Thirdhand cigarette smoke: factors affecting exposure and remediation

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 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.

Association between biomarkers of tobacco smoke exposure and clinical efficacy of ivacaftor in the G551D observational trial (GOAL)

BACKGROUND

Acrolein, an aldehyde in smoke from tobacco products, inhibits CFTR function in vitro. Ivacaftor is an FDA-approved potentiator that improves mutant CFTR function. This human clinical study investigated the relationship between two urinary markers of tobacco smoke exposure - the acrolein metabolite 3-HPMA and the nicotine metabolite NNAL - and sweat chloride response to ivacaftor in the G551D Observational Trial (GOAL).

METHODS

3-HPMA (low: <50th centile; moderate: 50-75th centile; high: >75th centile) and NNAL (detectable/undetectable) in GOAL samples was quantified with LC-MS/MS. Self-report of tobacco smoke exposure (Y/N) served as a subjective measure. Change in sweat chloride from pre- to 6 months post-ivacaftor treatment (ΔSC) was the primary CFTR-dependent readout.

RESULTS

The sample included 151 individuals, mean age 20.7 (SD 11.4) years, range 6-59 years. Smoke exposure prevalence was 15 % per self-reports but 27 % based on detectable NNAL. 3-HPMA was increased in those reporting tobacco smoke exposure (607 vs 354 ng/ml, p = 0.008), with a higher proportion of smoke-exposed in the high- vs low-acrolein group (31 % vs 9 %, p=0.040). Compared to low-acrolein counterparts, high-acrolein participants experienced less decrease in sweat chloride (-35.2 vs -48.2 mmol/L; p = 0.020) and had higher sweat chloride values (50.6 vs 37.6 mmol/L; p = 0.020) 6 months post-ivacaftor. The odds of ivacaftor-mediated potentiation to near normative CFTR function (defined as SC6mo <40 mmol/L) was more than twice as high in the low-acrolein cohort (OR: 2.51, p = 0.026).

CONCLUSIONS

Increased urinary 3-HPMA, an acrolein metabolite of tobacco smoke, is associated with a diminished sweat chloride response to ivacaftor potentiation of CFTR function.

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.

Perioperative exposure to volatile organic compounds in neonates undergoing cardiac surgery

OBJECTIVE

Volatile organic compounds (VOCs) are used in the sterilization and manufacture of medical equipment. These compounds have high vapor pressures with low water solubility and are emitted as gases from solids or liquids. They can be mutagenic, neurotoxic, genotoxic, and/or carcinogenic. Safe limits of exposure are not known for neonates. This study examined determinants of exposure in newborns undergoing cardiac surgery.

METHODS

Twenty metabolites of 16 VOCs (eg, xylene, cyanide, acrolein, acrylonitrile, N, N-dimethylformamide, 1,3-butadiene, styrene, and benzene) were measured as metabolites in daily urine samples collected from 10 neonates undergoing cardiac operations (n = 150 samples). Metabolites were quantified using reversed-phase ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry. Repeated measures analysis of covariance was performed for each metabolite to examine associations with use of medical devices.

RESULTS

At least 3 metabolites were detected in every sample. The median number of metabolites detected in each sample was 14 (range, 3-15). In a model controlling for other factors, the use of extracorporeal membrane oxygenation was associated with significantly (P ≤ .05) greater metabolite levels of acrolein, acrylonitrile, ethylene oxide, propylene oxide, styrene, and ethylbenzene. Patients breathing ambient air had greater levels of metabolites of acrolein, xylene, N,N-dimethylformamide, methyl isocyanate, cyanide, 1,3-butadiene (all P ≤ .05).

CONCLUSIONS

Exposure to volatile organic compounds is pervasive in newborns undergoing cardiac surgery. Sources of exposure likely include medical devices and inhalation from the air in the intensive care unit. The contribution of VOC exposure during cardiac surgery in newborns to adverse outcomes warrants further evaluation.

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.

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.

Measurement of airborne nicotine, as a marker of secondhand smoke exposure, in homes with residents who smoke in 9 European countries

OBJECTIVE

Smoke-free policies are effective in preventing secondhand smoke (SHS) exposure, but their adoption at home remains largely voluntary. This study aimed to quantify SHS exposure in homes with residents who smoke in Europe according to households' characteristics, tobacco consumption habits, and national contextual factors.

METHODS

Cross-sectional study (March 2017-September 2018) based on measurements of air nicotine inside 162 homes with residents who smoke from nine European countries. We installed passive samplers for seven consecutive days to monitor nicotine concentrations. Through self-administered questionnaires, we collected sociodemographic information and the number of individuals who smoke, smoking rules, frequency, location, and quantity of tobacco use in households. Country-level factors included the overall score in the Tobacco Control Scale 2016, the smoking prevalence, and self-reported SHS exposure prevalence. Nicotine concentrations were analyzed as continuous and dichotomous variables, categorized based on the limit of quantification of 0.02 μg/m³.

RESULTS

Overall, median nicotine concentration was 0.85 μg/m³ (interquartile range (IQR):0.15-4.42), and there was nicotine presence in 93% of homes. Participants reported that smoking was not permitted in approximately 20% of households, 40% had two or more residents who smoked, and in 79% residents had smoked inside during the week of sampling. We found higher nicotine concentrations in homes: with smell of tobacco smoke inside (1.45 μg/m³ IQR: 0.32-6.34), where smoking was allowed (1.60 μg/m³ IQR: 0.68-7.63), with two or more residents who smoked (2.42 μg/m³ IQR: 0.58-11.0), with more than 40 cigarettes smoked (2.92 μg/m³ IQR: 0.97-10.61), and where two or more residents smoked inside (4.02 μg/m³ IQR: 1.58-11.74). Household nicotine concentrations were significantly higher in countries with higher national smoking prevalence and self-reported SHS exposure prevalence (p < 0.05).

CONCLUSIONS

SHS concentrations in homes with individuals who smoke were approximately twenty times higher in homes that allowed smoking compared to those reporting smoke-free household rules. Evidence-based interventions promoting smoke-free homes should be implemented in combination with strengthening other MPOWER measures.

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.

Efficient Computation of the Interaction Energies of Very Large Non-covalently Bound Complexes

We present a new benchmark set consisting of 16 large non-covalently bound systems (LNCI16) ranging from 380 up to 1988 atoms and featuring diverse interaction motives. Gas-phase interaction energies are calculated with various composite DFT, semi-empirical quantum mechanical (SQM), and force field (FF) methods and are evaluated using accurate DFT reference values. Of the employed QM methods, PBEh-3c proves to be the most robust for large systems with a relative mean absolute deviation (relMAD) of 8.5% with respect to the reference interaction energies. r2SCAN-3c yields an even smaller relMAD, at least for the subset of complexes for which the calculation could be converged, but is less robust for systems with smaller HOMO–LUMO gaps. The inclusion of Fock-exchange is therefore important for the description of very large non-covalent interaction (NCI) complexes in the gas phase. GFN2-xTB was found to be the best performer of the SQM methods with an excellent result of only 11.1% deviation. From the assessed force fields, GFN-FF and GAFF achieve the best accuracy. Considering their low computational costs, both can be recommended for routine calculations of very large NCI complexes, with GFN-FF being clearly superior in terms of general applicability. Hence, GFN-FF may be routinely applied in supramolecular synthesis planning.

1 Introduction

2 The LNCI16 Benchmark Set

3 Computational Details

4 Generation of Reference Values

5 Results and Discussion

6 Conclusions

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.

Nicotine Affects Multiple Biological Processes in EpiDermTM Organotypic Tissues and Keratinocyte Monolayers

Dermal exposure to nicotine is common due to the widespread use of tobacco products. Here, we assessed the effects of nicotine at concentrations found in thirdhand smoke (THS) contaminated environments and electronic cigarette (EC) spills or leaks on a 3D human skin model (EpiDermTM) and on submerged keratinocyte cultures. Air liquid interface treatment of EpiDermTM with 10 or 400 μg/mL of nicotine for 24 h followed by proteomics analysis showed altered pathways related to inflammation, protein synthesis, cell–cell adhesion, apoptosis, and mitochondrial function. Submerged cultured keratinocytes were used to validate the proteomics data and further characterize the response of skin cells to nicotine. Mitochondrial phenotype changed from networked to punctate in keratinocytes treated with 10 or 400 μg/mL of nicotine for 48 h and 24 h, respectively. After 72 h, all concentrations of nicotine caused a significant decrease in the networked phenotype. In Western blots, keratinocytes exposed to 400 μg/mL of nicotine had a significant decrease in mitofusin 2, while mitofusin 1 decreased after 72 h. The shift from networked to punctate mitochondria correlated with a decrease in mitofusin 1/2, a protein needed to establish and maintain the networked phenotype. Mitochondrial changes were reversible after a 24 h recovery period. Peroxisomes exposed to 400 μg/mL of nicotine for 24 h became enlarged and were fewer in number. Nicotine concentrations in THS and EC spills altered the proteome profile in EpiDermTM and damaged organelles including mitochondria and peroxisomes, which are involved in ROS homeostasis. These changes may exacerbate skin infections, inhibit wound healing, and cause oxidative damage to cells in the skin.

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.

Parental Knowledge, Attitude, and Practice on Tobacco Use, Smoking Cessation, and Children's Environmental Tobacco Smoke Exposure

Background: Environmental tobacco smoke (ETS) exposure in children ranks one of the major public health problems in our time. Poor parental knowledge, attitude, and practice (KAP) on ETS often contribute to worse exposure of the kids. Thus, we aimed to document parental KAP regarding tobacco use, smoking cessation and children's ETS exposure, and to analyse how knowledge and attitude relate to practice.

Methods: Self-administered KAP questionnaires were distributed to smoking parents recruited from the pediatric unit at the Prince of Wales Hospital, which provides pediatric service to a population of 1.2 million in Hong Kong. The 60-item questionnaire had a range of 0–38 for knowledge, 0–44 for attitude, and 0–40 for practice. Descriptive analyses were performed for KAP response, regression analyses were performed for the exploration of associations and identification of predictive indicators.

Results: 145 smoking parents (mean age: 38.0 ± 6.7 yrs.; male: 85.5%) were included. Less than half (39.3%) of them reported a smoke-free policy at home. Among those parents who had private cars, less than half (45.2%) of them had smoke-free policy in their car that they never smoked in the car. Only 25.5% of the participants correctly answered ≥70% of the knowledge questions, and 11.8 % of the participants gave favorable responses to ≥70% of the attitude questions. The total knowledge and the total attitudes score were positively associated (r = 0.49, 95% CI: 0.35–0.79, p < 0.001), yet they were only modestly correlated with parental practice on children's ETS exposure. By multivariate regressions, potential predictive factors for more favorable parental KAP included higher household income, lower parental nicotine dependence level and breastfeeding practice.

Conclusions: Parental KAP related to tobacco use and children's ETS exposure needs improvement to address the significant gap between recommended and actual practice. The weak association between knowledge and practice suggested that parental education alone is not adequate to combat ETS exposure in children.

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.

Third-hand exposure at homes: Assessment using salivary cotinine

BACKGROUND/OBJECTIVES

While exposure to secondhand smoke (SHS) is a well-established problem, exposure to third-hand smoke (THS) is scanty known and needs to be studied. The objective of this work is to characterize salivary cotinine concentrations among people who self-reported exposure to SHS and THS at home.

METHODS

Cross-sectional study of a representative sample (n = 736) of the adult population (≥16 years) from the city of Barcelona carried out in 2013-2014. A questionnaire on tobacco use and passive exposure was administered, and a saliva sample was collected for cotinine determination. For this study, the information of the non-smoker participants who provided saliva sample (n = 519) was used. The geometric means (GM) and geometric standard deviations (GSD) of the cotinine concentration were compared according to the type of self-reported exposure at home: (1) Not exposed to SHS or THS; (2) Exposed to SHS and THS; and (3) Only exposed to THS. We used log-linear models to compare the cotinine concentration of each exposed group with respect to the unexposed group, adjusting for sex, age, educational level, and tobacco exposure in other settings.

RESULTS

The GM of the salivary cotinine concentration was 0.34 ng/ml (GSD = 0.16) among individuals reporting SHS and THS exposure, 0.22 ng/ml (GSD = 0.15) among those reporting only THS exposure and 0.11 ng/ml (GSD = 0.04) among those who declared not to be exposed to SHS nor THS (p-value for trend <0.001). The regression model showed a statistically significant increase in cotinine concentration among those exposed to SHS and THS (188% higher, 95% CI: 153%; 223%), and only exposed to THS (106% higher, IC95. %: 74.5%; 137.0%) when comparing with the unexposed group. No statistically significant differences in cotinine concentration were observed between those exposed to SHS and THS compared to the THS group (-25.8%, 95% CI: -69.5%; 17.9%).

CONCLUSIONS/RECOMMENDATIONS

People exposed to third-hand smoke at home had quantifiable cotinine levels in saliva. No differences in cotinine levels were found between those exposed to second-hand and third-hand smoke at home. The reduction of exposure to third-hand smoke at home should be put into the agenda of tobacco control.

Gender differences in the associations of early onset poly tobacco and drug use prior to age 18 with the prevalence of adult bronchitis in the United States

PURPOSE

We investigated the associations of early onset polysubstance use prior to age 18 with the prevalence of bronchitis among U.S. adults and tested whether the associations differ by gender.

METHODS

A total of 77,950 adults, of them 2,653 with bronchitis in the past year, were from the combined 2013 and 2014 National Survey on Drug Use and Health data. The variable cluster analysis was used to classify nine variables about substance use prior to age 18 (cigarettes, cigars, smokeless tobacco, marijuana, cocaine, heroin, methamphetamines, ecstasy, and phencyclidine). Weighted multivariate logistic regression analysis (MLR) was used to examine the associations with bronchitis.

RESULTS

Nine variables were divided into two clusters: early onset poly tobacco use (three tobacco use variables) and early onset poly drug use (six drug use variables). The overall prevalence of bronchitis was 3.8% (5.1% for females and 2.3% for males). MLR analysis showed that being female, elderly (ages 65 and above), obese, and early onset poly tobacco use were associated with increased odds of bronchitis (p < 0.05). Gender-stratified analyses showed that early-onset poly tobacco use was significantly associated with bronchitis only in males, whereas early onset poly drug use was associated with bronchitis only in females. Moreover, obesity and tobacco use in the past year revealed associations with bronchitis regardless of gender.

CONCLUSIONS

Obesity, early onset poly tobacco use prior to age 18, and tobacco use in the past year were positively associated with bronchitis; furthermore, the associations of early onset polysubstance use with bronchitis differed by gender, which indicated that gender differences should be considered in developing effective prevention strategies.

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.

Validity and reliability of Turkish version of Beliefs About Third-Hand Smoke Scale: BATHS-T

OBJECTIVE

Exposure to third-hand smoke (THS) poses health risk, especially for children. THS is mostly ignored in Turkey. The aim of this study is to adapt the Beliefs about Third-Hand Smoke (BATHS) scale to Turkish.

METHODS

The BATHS scale consists of 9 items, and the data collected from 273 people was considered sufficient for analyses in this methodological study. The BATHS scale is translated into Turkish and confirmatory factor analysis (CFA) was performed for the construct validity analysis of the scale.

RESULTS

The correlation between the overall BATHS scale and its two sub-dimensions was 0.937 (p < 0.001), and the correlation between the health and persistence sub-dimensions was 0.775 (p < 0.001). Since there was a statistically positive and highly significant relationship, the adapted BATHS scale was considered structurally compatible with the sub-dimensions. The reliability value of the entire scale is 0.90. Test-retest correlation values between the health and persistence dimensions were between 0.745 and 0.960, the values obtained were above 0.70 and had a statistically positive and high level of significant relationship (p < 0.001).

CONCLUSIONS

It is concluded that the Turkish version of the BATHS scale is reliable and valid. This scale will allow further research and training on third-hand smoke exposure. Tobacco control programmes success will improve.

How Is Indoor Air Quality during Sleep? A Review of Field Studies

This review aimed to provide an overview of the characterisation of indoor air quality (IAQ) during the sleeping period, based only on real life conditions’ studies where, at least, one air pollutant was considered. Despite the consensual complexity of indoor air, when focusing on sleeping environments, the available scientific literature is still scarce and falls to provide a multipollutants’ characterisation of the air breathed during sleep. This review, following PRISMA’s approach, identified a total of 22 studies that provided insights of how IAQ is during the sleeping period in real life conditions. Most of studies focused on carbon dioxide (77%), followed by particles (PM2.5, PM10 and ultrafines) and only 18% of the studies focused on pollutants such as carbon monoxide, volatile organic compounds and formaldehyde. Despite the high heterogeneity between studies (regarding the geographical area, type of surrounding environments, season of the year, type of dwelling, bedrooms’ ventilation, number of occupants), several air pollutants showed exceedances of the limit values established by guidelines or legislation, indicating that an effort should be made in order to minimise human exposure to air pollutants. For instance, when considering the air quality guideline of World Health Organisation of 10 µg·m−3 for PM2.5, 86% of studies that focused this pollutant registered levels above this threshold. Considering that people spend one third of their day sleeping, exposure during this period may have a significant impact on the daily integrated human exposure, due to the higher amount of exposure time, even if this environment is characterised by lower pollutants’ levels. Improving the current knowledge of air pollutants levels during sleep in different settings, as well as in different countries, will allow to improve the accuracy of exposure assessments and will also allow to understand their main drivers and how to tackle them.

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.

Tobacco smoke exposure in pediatric cystic fibrosis: A qualitative study of clinician and caregiver perspectives on smoking cessation

OBJECTIVE

Tobacco smoke exposure has negative impacts on the lung health of children with cystic fibrosis (CF), yet evidence-based strategies for smoking cessation have not been tested with or tailored to CF caregivers. This qualitative study identified barriers and facilitators of smoking cessation in this population and outlined potential interventional approaches.

METHODS

We conducted semi-structured interviews with CF familial caregivers who were current or former smokers, and with members of the CF care team. We asked about experiences, practices, and prerequisites for a successful program. Interviews were recorded, transcribed verbatim, and coded by two investigators. Analysis used a thematic approach guided by the PRECEDE model, which identifies predisposing (intrapersonal), reinforcing (interpersonal), and enabling (structural) factors relevant to health behaviors and programs.

RESULTS

Seventeen interviews were conducted-eight with familial caregivers and nine with CF team members. Whereas caregivers provided greater insight into internal difficulties and motivators to quit smoking, clinicians offered more extensive input on barriers and solutions related to the clinical environment. Based on study recommendations, a successful tobacco cessation program should include (a) family education about the harms of smoke exposure for children with CF; (b) screening for exposure, ideally with biochemical verification; (c) access to trained tobacco counselors; (d) affordable pharmacotherapy; and (e) outpatient follow-up of those undergoing tobacco treatment.

CONCLUSION

This qualitative study revealed intrapersonal, interpersonal, and structural barriers to eliminating tobacco smoke exposure in children with CF, outlined opportunities to address these barriers, and made recommendations for a comprehensive tobacco cessation strategy.

Parental Perceptions of Children's Exposure to Tobacco Smoke and Parental Smoking Behaviour

Around 40% of children are exposed to tobacco smoke, increasing their risk of poor health. Previous research has demonstrated misunderstanding among smoking parents regarding children's exposure. The parental perceptions of exposure (PPE) measure uses visual and textual vignettes to assess awareness of exposure to smoke. The study aimed to determine whether PPE is related to biochemical and reported measures of exposure in children with smoking parents. Families with at least one smoking parent and a child ≤ age 8 were recruited. In total, 82 parents completed the PPE questionnaire, which was assessed on a scale of 1-7 with higher scores denoting a broader perception of exposure. Parents provided a sample of their child's hair and a self-report of parental smoking habits. Parents who reported smoking away from home had higher PPE ratings than parents who smoke in and around the home (p = 0.026), constituting a medium effect size. PPE corresponded with home smoking frequency, with rare or no home exposure associated with higher PPE scores compared to daily or weekly exposure (p < 0.001). PPE was not significantly related to hair nicotine but was a significant explanatory factor for home smoking location. PPE was significantly associated with parental smoking behaviour, including location and frequency. High PPE was associated with lower exposure according to parental report. This implies that parental understanding of exposure affects protective behaviour and constitutes a potential target for intervention to help protect children.

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.

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.

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.

Tobacco carcinogens and the methionine metabolism in human bladder cancer

Cigarette smoking is a strong risk factor for bladder cancer. It has been shown that the duration of smoking is associated with a poor prognosis and a higher risk of recurrence. This is due to tobacco carcinogens forming adducts with DNA and proteins that participate in the DNA repair mechanisms. Additionally, polymorphisms of genes responsible for methyl group transfer in the methionine cycle and dosages of vitamins (from diet and supplements) can cause an increased risk of bladder cancer. Upregulated DNA methyltransferase 1 expression and activity results in a high level of methylated products of metabolism, as well as hypermethylation of tumor suppressor genes. The development of a market that provides new inhibitors of DNA methyltransferase or alternatives for current smokers is essential not only for patients but also for people who are under the danger of secondhand smoking and can experience its long-term exposure consequences.

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.

Secondhand Smoke From Multiple Sources, Thirdhand Smoke and Respiratory Symptoms in Hong Kong Adolescents

Introduction

Reports on involuntary tobacco smoke exposure in children have focused mostly on secondhand smoke (SHS) from smoking inside the home. We studied the separate and combined prevalence of SHS exposure from multiple sources and thirdhand smoke (THS) and the associations with respiratory symptoms in Hong Kong adolescents.

Methods

In 2010-2011, 61 810 Secondary 1 (US Grade 7) to seven students reported their smoking status, respiratory symptoms, and exposure to four sources of tobacco smoke in the past 7 days. Weighted prevalence of exposure was calculated. Associations with respiratory symptoms were analyzed in 50 762 never smokers using logistic regression.

Results

Tobacco smoke exposure at home was 23.2% considering SHS exposure from inside the home, but increased to 33.2% including SHS from neighbors and 36.2% further including THS. Including SHS outside home (55.3%), 63.3% of adolescents were exposed to SHS anywhere or THS at home. In never smokers, SHS from each source and THS at home were linearly associated with respiratory symptoms. Exposure to more sources yielded stronger associations with respiratory symptoms (p for trend<.001). The adjusted odds ratios (95% CI) were 1.04 (0.97-1.11), 1.12 (1.03-1.22), 1.40 (1.26-1.56) and 1.99 (1.74-2.28) for 1, 2, 3, and 4 sources, respectively.

Conclusions

Although Hong Kong's smoking prevalence is among the lowest in the developed world, over 60% of its adolescents were involuntarily exposed to tobacco smoke from one or more sources with a linear association with respiratory symptoms in never smokers. More stringent policies are needed to protect adolescents from tobacco smoke.

Implications

In a high-density urban setting, involuntary exposure to tobacco smoke in adolescents can be much higher than the smoking prevalence of the general population, especially if SHS exposure from multiple sources and THS are also considered. Such exposures have important health implications as demonstrated by their linear associations with respiratory symptoms. Tobacco control measures effective in reducing smoking prevalence may have little effect in reducing adolescent exposure to tobacco smoke, especially in the private home, in which other public health strategies are urgently needed.

Experimental Acute Exposure to Thirdhand Smoke and Changes in the Human Nasal Epithelial Transcriptome: A Randomized Clinical Trial

IMPORTANCE

No previous studies have shown that acute inhalation of thirdhand smoke (THS) activates stress and survival pathways in the human nasal epithelium.

OBJECTIVE

To evaluate gene expression in the nasal epithelium of nonsmoking women following acute inhalation of clean air and THS.

DESIGN, SETTING, AND PARTICIPANTS

Nasal epithelium samples were obtained from participants in a randomized clinical trial (2011-2015) on the health effects of inhaled THS. In a crossover design, participants were exposed, head only, to THS and to conditioned, filtered air in a laboratory setting. The order of exposures was randomized and exposures were separated by at least 21 days. Ribonucleic acid was obtained from a subset of 4 healthy, nonsmoking women.

EXPOSURES

By chance, women in the subset were randomized to receive clean air exposure first and THS exposure second. Exposures lasted 3 hours.

MAIN OUTCOMES AND MEASURES

Differentially expressed genes were identified using RNA sequencing with a false-discovery rate less than 0.1.

RESULTS

Participants were 4 healthy, nonsmoking women aged 27 to 49 years (mean [SD] age, 42 [10.2] years) with no chronic diseases. A total of 389 differentially expressed genes were identified in nasal epithelium exposed to THS, while only 2 genes, which were not studied further, were affected by clean air. Enriched gene ontology terms associated with stress-induced mitochondrial hyperfusion were identified, such as respiratory electron transport chain (q = 2.84 × 10-3) and mitochondrial inner membrane (q = 7.21 × 10-6). Reactome pathway analysis identified terms associated with upregulation of DNA repair mechanisms, such as nucleotide excision repair (q = 1.05 × 10-2). Enrichment analyses using ingenuity pathway analysis identified canonical pathways related to stress-induced mitochondrial hyperfusion (eg, increased oxidative phosphorylation) (P = .001), oxidative stress (eg, glutathione depletion phase II reactions) (P = .04), and cell survival (z score = 5.026).

CONCLUSIONS AND RELEVANCE

This study found that acute inhalation of THS caused cell stress that led to the activation of survival pathways. Some responses were consistent with stress-induced mitochondrial hyperfusion and similar to those demonstrated previously in vitro. These data may be valuable to physicians treating patients exposed to THS and may aid in formulating regulations for the remediation of THS-contaminated environments.

Comparison of indoor air quality during sleep in smokers and non-smokers' bedrooms: A preliminary study

People spend one third of their life sleeping, but the bedroom, as a specific micro-environment, is often neglected when assessing human exposure to air pollutants. However, exposure during sleep may be significant in the long-term to the integrated individual exposure. This study aimed to assess the exposure during sleep, focusing on a multi-pollutant approach (comfort parameters, carbon dioxide - CO₂, carbon monoxide - CO, formaldehyde (CH₂O), total volatile organic compounds (VOCs), particulate matter - PM_2.5 and PM₁₀ - and ultrafine particles, particle number concentrations - PNC - and lung deposited surface area - LDSA). For that, the air quality during sleep (in real conditions) was monitored using real-time devices in 12 bedrooms of urban (Lisbon and Vila Franca de Xira) and rural (Ponte de Sor) areas of Portugal for one night. Volunteers were smokers and non-smokers. Considering the Portuguese legislation for indoor air quality (IAQ), 67% of the bedrooms registered CO₂ levels above the limit value, while CH₂O, VOC, PM₁₀ and PM_2.5 thresholds were exceeded in 30, 100, 36, and 45% of cases, respectively. Regarding ultrafine parameters, LDSA and PNC ranged from 7.3 to 95.2 μm²/cm³ and from 0.6 to 4.8 × 10³/cm³, respectively. Even with no smoking indoors, smokers' bedrooms were found to have significant higher levels of CO, CH₂O, PM_2.5, PM₁₀ and LDSA than non-smokers' bedrooms, showing the effect of thirdhand smoke, exhalation of pollutants after smoking and infiltration on the degradation of the air quality in the bedroom. A recent new model of real-time monitor was also used for a wide set of IAQ parameters. Its performance to measure PM_2.5 and CO₂ was assessed, showing its applicability in real conditions. Although often neglected, these micro-environments should be considered in the integrated individual exposure to air pollutants and further studied. MAIN FINDINGS OF THE WORK: Several pollutants (CO₂, PM, VOCs and CH₂O) exceeded the guidelines during sleep; smokers are exposed to higher levels of CO, CH₂O, PM, and LDSA than non-smokers while sleeping.

Impacts of texture properties and airborne particles on accumulation of tobacco-derived chemicals in fabrics

Vapor-phase constituents of tobacco smoke are known to accumulate on clothing surfaces; however, the significance of texture properties, such as specific surface area, porosity, and surface roughness, and airborne particles to the sorption capacity of fabrics has not been adequately addressed. In the present study, cotton (t-shirt) and polyester (pajama and lab coat) fabrics were exposed to cigarette smoke containing gaseous and particulate tobacco-derived compounds (e.g., N-nitrosamines). Fabric-air distribution coefficients and particle deposition fluxes were then determined to evaluate the accumulation of the target analytes. Appreciable amounts of N'-nitrosoanabasine (NAB) and 4'-(nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) were detected in all three fabric types although particle-bound NAB and NNK were found only in cigarette smoke. In addition, the root mean square surface roughness heights for three types of clothes were within the same order of magnitude. As such, the deposition fluxes of particle-bound N'-nitrosonornicotine (NNN) and NNK to fabric surface may have contributed to 6-20% and 56-100% of total NNN and NNK in fabrics, respectively, estimated based on the assumed deposition velocity of 0.65 m h^-1. Apparently, the sorption capacity of fabrics can be greatly influenced by particle-bound compounds on clothing surfaces, resulting in either over- or under-estimation of fabric-air distribution/partitioning coefficients.

Contribution of thirdhand smoke to overall tobacco smoke exposure in pediatric patients: study protocol

BACKGROUND

Thirdhand smoke (THS) is the persistent residue resulting from secondhand smoke (SHS) that accumulates in dust, objects, and on surfaces in homes where tobacco has been used, and is reemitted into air. Very little is known about the extent to which THS contributes to children's overall tobacco smoke exposure (OTS) levels, defined as their combined THS and SHS exposure. Even less is known about the effect of OTS and THS on children's health. This project will examine how different home smoking behaviors contribute to THS and OTS and if levels of THS are associated with respiratory illnesses in nonsmoking children.

METHODS

This project leverages the experimental design from an ongoing pediatric emergency department-based tobacco cessation trial of caregivers who smoke and their children (NIHR01HD083354). At baseline and follow-up, we will collect urine and handwipe samples from children and samples of dust and air from the homes of smokers who smoke indoors, have smoking bans or who have quit smoking. These samples will be analyzed to examine to what extent THS pollution at home contributes to OTS exposure over and above SHS and to what extent THS continues to persist and contribute to OTS in homes of smokers who have quit or have smoking bans. Targeted and nontargeted chemical analyses of home dust samples will explore which types of THS pollutants are present in homes. Electronic medical record review will examine if THS and OTS levels are associated with child respiratory illness. Additionally, a repository of child and environmental samples will be created.

DISCUSSION

The results of this study will be crucial to help close gaps in our understanding of the types, quantity, and clinical effects of OTS, THS exposure, and THS pollutants in a unique sample of tobacco smoke-exposed ill children and their homes. The potential impact of these findings is substantial, as currently the level of risk in OTS attributable to THS is unknown. This research has the potential to change how we protect children from OTS, by recognizing that SHS and THS exposure needs to be addressed separately and jointly as sources of pollution and exposure.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02531594 . Date of registration: August 24, 2015.

E-cigarette nicotine deposition and persistence on glass and cotton surfaces

Nicotine from electronic cigarette aerosol will deposit on surfaces immediately after vaping, but how long deposited nicotine will persist on various surfaces is unknown. This work exposed glass and terrycloth (cotton) materials to electronic cigarette aerosols for 1 hr, assessed the initial nicotine sorption, and characterized surface persistence over a 72-hr period. Exponential decay of surface concentration was observed for both materials. Terrycloth had higher initial nicotine deposition and retained nicotine substantially longer than glass. Residual nicotine concentrations persisted on both surface types for 72 hr. Statistical modeling predicted surface concentrations to reach background levels after 4 and 16 days for glass and terrycloth, respectively. Nicotine persistence was long enough to pose a potential thirdhand nicotine exposure risk, and reactions to produce tobacco-specific nitrosamines may be possible from nicotine deposition from electronic cigarette aerosols, but further study is needed.

Identification and quantification of electronic cigarette exhaled aerosol residue chemicals in field sites

BACKGROUND

Electronic cigarette (EC) users may exhale large clouds of aerosol that can settle on indoor surfaces forming ECEAR (EC exhaled aerosol residue). Little is known about the chemical composition or buildup of this residue.

OBJECTIVE

Our objective was to identify and quantify ECEAR chemicals in two field sites: an EC user's living room and a multi-user EC vape shop.

METHODS

We examined the buildup of ECEAR in commonly used materials (cotton, polyester, or terrycloth towel) placed inside the field sites. Materials were subjected to different lengths of exposure. Nicotine, nicotine alkaloids, and tobacco-specific nitrosamines (TSNAs) were identified and quantified in unexposed controls and field site samples using analytical chemical techniques.

RESULTS

Nicotine and nicotine alkaloids were detected in materials inside the EC user's living room. Concentrations of ECEAR chemicals remained relatively constant over the first 5 months, suggesting some removal of the chemicals by air flow in the room approximating a steady state. ECEAR chemicals were detected in materials inside the vape shop after 6 h of exposure and levels continually increased over a month. By 1 month, the nicotine in the vape shop was 60 times higher than in the EC user's living room. ECEAR chemical concentrations varied in different locations in the vape shop. Control fabrics had either no detectable or very low concentrations of chemicals.

CONCLUSIONS

In both field sites, chemicals from exhaled EC aerosols were deposited on indoor surfaces and accumulated over time forming ECEAR. Non-smokers, EC users, and employees of vape shops should be aware of this potential environmental hazard.

Biological markers of harm can be detected in mice exposed for two months to low doses of Third Hand Smoke under conditions that mimic human exposure

Third-hand smoke (THS) is a recently discovered environmental health hazard that results from accumulation and aging of second-hand smoke (SHS) toxins on surfaces of environments where smoking has occurred. Our objective was to determine whether there is a dose-dependent effect of THS exposure on biological markers of harm (BMH) using an in vivo exposure system that mimics exposure of humans to THS. THS exposure generated from as low as the 10 cigarettes-smoking regimen, resulted in increased circulating inflammatory cytokines, tumor necrosis factor alpha, interleukin 1 alpha, and granulocyte macrophage colony-stimulating factor. We also found that there was an increase in adrenocorticotropic hormone and superoxide dismutase and a decrease in ATP levels in liver tissue. Many of the altered BMH that are related to oxidative stress and decrease in ATP levels, suggest mitochondrial dysfunction. THS exposure generated from the 20 and 40 cigarettes-smoking regimen resulted in further damage. Our studies are important because virtually nothing is known about the physiological damage caused by different levels of THS exposure. These studies can also serve to educate the public on the dangers of THS and the BMH we identified can potentially be used in the clinic, once verified in exposed humans.

Selective Uptake of Third-Hand Tobacco Smoke Components to Inorganic and Organic Aerosol Particles

Third-hand smoke (THS) is an emerging route of exposure to tobacco smoke in the indoor environment. Few studies have investigated the chemical behavior of THS, although initial findings suggest that semivolatile components of THS can partition to indoor aerosol. By exposing single-component particles to THS in an environmental chamber, this study demonstrates a pronounced dependence of THS uptake on aerosol composition. First, it was found that primarily reduced nitrogen compounds (that produced C xH yN z+ ion signal) in THS partitioned strongly to acidic ammoniated sulfate particles, whereas overall THS uptake to more pH-neutral sodium sulfate particles was minimal. Second, THS uptake to pure hydrocarbon particles (squalane) was even greater than to ammoniated sulfate particles with the uptake arising from mainly C xH y compounds. The greater uptake of THS to squalane was mostly driven by the dominant fraction of C xH y compounds in the side stream cigarette smoke aerosol, the composition of which is likely to be broadly similar to THS in these experiments. Third, oxygenated organic particles (sucrose) and solid ammonium sulfate particles showed minimal uptake. These results indicate that particulate THS inhalation exposure will be strongly dependent on the chemical nature of the particles present in the indoor environment.

Update on thirdhand smoke: A comprehensive systematic review

OBJECTIVE

The objective of this study is to perform a comprehensive review of the literature about thirdhand smoke (THS).

METHODS

Systematic review of all aspects of THS. Standard methodological procedures were used to search the following databases through April 2018: MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (WOS) in Indo-European languages. To identify published grey literature, the first 200 hits from Google Scholar™ were evaluated. Clinical trial databases, conference proceedings, and reference lists from the identified articles were also searched. Two unblinded review authors independently assessed trials for inclusion in the review. These same reviewers also extracted study data in accordance with PRISMA guidelines. The study protocol was registered with PROSPERO (CRD42018083619).

RESULTS

Sixty-eight articles were included in this systematic review. Of these, 28 analyzed the concentration of nicotine as a component of THS (the most commonly-used method to measure THS in those studies was chromatography, followed by the mass spectrometry), 21 evaluated the exposure and impact of THS on health (11 studies analyzed the effect of THS in cells [human and animal], 4 in animals, 1 in adults, and 5 in children), 16 investigated the beliefs, behaviours, and policies related to THS, and 3 evaluated other aspects such as THS in e-cigarettes or hookahs. In these 68 studies, THS was determined by measuring the following components: nicotine (30 studies), nitrosamines (17 studies) and cotinine (15 studies). The findings from most of these studies suggest a potential health impact of THS exposure (i.e.: cytotoxicity, metabolic alterations in metabolism, in glycemia; or cell structure; alterations in liver, lung, skin and behaviour in mice), and low awareness about the risks of THS among the general population.

CONCLUSIONS

Numerous specific biomarkers of THS were evaluated, with the most common being nicotine, nitrosamines, and cotinine. The most common method of preparing THS dust samples were cotton wipes, while chromatography, used alone or coupled with mass spectrometry, was the most common analytical technique. We have tried to establish common bases after reviewing all the current literature of the THS although, there is great heterogeneity between the studies and we have not always succeeded. The studies in this review demonstrate the harmful effects of THS on health in cells, in animal models, and in people including children. However, in people, the long-term effects remain unknown and more research is needed. These studies show that knowledge about THS and its potential harmful effects are poorly understood among the general population. For this reason, THS should receive greater emphasis in education and awareness policies.

Knowledge and attitudes toward thirdhand smoke among parents with children under 3 years in Spain

INTRODUCTION

The knowledge and beliefs about what is thirdhand smoke (THS) are limited. Our objective is to characterize the knowledge and beliefs about THS in parents of children under 3 years old in Spain.

METHODS

A cross-sectional study (n = 1406 parents) was conducted online in 2017. We collected information about the knowledge of THS given later, written information with the definition of THS, and asking about beliefs of the effects of THS on children's health.

RESULTS

A total of 27% of the respondents had heard about THS. We only found significant differences among smoking status, being the smokers who declare higher knowledge about THS. A total of 86% of the respondents believed that THS is harmful to their children with statistically significant differences according to educational level, higher among parents with a university degree (ORa = 2.6), and according to the previous knowledge on THS (ORa = 2.1).

CONCLUSIONS

This is the first study in Europe to describe the knowledge and belief of THS. Around 3 out of 10 parents have heard about THS and more than 8 out of 10 parents believed that THS is harmful to their children. Currently, they were not aware of THS but after providing brief information about it, most of them agreed that THS exposure is harmful to their children.

Parental Perceptions and Misconceptions of Child Tobacco Smoke Exposure

Introduction

Forty percent of young children worldwide are exposed to the harmful effects of tobacco smoke, predominantly by parental smoking. Little is known about why parents regularly expose their children to these risks; perhaps parents underestimate the degree of exposure. Qualitative methods were used to investigate parental perceptions of tobacco smoke exposure.

Methods

Sixty-five in-depth interviews were conducted with parents of young children in smoking families in central Israel. Parents were asked to explain what "exposure to smoking" meant. Thematic analysis was performed, a conceptual model of perceptions was built, and misconceptions were identified.

Results

Parents reported that exposure occurs when smoke or smokers are visible, when smoke can be smelled, felt, or inhaled, or when it "reaches" an individual. Conversely, some believed that exposure does not occur in the absence of odor, visible smoke, or smokers or if smoking occurs outdoors or in indoor ventilated environments. Proximity in space and time affected perceptions of exposure; some parents believed that smoke does not spread far but dissipates rapidly. There was some uncertainty regarding whether or not exposure was occurring.

Conclusions

Awareness of child exposure to tobacco smoke among parents in this study was based on sensory perceptions in the context of the physical environment. The limited capacity of humans to perceive tobacco smoke can lead to misconceptions about exposure. In order to protect children, parents must be convinced that exposure can occur even in situations where they are unable to sense it.

Implications

Parents use sensory perceptions (sight, smell, and feel) in the context of the physical environment to assess whether or not their children are exposed to tobacco smoke. Because 85% of smoke is invisible and the sense of smell is unreliable, assessments based on sensory perceptions cannot provide accurate information about the presence of tobacco smoke. In order to protect children, parents must be convinced that exposure can occur even in situations where they are unable to sense it. The scientific information summarized here about exposure in common situations should be useful in persuading parents to protect their children.

Clinical Trial Registration

This study is registered as a Phase I study which is part of a larger research endeavor entitled: A program to protect young children from tobacco smoke exposure. Registration number: NCT01335178.

Urinary metabolites of volatile organic compounds of infants in the neonatal intensive care unit

BackgroundPreterm infants (PTI) in the NICU are often placed in incubators that may increase their exposure to volatile organic chemicals (VOCs). To determine whether PTI in incubators have higher urinary concentrations of VOC metabolites compared with infants in cribs.MethodsUrine from 40 PTI in incubators and 40 infants in cribs was collected and analyzed for 28 urinary VOC biomarkers. Differences in metabolite concentrations between the two groups were compared.ResultsTwenty two of the VOC metabolites were detected in at least one urine sample. All urine samples tested had measurable levels of six VOC metabolites. Biomarkers for acrolein, acrylonitrile, carbon disulfide, cyanide, N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, toluene/benzyl alcohol, vinyl chloride, and xylene were higher in the incubator group. The geometric means of five VOC metabolites were 2-fold higher than those reported for NHANES children 6-11 years of age in one or both of the groups with benzyl mercapturic acid being 7-fold and 12-fold greater than NHANES in the crib and incubator group, respectively.ConclusionAll infants were exposed to VOCs. PTI in incubators have a different VOC exposure profile compared with infants in cribs. The health implications associated with these exposures require further study.

Exposure to third-hand smoke during pregnancy may increase the risk of postpartum depression in China

INTRODUCTION

Our aim was to investigate the association between third-hand smoke exposure (THS) during pregnancy and postpartum depression (PPD) among Chinese women.

METHODS

A total of 973 participants that completed the questionnaire and reviews were included in this cross-sectional study. The THS exposure was assessed based on a questionnaire with key questions from the Global Adult Tobacco Survey (2nd edition) while postpartum depression status was assessed using the Edinburgh Postnatal Depression Scale. Logistic regression models were used to estimate the association between THS exposure during pregnancy and risk of PPD, after adjustment for potential confounders.

RESULTS

The prevalence of postpartum depression among all participants was 17.8%. Of the 973 participants, 725 (74.5%) were exposed to THS during pregnancy while 248 (25.5%) were not. Compared with those who were never exposed to passive smoking, puerperal women who were exposed to THS were at higher risk of PPD (OR=1.71, 95% CI: 1.12-2.60) in the logistic regression model.

CONCLUSIONS

Our study suggests that exposure to third-hand smoke may be a risk factor for postpartum depression among Chinese women. Future preventive interventions should include strategies that target the puerperal women who are exposed to THS during pregnancy. Tobacco control measures that are effective in reducing the prevalence of smoking may have little effect in reducing women's exposure to THS during pregnancy, especially in private places that urgently need other public health strategies.

Assessment of Tobacco Consumption and Control in India

Tobacco consumption is a huge public health issue in India and its impact is especially devastating among the poor. Effective tobacco control should be a top priority, both as a health issue and as a method to reduce poverty. Tobacco use is deeply ingrained as a cultural practice and there are a myriad of tobacco types. We reviewed multiple determinants of tobacco consumption including socio-economic status, marriage, population growth, marketing strategies, and price. We also considered the tobacco burden including economic and social costs and adverse health impacts especially those resulting from oral cancer. We then addressed the history of tobacco control legislation in India and challenges in implementation. Tobacco consumption in India is continuing to increase despite tobacco control policy. Needed are more visible and aggressive anti-tobacco campaigns including increased public awareness of tobacco harms and active engagement of worksites and health professionals in promoting tobacco cessation.

Short-term early exposure to thirdhand cigarette smoke increases lung cancer incidence in mice

Exposure to thirdhand smoke (THS) is a recently described health concern that arises in many indoor environments. However, the carcinogenic potential of THS, a critical consideration in risk assessment, remains untested. Here we investigated the effects of short-term early exposure to THS on lung carcinogenesis in A/J mice. Forty weeks after THS exposure from 4 to 7 weeks of age, the mice had increased incidence of lung adenocarcinoma, tumor size and, multiplicity, compared with controls. In vitro studies using cultured human lung cancer cells showed that THS exposure induced DNA double-strand breaks and increased cell proliferation and colony formation. RNA sequencing analysis revealed that THS exposure induced endoplasmic reticulum stress and activated p53 signaling. Activation of the p53 pathway was confirmed by an increase in its targets p21 and BAX. These data indicate that early exposure to THS is associated with increased lung cancer risk.

A Casino goes smoke free: a longitudinal study of secondhand and thirdhand smoke pollution and exposure

Background

Secondhand smoke (SHS) in US casinos is common, but little is known about the residue of tobacco smoke pollutants left behind in dust and on surfaces, commonly referred to as thirdhand smoke (THS). We examined SHS and THS pollution and exposure before and during a casino smoking ban and after smoking resumed.

Methods

A casino was visited nine times over a 15-month period to collect dust, surface and air samples in eight locations. Finger wipe and urine samples were collected from non-smoking confederates before and after a 4-hour casino visit. Samples were analysed for markers of SHS and THS pollution and exposure.

Results

Exceptionally high levels of THS were found in dust and on surfaces. Although the smoking ban led to immediate improvements in air quality, surface nicotine levels were unchanged and remained very high for the first month of the smoking ban. Surface nicotine decreased by 90% after 1 month (P<0.01), but nicotine and tobacco-specific nitrosamines in dust decreased more slowly, declining by 90% only after 3 months (P<0.01). Exposure was significantly reduced after the ban, but the benefits of the ban were reversed after smoking resumed.

Conclusions

Long-term smoking in a casino creates deep THS reservoirs that persist for months after a smoking ban. A complete smoking ban immediately improves air quality and significantly reduces exposure to SHS and THS. However, THS reservoirs contribute to continued low-level exposure to toxicants. To accelerate the effect of smoking bans, remediation efforts should address specific THS reservoirs, which may require intensive cleaning as well as replacement of carpets, furniture and building materials.

Early exposure to thirdhand cigarette smoke affects body mass and the development of immunity in mice

Thirdhand smoke (THS) is the fraction of cigarette smoke that persists in indoor environments after smoking. We investigated the effects of neonatal and adult THS exposure on bodyweight and blood cell populations in C57BL/6 J mice. At the end of neonatal exposure, THS-treated male and female mice had significantly lower bodyweight than their respective control mice. However, five weeks after neonatal exposure ended, THS-treated mice weighed the same as controls. In contrast, adult THS exposure did not change bodyweight of mice. On the other hand, both neonatal and adult THS exposure had profound effects on the hematopoietic system. Fourteen weeks after neonatal THS exposure ended, eosinophil number and platelet volume were significantly higher, while hematocrit, mean cell volume, and platelet counts were significantly lower compared to control. Similarly, adult THS exposure also decreased platelet counts and increased neutrophil counts. Moreover, both neonatal and adult THS exposure caused a significant increase in percentage of B-cells and significantly decreased percentage of myeloid cells. Our results demonstrate that neonatal THS exposure decreases bodyweight and that THS exposure induces persistent changes in the hematopoietic system independent of age at exposure. These results also suggest that THS exposure may have adverse effects on human health.

Early exposure to thirdhand cigarette smoke affects body mass and the development of immunity in mice

Thirdhand smoke (THS) is the fraction of cigarette smoke that persists in indoor environments after smoking. We investigated the effects of neonatal and adult THS exposure on bodyweight and blood cell populations in C57BL/6 J mice. At the end of neonatal exposure, THS-treated male and female mice had significantly lower bodyweight than their respective control mice. However, five weeks after neonatal exposure ended, THS-treated mice weighed the same as controls. In contrast, adult THS exposure did not change bodyweight of mice. On the other hand, both neonatal and adult THS exposure had profound effects on the hematopoietic system. Fourteen weeks after neonatal THS exposure ended, eosinophil number and platelet volume were significantly higher, while hematocrit, mean cell volume, and platelet counts were significantly lower compared to control. Similarly, adult THS exposure also decreased platelet counts and increased neutrophil counts. Moreover, both neonatal and adult THS exposure caused a significant increase in percentage of B-cells and significantly decreased percentage of myeloid cells. Our results demonstrate that neonatal THS exposure decreases bodyweight and that THS exposure induces persistent changes in the hematopoietic system independent of age at exposure. These results also suggest that THS exposure may have adverse effects on human health.