children (9-11 years), from five public schools in the island of Malta, from questionnaire information about smoking at home and verify it by urinary biomarker data of COT, 3HC and NNAL. These biomarkers were measurable in 99.4%, 95.4% and 98.3% of the participating children respectively. From the children reporting smoking at home, 11% had a history of asthma and had COT, 3HC and NNAL geometric mean concentrations double compared to the non-asthmatic group. In has been confirmed that non-smokers exposed to SHS and THS have a higher NNAL/COT ratio than the group identified as smokers according to specific and defined COT threshold levels (despite the fact that a priori, the entire study group was composed of non-smokers). The implication of high measured levels of urinary NNAL in children should be of concern given its potency. A main effects multifactor ANOVA model was developed and the children's house and school locations and the smoking frequency were statistically significant to predict the levels of the three metabolites. For 3HC only, the status of the employment of the mother was also an important predictor.

Tobacco-specific and combustion pollutants in settled house dust in Malta

Aim

Most of the carcinogenic pollutants coming from tobacco smoking or other combustion processes tend to accumulate in settled house dust (SHD) over time. This study evaluated the load of these pollutants in smokers and non-smokers' houses from relatively fresh SHD collected in five different districts on the island of Malta.

Methods

An improved, efficient extraction method to obtain three fractions from a 200 mg of SHD was developed. It was validated for the analysis of nicotine and polycyclic aromatic hydrocarbons (PAH) by GC-MS/MS and nicotelline and TSNA by LC-MS/MS. Kruskal-Wallis H tests were used to evaluate differences across districts, while a Mann-Whitney U test was used to check differences between smokers and non-smokers' houses. Diagnostic ratios were used to evaluate the carcinogenicity of PAH in SHD in Malta.

Results

For all analytes, no statistical difference was observed across different districts, but, in smokers' houses, 97.9% of the total concentration of all target analytes found in SHD is nicotine, 0.1% is TSNA, and 2.0% is PAH. In non-smokers' houses, nicotine represents 16.8% of the load, while 0.4% and 82.8% are TSNA and PAH, respectively. The carcinogenicity of the PAH mixture in Maltese SHD, expressed as the mean benzo(a)pyrene equivalent (BaPeq) is 371 ng/g.

Conclusion

Indoor activities, ventilation practices, and infiltration of outdoor pollutants contribute to a complex SHD composition. Although the BaPeq is on the lower end of carcinogenicity, the effects of a mixture including tobacco-related potent carcinogens in SHD are largely unknown. In view of indoor, continuous exposure to SHD through several pathways, further research is warranted.

Thirdhand smoke from tobacco, e-cigarettes, cannabis, methamphetamine and cocaine: Partitioning, reactive fate, and human exposure in indoor environments

A source of chemical exposure to humans, thirdhand smoke (THS) refers to the contamination that persists indoors following the cessation of a smoking event. The composition of thirdhand smoke depends on the type of substance from which it originates. Although past studies have investigated the effects of tobacco THS on indoor air quality and human health, few have focused on the chemical composition and health impacts of other sources and components of THS. Here we review the state of knowledge of the composition and partitioning behavior of various types of indoor THS, with a focus on THS from tobacco, e-cigarettes, cannabis, and illicit substances (methamphetamine and cocaine). The discussion is supplemented by estimates of human exposure to THS components made with a chemical fate and exposure model. The modeling results show that while very volatile THS compounds (i.e., aromatics) are likely to be taken up by inhalation, highly water-soluble compounds tended to be dermally absorbed. Conversely, minimally volatile THS compounds with low solubility are predicted to be ingested through hand-to-mouth and object-to-mouth contact.

Nanoscopic Study of Water Uptake on Glass Surfaces with Organic Thin Films and Particles from Exposure to Indoor Cooking Activities: Comparison to Model Systems

Water uptake by thin organic films and organic particles on glass substrates at 80% relative humidity was investigated using atomic force microscopy-infrared (AFM-IR) spectroscopy. Glass surfaces exposed to kitchen cooking activities show a wide variability of coverages from organic particles and organic thin films. Water uptake, as measured by changes in the volume of the films and particles, was also quite variable. A comparison of glass surfaces exposed to kitchen activities to model systems shows that they can be largely represented by oxidized oleic acid and carboxylate groups on long and medium hydrocarbon chains (i.e., fatty acids). Overall, we demonstrate that organic particles and thin films that cover glass surfaces can take up water under indoor-relevant conditions but that the water content is not uniform. The spatial heterogeneity of the changes in these aged glass surfaces under dry (5%) and wet (80%) conditions is quite marked, highlighting the need for studies at the nano- and microscale.

Eyelid carcinomas: Tumor aggressiveness tendencies for smokers compared to non‑smokers

During the past few years, several studies have demonstrated that head and neck carcinomas present more aggressive forms for smokers, relative to non-smokers. Our aim was to investigate the tumor aggressiveness for patients with eyelid carcinomas, in relation to tobacco consumption, as well as other demographic and clinical data. For 98 patients with eyelid carcinomas, we studied the relationship between the duration of their symptoms and their tumor stage at first diagnosis, trying to determine potential correlations with smoking status and several other clinical parameters. Our data revealed that, for the same duration of symptoms, tobacco consumers tended to have higher tumor stages, which did not correlate with other variables. For early diagnosed tumors, within the first year of symptoms, smokers presented 6.044 times higher odds to exhibit more advanced tumor stages, compared to non-smokers, and this value decreased to 4.501, up to 5 years of the presence of symptoms (P<0.05). We also noted that, for smokers, an increased age was associated with increased tumor stages, which was opposed to non-smokers, regardless of their symptom duration [average odds ratio (OR) 1.122, P<0.05]. Tumor aggressiveness was therefore associated with tobacco consumption, leading to an increased risk of developing more aggressive forms of eyelid carcinomas for smokers, compared to non-smokers.

Determination of 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone (NNK) arising from tobacco smoke in airborne particulate matter

The most important tobacco-specific nitrosamine found in cigarette smoke and formed in ageing smoke after cigarettes are extinguished is 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). It is formed from nitrosation of nicotine, under particular conditions both in indoor and outdoor environments. NNK has been classified as a potent lung carcinogen which is expected to be found primarily in the particle-phase and to be stable in particulate matter. In this study tests have been carried out to show that a bisulfate-treated filter is more efficient than an untreated filter to collect both nicotine and NNK, and that the latter is stable in outdoor particulate matter. To characterize NNK in the outdoor environment, airborne samples were collected from 11 cities in USA, UK, Hong Kong and Malta with characteristics varying from low to high population densities and from urban to suburban to rural, and with desert characteristics and distinct climates. It has been shown that airborne particle + gas phase nicotine and particle-phase NNK behave in a linearly correlated manner. A seasonal analysis was carried out on a subset of data available from five sites in California, where the load of NNK in PM10 is driven by long range transport of the air masses passing over densely populated cities. In the winter season, the load of NNK in PM is higher than in summer in a statistically significant manner. The contamination of PM with NNK shows variability, but is observed at all sites. This paper highlights the potential risk of chronic exposure to NNK in particulate matter by the inhalation pathway.

Capability of Relative Odor Level Monitors to Measure the Odor of Thirdhand Smoke

We investigated the probability of measuring the odor of thirdhand smoke using four odor-measuring monitors and three gas detector tubes. We measured the changes in tobacco odor on paper towels and cloth products over time. The results of the measurements were plotted against time to obtain an exponential approximation curve. The coefficient of x and the R² values were calculated from this curve. The odor indicated by four types of odor-measuring monitors and three types of gas detector tubes decreased exponentially over time. The curves obtained from all measuring devices had coefficients of e^x between -0.001 and -0.021, and R² values of >0.8. The reproducibility of measuring relative odor levels through all measuring devices was high, suggesting a good capability of measuring thirdhand smoke odor. Two different odor-level standard gases can be used for the calibration of the regression curve for each monitor.

Nitrous acid emission from soil bacteria and related environmental effect over the North China Plain

Soil bacteria could be one of the important sources for ambient HONO. However, the HONO emission from soil bacteria over North China Plain (NCP) with vast croplands has not yet been evaluated. In this study, high-resolution simulations are created to explore the HONO emission from soil bacteria over NCP and related influences on atmospheric chemistry. Ground measurements of critical air pollutants including O₃, HONO, and PM_2.5 compositions are incorporated to constrain the model simulations. Results show that abundant HONO is emitted from soil bacteria over NCP during summertime and the emission rate varies dramatically for different areas (about 0.2 kg km^-2 d^-1 - 2.0 kg km^-2 d^-1). The HONO emission rate presents clear diurnal cycles with peaks of 1.5 kg km^-2 d^-1 in the afternoon and valleys of 0.4 kg km^-2 d^-1 during the early morning hours. The resulting HONO concentration ranges from 0.2 μg m^-3 to 1.4 μg m^-3, which predominates the total HONO concentration in ambient air, particularly in western NCP. The soil bacteria source can significantly alter the diurnal cycles of ambient HONO and OH concentrations over NCP, but only slightly change O₃ and PM_2.5 concentrations via participating photochemistry and secondary aerosol formations. These results highlight the pressing need for the involvement of HONO emission from soil bacteria in modeling studies regarding atmospheric chemistry, particularly in rural areas.

Characterization of Tobacco Microbiome by Metagenomics Approach

Chronic consumption of tobacco in all forms, either smoked/smokeless forms, causes major health hazards to humans that include cancer, cardiovascular, lung diseases, diabetes, fertility issues, etc. Among tobacco-mediated cancers, the prominent one being the oral cancers are caused due to chronic tobacco chewing. The biochemicals present in tobacco are involved in carcinogenesis, and their presence is partly mediated by the existence of microbes in tobacco products. The microbial characterization has been evolved from classical microscopical observation to the recent development of 16S rRNA sequencing by next-generation sequencing methods. The metagenomics approach using 16S rRNA-based next-generation sequencing methods enables the detection and characterization of the complete microbial community of tobacco, including both cultivable and non-cultivable microorganisms. Identification of microbes will help in devising strategies to limit the carcinogenic compounds present in tobacco.

Increased disinfection byproducts in the air resulting from intensified disinfection during the COVID-19 pandemic

Intensified use of disinfectants to control COVID-19 could unintentionally increase the disinfection byproducts (DBPs) in the environment. In indoor spaces, it is critical to determine the optimal disinfection practice to prevent the spread of the virus while keeping DBPs at relatively low levels in the air. The formation of DBPs exceed 0.1 μg/mg while hypochlorite dosed at >10 mg/m3. The total DBP concentrations in highly disinfected places (100-200 mg/m3 hypochlorite) were as high as 66.8 μg/m3, and the Hazard Index (HI) was up to 0.84, and both values were much higher than those in less disinfected places (<10 mg/m3 hypochlorite). Taking into account the HI, formation yields and the origin of the DBPs, we recommended 10 mg/m3 as the suggested hypochlorite dose to minimize DBPs generation during routine disinfection for controlling the coronavirus. DBPs in indoor air could be eliminated by ventilation, reducing the usage of personal care products, and wiping the solid surface with water before or after disinfection. These results highlighted the necessity to control air-borne DBPs and their associated health risks arising from intensified disinfection, and will guide the further development of evidence-based regulation on DBP exposure during disinfection and improve public health protection.