Thirdhand smoke causes DNA damage in human cells

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.

Thirdhand smoke exposure promotes gastric tumor development in mouse and human

The pollution of indoor environments and the consequent health risks associated with thirdhand smoke (THS) are increasingly recognized in recent years. However, the carcinogenic potential of THS and its underlying mechanisms have yet to be thoroughly explored. In this study, we examined the effects of short-term THS exposure on the development of gastric cancer (GC) in vitro and in vivo. In a mouse model of spontaneous GC, CC036, we observed a significant increase in gastric tumor incidence and a decrease in tumor-free survival upon THS exposure as compared to control. RNA sequencing of primary gastric epithelial cells derived from CC036 mice showed that THS exposure increased expression of genes related to the extracellular matrix and cytoskeletal protein structure. We then identified a THS exposure-induced 91-gene expression signature in CC036 and a homologous 84-gene signature in human GC patients that predicted the prognosis, with secreted phosphoprotein 1 (SPP1) and tribbles pseudokinase 3 (TRIB3) emerging as potential targets through which THS may promote gastric carcinogenesis. We also treated human GC cell lines in vitro with media containing various concentrations of THS, which, in some exposure dose range, significantly increased their proliferation, invasion, and migration. We showed that THS exposure could activate the epithelial-mesenchymal transition (EMT) pathway at the transcript and protein level. We conclude that short-term exposure to THS is associated with an increased risk of GC and that activation of the EMT program could be one potential mechanism. Increased understanding of the cancer risk associated with THS exposure will help identify new preventive and therapeutic strategies for tobacco-related disease as well as provide scientific evidence and rationale for policy decisions related to THS pollution control to protect vulnerable subpopulations such as children.

Third-hand smoke perception and awareness among medical students: a survey study

Third-hand smoke (THS) is tobacco smoke impurities that adhere to indoor materials such as clothing, dust, and surfaces and are released into the air. It is a major public health concern that, if unaddressed, could cause future harm. The aim of this study was to assess medical students' knowledge of THS and to increase awareness. In March and April 2023, students enrolled in the medical programs at the School of Medicine for the 2022-2023 academic year were contacted using an online Google survey method and asked to complete the survey questions. The survey included questions on participants' sociodemographic characteristics and the Beliefs about Third-Hand Smoke Scale (BATHS-T). The median age of the 351 students who voluntarily participated in the study was 20.0 (IQR = 2.0) years, 55.3% were female and 16% were smokers. The mean score of the answers given by the participants to the scale questions asking their level of knowledge about third-hand smoke was 35.3 ± 5.9. The least known question was "cigarette smoke particles can stay in a room for weeks". The most frequently answered question was "breathing the air in a room where people smoked yesterday can damage the health of babies and children". Scale scores were significantly higher for participants who did not have smokers living in their home, who did not allow smoking in their home, and who reported having information about passive smoking. Medical students had sufficient knowledge and awareness of third-hand smoke. Third-hand smoke should be included in training to increase knowledge and awareness of medical students as part of preventive medicine practice.

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.

Dermal thirdhand smoke exposure induced epidermal alterations in human keratinocyte cells through oxidative damage and MMP-1 expression

Thirdhand smoke (THS) is the residual cigarette smoke that settles on indoor surface fabrics, dust and can accumulate in the environment. Therefore, it can be a risk factor for individuals who have frequent dermal contact with THS-contaminated surfaces. In the present study, it was aimed to elucidate the toxicity of dermal THS exposure in HaCaT human keratinocytes. The THS was extracted from terrycloth exposed to 3R4F research cigarette smoke in a closed chamber and the adverse outcomes induced by THS were determined through assessment of cytotoxicity tests (MTT and NRU), intracellular GSH level, total SOD activity, matrix metalloproteinase-1 (MMP-1) and IL-6 levels. The wound healing capacity of THS-exposed keratinocytes was evaluated via scratch assay. A potent antioxidant isothiocyanate compound, sulforaphane (SFN), was used as a negative control. THS was dose-dependently cytotoxic (12.5%-100%, v/v) to the HaCaT cells through mitochondrial cell dysfunction (p < 0.01), which was ameliorated by SFN (0.62 μM) pre-treatment. In parallel, THS exposure significantly decreased the intracellular GSH deposits and T-SOD activity in keratinocytes. Collagen degradation through elevated MMP-1 expression was observed in THS-exposed cells in parallel with the delay of wound healing and increased pro-inflammatory response in a dose-dependent manner (p < 0.05). The findings are expected to raise awareness about THS as an environmental pollutant for skin, particularly in the highest-ranked countries in cigarette consumption. To conclude, these results might contribute to the studies on the importance of dermal exposure to THS in the pathogenesis of epidermal alterations and the other skin diseases.

Turkish Pediatrician Beliefs About Third-hand Smoking

INTRODUCTION

Although third-hand smoke (THS) is a relatively new concept, it emerges as an important health problem. This study evaluated the beliefs of Turkish Pediatricians about THS.

METHOD

The survey, designed to be self-filled by pediatricians, provided information on demographic data, lifestyle factors, and beliefs about THS. Participant beliefs about THS were evaluated using the Beliefs About Third-Hand Smoke scale. This study was conducted by applying a web-based survey to pediatricians in Turkey.

RESULTS

The Beliefs About Third-Hand Smoke scale scores were lower in participants who were male (odds ratio [OR] = 1.479; 95% confidence interval [CI], 0.246-0.526; p < .001), have children (OR = 0.656; 95% CI, 0.156-0.665; p = .002), widowed/separated (OR = 0.498; 95% CI, -1.072 to -0.360; p < .001), a smoker (OR = 0.586; 95% CI, -0.711 to -0.355; p < .001), worked in State Hospital (OR = 0.574; 95% CI, -0.768 to -0.423; p < .001), and specialists (OR = 0.621; 95% CI, -0.608 to -0.207; p < .001).

DISCUSSION

This study showed that pediatricians who were male, widowed/separated, a smoker, with children, working in a State Hospital, and specialists had less belief in the side effects of THS.

Thirdhand smoke beliefs, exposure status and associated factors among young people in China: A cross-sectional study

INTRODUCTION

Thirdhand smoke is an emerging threat to global public health. There is no research on young people's exposure to thirdhand smoke in China. This study aims to investigate the exposure status and beliefs of thirdhand smoke among young Chinese people and provide a reference for policy regarding thirdhand smoke.

METHODS

Data from the 2022 Chinese Resident Psychological and Behavioral Survey were used to select young people aged 15-24 years. A total of 11781 subjects were included in this study. Demographic information, beliefs about thirdhand smoke, and exposure status to thirdhand smoke were investigated.

RESULTS

Among the participants, 47.8% reported being exposed to thirdhand smoke (males: 49.1%, females: 47.0%). Young people living in urban areas (AOR=0.84, 95% CI: 0.77-0.91, p<0.001) and those with a monthly family income >12000 RMB (AOR=0.81, 95% CI: 0.71-0.92, p=0.001) were less likely to be exposed to thirdhand smoke. Young people with junior high school education or higher, and current or former smokers, were more likely to be exposed to thirdhand smoke. There is room for improvement in the beliefs about thirdhand smoke among young people.

CONCLUSIONS

Thirdhand smoke exposure is an issue that should be addressed in public health policy. Young people with low income and current or former smokers are populations that should be mainly focused on in public education and prevention work on thirdhand smoke.

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.

Vaping Dose, Device Type, and E-Liquid Flavor are Determinants of DNA Damage in Electronic Cigarette Users

INTRODUCTION

Despite the widespread use of electronic cigarettes, the long-term health consequences of vaping are largely unknown.

AIMS AND METHODS

We investigated the DNA-damaging effects of vaping as compared to smoking in healthy adults, including "exclusive" vapers (never smokers), cigarette smokers only, and nonusers, matched for age, gender, and race (N = 72). Following biochemical verification of vaping or smoking status, we quantified DNA damage in oral epithelial cells of our study subjects, using a long-amplicon quantitative polymerase chain reaction assay.

RESULTS

We detected significantly increased levels of DNA damage in both vapers and smokers as compared to nonusers (p = .005 and p = .020, respectively). While the mean levels of DNA damage did not differ significantly between vapers and smokers (p = .522), damage levels increased dose-dependently, from light users to heavy users, in both vapers and smokers as compared to nonusers. Among vapers, pod users followed by mod users, and those who used sweet-, mint or menthol-, and fruit-flavored e-liquids, respectively, showed the highest levels of DNA damage. The nicotine content of e-liquid was not a predictor of DNA damage in vapers.

CONCLUSIONS

This is the first demonstration of a dose-dependent formation of DNA damage in vapers who had never smoked cigarettes. Our data support a role for product characteristics, specifically device type and e-liquid flavor, in the induction of DNA damage in vapers. Given the popularity of pod and mod devices and the preferability of sweet-, mint or menthol-, and fruit-flavored e-liquids by both adult- and youth vapers, our findings can have significant implications for public health and tobacco products regulation.

IMPLICATIONS

We demonstrate a dose-dependent formation of DNA damage in oral cells from vapers who had never smoked tobacco cigarettes as well as exclusive cigarette smokers. Device type and e-liquid flavor determine the extent of DNA damage detected in vapers. Users of pod devices followed by mod users, and those who use sweet-, mint or menthol-, and fruit-flavored e-liquids, respectively, show the highest levels of DNA damage when compared to nonusers. Given the popularity of pod and mod devices and the preferability of these same flavors of e-liquid by both adult- and youth vapers, our findings can have significant implications for public health and tobacco products regulation.

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.

Genistein and Procyanidin B2 Reduce Carcinogen-Induced Reactive Oxygen Species and DNA Damage through the Activation of Nrf2/ARE Cell Signaling in Bronchial Epithelial Cells In Vitro

Cancer is one of the leading causes of death worldwide. Chemotherapy and radiation therapy are currently providing the basis for cancer therapies, although both are associated with significant side effects. Thus, cancer prevention through dietary modifications has been receiving growing interest. The potential of selected flavonoids in reducing carcinogen-induced reactive oxygen species (ROS) and DNA damage through the activation of nuclear factor erythroid 2 p45 (NF-E2)-related factor (Nrf2)/antioxidant response element (ARE) pathway was studied in vitro. Dose-dependent effects of pre-incubated flavonoids on pro-carcinogen 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKAc)-induced ROS and DNA damage in human bronchial epithelial cells were studied in comparison to non-flavonoids. The most effective flavonoids were assessed for the activation of Nrf2/ARE pathway. Genistein, procyanidin B2 (PCB2), and quercetin significantly suppressed the NNKAc-induced ROS and DNA damage. Quercetin significantly upregulated the phosphorylated protein kinase B/Akt. PCB2 significantly upregulated the activation of Nrf2 and Akt through phosphorylation. Genistein and PCB2 significantly upregulated the phospho-Nrf2 nuclear translocation and catalase activity. In summary, genistein and PCB2 reduced the NNKAc-induced ROS and DNA damage through the activation of Nrf2. Further studies are required to understand the role of dietary flavonoids on the regulation of the Nrf2/ARE pathway in relation to carcinogenesis.

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.

Thirdhand Smoke May Promote Lung Adenocarcinoma Development through HN1

Thirdhand smoke (THS) refers to residual tobacco smoking pollutants that can be adsorbed to indoor surfaces and dust and persist for years after active smoking. THS-related chemicals such as N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are tobacco-specific lung carcinogens that involved in lung cancer development and progression. In this study, we computed the differentially expressed genes (DEGs) between THS and paired control samples. THS-related overexpressed genes (OEs) were overlapped with OEs of lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Survival analyses of these overlapped genes were performed using LUAD and LUSC data. 6 genes were selected for validation based on their expression levels and prognostic value. Hematological and neurological expressed 1 (HN1) was further selected due to its novelty in LUAD research. The potential roles of HN1 in LUAD were explored in several ways. In summary, HN1 is overexpressed in THS samples and is associated with the prognosis of patients with LUAD. It may promote cancer progression through several pathways and could serve as a potential therapeutic target especially for THS-related LUAD. In-depth mechanistic studies and clinical trials are warranted.

Modelling the equilibrium partitioning of low concentrations of airborne volatile organic compounds in human IVF laboratories

RESEARCH QUESTION

Can volatile organic compounds (VOC) be modelled in an IVF clinical setting?

DESIGN

The study performed equilibrium modelling of low concentrations of airborne VOC partitioning from the air phase into the oil cover layer into the water-based culture media and into/onto the embryo (air-oil-water-embryo). The air-phase VOC were modelled based on reported VOC concentrations found in modern assisted reproductive technology (ART) suites, older IVF clinics, and hospitals, as well as at 10 parts per billion (ppb) and 100 ppb for all compounds. The modelling was performed with 23 documented healthcare-specific VOC.

RESULTS

Based on the partitioning model, seven compounds (acrolein, formaldehyde, phenol, toluene, acetaldehyde, ethanol and isopropanol) should be of great concern to the embryologist and clinician. Acrolein, formaldehyde, phenol, toluene and acetaldehyde are the VOC with the most potent cytotoxic factor and the highest toxic VOC concentration in media. In addition, ethanol and isopropanol are routinely found in the greatest air-phase concentrations and modelled to have the highest water-based culture concentrations.

CONCLUSIONS

The results of the equilibrium partitioning modelling of VOC provides a fundamental understanding of how airborne VOC partition from the air phase and negatively influence human IVF outcomes. The results presented here are based on the theoretical model and the values presented have not yet been measured in a laboratory or clinical setting. High air-phase concentrations and toxic concentrations of VOC in culture media are likely indicators of poor clinical outcomes. Based on this model, improved air quality in IVF laboratories reduces the chemical burden imparted on embryos, which supports findings of improved IVF outcomes with reduced air-phase VOC concentrations.

A DNA Cleavage Assay Using Synthetic Oligonucleotide Containing a Single Site-Directed Lesion for In Vitro Base Excision Repair Study

Many chemicals cause mutation or cancer in animals and humans by forming DNA lesions, including base adducts, which play a critical role in mutagenesis and carcinogenesis. A large number of such adducts are repaired by the DNA glycosylase-mediated base excision repair (BER) pathway, and some are processed by nucleotide excision repair (NER) and nucleotide incision repair (NIR). To understand what structural features determine repair enzyme specificity and mechanism in chemically modified DNA in vitro, we developed and optimized a DNA cleavage assay using defined oligonucleotides containing a single, site specifically placed lesion. This assay can be used to investigate novel activities against any newly identified derivatives from chemical compounds, substrate specificity and cleavage efficiency of repair enzymes, and quantitative structure-function relationships. Overall, the methodology is highly sensitive and can also be modified to explore whether a lesion is processed by NER or NIR activity, as well as to study its miscoding properties in translesion DNA synthesis (TLS).

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.

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.

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.

Evaluation of Thirdhand Smoke Exposure after Short Visits to Public Facilities (Noraebang and Internet Cafés): A Prospective Cohort Study

We aimed to evaluate the degree of thirdhand smoke (THS) caused by short-term exposure to smoking-related substances. To this end, we evaluated the change in concentration of a smoking-related urine biomarker in volunteers before and after visiting public spaces where there is likely THS exposure. We hypothesized that a visit to such public spaces would result in an increase in such biomarkers. Participants visited one of the predetermined facilities (noraebang, PC café) and revisited the same facility after 24 h, spending around 2 h per visit. We selected creatinine-corrected urine cotinine (CUC) as a biomarker to evaluate THS. In addition, we collected nicotine-derived nitrosamine ketone (NNK) from surface dust at each site with cotton swabs (diameter of 2.5 cm). We examined whether CUC concentration significantly changed across three time points (baseline, first visit, and second visit) via repeated-measures analysis of variance (RM-ANOVA). Moreover, we analyzed the interaction to determine whether cigarette smell affects the CUC concentration. Finally, CUC and dust NNK were analyzed with Pearson’s correlation. The CUC concentration did not increase from baseline to the first visit, but increased from the baseline to the second visit (Diff = Ln [0.565] ng/mg, P < 0.01). Further, the CUC concentration increased from the first to the second visit (Diff = Ln [0.393] ng/mg, p < 0.01). In the case of the interaction effect, there were statistically significant differences in CUC concentration depending on the smell of smoke in the facility (Diff = Ln [0.325], F value = 4.438, p value = 0.041). The change in CUC concentration from baseline to the second visit (r = 0.562, p < 0.001) and from the first to the second visit (r = 0.544, p < 0.001) were correlated with NNK concentration. We evaluated whether a short stay in a facility with smoke-related substances that adhere to the surrounding environment would expose individuals to THS even if they do not smell or are directly exposed to cigarette smoke. We confirmed that even two relatively short stays (approximately 2 h each) in a facility in which people had previously smoked can lead to THS exposure.

Alterations of Mitochondrial Network by Cigarette Smoking and E-Cigarette Vaping

Toxins present in cigarette and e-cigarette smoke constitute a significant cause of illnesses and are known to have fatal health impacts. Specific mechanisms by which toxins present in smoke impair cell repair are still being researched and are of prime interest for developing more effective treatments. Current literature suggests toxins present in cigarette smoke and aerosolized e-vapor trigger abnormal intercellular responses, damage mitochondrial function, and consequently disrupt the homeostasis of the organelle's biochemical processes by increasing reactive oxidative species. Increased oxidative stress sets off a cascade of molecular events, disrupting optimal mitochondrial morphology and homeostasis. Furthermore, smoking-induced oxidative stress may also amalgamate with other health factors to contribute to various pathophysiological processes. An increasing number of studies show that toxins may affect mitochondria even through exposure to secondhand or thirdhand smoke. This review assesses the impact of toxins present in tobacco smoke and e-vapor on mitochondrial health, networking, and critical structural processes, including mitochondria fission, fusion, hyper-fusion, fragmentation, and mitophagy. The efforts are focused on discussing current evidence linking toxins present in first, second, and thirdhand smoke to mitochondrial dysfunction.

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.

The Potential Role of Nutrition in Lung Cancer Establishment and Progression

Lung cancer is a devastating disease with a high incidence and low survival rates, so recent studies have focused on analyzing the risk factors that might prevent this disease from developing or have protective/therapeutic effects. Nutrition is an important key factor in the prevention and treatment of lung cancer. Various factors appear to be involved in the development of the latter, such as cigarette smoking or certain external environmental factors. The increase in oxidative stress is therefore an integral part of the carcinogenesis process. The biological role of bioactive factors derived from adipose tissue, mainly adipokines, is implicated in various cancers, and an increasing body of evidence has shown that certain adipocytokines contribute to the development, progression and prognosis of lung cancer. Not all adipokines stimulate tumor growth; in fact, adiponectin inhibits carcinogenesis by regulating both cell growth and the levels of inflammatory cytokines. Adiponectin expression is deregulated in several cancer types. Many nutritional factors have been shown to increase adiponectin levels and therefore could be used as a new therapeutic strategy for combating lung cancer. In addition, foods with antioxidant and anti-inflammatory properties play a key role in the prevention of many human diseases, including lung cancer. The purpose of this review is to analyze the role of diet in lung cancer in order to recommend dietary habit and lifestyle changes to prevent or treat this pathology.

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.

Vitamin-Containing Antioxidant Formulation Reduces Carcinogen-Induced DNA Damage through ATR/Chk1 Signaling in Bronchial Epithelial Cells In Vitro

Lung cancer has the highest mortality rate worldwide and is often diagnosed at late stages, requiring genotoxic chemotherapy with significant side effects. Cancer prevention has become a major focus, including the use of dietary and supplemental antioxidants. Thus, we investigated the ability of an antioxidant formulation (AOX1) to reduce DNA damage in human bronchial epithelial cells (BEAS-2B) with and without the combination of apple peel flavonoid fraction (AF4), or its major constituent quercetin (Q), or Q-3-O-d-glucoside (Q3G) in vitro. To model smoke-related genotoxicity, we used cigarette-smoke hydrocarbon 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) as well as methotrexate (MTX) to induce DNA damage in BEAS-2B cells. DNA fragmentation, γ-H2AX immunofluorescence, and comet assays were used as indicators of DNA damage. Pre-exposure to AOX1 alone or in combination with AF4, Q, or Q3G before challenging with NNKOAc and MTX significantly reduced intracellular reactive oxygen species (ROS) levels and DNA damage in BEAS-2B cells. Although NNKOAc-induced DNA damage activated ATM-Rad3-related (ATR) and Chk1 kinase in BEAS-2B cells, pre-exposure of the cells with tested antioxidants prior to carcinogen challenge significantly reduced their activation and levels of γ-H2AX (p ≤ 0.05). Therefore, AOX1 alone or combined with flavonoids holds promise as a chemoprotectant by reducing ROS and DNA damage to attenuate activation of ATR kinase following carcinogen exposure.

Beliefs of parents in Kuwait about thirdhand smoke and its relation to home smoking rules: A cross-sectional study

INTRODUCTION

Thirdhand smoke (THS) is the toxic residue of tobacco smoke that persists long after tobacco smoking on the clothing and hair of smokers and in the surrounding environment. This study aimed to assess parents' beliefs about THS in terms of harm and persistence in the environment and evaluate associations between parents' THS beliefs and home smoking rules.

METHODS

A sample of parents living in Kuwait were enrolled in a cross-sectional study. Parents reported home smoking rules (strict, partial, and no, home smoking ban) and completed the 9-item Beliefs About ThirdHand Smoke (BATHS) scale that assessed parents' overall, health, and persistence beliefs about THS. Associations between the quartiles of THS overall, health, and persistence beliefs scores and home smoking rules were evaluated using a modified Poisson regression, and adjusted prevalence ratios (APR) and 95% confidence intervals (CI) were estimated.

RESULTS

In total, 536 parents (404 females) were enrolled in the study, with 42.0% (n=225) and 43.6% (n=234) reporting a strict or partial home smoking ban, respectively. The prevalence of a strict home smoking ban was higher among never smokers than among ever smokers (49.1% vs 25.2%, p<0.001). The majority of participants indicated that THS exposure harms the health of children (67.2%) and adults (60.6%) and THS residue could remain for days in the environment (58.9%). The prevalence of a strict home smoking ban increased as THS overall (APR_{Q4 vs Q1} = 1.48; 95% CI: 1.12-1.96), health (APR_{Q4 vs Q1} = 1.22; 1.02-1.45), and persistence (APR_{Q4 vs Q1} = 1.55; 1.17-2.05) beliefs scores increased.

CONCLUSIONS

Parents' harm and persistence beliefs about THS were associated with enforcing a strict home smoking ban, which provides a safer environment for children and non-smokers. Therefore, tobacco prevention programs need to incorporate educational messages about the harm of THS in an attempt to promote smoke-free homes.

Chemical changes in thirdhand smoke associated with remediation using an ozone generator

Ozonation is a common remediation approach to eliminate odors from mold, tobacco and fire damage in buildings. Little information exists to: 1) assess its effectiveness; 2) provide guidance on operation conditions; and 3) identify potential risks associated with the presence of indoor ozone and ozonation byproducts. The goal of this study is to evaluate chemical changes in thirdhand smoke (THS) aerosols induced by high levels of ozone, in comparison with THS aerosols aged under similar conditions in the absence of ozone. Samples representing different stages of smoke aging in the absence of ozone, including freshly emitted secondhand smoke (SHS) and THS, were collected inside an 18-m3 room-sized chamber over a period of 42 h after six cigarettes were consumed. The experiments involved collection and analysis of gas phase species including volatile organic compounds (VOCs), volatile carbonyls, semivolatile organic compounds (SVOCs), and particulate matter. VOC analysis was carried out by gas chromatography/mass spectrometry with a thermal desorption inlet (TD-GC/MS), and volatile carbonyls were analyzed by on-line derivatization with dinitrophenylhydrazine (DNPH), followed by liquid chromatography with UV/VIS detection. SVOCs were extracted from XAD-coated denuders and Teflon-coated fiberglass filters in the absence of ozone. In those extracts, tobacco-specific nitrosamines (TSNAs) and other SVOCs were analyzed by gas chromatography with positive chemical ionization-triple quadrupole mass spectrometric detection (GC/PCI-QQQ-MS), and polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography with ion trap mass spectrometric detection (GC/IT-MS) in selected ion monitoring mode. Particulate matter concentration was determined gravimetrically. In a second experiment, a 300 mg h-1 commercial ozone generator was operated during 1 h, one day after smoke was generated, to evaluate the remediation of THS by ozonation. VOCs and volatile carbonyls were analyzed before and after ozonation. Extracts from fabrics that were exposed in the chamber before and after ozonation as surrogates for indoor furnishings were analyzed by GC/IT-MS, and aerosol size distribution was studied with a scanning mobility particle sizer. Ozone concentration was measured with a photometric detector. An estimated 175 mg ozone reacted with THS after 1 h of treatment, corresponding to 58% of the total O3 released during that period. Fabric-bound nicotine was depleted after ozonation, and the surface concentration of PAHs adsorbed to fabric specimens decreased by an order of magnitude due to reaction with ozone, reaching pre-smoking levels. These results suggest that ozonation has the potential to remove harmful THS chemicals from indoor surfaces. However, gas phase concentrations of volatile carbonyls, including formaldehyde, acetaldehyde and acetone were higher immediately after ozonation. Ultrafine particles (UFP, in most cases with size <60 nm) were a major ozonation byproduct. UFP number concentrations peaked shortly after ozonation ended, and remained at higher-than background levels for several hours. Based on these results, minimum re-entry times after ozone treatment were predicted for different indoor scenarios. Clearly defining re-entry times can serve as a practical measure to prevent acute exposures to ozone and harmful ozonation byproducts after treatment. This study evaluated potential benefits and risks associated with THS remediation using ozone, providing insights into this technology.

Genetic background influences the effect of thirdhand smoke exposure on anxiety and memory in Collaborative Cross mice

Growing evidence indicates that thirdhand smoke (THS) exposure induces many adverse health effects. However, it is unclear how THS exposure affects behavior and how host genetic background modulates phenotypic changes. Here we used the Collaborative Cross (CC) mouse population-based model to assess behavioral alterations immediately after THS exposure from 4 to 9 weeks of age. We first measured anxiety-like behavior in six strains using light/dark box combined with a custom multivariate mouse tracking system. We developed an anxiety risk scoring system based on anxiety-related traits and then evaluated the THS impact on them. THS exposure significantly decreased anxiety risk in CC019 (P = 0.002) and CC051 (P = 0.009), but increased anxiety risk in CC036 (P < 0.001), while the other three strains did not show significant changes in anxiety-related traits. Such differences were driven by female mice for the six measures of anxiety-like behavior. Memory potential was measured in the same cohort of mice using the passive avoidance assay. Both THS-exposed male and female CC019 mice displayed significant memory loss compared to controls while no significant changes were found in the other five strains. This study provides strong evidence that THS exposure leads to strain-dependent changes in anxiety-like behavior and memory, suggesting that host genetic variations play a critical role in individual susceptibility to THS-induced effects.

Thirdhand cigarette smoke leads to age-dependent and persistent alterations in the cecal microbiome of mice

The gut microbiome composition is influenced by many factors including environmental exposures. Here, we investigated the effect of thirdhand cigarette smoke (THS) and exposure age on gut microbiome diversity. C57BL/6 mice were exposed to THS at human exposure relevant levels for three weeks during three different life stages: postnatal (0-3 weeks of age), pubescent (4-7 weeks of age), and adult (9-12 weeks of age), respectively. Cecal microbiome profiles were assessed at 17 weeks of age by 16S rRNA gene sequencing. We found that age at THS exposure strongly influenced the cecal microbiome composition. Although postnatal THS exposure significantly influenced the microbial composition, pubescent and adulthood exposures only had minor effects. The microbiome of postnatally THS-exposed mice significantly increased several degradation pathways that regulate glycolysis and pyruvate decarboxylation, and significantly decreased coenzyme A biosynthesis and pyrimidine deoxyribonucleoside salvage. Our results indicate that mouse postnatal development is particularly susceptible to persistent THS exposure effects on the gut microbiome.

Adhesion and Removal of Thirdhand Smoke from Indoor Fabrics: A Method for Rapid Assessment and Identification of Chemical Repositories

Thirdhand smoke (THS) is an environmental contaminant that may cause adverse health effects in smokers and nonsmokers. Currently, time-consuming analytical methods are necessary to assess chemicals in THS repositories, like upholstered furniture and clothing. Our goal was to develop a rapid, accessible method that can be used to measure THS contamination in common household fabrics and to evaluate remediation. Cotton, terry cloth, polyester, and wool were exposed to THS for various times in a controlled laboratory environment and then extracted in various media at room temperature or 60 °C to develop an autofluorescent method to quantify THS. Concentrations of nicotine and related alkaloids in the extracts were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-performance liquid chromatography (HPLC). The autofluorescence of extracts was proportional to the time and amount of THS exposure received by cotton and terry cloth. Extracts of polyester and wool did not show autofluorescence unless heat was applied during extraction. Nicotine, nicotine alkaloids, and TSNA concentrations were higher in THS extracts from cotton and terry cloth than extracts of polyester and wool carpet, in agreement with the autofluorescence data. For fabrics spiked with 10 mg of nicotine, extraction efficiency was much higher from terry cloth (7 mg) than polyester (0.11 mg). In high relative humidity, nicotine recovery from both cotton and polyester was 80% (~8 mg). Our results provide a simple, rapid method to assess THS contaminants in household fabrics and further show that THS extraction is influenced by fabric type, heat, and humidity. Thus, remediation of THS environments may need to vary depending on the fabric reservoirs being treated. Understanding the dynamics of THS in fabrics can help set up appropriate remediation policies to protect humans from exposure.

Waterpipe smoke condensate influences epithelial to mesenchymal transition and interferes with the cytotoxic immune response in non-small cell lung cancer cell lines

Waterpipe tobacco smoking (WPS) continues to spread globally and presents serious health hazards. The aim of the present study was to investigate the effects of treatment with WPS condensate (WPSC) on lung cell proliferation and plasticity as well as tumor cell recognition and killing by natural killer (NK) cells using cytotoxicity assays. The results indicated that exposure of normal and cancer lung cell lines to WPSC resulted in a decrease in their in vitro growth in a dose-dependent manner and it induced tumor senescence. In addition, WPSC selectively caused DNA damage as revealed by an increase in γH2AX and 53BP1 in tumor lung cells. To gain further insight into the molecular mechanisms altered by WPSC, we conducted a global comprehensive transcriptome analysis of WPSC-treated tumor cells. Data analysis identified an expression profile of genes that best distinguished treated and non-treated cells involving several pathways. Of these pathways, we focused on those involved in epithelial to mesenchymal transition (EMT) and stemness. Results showed that WPSC induced an increase in SNAI2 expression associated with EMT, ACTA2 and SERPINE2 were involved in invasion and CD44 was associated with stemness. Furthermore, WPSC exposure increased the expression of inflammatory response genes including CASP1, IL1B, IL6 and CCL2. While immune synapse formation between NK and WPSC-treated lung cancer target cells was not affected, the capacity of NK cells to kill these target cells was reduced. The data reported in the present study are, to the best of our knowledge, the first in vitro demonstration of WPSC effects on lung cellular parameters providing evidence of its potential involvement in tumor physiology and development.

Thirdhand smoke beliefs and behaviors among families of primary school children in Shanghai

INTRODUCTION

There are few reports on the beliefs about thirdhand smoke in Chinese families with primary school children. This study aims to understand the beliefs about thirdhand smoke among parents or grandparents of primary school children in Shanghai and to provide an evidence base to incorporate thirdhand smoke preventative action into tobacco control interventions.

METHODS

We performed a cross-sectional survey among parents and grandparents of children aged 6–13 years in the Changjiang Road Primary School and recruited 843 participants to make assessments on the ‘beliefs about thirdhand smoke’ (BATHS) scale. Sociodemographic details including age, gender, marital status, education level, personal income and type of home ownership (new house, secondhand house with or without redecoration) and health status of children (whether they suffered from respiratory diseases or not) were investigated. Scale assessment, univariate and multivariate analyses to explore the factors influencing the BATHS scale and subscale scores, were performed using SPSS version 22.0.

RESULTS

Participants who were aged >65 years were more likely to get lower scores on the BATHS scale (OR=0.476; 95% CI: 0.311–0.728, p=0.001). Undergraduates (OR=1.190; 95% CI: 1.020–1.388, p=0.027) and graduates (OR=1.4490; 95% CI: 1.102–1.906, p=0.008) obtained higher scores. Moreover, the scores of residents living in a secondhand house with redecoration (OR=0.882; 95% CI: 0.782–0.995, p=0.041) and without redecoration (OR=0.801; 95% CI: 0.698–0.919, p=0.002) were lower compared with those of new-house owners. The scores for participants whose children suffered from respiratory diseases in the past six months (OR=1.104; 95% CI: 1.003–1.216, p=0.043) were higher than those whose children had no respiratory diseases.

CONCLUSIONS

This study shows that younger people, females, those with higher incomes, and higher education levels, were more likely to believe the thirdhand smoke impacts on health and its persistence in the environment. Our findings can guide targeted actions for smoke-free home interventions.

Remediating Thirdhand Smoke Pollution in Multiunit Housing: Temporary Reductions and the Challenges of Persistent Reservoirs

INTRODUCTION

Toxic tobacco smoke residue, also known as thirdhand smoke (THS), can persist in indoor environments long after tobacco has been smoked. This study examined the effects of different cleaning methods on nicotine in dust and on surfaces.

AIMS AND METHODS

Participants had strict indoor home smoking bans and were randomly assigned to: dry/damp cleaning followed by wet cleaning 1 month later (N = 10), wet cleaning followed by dry/damp cleaning (N = 10) 1 month later, and dry/damp and wet cleaning applied the same day (N = 28). Nicotine on surfaces and in dust served as markers of THS and were measured before, immediately after, and 3 months after the cleaning, using liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS).

RESULTS

Over a 4-month period prior to cleaning, surface nicotine levels remained unchanged (GeoMean change: -11% to +8%; repeated measures r = .94; p < .001). Used separately, dry/damp and wet cleaning methods showed limited benefits. When applied in combination, however, we observed significantly reduced nicotine on surfaces and in dust. Compared with baseline, GeoMean surface nicotine was 43% lower immediately after (z = -3.73, p < .001) and 53% lower 3 months later (z = -3.96, p < .001). GeoMean dust nicotine loading declined by 60% immediately after (z = -3.55, p < .001) and then increased 3 months later to precleaning levels (z = -1.18, p = .237).

CONCLUSIONS

Cleaning interventions reduced but did not permanently remove nicotine in dust and on surfaces. Cleaning efforts for THS need to address persistent pollutant reservoirs and replenishment of reservoirs from new tobacco smoke intrusion. THS contamination in low-income homes may contribute to health disparities, particularly in children.

IMPLICATIONS

Administered sequentially or simultaneously, the tested cleaning protocols reduced nicotine on surfaces by ~50% immediately after and 3 months after the cleaning. Nicotine dust loading was reduced by ~60% immediately after cleaning, but it then rebounded to precleaning levels 3 months later. Cleaning protocols were unable to completely remove THS, and pollutants in dust were replenished from remaining pollutant reservoirs or new secondhand smoke intrusion. To achieve better outcomes, cleaning protocols should be systematically repeated to remove newly accumulated pollutants. New secondhand smoke intrusions need to be prevented, and remaining THS reservoirs should be identified, cleaned, or removed to prevent pollutants from these reservoirs to accumulate in dust and on surfaces.

Indoor Air Quality and Passive E-cigarette Aerosol Exposures in Vape-Shops

INTRODUCTION

Direct emissions of nicotine and harmful chemicals from electronic cigarettes (e-cigarettes) have been intensively studied, but secondhand and thirdhand e-cigarette aerosol (THA) exposures in indoor environments are understudied.

AIMS AND METHODS

Indoor CO2, NO2, particulate matter (PM2.5), aldehydes, and airborne nicotine were measured in five vape-shops to assess secondhand exposures. Nicotine and tobacco-specific nitrosamines were measured on vape-shop surfaces and materials (glass, paper, clothing, rubber, and fur ball) placed in the vape-shops (14 days) to study thirdhand exposures.

RESULTS

Airborne PM2.5, formaldehyde, acetaldehyde, and nicotine concentrations during shop opening hours were 21, 3.3, 4.0, and 3.8 times higher than the levels during shop closing hours, respectively. PM2.5 concentrations were correlated with the number of e-cigarette users present in vape-shops (ρ = 0.366-0.761, p < .001). Surface nicotine, 4-(N-methyl-N-nitrosamino)-4-(3-pyridyl)butanal (NNA), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were also detected at levels of 223.6 ± 313.2 µg/m2, 4.78 ± 11.8 ng/m2, and 44.8 ± 102.3 ng/m2, respectively. Substantial amounts of nicotine (up to 2073 µg/m2) deposited on the materials placed within the vape-shops, and NNA (up to 474.4 ng/m2) and NNK (up to 184.0 ng/m2) were also formed on these materials. The deposited nicotine concentrations were strongly correlated with the median number of active vapers present in a vape-shop per hour (ρ = 0.894-0.949, p = .04-.051). NNK levels on the material surfaces were significantly associated with surface nicotine levels (ρ=0.645, p = .037).

CONCLUSIONS

Indoor vaping leads to secondhand and THA exposures. Thirdhand exposures induced by e-cigarette vaping are comparable or higher than that induced by cigarette smoking. Long-term studies in various microenvironments are needed to improve our understanding of secondhand and THA exposures.

IMPLICATIONS

This study adds new convincing evidence that e-cigarette vaping can cause secondhand and THA exposures. Our findings can inform Occupational Safety and Health Administration, state authorities, and other government agencies regarding indoor air policies related to e-cigarette use, particularly in vape-shops. There is an urgent need to ensure that vape-shops maintain suitable ventilation systems and cleaning practices to protect customers, employees, and bystanders. Our study also demonstrates that nicotine can deposit or be adsorbed on baby's clothes and toys, and that tobacco-specific nitrosamines can form and retain on baby's clothes, highlighting children's exposure to environmental e-cigarette aerosol and THA at home is of a particular concern.

Unravelling the metabolic alterations of liver damage induced by thirdhand smoke

BACKGROUND

Thirdhand smoke (THS) is the accumulation of tobacco smoke gases and particles that become embedded in materials. Previous studies concluded that THS exposure induces oxidative stress and hepatic steatosis in liver. Despite the knowledge of the increasing danger of THS exposure, the metabolic disorders caused in liver are still not well defined.

OBJECTIVES

The aim of this study is to investigate the metabolic disorders caused by THS exposure in liver of male mice and to evaluate the effects of an antioxidant treatment in the exposed mice.

METHODS

We investigated liver from three mice groups: non-exposed mice, exposed to THS in conditions that mimic human exposure and THS-exposed treated with antioxidants. Liver samples were analyzed using a multiplatform untargeted metabolomics approach including nuclear magnetic resonance (1H NMR), liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) and laser desorption/ionization mass spectrometry imaging (MSI), able to map lipids in liver tissues.

RESULTS

Our multiplatform approach allowed the annotation of eighty-eight metabolites altered by THS exposure, including amino acids, nucleotides and several types of lipids. The main dysregulated pathways by THS exposure were D-glutamine and D-glutamate metabolism, glycerophospholipid metabolism and oxidative phosphorylation and glutathione metabolism, being the last two related to oxidative stress. THS-exposed mice also presented higher lipid accumulation and decrease of metabolites involved in the phosphocholine synthesis, as well as choline deficiency, which is related to Non-Alcoholic Fatty Liver Disease and steatohepatitis. Interestingly, the antioxidant treatment of THS-exposed mice reduced the accumulation of some lipids, but could not revert all the metabolic alterations, including some related to the impairment of the mitochondrial function.

CONCLUSIONS

THS alters liver function at a molecular level, dysregulating many metabolic pathways. The molecular evidences provided here confirm that THS is a new factor for liver steatosis and provide the basis for future research in this respect.

Heterogeneous Ozonolysis of Tetrahydrocannabinol: Implications for Thirdhand Cannabis Smoke

Thirdhand smoke (THS) deposits to surfaces following smoking events and is a source of chemical exposure to humans. However, the evolution of THS in indoor environments is not well understood. Cannabis THS is a chemically distinct and prevalent form of THS, which has not been studied. The heterogeneous reaction of Δ⁹-tetrahydrocannabinol (THC), a major component of cannabis smoke, with ozone was examined as a pure compound and within cannabis smoke. Oxidative decay via ozonolysis and product formation were monitored by liquid chromatography-tandem mass spectrometry. Epoxide, dicarbonyl, and secondary ozonide THC reaction products were detected from both pure THC and cannabis experiments, with the product ratios dependent on relative humidity. The observed reaction kinetics for loss of THC on glass and cotton surfaces are consistent with a relatively short loss lifetime, which will be strongly dependent on the film thickness, ozone mixing ratio, and ozone reactivity of the surface substrate. The low volatility of THC and its oxidation products suggest that their contributions to thirdhand cannabis smoke will be less significant than the role that nicotine plays in thirdhand tobacco smoke.

Living with parents who smoke predicts levels of toxicant exposure in children

The detrimental effect of secondhand smoke (SHS) on health is well known; due to various factors, efforts to prevent SHS cannot completely eliminate the effect of smoking substances, and SHS has not been sufficiently investigated among children. This study aimed to assess children's smoke exposure with respect to parents smoking patterns using biomarkers. This study used data from the 2016/2017 Korea National Health and Nutrition Examination Survey. Data pertaining to 486 subjects was extracted. Exposure to smoking among non-smoking children was assessed based on urine levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). The urine NNAL concentration was highest among children with smoking parents and SHS exposure at home (3.829 pg/mg, 95% confidence interval [CI: 1.499-8.330), followed by children with smoking parents and no SHS exposure at home (1.297, 95% CI: 1.080-1.536), and children with nonsmoking parents and no SHS exposure at home (0.996 pg/mg, 95% CI: 1.026-1.427). Living with a smoking parent was associated with exposure to carcinogens, and a critical predictor of tobacco-specific nitrosamine. Prohibition of smoking at home is effective at preventing SHS in children. However, it cannot completely prevent passive smoking, which might be attributable to thirdhand smoking and undetected secondhand smoke.

Differential regulation of hypoxanthine and xanthine by obesity in a general population

AIMS/INTRODUCTION

Uric acid is synthesized by oxidation of hypoxanthine and xanthine using a catalyzing enzyme, xanthine oxidoreductase (XOR), which can be a source of reactive oxygen species. Plasma XOR activity is a metabolic biomarker associated with obesity, hyperuricemia, liver dysfunction and insulin resistance. However, it has recently been reported that XOR activity in fat tissue is low in humans, unlike in rodents, and that hypoxanthine is secreted from human fat tissue.

MATERIALS AND METHODS

The associations of obesity with hypoxanthine, xanthine and plasma XOR activity were investigated in 484 participants (men/women: 224/260) of the Tanno-Sobetsu Study.

RESULTS

Levels of hypoxanthine, xanthine and plasma XOR activity were significantly higher in men than in women. In 59 participants with hyperuricemia, 11 (men/women: 11/0) participants were being treated with an XOR inhibitor and had a significantly higher level of xanthine, but not hypoxanthine, than that in participants without treatment. In all of the participants, hypoxanthine concentration in smokers was significantly higher than that in non-smokers. Stepwise and multivariate regression analyses showed that body mass index, smoking habit and xanthine were independent predictors of hypoxanthine after adjustment of age, sex and use of antihyperuricemic drugs. Whereas, alanine transaminase, hypoxanthine and plasma XOR activity were independent predictors for xanthine, and alanine transaminase, triglycerides and xanthine were independent predictors for plasma XOR activity.

CONCLUSIONS

The concentration of hypoxanthine, but not that of xanthine, is independently associated with obesity and smoking habit, indicating differential regulation of hypoxanthine and xanthine in a general population.

Thirdhand smoke exposure causes replication stress and impaired transcription in human lung cells

Thirdhand cigarette smoke (THS) is a newly described toxin that lingers in the indoor environment long after cigarettes have been extinguished. Emerging results from both cellular and animal model studies suggest that THS is a potential human health hazard. DNA damage derived from THS exposure could have genotoxic consequences that would lead to the development of diseases. However, THS exposure-induced interference with fundamental DNA transactions such as replication and transcription, and the role of DNA repair in ameliorating such effects, remain unexplored. Here, we found that THS exposure increased the percentage of cells in S-phase, suggesting impaired S-phase progression. Key DNA damage response proteins including RPA, ATR, ATM, CHK1, and BRCA1 were activated in lung cells exposed to THS, consistent with replication stress. In addition, THS exposure caused increased 53BP1 foci, indicating DNA double-strand break induction. Consistent with these results, we observed increased micronuclei formation, a marker of genomic instability, in THS-exposed cells. Exposure to THS also caused a significant increase in phosphorylated RNA Polymerase II engaged in transcription elongation, suggesting an increase in transcription-blocking lesions. In agreement with this conclusion, ongoing RNA synthesis was very significantly reduced by THS exposure. Loss of nucleotide excision repair exacerbated the reduction in RNA synthesis, suggesting that bulky DNA adducts formed by THS are blocks to transcription. The adverse impact on both replication and transcription supports genotoxic stress as a result of THS exposure, with important implications for both cancer and other diseases.

Anthocyanin-rich haskap (Lonicera caerulea L.) berry extracts reduce nitrosamine-induced DNA damage in human normal lung epithelial cells in vitro

Diets rich in polyphenols are known to reduce cancer among high-risk populations. Haskap (Lonicera caerulea L.) berry has abundant phenolic acids and flavonoids, especially anthocyanins. Tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) present in cigarette smoke, is a major lung carcinogenic factor. We analyzed the efficacy of anthocyanin-rich haskap berry extracts in preventing DNA damage induced by 4-[(acetoxymethyl) nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc), a precursor of NKK, in human lung epithelial BEAS-2B cells in vitro. A cocktail of monomeric polyphenols from haskap berries was extracted separately in ethanol and water and profiled. Sub-lethal concentrations of NNKOAc were used to induce DNA damage in BEAS-2B cells, and a cell viability assay was performed to confirm that the tested concentrations of haskap extracts were not cytotoxic to BEAS-2B cells. Cells were pre-treated with the haskap extracts prior to NNKOAc exposure. Dose-dependent DNA damage was observed with carcinogenic NNKOAc, but did not occur in the presence of the haskap extracts. Pre-treatment of the cells with the haskap extracts significantly reduced NNKOAc-induced DNA damage, DNA fragmentation, and intracellular reactive oxygen species and upregulated the ATM-dependent DNA damage repair cascade compared to non-treated BEAS-2B cells. The protective effect of haskap extracts could be related to their polyphenol content and high antioxidant capacity.

Thirdhand Smoke at Philip Morris

INTRODUCTION

Thirdhand cigarette smoke is the fraction of cigarette smoke that remains in the environment long after a cigarette is extinguished.

METHODS

The Truth Tobacco Industry Documents collection at the University of California San Francisco was searched for information on thirdhand smoke.

RESULTS

In 1991, scientists at Philip Morris Inc conducted some of the first studies on thirdhand cigarette smoke. For 110 days, 8 hours a day, they ran sidestream cigarette smoke through a 30 m3 room that contained carpet, curtain, and textured wallpaper. The room was ventilated with clean air every night. By comparing the chemicals in the air during the 8-hour smoking period and during the clean air ventilation period, they showed that some smoke chemicals persist in the air 12 hours after smoking. By extracting the nicotine and nitrosamines from samples of the carpet, curtain, and wallpaper, they found that high concentrations of nicotine and the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) persisted in the room for more than 50 days; that surface chemistry affected nitrosamine concentrations; and that the concentration of NNK in the room, 110 days after the last cigarette was extinguished, could exceed the mass of NNK that entered the room as smoke.

CONCLUSIONS

These data, from a controlled environment where the total number of cigarettes smoked is known, provide further evidence that cigarette smoke chemicals remain in the environment for months after smoking, that they reemit back into the air, and that they react to form new toxins and carcinogens. Smoke-free policies are the best method to reduce exposure to thirdhand smoke.

IMPLICATIONS

This unpublished, original research from Philip Morris Inc demonstrates that majority of the nicotine and tobacco-specific nitrosamines in the secondhand smoke from each cigarette smoked indoors remains on indoor surfaces for months after the cigarette is extinguished. It also demonstrates that elevated concentrations of nicotine, ammonia, formaldehyde, and the gas-phase nitrosamine, N-nitrosopyrrolidine, can be found in the air for more than 12 hours after smoking; that surface chemistry affects nitrosamine formation and persistence; and that the amount of the carcinogenic nitrosamine NNK that persists months after smoking ends can exceed the amount that actually came out of the cigarettes.

Genetic Susceptibility to Thirdhand-Smoke-Induced Lung Cancer Development

Recently, potential health concerns have been raised about thirdhand smoke (THS), a much less well-understood type of smoke exposure defined as residual tobacco smoke sorbed onto indoor surfaces after active smoking has ceased. THS exposure is derived from the involuntary inhalation, ingestion, or dermal uptake of indoor pollutants. The timescale for exposure to THS pollution is generally much longer than secondhand smoke, and could stretch to days, months, or years (long-term, low-level exposure). Recent studies showed that exposure to THS at early age in mice can affect body weight, immunity, and lung cancer development. However, adverse health effects of THS in human populations remain poorly understood and many questions remain unanswered. One major question is how genetic factors influence susceptibility to THS-induced health effects, especially tumor development and whether there is an age-specific window of susceptibility for these effects. By addressing these questions, we will provide a better understanding of the effects of THS on human health and disease. This information would address critical knowledge gaps that are required for the formulation of policies related to indoor air quality.

IMPLICATIONS

THS, the residual tobacco smoke remaining in the environment after tobacco has been smoked, represents an underestimated public health hazard. Evidence supports its widespread presence in indoor environments. Vulnerable populations are believed to include infants and children living in a smoking household exposed to THS and/or secondhand smoke, and exposure has been identified as a risk factor for lung cancer later in life. These and future studies will provide novel and important evidence of how early-life exposure to THS affects cancer development and other diseases, which should be useful for framing and enforcing new policies against passive smoking in the world.

Persistent tobacco smoke residue in multiunit housing: Legacy of permissive indoor smoking policies and challenges in the implementation of smoking bans

Secondhand smoke (SHS) is a common indoor pollutant in multiunit housing (MUH). It is also the precursor of thirdhand smoke (THS), the toxic mixture of tobacco smoke residue that accumulates in indoor environments where tobacco has been used. This study examined the levels, distribution, and factors associated with THS pollution in low-income MUH. Interviews were conducted 2016-2018 in a cross-sectional study of N = 220 MUH homes in San Diego, California. Two surface wipe samples were collected per home and analyzed for nicotine, a THS marker, using liquid chromatography-triple quadrupole mass spectrometry. Nicotine was detected in all homes of nonsmokers with indoor smoking bans (Geo Mean = 1.67 µg/m²; 95% CI = [1.23;2.30]) and smokers regardless of an indoor ban (Geo Mean = 4.80 µg/m²; 95% CI = [1.89;12.19]). Approximately 10% of nonsmokers' homes with smoking bans showed nicotine levels higher than the average level in homes of smokers without smoking bans from previous studies (≥30 µg/m²). Housing for seniors, smoking bans on balconies, indoor tobacco use, difficult to reach surfaces, and self-reported African-American race/ethnicity were independently associated with higher THS levels. Individual cases demonstrated that high levels of surface nicotine may persist in nonsmoker homes for years after tobacco use even in the presence of indoor smoking bans. To achieve MUH free of tobacco smoke pollutants, attention must be given to identifying and remediating highly polluted units and to implementing smoking policies that prevent new accumulation of THS. As THS is a form of toxic tobacco product waste, responsibility for preventing and mitigating harmful impacts should include manufacturers, suppliers, and retailers.

Bilevel Positive Airway Pressure ventilation efficiently improves respiratory distress in initial hours treating children with severe asthma exacerbation

OBJECTIVE

Treatment of severe asthma exacerbation could be challenging, especially in the initial hours of acute attack when systemic corticosteroid is yet to take effect. In spite of using inhaled agents, the role of non-invasive ventilation (NIV), including Bilevel Positive Airway Pressure (BiPAP), had been addressed recently.

METHODS

We reviewed 5-year experience in our hospital for records of patients who were admitted to pediatric intensive care unit because of severe asthma attack. The included admission records from 2012 to 2017 were grouped according to BiPAP use (Yes/No). Clinical parameters (heart rate (HR), respiratory rate (RR), SpO2 and serum pCO2) at selected time intervals of treatment were collected for both groups and analyzed.

RESULTS

We included data of 46 admissions from 33 different patients (24 with BiPAP and 21 without BiPAP.) The BiPAP group had significantly higher initial RR as well as higher severity scores compared with the other group (p < 0.001). The RR improved significantly in the following time intervals in BiPAP group. There was no significant difference in HR between groups in any of the time intervals. The serum pCO2 levels decreased significantly after initiation of ventilation support in the BiPAP group, and SpO2 levels improved significantly for both groups.

CONCLUSION

BiPAP seemed efficient in improving respiratory rate and oxygenation in our study. It does not seem to cause additional irritation regarding that HR was not increased in BiPAP group compared with non-BiPAP group. Overall, BiPAP ventilation is safe and efficient in treating children with severe asthma attack.

Toxic effects of 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal on the reproduction of female mice

Cigarette smoke can affect female reproductive health by causing follicle destruction and oocyte dysfunction. Third-hand smoke has received increasing attention as a public health issue. However, the effects of third-hand smoke on the female reproductive system, particularly the ovaries, remain unclear. 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA) can be used as a biomarker of third-hand smoke. We studied the in vivo toxic effects of NNA on mice ovaries and offspring development. Three-week-old premature female mice were exposed to NNA at two different concentrations (0.075 μg/kg and 0.15 μg/kg body weight) and tap water (blank control) and diluted dimethylsulfoxide (solvent control) for 30 days. We found that oral administration of NNA (0.075 μg/kg and 0.15 μg/kg) significantly reduced ovary weight (the 0.15 μg/kg group was reduced to 18.69% ± 0.89%) and ovarian follicle number (reduced by about 30%) (p < 0.05). Consumption of 0.15 μg/kg NNA reduced the survival rate of superovulated oocytes from 91.36% to 60.55% (p < 0.05). In addition, treated female mice in each group were mated with normal male mice to observe the effects of NNA on the F1 offspring, and during mating and lactation, all groups were given tap water. Two different concentrations of NNA exposure also significantly reduced body weight and impaired ear opening, tooth eruption and eye opening in F1 offspring, especially those exposed to 0.15 μg/kg NNA (p < 0.05). Our study suggested that NNA exposure had toxic effects on the reproductive health of female mice and their offspring. The results obtained may help evaluate the risks of third-hand smoke to women's reproductive health and to the health of their offspring.

Toxic effects of 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal on the maturation and subsequent development of murine oocyte

Cigarette smoke can cause follicle destruction and oocyte dysfunction and increase the risks of spontaneous abortion, stillbirth, and tubal ectopic pregnancy, affecting female reproductive health. Third-hand smoke (THS) is residual tobacco smoke existing in the environment long after cigarettes are extinguished, which can react with other compounds in the environment to produce secondary pollutants. However, the effects of THS on the female reproductive system, particularly the maturation of the oocyte, remain unclear. 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA), a component of THS, is a logical biomarker of THS exposure. Thus, this study aims to investigate the toxic effects of NNA on the maturation of murine oocytes and subsequent developmental competence. Herein, murine oocytes were exposed to 0 (control group), 0.1, 1.0, 10, and 50 μM NNA for 24 h. Our results showed that NNA exposure reduced the polar body extrusion rate by causing 8-oxo-deoxyguanosine (8-OHdG) to increase and disrupting the meiotic spindle morphology by inhibiting ERK1/2 activation during in vitro maturation. Additionally, NNA exposure resulted in cleavage and blastocyst rate reduction by altering DNA and histone methylations by reducing 5 mC and H3K4me2 levels and by inducing apoptosis caused by mitochondrial dysfunction and reactive oxygen species accumulation, as shown by the increased superoxide dismutase mRNA level and by the decreased Bcl-x mRNA level. Collectively, our results demonstrate that NNA exposure reduces the maturation and developmental capability of murine oocytes by increasing the risk of DNA damage and abnormal spindle morphology, altering epigenetic modifications, and inducing apoptosis, suggesting the toxic effect of NNA on mammalian productive health.

Thirdhand smoke: Genotoxicity and carcinogenic potential

Thirdhand smoke (THS), the residual tobacco smoke remaining in the environment after tobacco has been smoked, represents a hidden and underestimated public health hazard. Evidence supports its widespread presence in indoor environments. Exposure to secondhand smoke (SHS), a precursor of THS, has been well documented as a risk factor for human cancers, especially lung cancer. However, the concept of THS as a distinct entity that poses health risks for small children has developed only recently and the associations of THS with cancer risk and other chronic diseases are poorly understood due to limited numbers of studies to date. In this perspective, we mainly summarize all published studies on the genotoxicity and carcinogenic potential of THS exposure. These studies begin to fill the knowledge gap in our understanding of cancer risk of THS. Accumulating data from existing and future studies will help reduce the tobacco-related cancer incidence through changes in lifestyle and tobacco control policies.

Electronic cigarette chemicals transfer from a vape shop to a nearby business in a multiple-tenant retail building

BACKGROUND

Electronic cigarettes (ECs) are nicotine delivery devices that produce aerosol without combustion of tobacco; therefore, they do not produce sidestream smoke. Nevertheless, many users exhale large clouds of aerosol that can result in passive exposure of non-users. Analogous to thirdhand cigarette smoke, the exhaled aerosol also settles on indoor surfaces where it can produce a residue. We refer to this residue as EC exhaled aerosol residue (ECEAR). Our objective was to determine if exhaled EC aerosol transferred from a vape shop in a multiple-tenant retail building, where it was produced, to a nearby business (field site) where it could deposit as ECEAR.

METHODS

We examined the build-up of ECEAR in commonly used materials (cotton towel and paper towels) placed inside the field site across from the vape shop. Materials were subjected to short-term (days) and long-term (months) exposures. Nicotine, other alkaloids and tobacco-specific nitrosamines (TSNAs) were identified and quantified in controls and field site samples using analytical chemical techniques.

RESULTS

Nicotine and other alkaloids were detected after 1 day of exposure in the field site, and these chemicals generally increased as exposure times increased. TSNAs, which have been linked to carcinogenesis, were also detected in short-term and long-term exposed samples from the field site.

CONCLUSIONS

In a multiple-tenant retail building, chemicals in EC aerosol travelled from a vape shop into an adjacent business where they deposited forming ECEAR. Regulatory agencies and tenants occupying such buildings should be aware of this potential environmental hazard.