Comparison of Emissions across Tobacco Products: A Slippery slope in tobacco control

In this narrative review, we highlight the challenges of comparing emissions from different tobacco products under controlled laboratory settings (using smoking/ vaping machines). We focus on tobacco products that generate inhalable smoke or aerosol, such as cigarettes, cigars, hookah, electronic cigarettes, and heated tobacco products. We discuss challenges associated with sample generation including variability of smoking/vaping machines, lack of standardized adaptors that connect smoking/vaping machines to different tobacco products, puffing protocols that are not representative of actual use, and sample generation session length (minutes or number of puffs) that depends on product characteristics. We also discuss the challenges of physically characterizing and trapping emissions from products with different aerosol characteristics. Challenges to analytical method development are also covered, highlighting matrix effects, order of magnitude differences in analyte levels, and the necessity of tailored quality control/quality assurance measures. The review highlights two approaches in selecting emissions to monitor across products, one focusing on toxicants that were detected and quantified with optimized methods for combustible cigarettes, and the other looking for productspecific toxicants using non-targeted analysis. The challenges of data reporting and statistical analysis that allow meaningful comparison across products are also discussed. We end the review by highlighting that even if the technical challenges are overcome, emission comparison may obscure the absolute exposure from novel products if we only focus on relative exposure compared to combustible products

Toxicity of Waterpipe Tobacco Smoking: the Role of Flavors, Sweeteners, Humectants, and Charcoal

Waterpipe tobacco (WPT) smoking is a public health concern, particularly among youth and young adults. The global spread of WPT use has surged since the introduction of pre-packaged flavored and sweetened WPT, which is widely marketed as a safer tobacco alternative. Besides flavorants and sugars, WPT additives include humectants, which enhance the moisture and sweetness of WPT, act as solvents for flavors, and impart smoothness to the smoke, thus increasing appeal to users. In the United States (U.S.), unlike cigarette tobacco flavoring (with the exception of menthol), there is no FDA product standard or policy in place prohibiting sales of flavored WPT. Research has shown that the numerous fruit, candy, and alcohol flavors added to WPT entice individuals to experience those flavors, putting them at an increased risk of exposure to WPT smoke-related toxicants. Additionally, burning charcoal briquettes-used as a heating source for WPT-contributes to the harmful health effects of WPT smoking. This review presents existing evidence on the potential toxicity resulting from humectants, sugars, and flavorants in WPT, and from the charcoal used to heat WPT. The review discusses relevant studies of inhalation toxicity in animal models and of biomarkers of exposure in humans. Current evidence suggests that more data are needed on toxicant emissions in WPT smoke to inform effective tobacco regulation to mitigate the adverse impact of WPT use on human health

A Review of the Toxicity of Ingredients in E-Cigarettes, Including Those Ingredients Having the Fda\u27s generally Recognized As Safe (GRAS) Regulatory Status for Use in Food.

Some firms and marketers of electronic cigarettes (e-cigarettes; a type of electronic nicotine delivery system (ENDS)) and refill liquids (e-liquids) have made claims about the safety of ingredients used in their products based on the term GRAS or Generally Recognized As Safe (GRAS). However, GRAS is a provision within the definition of a food additive under section 201(s) (21 U.S.C. 321(s)) of the U.S. Federal Food Drug and Cosmetic Act (FD&C Act). Food additives and GRAS substances are by the FD&C Act definition intended for use in food, thus safety is based on oral consumption; the term GRAS cannot serve as an indicator of the toxicity of e-cigarette ingredients when aerosolized and inhaled (i.e., vaped). There is no legal or scientific support for labeling e-cigarette product ingredients as GRAS . This review discusses our concerns with the GRAS provision being applied to e-cigarette products and provides examples of chemical compounds that have been used as food ingredients but have been shown to lead to adverse health effects when inhaled. The review provides scientific insight into the toxicological evaluation of e-liquid ingredients and their aerosols to help determine the potential respiratory risks associated with their use in e-cigarettes

Évaluation des propriétés électroniques des composés à base de carbone(0) par la catalyse a l’or et analyse des structures aux rayons-X.

La plupart des composés organiques ont un atome de carbone tétravalent, où tous les électrons de valence sont utilisés pour former des liaisons covalentes. En parallèle, la chimie des composés divalents ayant un carbone(II) s’est développée après l’isolement de carbènes stables par Bertrand en 1985. Auparavant, en 1961, Ramirez a rapporté l’isolement de l’hexaphénylcarbodiphosphorane, que l’on peut considérer comme un composé présentant un carbone(0) avec ses deux doublets libres, lui permettant de coordiner jusqu’à deux acides de Lewis. A partir de 2006, les propriétés électroniques de ces ligands ont été étudiées au travers d’études théoriques par Frenking ; ce qui a permis à Bertrand et Fürstner d’isoler et d’ajouter des nouveaux membres à cette famille. Cette classe de ligand est aujourd’hui connue sous le nom de “carbônes”, avec comme formule générale CL2 (L = PR3 ou carbène).Cette famille n’a jamais été utilisée dans le domaine de la catalyse. C’est pourquoi nous avons, décidé d’etudier les propriétés électroniques de ce ces composés au travers de la catalyse à l’or, afin de les comparer aux NHC, phosphines, et phosphites. Récemment, nous avons utilisé ces composés pour générer des complexes donneur accepteur avec du GaCl3, et de corréler leurs différentes caractéristiques géometriques à leurs propriétés électroniques en utilisant les règles de Gutmann sur des adduits acide/base de Lewis. De plus, nous avons isolé des “dimères” ioniques dont la formation peut être expliquée par les propriétés intrinsèques des ligands. Nous avons ainsi démontré par ces deux approches que les “carbônes” sont de meilleurs donneurs que les NHC.Most organic compounds which are stable in the condensed phase contain tetravalent carbon atoms, where all four valence electrons are being engaged in chemical bonds. On the other hand, the chemistry of divalent carbon(II) was only recognized after the isolation of a stable persistent carbene by Bertrand and co-workers in 1985. Such products display one s-type lone pair orbital and are thus good ligands. Earlier on, concern was also paid to a new family of compounds, first reported in 1961 by Ramirez and co-workers. They can be considered as divalent carbon(0) derivatives with two lone pairs at the central carbon, with a possibility of double coordination of two Lewis acids to this carbon. This feature was proposed by Kaska in 1973, and verified later by the isolation of di-metalated adducts. From 2006, these compounds were the centre of extensive theoretical investigations by Frenking, which led to the isolation of new members of this family by Fürstner and Bertrand. This family is now referred to as “carbones”, of general formula CL2 (L =PR3 or carbene).“Carbones” are still virtually unused in catalysis. Thus, we have decided to study these derivatives, especially in the field of gold catalysis, and to compare them with well-known ligands such as NHCs, phosphines and phosphites. Recently, we were able to synthesize their corresponding GaCl3 complexes and to rationalize their electronic properties through Gutmann’s rules for Lewis acid/Lewis base adducts. In addition, we obtained some ionic “dimers” and we explained their formation on the basis of ligand’s electronic properties. We have shown through these two approaches that carbones are far better donors than NHCs

Évaluation des propriétés électroniques des composés à base de carbone(0) par la catalyse a l or et analyse des structures aux rayons-X.

La plupart des composés organiques ont un atome de carbone tétravalent, où tous les électrons de valence sont utilisés pour former des liaisons covalentes. En parallèle, la chimie des composés divalents ayant un carbone(II) s est développée après l isolement de carbènes stables par Bertrand en 1985. Auparavant, en 1961, Ramirez a rapporté l isolement de l hexaphénylcarbodiphosphorane, que l on peut considérer comme un composé présentant un carbone(0) avec ses deux doublets libres, lui permettant de coordiner jusqu à deux acides de Lewis. A partir de 2006, les propriétés électroniques de ces ligands ont été étudiées au travers d études théoriques par Frenking ; ce qui a permis à Bertrand et Fürstner d isoler et d ajouter des nouveaux membres à cette famille. Cette classe de ligand est aujourd hui connue sous le nom de carbônes , avec comme formule générale CL2 (L = PR3 ou carbène).Cette famille n a jamais été utilisée dans le domaine de la catalyse. C est pourquoi nous avons, décidé d etudier les propriétés électroniques de ce ces composés au travers de la catalyse à l or, afin de les comparer aux NHC, phosphines, et phosphites. Récemment, nous avons utilisé ces composés pour générer des complexes donneur accepteur avec du GaCl3, et de corréler leurs différentes caractéristiques géometriques à leurs propriétés électroniques en utilisant les règles de Gutmann sur des adduits acide/base de Lewis. De plus, nous avons isolé des dimères ioniques dont la formation peut être expliquée par les propriétés intrinsèques des ligands. Nous avons ainsi démontré par ces deux approches que les carbônes sont de meilleurs donneurs que les NHC.Most organic compounds which are stable in the condensed phase contain tetravalent carbon atoms, where all four valence electrons are being engaged in chemical bonds. On the other hand, the chemistry of divalent carbon(II) was only recognized after the isolation of a stable persistent carbene by Bertrand and co-workers in 1985. Such products display one s-type lone pair orbital and are thus good ligands. Earlier on, concern was also paid to a new family of compounds, first reported in 1961 by Ramirez and co-workers. They can be considered as divalent carbon(0) derivatives with two lone pairs at the central carbon, with a possibility of double coordination of two Lewis acids to this carbon. This feature was proposed by Kaska in 1973, and verified later by the isolation of di-metalated adducts. From 2006, these compounds were the centre of extensive theoretical investigations by Frenking, which led to the isolation of new members of this family by Fürstner and Bertrand. This family is now referred to as carbones , of general formula CL2 (L =PR3 or carbene). Carbones are still virtually unused in catalysis. Thus, we have decided to study these derivatives, especially in the field of gold catalysis, and to compare them with well-known ligands such as NHCs, phosphines and phosphites. Recently, we were able to synthesize their corresponding GaCl3 complexes and to rationalize their electronic properties through Gutmann s rules for Lewis acid/Lewis base adducts. In addition, we obtained some ionic dimers and we explained their formation on the basis of ligand s electronic properties. We have shown through these two approaches that carbones are far better donors than NHCs.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Molecular versus Ionic Structures in Adducts of GaX₃ with Monodentate Carbon-Based Ligands

A molecular donor–acceptor adduct has been isolated by the reaction of the <i>N</i>-heterocyclic carbene 1,3-dimethyl imidazol-2-ylidene (diMe-IMD) with GaCl₃. In contrast, the structurally related, yet much more nucleophilic, 1,3-dimethyl-2-methylene-2,3-dihydro-1<i>H</i>-imidazole (diMe-MDI) gave rise to ion pairs of type [L₂GaX₂]­[GaX₄], where X = Cl, Br, or I. With IBioxMe₄, a <i>N</i>-heterocyclic carbene that is more nucleophilic than diMe-IMD, the outcome of the reaction was dependent on the nature of the halide. Ionic 1:1 adducts between monodentate ligands and GaX₃ salts have only one precedent in the literature. The peculiar behavior of carbon-based ligands was explained on the basis of their electronic properties and reaction kinetics

Molecular versus Ionic Structures in Adducts of GaX₃ with Monodentate Carbon-Based Ligands

A molecular donor–acceptor adduct has been isolated by the reaction of the <i>N</i>-heterocyclic carbene 1,3-dimethyl imidazol-2-ylidene (diMe-IMD) with GaCl₃. In contrast, the structurally related, yet much more nucleophilic, 1,3-dimethyl-2-methylene-2,3-dihydro-1<i>H</i>-imidazole (diMe-MDI) gave rise to ion pairs of type [L₂GaX₂]­[GaX₄], where X = Cl, Br, or I. With IBioxMe₄, a <i>N</i>-heterocyclic carbene that is more nucleophilic than diMe-IMD, the outcome of the reaction was dependent on the nature of the halide. Ionic 1:1 adducts between monodentate ligands and GaX₃ salts have only one precedent in the literature. The peculiar behavior of carbon-based ligands was explained on the basis of their electronic properties and reaction kinetics