Tobacco smoke is a toxic and carcinogenic mixture of more than 5,000 chemicals. The present article provides a list of 98 hazardous smoke components, based on an extensive literature search for known smoke components and their human health inhalation risks. An electronic database of smoke components containing more than 2,200 entries was generated. Emission levels in mainstream smoke have been found for 542 of the components and a human inhalation risk value for 98 components. As components with potential carcinogenic, cardiovascular and respiratory effects have been included, the three major smoke-related causes of death are all covered by the list. Given that the currently used Hoffmann list of hazardous smoke components is based on data from the 1990s and only includes carcinogens, it is recommended that the current list of 98 hazardous components is used for regulatory purposes instead. To enable risk assessment of components not covered by this list, thresholds of toxicological concern (TTC) have been established from the inhalation risk values found: 0.0018 μg day−1 for all risks, and 1.2 μg day−1 for all risks excluding carcinogenicity, the latter being similar to previously reported inhalation TTCs.

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The binding of a series of p-alkylbenzamidinium chloride inhibitors to the serine proteinase trypsin over a range of temperatures has been studied using isothermal titration (micro)calorimetry and molecular dynamics simulation techniques. The inhibitors have small structural variations at the para position of the benzamidinium ion. They show small differences in relative binding affinity but large compensating differences in enthalpy and entropy. Binding affinity decreases with increased branching at the first carbon but increases with increasing the length of a linear alkyl substituent, suggesting that steric hindrance and hydrophobic interactions play dominant roles in binding. Structural analysis showed that the backbone of the enzyme was unaffected by the change of the para substituent. In addition, binding does not correlate strongly with octanol/water partition data. To further characterize this system, the change in the heat capacity on binding, the change in solvent-accessible surface area on binding, the effect of inhibitor binding on the hydration of the active site, the pK(a) of His57, and interactions within the catalytic triad have been investigated. Although the changes in inhibitor structure are small, it is demonstrated that simple concepts such as steric hindrance, hydrophobicity, and buried surface area are insufficient to explain the binding data. Other factors, such as access to the binding site and the cost of dehydration of the active site, are of equal or greater importance.

This paper aims to provide an in-depth understanding of the attractiveness of e-cigarettes for several different groups. For this purpose, perceptions of and reasons for e-cigarette use were systematically reviewed as reported by e-cigarette users, cigarette smokers, dual users, and non-users, among both adults and youth. MEDLINE® and Scopus were used to search for relevant articles, and references of included studies were also investigated. Two reviewers screened all titles and abstracts independently, blinded to authors and journal titles (Cohen’s Kappa = 0.83), resulting in 72 eligible articles. Risk perceptions, perceived benefits, and reasons for e-cigarette use were categorized in themes and sub-themes. Risk perceptions included harmfulness in general, and specific health risks. Perceived benefits included improved taste and smell, and safety for bystanders. Reasons for use included (health) benefits, curiosity, smoking cessation, and friends using e-cigarettes. The findings highlight that there is a variety of perceptions and reasons mentioned by adult and youth e-cigarette users, cigarette smokers, dual users, and non-users. As such, this overview provides valuable information for scientists, public health professionals, behavior change experts, and regulators to improve future research, risk communication, and possibilities to effectively regulate e-cigarettes.

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