The generation of formaldehyde in cigarettes--Overview and recent experiments

Advanced Materials Design for Adsorption of Toxic Substances in Cigarette Smoke

Cigarettes, despite being economically important legal consumer products, are highly addictive and harmful, particularly to the respiratory system. Tobacco smoke is a complex mixture containing over 7000 chemical compounds, 86 of which are identified to have "sufficient evidence of carcinogenicity" in either animal or human tests. Thus, tobacco smoke poses a significant health risk to humans. This article focuses on materials that help reduce the levels of major carcinogens in cigarette smoke; these include nicotine, polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, hydrogen cyanide, carbon monoxide, and formaldehyde. Specifically, the research progress on adsorption effects and mechanisms of advanced materials such as cellulose, zeolite, activated carbon, graphene, and molecularly imprinted polymers are highlighted. The future trends and prospects in this field are also discussed. Notably, with advancements in supramolecular chemistry and materials engineering, the design of functionally oriented materials has become increasingly multidisciplinary. Certainly, several advanced materials can play a critical role in reducing the harmful effects of cigarette smoke. This review aims to serve as an insightful reference for the design of hybrid and functionally oriented advanced materials.

Toxicological Mechanism of Individual Susceptibility to Formaldehyde-Induced Respiratory Effects

Understanding the mechanisms of individual susceptibility to exposure to environmental pollutants has been a challenge in health risk assessment. Here, an integrated approach combining a CRISPR screen in human cells and epidemiological analysis was developed to identify the individual susceptibility to the adverse health effects of air pollutants by taking formaldehyde (FA) and the associated chronic obstructive pulmonary disease (COPD) as a case study. Among the primary hits of CRISPR screening of FA in human A549 cells, HTR4 was the only gene genetically associated with COPD susceptibility in global populations. However, the association between HTR4 and FA-induced respiratory toxicity is unknown in the literature. Adverse outcome pathway (AOP) network analysis of CRISPR screen hits provided a potential mechanistic link between activation of HTR4 (molecular initiating event) and FA-induced lung injury (adverse outcome). Systematic toxicology tests (in vitro and animal experiments) were conducted to reveal the HTR4-involved biological mechanisms underlying the susceptibility to adverse health effects of FA. Functionality and enhanced expression of HTR4 were required for susceptibility to FA-induced lung injury, and FA-induced epigenetic changes could result in enhanced expression of HTR4. Specific epigenetic and genetic characteristics of HTR4 were associated with the progression and prevalence of COPD, respectively, and these genetic risk factors for COPD could be potential biomarkers of individual susceptibility to adverse respiratory effects of FA. These biomarkers could be of great significance for defining subpopulations susceptible to exposure to FA and reducing uncertainty in the next-generation health risk assessment of air pollutants. Our study delineated a novel toxicological pathway mediated by HTR4 in FA-induced lung injury, which could provide a mechanistic understanding of the potential biomarkers of individual susceptibility to adverse respiratory effects of FA.

Probe on Various Experimental Cigarette Smoke Subjection Structure

Different methods of subjection to smoke from experimental cigarettes are essential for understanding tobacco smoke. The major toxicants found in tobacco are acetaldehyde, acetone, acrolein, acrylonitrile, ammonia, benzene, cadmium, catechol, chromium, cyanide hydrogen, arsenic, nickel, nitric oxide, nicotine last but not least, mono-oxide gases. While experts say, cigarette smoke contains more than 4000 different compounds. These are substantially toxic and can destroy cells, and many of them are carcinogenic. Various smoke-exposure devices are used for in-vitro tobacco smoke generation, dilution, and distribution. Such devices are used widely by well-known manufacturers or can be tailor-made setups. We can set up different in-vitro models to better treat smoke-related diseases using these subjection structures. The fundamental goal will be to build a tobacco-free society of available subjection systems. Some have been identified and established as biological endpoints in some published scientific literature. In the scientific field, many new technologies are coming out and showing their presence. There are many systems of exposure to cigarette smoke in vitro which offer a more flexible approach to the challenges of exposure to tobacco smoke. This review covers some topics such as the description of available new subjection structures and reviews their work, setting up and application for Scenarios of in-vitro treatment. The benefits and disadvantages of both subjection mechanisms and the similarities between the setups and the data extracted from these structures. Measuring the smoke dose is also discussed here as an important field of research, particularly in the preclinical phase. Keywords: Cigarette smoke; Cigarette Subjection Structures; Cigarette Subjection Mechanisms; Cigarette Subjection Advantages; Cigarette Subjection Use; Cigarette Subjection Modern advancements.

Particulate matter and volatile organic compound phytoremediation by perennial plants: Affecting factors and plant stress response

Air pollution by particulate matter (PM) and volatile organic compounds (VOCs) is a major global issue. Many technologies have been developed to address this problem. Phytoremediation is one possible technology to remediate these air pollutants, and a few studies have investigated the application of this technology to reduce PM and VOCs in a mixture of pollutants. This study aimed to screen plant species capable of PM and VOC phytoremediation and identify plant physiology factors to be used as criteria for plant selection for PM and VOC phytoremediation. Wrightia religiosa removed PM and VOCs. In addition, the relative water content in the plant and ethanol soluble wax showed positive relationships with PM and VOC phytoremediation, with a high correlation coefficient. For plant stress responses, several plant species maintained and/or increased the relative water content after short-term exposure to PM and VOCs. In addition, based on proteomic analysis, most of the proteins in W. religiosa leaves related to photosystems I and II were significantly reduced by PM_2.5. When a high water content was achieved in W. religiosa (80% soil humidity), W. religiosa can effectively remove PM. The results suggested that PM can reduce plant photosynthesis. In addition, plants might require a high water supply to maintain their health under PM and VOC stress.

Investigation of the thermal decomposition mechanism of glycerol: the combination of a theoretical study based on the Minnesota functional and experimental support

The multiple thermal decomposition channels of glycerol are calculated at the M06-2X-D3/6-311+G(d,p) level. In addition, the CAM-B3LYP and ωB97X-D functionals are used to show the functional influence on the free energy barrier. For the highly competitive primary channels, the DLPNO-CCSD(T)/CBS method is applied for the energy calculations. The results show that the dominant paths are: (1) breakage of the C-C, C-O, and O-H bonds of glycerol successively to form carbonyl and alkene, and then generation of water, formaldehyde, and acetaldehyde; (2) glycerol undergoing an intramolecular dehydration reaction and producing 3-hydroxypropionaldehyde; it has two subsequent reactions: ① C-C bond fracture occurring to form formaldehyde, acetaldehyde, and water; and ② intramolecular dehydration forming acrolein and water. The ΔG₁ is 65.6 kcal mol^-1 while the ΔG₂ is 65.5 kcal mol^-1 at 101 kPa and 298 K, and fitted rate equations are 1.09 × 10¹³ exp[65.6 × 10³/RT] s^-1 and 8.07 × 10¹² exp[65.4 × 10³/RT] s^-1, respectively. Besides, UPLC and TG-GC/MS are applied complementarily to investigate the anaerobic pyrolysis products of glycerol at different temperatures. The experimental results are consistent with theoretical calculations.

Formaldehyde and De/Methylation in Age-Related Cognitive Impairment

Formaldehyde (FA) is a highly reactive substance that is ubiquitous in the environment and is usually considered as a pollutant. In the human body, FA is a product of various metabolic pathways and participates in one-carbon cycle, which provides carbon for the synthesis and modification of bio-compounds, such as DNA, RNA, and amino acids. Endogenous FA plays a role in epigenetic regulation, especially in the methylation and demethylation of DNA, histones, and RNA. Recently, epigenetic alterations associated with FA dysmetabolism have been considered as one of the important features in age-related cognitive impairment (ARCI), suggesting the potential of using FA as a diagnostic biomarker of ARCI. Notably, FA plays multifaceted roles, and, at certain concentrations, it promotes cell proliferation, enhances memory formation, and elongates life span, effects that could also be involved in the aetiology of ARCI. Further investigation of and the regulation of the epigenetics landscape may provide new insights about the aetiology of ARCI and provide novel therapeutic targets.

Aldehyde and Volatile Organic Compound Yields in Commercial Cigarette Mainstream Smoke Are Mutually Related and Depend on the Sugar and Humectant Content in Tobacco

Introduction

The World Health Organization (WHO) Framework Convention on Tobacco control recognizes the need for tobacco product regulation. In line with that, the WHO Study Group on Tobacco Product Regulation (TobReg) proposed to regulate nine toxicants in mainstream cigarette smoke, including aldehydes, volatile organic compounds (VOCs), and carbon monoxide (CO). We analyzed their relations in 50 commercially available cigarette brands, using two different smoking regimes, and their dependence on sugar and humectant concentrations in tobacco filler.

Methods

We measured sugar and humectant in tobacco filler and aldehydes, VOCs, and tar, nicotine, and CO (TNCO) in mainstream smoke. The general statistics, correlations between emission yields, and correlations between contents and emissions yields were determined for these data.

Results

For aldehydes, several significant correlations were found with precursor ingredients in unburnt tobacco when smoked with the Intense regime, most prominently for formaldehyde with sucrose, glucose, total sugars, and glycerol. For VOCs, 2,5-dimethylfuran significantly correlates with several sugars under both International Standards Organization (ISO) and Intense smoking conditions. A correlation network visualization shows connectivity between a sugar cluster, an ISO cluster, and an Intense cluster, with Intense formaldehyde as a central highest connected hub.

Conclusions

Our multivariate analysis showed several strong connections between the compounds determined. The toxicants proposed by WHO, in particular, formaldehyde, can be used to monitor yields of other toxicants under Intense conditions. Emissions of formaldehyde, acetaldehyde, acrolein, and 2,5-dimethylfuran may decrease when sugar and humectants contents are lowered in tobacco filler.

Implications

Our findings suggest that the aldehydes and VOCs proposed by TobReg are a representative selection for smoke component market monitoring purposes. In particular, formaldehyde yields may be useful to monitor emissions of other toxicants under Intense conditions. Since the most and strongest correlations were observed with the Intense regime, policymakers are advised to prescribe this regime for regulatory purposes. Policymakers should also consider sugars and humectants contents as targets for future tobacco product regulations, with the additional advantage that consumer acceptance of cigarette smoke is proportional to their concentrations in the tobacco blend.

Associations between observed formaldehyde concentrations and smoking, environmental tobacco smoke, and self-reported cancers and asthma: data for US children, adolescents, and adults

For the first time, the National Health and Nutrition Examination Survey (NHANES) released data on hemoglobin adducts of formaldehyde (HCHO) in public domain for US children aged 6-11 years, adolescents aged 12-19 years, and adults aged > = 20 years for 2015-2016. This study was undertaken to evaluate the associations between concentrations of HCHO in whole blood and smoking, exposure to environmental tobacco smoke (ETS), and self-reported diagnoses of cancers and asthma. Adult smokers were found to have higher adjusted concentrations of HCHO than nonsmokers (127.7 vs. 125.1 pmol/g Hb, p = 0.02). Exposure to ETS was not found to affect the adjusted concentrations of HCHO. No associations were observed between HCHO concentrations and self-reported diagnosis of "ever" cancer as well as self-reported presence of asthma at the time of participation in NHANES. HCHO concentrations were not found to differ across genders and racial/ethnic groups for children and adolescents. Among adults, non-Hispanic blacks (120.0 pmol/g Hb) had lower adjusted concentrations (p < = 0.01) of HCHO than non-Hispanic whites (128.8 pmol/g Hb), Mexican Americans (129.4 pmol/g Hb), other Hispanics (130.3 pmol/g Hb), and non-Hispanic Asians (127.9 pmol/g Hb). In conclusion, self-reported diagnoses of cancer and asthma were not found to be associated with observed concentrations of HCHO in whole blood.

Analysis of waterpipe aerosol constituents in accordance with the ISO standard 22486

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ISO 22486 to be complemented with real conditions for the evaluation of waterpipe.

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Charcoal is the main contributor to CO and BaP in waterpipe aerosols.

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Correlation between sugars content in tobaccos and formaldehyde yields in aerosols.

This study analyzed commercial waterpipe tobacco products in accordance with the newly developed ISO 22486 as well as with commercial waterpipes and charcoals using the ISO 22486 puffing regime for comparison. The aerosols from these products were analyzed for their nicotine, humectant, tobacco specific nitrosamine, carbonyl, benzo[a]pyrene, and metal yields. Significant differences were observed among the waterpipe tobacco products when analyzed in accordance with the ISO standard 22486 and with different commercial waterpipes and charcoals. The concentrations of CO and benzo[a]pyrene observed in the consumers’ configuration using the ISO 22486 puffing regime (with lit charcoal) were higher than those obtained with the ISO standard using electrical heating, with the yields for carbonyl compounds being lower or higher. The use of the recently published ISO standard for generating water pipe tobacco aerosols should be complemented with analysis by using the consumers’ configuration. The necessity for this was demonstrated by the differences in CO and benzo[a]pyrene yields in the present work. It appears that the temperature (280°C) selected for electrical heating of waterpipe tobacco products in ISO 22486 is somewhat lower than that obtained with commercial charcoals, resulting in a generally lower yield of nicotine and total collected matter. In addition, there is a need to evaluate the contribution of commercial charcoals to the concentration of constituents in waterpipe aerosols. This is particularly true for compounds resulting from charcoal combustion, such as CO and benzo[a]pyrene.

Tobacco Smoke and Endothelial Dysfunction: Role of Aldehydes?

PURPOSE OF REVIEW

Tobacco smoking is the most significant modifiable risk factor in the development of cardiovascular disease (CVD). Exposure to mainstream cigarette smoke (MCS) is associated with CVD through the development of endothelial dysfunction, a condition characterized by an imbalance of vasoactive factors in the vasculature. This dysfunction is thought to be induced in part by aldehydes generated at high levels in MCS.

RECENT FINDINGS

Electronic cigarettes (e-cigs) may also pose CVD risk. Although the health effects of e-cigs are still largely unknown, the presence of aldehydes in e-cig aerosol suggests that e-cigs may induce adverse cardiovascular outcomes similar to those seen with MCS exposure. Herein, we review studies of traditional and emerging tobacco product use, shared harmful and potentially harmful constituents, and measures of biomarkers of harm (endothelial dysfunction) to examine a potential and distinct role of aldehydes in cardiovascular harm associated with cigarette and e-cig use.

Carbohydrates-Key Players in Tobacco Aroma Formation and Quality Determination

Carbohydrates are important compounds in natural products where they primarily serve as a source of energy, but they have important secondary roles as precursors of aroma or bioactive compounds. They are present in fresh and dried (cured) tobacco leaves as well. The sugar content of tobacco depends on the tobacco variety, harvesting, and primarily on the curing conditions (temperature, time and moisture). If the process of curing employs high temperatures (flue-curing and sun-curing), final sugar content is high. In contrast, when air curing has a lower temperature, at the end of the process, sugar level is low. Beside simple sugars, other carbohydrates reported in tobacco are oligosaccharides, cellulose, starch, and pectin. Degradation of polysaccharides results in a higher yield of simple sugars, but at the same time reduces sugars oxidization and transfer into carbon dioxide and water. Loss of sugar producers will compensate with added sugars, to cover undesirable aroma properties and achieve a better, pleasant taste during smoking. However, tobacco carbohydrates can be precursors for many harmful compounds, including formaldehyde and 5-hydroxymethylfurfural. Keeping in mind that added sugars in tobacco production are unavoidable, it is important to understand all changes in carbohydrates from harvesting to consuming in order to achieve better product properties and avoid the formation of harmful compounds. This review summarizes current knowledge about tobacco carbohydrates, including changes during processing with special focus on carbohydrates as precursors of harmful compounds during smoking.

Nonanimal toxicology testing approaches for traditional and deemed tobacco products in a complex regulatory environment: Limitations, possibilities, and future directions

The evaluation of tobacco products is complex due to a multitude of factors including product diversity, limited testing standards, and variability in user behavior. Alternative approaches in current testing paradigms have limitations that generally truncate their applicability beyond screening for hazard identification; this is also true for toxicological evaluations of tobacco products. In a regulatory context, results from tobacco product toxicity assessments are extrapolated to the in vivo condition to assess human health relevance at the individual and population level. A key limitation of alternative approaches is the difficulty and uncertainty in extrapolating results to adverse outcomes relevant to chronic tobacco exposures in humans. This difficulty and uncertainty are increased when comparing toxicological outcomes between tobacco products. Given that the interpretation and quantification of differences in assay results (e.g., mutagenicity) for tobacco product comparison may be inconclusive, the predictive value of these approaches for human risk of relevant downstream pathologies (e.g., carcinogenesis) can be limited. Development and validation of fit-for-purpose alternative approaches that are predictive of human toxicity and dose response assays with adequate sensitivity and specificity for product comparisons would help advance the field of predictive toxicology.

Monitoring and assessment of formaldehyde levels in residential areas from two cities in Romania

Formaldehyde has become a ubiquitous contaminant in the air, and people are exposed to it worldwide. However, few studies have evaluated the temporal-spatial levels/changes of formaldehyde exposure at residences, and the relationship between its outdoor and indoor levels has been rarely examined. The aim of this study was to assess community formaldehyde exposure in Sebes and Aiud, Romania to identify: (1) home environment characteristics that may play an important role in exposure; and understand: (2) if there were differences in formaldehyde levels between the two cities; (3) if there were temporal variations within each city; and (4) whether outdoor formaldehyde levels influence indoor levels. We simultaneously performed indoor and outdoor active air sampling for formaldehyde at each investigated residential location over a 3-year period and analyzed the samples by gas chromatography with flame ionization detector (GC-FID). The mean values of indoor and outdoor formaldehyde levels in both cities fell in the range 0.014-0.035 mg/m3. The correlation analysis indicated mostly positive but not significant (p > 0.05) correlations between indoor formaldehyde and microclimate factors (temperature, humidity, pressure). Notably, home insulation was found to be significantly correlated with increased indoor formaldehyde levels. There were no significant differences in mean indoor or outdoor formaldehyde levels between Sebes and Aiud over the 3-year study period. When comparing the formaldehyde levels in both cities over the 3-year period, only outdoor formaldehyde levels were significantly higher in 2016, as compared to those in 2017 and 2018.

A Wearable IoT Aldehyde Sensor for Pediatric Asthma Research and Management

A cloud-based wearable IoT aldehyde sensor system for asthma research and management.

Emission level of seven mainstream smoke toxicants from cigarette with variable tobacco leaf constituents

[Introduction] Seven smoke constituents, including hydrogen cyanide (HCN), ammonia (NH3), phenol, benzo[α]pyrene (B[a]P), carbon monoxide (CO)¸ crotonaldehyde, and 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanone (NNK), are proposed be the most relevant constituents for smoking-related diseases. [Methods] Different combinations of leaf stalk positions, varieties and locations were used to create variable chemistry of cigarette filler and smoke. Experimental cigarettes were measured for emission level of seven smoke toxicants and content of seventy-three filler components. [Results] The ranges of coefficient of variation (CV) for seven smoke toxicants were 15.43%-43.15%. The emission pattern of NNK and crotonaldehyde were different from that of other five smoke toxicants. Most of the seven smoke toxicants were influenced in following order: stalk position > location > variety. The leaf constitutes closely correlated with seven smoke toxicants were analyzed. [Conclusions] The results showed that seven toxicants were significantly influenced by leaf position and location, and closely correlated with leaf components, such as potassium, malate and alkaloid contents. The results provide useful and comprehensive information on the affecting factors and correlating leaf constituents for the variations of seven smoke toxicants.

Cigarette smoke extract may induce lysosomal storage disease-like adverse health effects

Cigarette smoke is known to be associated with the incidence of a variety of pulmonary diseases, and alveolar macrophages are a key player in the defense mechanism against inhalable toxicants. Herein, we have found that a hydrophilic fraction in smoke extracts from 3R4F reference cigarettes (CSE) contains high concentrations of volatile substances compared to cigarette smoke condensate (amphoteric fraction). We also identified the toxic mechanism of CSE using MH-S, a mouse alveolar macrophage cell line. CSE decreased cell viability accompanying increased lactate dehydrogenase release. Additionally, mitochondrial volume and the potential increased along with enhanced expression of mitochondrial fusion proteins and decreased adenosine triphosphate production. Similarly, CSE clearly induced increase of catalase activity and intracellular calcium concentration and decrease of endoplasmic reticulum and lysosome volume at the highest dose. More interestingly, damaged organelles accumulated in the cytosol, and CSE-containing particles specifically penetrated to mitochondria. Meanwhile, any significant change in autophagy related protein expression was not found in CSE-treated cells. Subsequently, we evaluated the effects of CSE on secretion of inflammatory related cytokines and chemokines, considering the relationship between organelle damage and the disturbed immune response. Very importantly, we found that expression of innate and adaptive immunity related mediators is disrupted following CSE exposure. Taken together, we suggest that CSE may cause the accumulation of damaged organelles in the cytoplasm by impairing selective autophagic function. In addition, this accumulation is responsible for the inadequate ability of immune cells to repair the damage of lung tissue following exposure to CSE.

Determination of Humectants in Tobacco Filler by High Performance Chromatography/Single Quadrupole Mass Spectrometry

Glycerol, and 1,2-propylene glycol are the humectants most commonly used by the tobacco industry. They are found in a variety of tobacco products and are often present at high levels (~2-5 % w/w). While humectants are generally considered safe, they may serve as precursors in the formation of harmful carbonyl compounds. A selective, precise, and sensitive method for the quantification of several humectants in cigarette filler was developed. The method's sample clean-up is a two-step process consisting of a mechanical extraction, followed by solid phase extraction. Individual humectants are separated, identified, and measured using liquid chromatography coupled to a single quadrupole mass spectrometer as the detector (LC/MS). Detection limits were 0.105, 0.575, and 0.039 mg/cigarette for glycerol, 1,2-propylene glycol and triethylene glycol, respectively. The quantification range for these analytes was 0.4-75.0 mg/cigarette. Twenty-seven brands of domestic commercial cigarettes were evaluated to assess typical levels of humectants in the tobacco filler.

Cigarette Filter Ventilation and Smoking Protocol Influence Aldehyde Smoke Yields

The WHO study group on tobacco product regulation (TobReg) advised regulating and lowering toxicant levels in cigarette smoke. Aldehydes are one of the chemical classes on the TobReg smoke toxicants priority list. To provide insight in factors determining aldehyde yields, the levels of 12 aldehydes in mainstream cigarette smoke of 11 Dutch brands were quantified. Variations in smoking behavior and cigarette design affecting human exposure to aldehydes were studied by using four different machine testing protocols. Machine smoking was based on the International Standardization Organization (ISO) and Health Canada Intense (HCI) regime, both with and without taping the filter vents. The 11 cigarette brands differed in (i) design and blend characteristics; (ii) tar, nicotine, and carbon monoxide (TNCO) levels; (iii) popularity; and (iv) manufacturer. Cigarette smoke was trapped on a Cambridge filter pad and carboxen cartridge. After being dissolved in methanol/CS2 and derivatization with DNPH, the aldehyde yields were determined using HPLC-DAD. Using an intense smoking regime (increased puff volume, shorter puff interval) significantly increased aldehyde yields, following the pattern: ISO < ISO-taped < HCI-untaped < HCI. For all of the regimes, acetaldehyde and acrolein yields were strongly correlated ( r = 0.804). The difference in TNCO and aldehyde levels between regular and highly ventilated low-TNCO cigarettes (as measured using ISO) diminished when smoking intensely; this effect is stronger when combined with taping filter vents. The highly ventilated low-TNCO brands showed six times more aldehyde production per mg nicotine for the intense smoking regimes. In conclusion, acetaldehyde and acrolein can be used as representatives for the class of volatile aldehydes for the different brands and smoking regimes. The aldehyde-to-nicotine ratio increased when highly ventilated cigarettes were smoked intensely, similar to real smokers. Thus, a smoker of highly ventilated low-TNCO cigarettes has an increased potential for higher aldehyde exposures compared to a smoker of regular cigarettes.

Community interest and feasibility of using a novel smartphone-based formaldehyde exposure detection technology

OBJECTIVE

This study is the first community engagement phase of a project to develop a residential formaldehyde detection system. The objectives were to conduct a feasibility assessment for device use, and identify factors associated with concerns about environmental exposure and community interest in this device.

DESIGN AND SAMPLE

A cross-sectional, internet-based survey employing community-based participatory research principles was utilized. 147 individuals participated from a focused Waycross, Georgia (58.5%) and broader national sample (41.5%).

MEASURES

Variables included acceptable cost and number of testing samples, interest in conducting tests, levels of concern over pollutants, health status, housing, and demographics.

RESULTS

The majority of participants desired a system with fewer than 10 samples at ≤$15.00 per sample. Statistically significant higher levels of concern over air quality, formaldehyde exposure, and interest in testing formaldehyde were observed for those with overall worse health status and living in the Waycross, Georgia geographic region. Significant differences in formaldehyde testing interest were observed by health status (OR = 0.31, 95% CI = 0.12-0.81 for home testing) and geographic location (OR = 3.16, 95% CI = 1.22-8.14 for home and OR = 4.06, 95% CI = 1.48-11.12 for ambient testing) in multivariate models.

CONCLUSIONS

Geographic location and poorer general health status were associated with concerns over and interest in formaldehyde testing.

Novel approach for selective reduction of NNN in cigarette tobacco filler and mainstream smoke

Research conducted during past decades to reduce the level of the tobacco specific nitrosamine N-nitrosonornicotine (NNN) and its precursor nornicotine in tobacco yielded identification of three tobacco genes encoding for cytochrome P450 nicotine demethylases converting nicotine to nornicotine. We carried out trials to investigate the effect of using tobaccos containing three non-functional nicotine demethylase genes on the selective reduction of NNN in cigarette tobacco filler and mainstream smoke. Our results indicate that the presence of non-functional alleles of the three genes reduces the level of nornicotine and NNN in Burley tobacco by 70% compared to the level observed in currently available low converter (LC) Burley tobacco varieties. The new technology, named ZYVERT™, does not require a regular screening process, while a yearly selection process is needed to produce LC Burley tobacco seeds for NNN reduction. The reduction of NNN observed in smoke of blended prototype cigarettes is proportional to the inclusion level of tobacco having ZYVERT™ technology. Inclusion of Burley tobacco possessing the new trait into a typical American blend resulted in a selective reduction of NNN in cigarette smoke, while the levels of other Harmful and Potentially Harmful Constituents (HPHC) currently in the abbreviated list provided by the US Food and Drug Administration are statistically equivalent in comparison with the levels obtained in reference prototype cigarettes containing LC Burley.

A Novel Acetaldehyde Dehydrogenase with Salicylaldehyde Dehydrogenase Activity from Rhodococcus ruber Strain OA1

Salicylaldehyde dehydrogenase (sALDH) can oxidize salicylaldehyde, which is an intermediate in the naphthalene catabolism in bacteria. However, genes encoding sALDH have not been discovered so far in Rhodococcus. Here, we report the discovery of a novel aldehyde dehydrogenase (ALDH) gene in the naphthalene degrader Rhodococcus ruber OA1 based on phylogenetic analysis. Interestingly, apart from ALDH activity, ALDH of R. ruber OA1 (OA1-ALDH) also showed sALDH activity. Moreover, its sALDH specific activity was higher than its ALDH specific activity. Based on a comparison with the ALDH of Thermomonospora curvata DSM 43,183, a putative active site Cys123 and NAD⁺ binding site Asn263 were proposed in R. ruber OA1. Multiple alignment of OA1-ALDH with ALDHs from other organisms indicated that the residues Ser122 and Ala124 might influence the enzyme activity and substrate specificity that render OA1-ALDH the ability to catalyze salicylaldehyde better than acetaldehyde. These results support the possibility that OA1-ALDH plays the role of sALDH in the oxidation of salicylaldehyde to salicylate in R. ruber OA1. In summary, our study would contribute to the understanding of the structure and roles of ALDH in Rhodococcus.

Influence of cigarette circumference on smoke chemistry, biological activity, and smoking behaviour

Cigarettes with reduced circumference are increasingly popular in some countries, hence it is important to understand the effects of circumference reduction on their burning behaviour, smoke chemistry and bioactivity. Reducing circumference reduces tobacco mass burn rate, puff count and static burn time, and increases draw resistance and rod length burned during puff and smoulder periods. Smoulder temperature increases with decreasing circumference, but with no discernible effect on cigarette ignition propensity during a standard test. At constant packing density, mainstream (MS) and sidestream (SS) tar and nicotine yields decrease approximately linearly with decreasing circumference, as do the majority of smoke toxicants. However, volatile aldehydes, particularly formaldehyde, show a distinctly non-linear relationship with circumference and increases in the ratios of aldehydes to tar and nicotine have been observed as the circumference decreases. Mutagenic, cytotoxic and tumorigenic specific activities of smoke condensates (i.e. per unit weight of condensate) decrease as circumference decreases. Recent studies suggest that there is no statistical difference in mouth-level exposure to tar and nicotine among smokers of cigarettes with different circumferences. Commercially available slim cigarettes usually have changes in other cigarette design features compared with cigarettes with standard circumference, so it is difficult to isolate the effect of circumference on the properties of commercial products. However, available data shows that changes in cigarette circumference offer no discernible change to the harm associated with smoking.

A simple naphthalene-based fluorescent probe for high selective detection of formaldehyde in toffees and HeLa cells via aza-Cope reaction

A simple naphthalene-based fluorescent probe (AENO) for formaldehyde (FA) was successfully synthesized, which exhibited a significant fluorescence turn-on response towards FA in aqueous solution. The probe could quantitatively determine the concentration of FA (0-1.0mM) with excellent selectivity, high sensitivity and low limit of detection (0.57µM). The sensing mechanism was proposed as 2-aza-Cope rearrangement for AENO after reaction with FA, which was confirmed by (1)H NMR, HR-MS, FT-IR, UV-vis and fluorescence spectra. The probe has been employed to determine the FA contents in several commercially available toffee samples with satisfactory performance. Thus, AENO might be used as a promising tool for quantitative detection of FA in food. Furthermore, fluorescence imaging of HeLa cells indicated that the probe was cell membrane permeable and could be used for visualizing/imaging the FA trace/transportation in cancer cells.

Tobacco alkaloids reduction by casings added/enzymatic hydrolysis treatments assessed through PLSR analysis

Based on encouraged development of potential reduced-exposure products (PREPs) by the US Institute of Medicine, casings (glucose and peptides) added treatments (CAT) and enzymatic (protease and xylanase) hydrolysis treatments (EHT) were developed to study their effect on alkaloids reduction in tobacco and cigarette mainstream smoke (MS) and further investigate the correlation between sensory attributes and alkaloids. Results showed that the developed treatments reduced nicotine by 14.5% and 24.4% in tobacco and cigarette MS, respectively, indicating that both CAT and EHT are potentially effective for developing lower-risk cigarettes. Sensory and electronic nose analysis confirmed the significant influence of treatments on sensory and cigarette MS components. PLSR analysis demonstrated that tobacco alkaloids were positively correlated to the off-taste, irritation and impact attributes, and negatively correlated to the aroma and softness attributes. Additionally, nicotine and anabasine from tobacco leaves positively contributed to the impact attribute, while they negatively contributed to the aroma attribute (P<0.05). Meanwhile, most alkaloids in cigarette MS positively contributed to the impact and irritation attributes (P<0.05). Hence, this study paved a way to better understand the correlation between tobacco alkaloids and sensory attributes.

A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies

As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb.

Empirical characterisation of ranges of mainstream smoke toxicant yields from contemporary cigarette products using quantile regression methodology

Approximately 100 toxicants have been identified in cigarette smoke, to which exposure has been linked to a range of serious diseases in smokers. Smoking machines have been used to quantify toxicant emissions from cigarettes for regulatory reporting. The World Health Organization Study Group on Tobacco Product Regulation has proposed a regulatory scenario to identify median values for toxicants found in commercially available products, which could be used to set mandated limits on smoke emissions. We present an alternative approach, which used quantile regression to estimate reference percentiles to help contextualise the toxicant yields of commercially available products with respect to a reference analyte, such as tar or nicotine. To illustrate this approach we examined four toxicants (acetone, N'-nitrosoanatabine, phenol and pyridine) with respect to tar, and explored International Organization for Standardization (ISO) and Health Canada Intense (HCI) regimes. We compared this approach with other methods for assessing toxicants in cigarette smoke, such as ratios to nicotine or tar, and linear regression. We concluded that the quantile regression approach effectively represented data distributions across toxicants for both ISO and HCI regimes. This method provides robust, transparent and intuitive percentile estimates in relation to any desired reference value within the data space.

Approaches for the design of reduced toxicant emission cigarettes

Cigarette smoking causes serious diseases through frequent and prolonged exposure to toxicants. Technologies are being developed to reduce smokers’ toxicant exposure, including filter adsorbents, tobacco treatments and substitutes. This study examined the effect of modifications to filter ventilation, variations in cigarette circumference and active charcoal filter length and loading, as well as combinations of these features in a reduced-toxicant prototype (RTP) cigarette, on the yields of toxicants in cigarette smoke. An air-dilution mechanism, called split-tipping, was developed in which a band of porous paper in the centre of the filter tipping functions to minimise the loss of effective filter ventilation that occurs at the high flow rates encountered during human-smoking, and to facilitate the diffusional loss of volatile toxicants. As compared with conventional filter ventilation cigarettes, split-tipping reduced tar and volatile smoke constituent emissions under high flow rate machine-smoking conditions, most notably for products with a 1-mg ISO tar yield. Furthermore, mouth level exposure (MLE) to tar and nicotine was reduced among smokers of 1-mg ISO tar cigarettes in comparison to smokers of cigarettes with traditional filter ventilation. For higher ISO tar level cigarettes, however, there were no significant reductions in MLE. Smaller cigarette circumferences reduced sidestream toxicant yields and modified the balance of mainstream smoke chemistry with reduced levels of aromatic amines and benzo[a]pyrene but increased yields of formaldehyde. Smaller circumference cigarettes also had lower mainstream yields of volatile toxicants. Longer cigarette filters containing increased levels of high-activity carbon (HAC) showed reduced machine-smoking yields of volatile toxicants: with up to 97% removal for some volatile toxicants at higher HAC loadings. Split-tipping was combined with optimal filter length and cigarette circumference in an RTP cigarette that gave significantly lower mainstream (up to ~90%) and sidestream (predominately 20%–60%) smoke yields of numerous toxicants as compared with a commercial comparator cigarette under machine-smoking conditions. Significantly lower mainstream and sidestream smoke toxicant yields were observed for an RTP cigarette comprising several toxicant reducing technologies; these observations warrant further evaluation in clinical studies where real-world relevance can be tested using biomarkers of exposure and physiological effect.

CSEO - the Cigarette Smoke Exposure Ontology

BACKGROUND

In the past years, significant progress has been made to develop and use experimental settings for extensive data collection on tobacco smoke exposure and tobacco smoke exposure-associated diseases. Due to the growing number of such data, there is a need for domain-specific standard ontologies to facilitate the integration of tobacco exposure data.

RESULTS

The CSEO (version 1.0) is composed of 20091 concepts. The ontology in its current form is able to capture a wide range of cigarette smoke exposure concepts within the knowledge domain of exposure science with a reasonable sensitivity and specificity. Moreover, it showed a promising performance when used to answer domain expert questions. The CSEO complies with standard upper-level ontologies and is freely accessible to the scientific community through a dedicated wiki at https://publicwiki-01.fraunhofer.de/CSEO-Wiki/index.php/Main_Page.

CONCLUSIONS

The CSEO has potential to become a widely used standard within the academic and industrial community. Mainly because of the emerging need of systems toxicology to controlled vocabularies and also the lack of suitable ontologies for this domain, the CSEO prepares the ground for integrative systems-based research in the exposure science.

An evaluation of sucrose as a possible contaminant in e-liquids for electronic cigarettes by hydrophilic interaction liquid chromatography-tandem mass spectrometry

The influence of sucrose combustion products on smoking and nicotine addiction is still controversial because the presence of the sucrose may be treated as a source of aldehydes and organic acids. In e-liquids used as refills for electronic cigarettes, which are made primarily of poly(propylene glycol), glycerine and ethanol, sucrose may be present at trace levels, and its impact on mainstream smoke formation, and hence on human health and smoking/nicotine addiction is unknown. An analytical method was developed where high-performance liquid chromatography in hydrophilic interaction liquid chromatography mode and tandem mass spectrometry were used for fast and simple determination of sucrose and other saccharides in e-liquids for electronic cigarettes. Minimal effort was required in the sample preparation step, and satisfactory results were obtained, and the sample matrix had an insignificant impact. The chromatographic separation was done using an Ascentis Express OH5 column (150 mm × 2.1 mm, 2.7 μm). The coefficients of variation for within-day precision for three concentrations were 2.4 %, 1.6 % and 2.3 %, and the between-day coefficients of variation for a single concentration were 2.1 %, 2.5 % and 1.7 % measured on the next 3 days. The detection limit was 0.73 μg/g, and the sucrose content in e-liquids ranged from 0.76 to 72.93 μg/g among 37 samples. Moreover, with the method presented it is possible to determine the presence of other saccharides such as fructose, glucose, maltose and lactose. However, only sucrose was found in all samples of e-liquids. The proposed method is rapid, simple and reliable in terms of high-performance liquid chromatography coupled with tandem mass spectrometry.

A review of in vitro cigarette smoke exposure systems

In vitro test methods may be vital in understanding tobacco smoke, the main toxicants responsible for adverse health effects, and elucidating disease mechanisms. There is a variety of 'whole smoke' exposure systems available for the generation, dilution and delivery of tobacco smoke in vitro; these systems can be procured commercially from well-known suppliers or can be bespoke set-ups. These exposure technologies aim to ensure that there are limited changes in the tobacco smoke aerosol from generation to exposure. As the smoke aerosol is freshly generated, interactions in the smoke fractions are captured in any subsequent in vitro analysis. Of the commercially available systems, some have been characterised more than others in terms of published scientific literature and developed biological endpoints. Others are relatively new to the scientific field and are still establishing their presence. In addition, bespoke systems are widely used and offer a more flexible approach to the challenges of tobacco smoke exposure. In this review, the authors present a summary of the major tobacco smoke exposure systems available and critically review their function, set-up and application for in vitro exposure scenarios. All whole smoke exposure systems have benefits and limitations, often making it difficult to make comparisons between set-ups and the data obtained from such diverse systems. This is where exposure and dose measurements can add value and may be able to provide a platform on which comparisons can be made. The measurement of smoke dose, as an emerging field of research, is therefore also discussed and how it may provide valuable and additional data to support existing whole smoke exposure set-ups and aid validation efforts.

The analysis of mainstream smoke emissions of Canadian 'super slim' cigarettes

BACKGROUND

Super slim cigarettes are a relatively new type of cigarette in Canada, and an analysis of select toxicants in the mainstream smoke emissions of the super slim cigarette was conducted.

METHOD

The yields of selected toxicants in the mainstream smoke emissions of six brands of super slim cigarettes were compared with the Canadian Benchmark, which represents the cigarette designs most commonly found in Canada. A super slim cigarette was also compared with a 'Reference Cigarette' to study the impact of the significantly reduced circumference on mainstream smoke emissions.

RESULTS

Compared with the Canadian Benchmark, the yields of carbon monoxide, the carbonyls, volatiles and the aromatic amines were significantly lower for the super slim cigarette, but the yields of formaldehyde and ammonia were significantly higher. For brands containing a mixed tobacco blend, the yields of tobacco-specific nitrosamines were increased significantly. The reduced circumference of the super slim cigarette resulted in a lower tobacco weight, which together with filter ventilation resulted in lower yields of many toxicants. However, the reduced circumference increased significantly the yields of formaldehyde and phenols in mainstream smoke emissions.

CONCLUSIONS

The notably slimmer design of the super slim cigarette resulted in lower yields of some toxicants in the mainstream smoke emissions. However, there were also significant increases in some toxicant levels in the mainstream smoke emissions including formaldehyde, ammonia and the phenols. There are no changes in emission levels that have been shown to reduce exposure or risk in a way that is meaningful, and therefore, the super slim cigarette should not be considered a 'less harmful' cigarette.

Characterisation of a Vitrocell® VC 10 in vitro smoke exposure system using dose tools and biological analysis

Background

The development of whole smoke exposure systems have been driven by the fact that traditional smoke exposure techniques are based on the particulate phase of tobacco smoke and not the complete smoke aerosol. To overcome these challenges in this study, we used a Vitrocell® VC 10 whole smoke exposure system. For characterisation purposes, we determined smoke deposition in relationship to airflow (L/min), regional smoke deposition within the linear exposure module, vapour phase dilution using a known smoke marker (carbon monoxide) and finally assessed biological responses using two independent biological systems, the Ames and Neutral Red uptake (NRU) assay.

Results

Smoke dilution correlates with particulate deposition (R² = 0.97) and CO concentration (R² = 0.98). Regional deposition analysis within the linear exposure chamber showed no statistical difference in deposited mass across the chamber at any airflows tested. Biological analysis showed consistent responses and positive correlations with deposited mass for both the Ames (R² = 0.76) and NRU (R² = 0.84) assays.

Conclusions

We conclude that in our study, under the experimental conditions tested, the VC 10 can produce stable tobacco smoke dilutions, as demonstrated by particulate deposition, measured vapour phase smoke marker delivery and biological responses from two independent in vitro test systems.

Formation of mainstream cigarette smoke constituents prioritized by the World Health Organization--yield patterns observed in market surveys, clustering and inverse correlations

The WHO TobReg proposed mandating ceilings on selected smoke constituents determined from the market-specific median of nicotine-normalized yield distributions. Data validating this regulatory concept were obtained from essentially single-blend surveys. This process is strongly impacted by inverse correlations among yields. In the present study, 18 priority WHO smoke constituent yields (nicotine-normalized) were determined (using two smoking regimens) from 262 commercial brands including American, Virginia and local blends from 13 countries. Principal Component Analysis was used to identify yields patterns, clustering of blend types and the inverse correlations causing these clusters. Three principal components explain about 75% of total data variability. PC1 was sensitive to the relative levels of gas- and particle-phase compounds. PC2 and PC3 cluster American- and Virginia-blends, revealing inverse correlations: Nitrogen oxides and amino- or nitroso-aromatic compounds inversely correlate to either formaldehyde and acrolein, or benzo(a)pyrene and di-hydroxybenzenes. These results can be explained by reviewing the processes determining each components smoke delivery. Regulatory initiatives simultaneously targeting selected smoke constituents in markets with mixed blend styles will be strongly impacted by the inverse correlations described. It is difficult to predict the ultimate impact of such regulations on public health, considering the complex chemistry of cigarette smoke formation.

Does e-cigarette consumption cause passive vaping?

Electronic cigarette consumption ('vaping') is marketed as an alternative to conventional tobacco smoking. Technically, a mixture of chemicals containing carrier liquids, flavors, and optionally nicotine is vaporized and inhaled. The present study aims at the determination of the release of volatile organic compounds (VOC) and (ultra)fine particles (FP/UFP) from an e-cigarette under near-to-real-use conditions in an 8-m(3) emission test chamber. Furthermore, the inhaled mixture is analyzed in small chambers. An increase in FP/UFP and VOC could be determined after the use of the e-cigarette. Prominent components in the gas-phase are 1,2-propanediol, 1,2,3-propanetriol, diacetin, flavorings, and traces of nicotine. As a consequence, 'passive vaping' must be expected from the consumption of e-cigarettes. Furthermore, the inhaled aerosol undergoes changes in the human lung that is assumed to be attributed to deposition and evaporation.

PRACTICAL IMPLICATIONS

The consumption of e-cigarettes marks a new source for chemical and aerosol exposure in the indoor environment. To evaluate the impact of e-cigarettes on indoor air quality and to estimate the possible effect of passive vaping, information about the chemical characteristics of the released vapor is needed.

Investigations of potential susceptibility toward formaldehyde-induced genotoxicity

Blood samples were taken from three groups of volunteers (30 male smokers, 30 female non-smokers, and 30 school children) and tested for ex vivo susceptibility toward formaldehyde (FA)-induced genotoxicity. Blood samples were exposed to 150 μM FA for 2 h, and the induction of DNA-protein crosslinks (DPX) in leukocytes was measured by a modification of the alkaline comet assay (i.e., reduction of γ-irradiation induced DNA migration). Removal of DPX was determined by the abolition of FA-induced reduction in DNA migration within 4 h after the end of the exposure. Induction and persistence of FA-induced DNA lesions was also measured by the sister chromatid exchange (SCE) test with cultured lymphocytes after treatment of whole blood cultures with FA (150 μM). Furthermore, the expression (mRNA level) of the GSH-dependent formaldehyde dehydrogenase (FDH, identical to alcohol dehydrogenase 5; ADH5) was measured in leukocytes by quantitative real-time RT-PCR with TaqMan probes. The subjects were also analyzed for the GSTM1 and GSTT1 metabolic gene polymorphisms and a correlation analysis with the investigated genetic endpoints for FA-induced genotoxicity was performed. The results indicate that there are no biologically relevant differences between the three study groups with regard to the various indicators of cellular sensitivity toward FA-induced genotoxic effects and the expression of FDH. The induced genotoxic effects were not associated with polymorphisms in GSTM1 and GSTT1. None of the study groups showed particular mutagen sensitivity toward FA-induced genotoxicity. These results suggest that a low scaling factor to address possible human inter-individual differences in FA-induced genotoxicity could be reasonable.

Scientific assessment of the use of sugars as cigarette tobacco ingredients: a review of published and other publicly available studies

Sugars, such as sucrose or invert sugar, have been used as tobacco ingredients in American-blend cigarettes to replenish the sugars lost during curing of the Burley component of the blended tobacco in order to maintain a balanced flavor. Chemical-analytical studies of the mainstream smoke of research cigarettes with various sugar application levels revealed that most of the smoke constituents determined did not show any sugar-related changes in yields (per mg nicotine), while ten constituents were found to either increase (formaldehyde, acrolein, 2-butanone, isoprene, benzene, toluene, benzo[k]fluoranthene) or decrease (4-aminobiphenyl, N-nitrosodimethylamine, N-nitrosonornicotine) in a statistically significant manner with increasing sugar application levels. Such constituent yields were modeled into constituent uptake distributions using simulations of nicotine uptake distributions generated on the basis of published nicotine biomonitoring data, which were multiplied by the constituent/nicotine ratios determined in the current analysis. These simulations revealed extensive overlaps for the constituent uptake distributions with and without sugar application. Moreover, the differences in smoke composition did not lead to relevant changes in the activity in in vitro or in vivo assays. The potential impact of using sugars as tobacco ingredients was further assessed in an indirect manner by comparing published data from markets with predominantly American-blend or Virginia-type (no added sugars) cigarettes. No relevant difference was found between these markets for smoking prevalence, intensity, some markers of dependence, nicotine uptake, or mortality from smoking-related lung cancer and chronic obstructive pulmonary disease. In conclusion, thorough examination of the data available suggests that the use of sugars as ingredients in cigarette tobacco does not increase the inherent risk and harm of cigarette smoking.

Design and chemical evaluation of reduced machine-yield cigarettes

Experimental cigarettes (ECs) were made by combining technological applications that individually reduce the machine measured yields of specific toxicants or groups of toxicants in mainstream smoke (MS). Two tobacco blends, featuring a tobacco substitute sheet or a tobacco blend treatment, were combined with filters containing an amine functionalised resin (CR20L) and/or a polymer-derived, high activity carbon adsorbent to generate three ECs with the potential for generating lower smoke toxicant yields than conventional cigarettes. MS yields of smoke constituents were determined under 4 different smoking machine conditions. Health Canada Intense (HCI) machine smoking conditions gave the highest MS yields for nicotine-free dry particulate matter and for most smoke constituents measured. Toxicant yields from the ECs were compared with those from two commercial comparator cigarettes, three scientific control cigarettes measured contemporaneously and with published data on 120 commercial cigarettes. The ECs were found to generate some of the lowest machine yields of toxicants from cigarettes for which published HCI smoke chemistry data are available; these comparisons therefore confirm that ECs with reduced MS machine toxicant yields compared to commercial cigarettes can be produced. The results encourage further work examining human exposure to toxicants from these cigarettes, including human biomarker studies.

Research opportunities related to establishing standards for tobacco products under the Family Smoking Prevention and Tobacco Control Act

INTRODUCTION

This paper was written in response to a request from the U.S. National Cancer Institute. The goal is to discuss some research directions related to establishing tobacco product standards under the Family Smoking Prevention and Tobacco Control Act, which empowers the U.S. Food and Drug Administration to regulate tobacco products. Potential research related to tobacco product ingredients, nicotine, and harmful or potentially harmful constituents of tobacco products is discussed.

DISCUSSION

Ingredients, which are additives, require less attention than nicotine and harmful or potentially harmful constituents. With respect to nicotine, the threshold level in tobacco products below which dependent users will be able to freely stop using the product if they choose to do so is a very important question. Harmful and potentially harmful constituents include various toxicants and carcinogens. An updated list of 72 carcinogens in cigarette smoke is presented. A crucial question is the appropriate levels of toxicants and carcinogens in tobacco products. The use of carcinogen and toxicant biomarkers to determine these levels is discussed.

CONCLUSIONS

The need to establish regulatory standards for added ingredients, nicotine, and other tobacco and tobacco smoke constituents leads to many interesting and potentially highly significant research questions, which urgently need to be addressed.

The fate of ingredients in and impact on cigarette smoke

A series of experiments are described, undertaken on both volatile and non-volatile ingredients either during cigarette smoking or under pyrolysis conditions that try to simulate cigarette smoking. In particular, the fate of a series of deuterium and (13)C labelled volatiles was studied which demonstrated that, in a similar way to unlabelled volatiles, a large proportion of each was transferred intact into mainstream smoke. The unaccounted material, which was not transferred intact, in the studies of both volatile and non-volatile ingredients was primarily transformed into products of complete combustion such as carbon monoxide or carbon dioxide with only very minor amounts transformed into products of incomplete combustion. In addition, the studies on both unlabelled and deuterium labelled compounds demonstrated that the utility of pyrolysis studies lies mainly in distinguishing between those compounds that transfer intact into mainstream smoke from those that might be liable to degrade. Pyrolysis does not provide a robust prediction of the compounds that are formed from ingredients during cigarette smoking studies.

Carbonyl compounds in gas and particle phases of mainstream cigarette smoke

Carbonyl compounds (carbonyls) are important constituents of cigarette smoke and some are toxic and may be carcinogenic or mutagenic to humans. In this study carbonyl emissions in the gas and particle phases of mainstream cigarette smoke were assessed by GC-MS with pentafluorophenyl hydrazine (PFPH) derivatization. Seven brands of cigarettes and one brand of cigar common in the UK market and having differing nicotine, tar and carbon monoxide yields were investigated. Sixteen carbonyl components were identified in gaseous emissions and twenty in the particle phase. In the gaseous emissions, acetaldehyde presented as the predominant species, followed by formaldehyde, 2-propenal, and pentanal. In the particulate emissions, 1-hydroxy-2-propanone was the most abundant followed by formaldehyde, benzaldehyde, and 2,5-dimethylbenzaldehyde. Significant differences were found in carbonyl emissions among the brands of cigarettes. The gaseous carbonyl emissions varied in the range of 216-405 μg cigarette(-1) (μg cig(-1)) and the particulate carbonyl emissions varied in the range of 23-127 μg cig(-1). Positive correlations were found between the total emission of carbonyls, tar yield and carbon monoxide yield. Similar gas/particle (G/P) partitioning ratios of carbonyls were found among all cigarettes, which implies that G/P partitions of carbonyls in smoke mainly depend on the physical properties of the carbonyls. The gaseous carbonyl emissions were enhanced by 40% to 130% when some of the water, accounting for 8-12% of cigarettes in mass, was removed from the tobacco. Non-filtered cigarettes showed significantly higher carbonyl emissions compared to their filtered equivalents. Carbonyl particulate accounted for 11-19% by mass of total particulate matter from tobacco smoke. The cigar generated 806 μg cig(-1) gaseous and 141 μg cig(-1) particulate carbonyls, which is 2-4 times greater than the cigarettes.

Exposure to formaldehyde and its potential human health hazards

A widely used chemical, formaldehyde is normally present in both indoor and outdoor air. The rapid growth of formaldehyde-related industries in the past two decades reflects the result of its increased use in building materials and other commercial sectors. Consequently, formaldehyde is encountered almost every day from large segments of society due to its various sources. Many governments and agencies around the world have thus issued a series of standards to regulate its exposure in homes, office buildings, workshops, public places, and food. In light of the deleterious properties of formaldehyde, this article provides an overview of its market, regulation standards, and human health effects.

The use of a novel tobacco treatment process to reduce toxicant yields in cigarette smoke

The US Institute of Medicine has encouraged the pursuit and development of potential reduced-exposure products (PREPs) - tobacco products that substantially reduce exposure to one or more tobacco toxicants and can reasonably be expected to reduce the risk of one or more specific diseases or other adverse health effects. One potential approach is to reduce levels of some smoke toxicant precursors, such as proteins and polyphenols, in tobacco. We describe a treatment process involving aqueous tobacco extraction and treatment with protease; filtration of the extract to remove peptides, amino acids and polyphenols, and recombination of extract and treated tobacco. The process reduced levels of protein nitrogen (59%), polyphenols (33-78%) and nicotine (12%) while sugars increased 16%. ISO mainstream smoke yields of 43 toxicants were measured from cigarettes containing treated tobaccos; lower yields of tar, nicotine, carbon monoxide (16-20%), acrylonitrile, ammonia, aromatic amines, pyridine, quinolene and hydrogen cyanide (33-51%), tobacco specific nitrosamines (25-32%); phenolics (24-56%), benzene (16%), toluene (25%) and cadmium (34%) were obtained. There were significantly increased yields of formaldehyde (49%) and isoprene (17%). Reductions in sidestream yields of nitrogenous smoke toxicants and increases in sidestream yields of several carbonyls, benzo(a)pyrene and isoprene were also observed.