Wentai Luo

Hidden Formaldehyde in E-Cigarette Aerosols

This letter reports a chemical analysis of vapor from electronic cigarettes that shows high levels of formaldehyde, a known carcinogen. The authors project that the associated incremental lifetime risk of cancer could be higher than that from long-term smoking.

Flavour chemicals in electronic cigarette fluids

Background Most e-cigarette liquids contain flavour chemicals. Flavour chemicals certified as safe for ingestion by the Flavor Extracts Manufacturers Association may not be safe for use in e-cigarettes. This study identified and measured flavour chemicals in 30 e-cigarette fluids. Methods Two brands of single-use e-cigarettes were selected and their fluids in multiple flavour types analysed by gas chromatography/mass spectrometry. For the same flavour types, and for selected confectionary flavours (eg, bubble gum and cotton candy), also analysed were convenience samples of e-cigarette fluids in refill bottles from local ‘vape’ shops and online retailers. Results In many liquids, total flavour chemicals were found to be in the ∼1–4% range (10–40 mg/mL); labelled levels of nicotine were in the range of 0.6–2.4% (6 to 24 mg/mL). A significant number of the flavour chemicals were aldehydes, a compound class recognised as ‘primary irritants’ of mucosal tissue of the respiratory tract. Many of the products contained the same flavour chemicals: vanillin and/or ethyl vanillin was found in 17 of the liquids as one of the top three flavour chemicals, and/or at ≥0.5 mg/mL. Conclusions The concentrations of some flavour chemicals in e-cigarette fluids are sufficiently high for inhalation exposure by vaping to be of toxicological concern. Regulatory limits should be contemplated for levels of some of the more worrisome chemicals as well as for total flavour chemical levels. Ingredient labeling should also be required.

Occurrence and Toxicity of Disinfection Byproducts in European Drinking Waters in Relation with the HIWATE Epidemiology Study

The HIWATE (Health Impacts of long-term exposure to disinfection byproducts in drinking WATEr) project was a systematic analysis that combined the epidemiology on adverse pregnancy outcomes and other health effects with long-term exposure to low levels of drinking water disinfection byproducts (DBPs) in the European Union. The present study focused on the relationship of the occurrence and concentration of DBPs with in vitro mammalian cell toxicity. Eleven drinking water samples were collected from five European countries. Each sampling location corresponded with an epidemiological study for the HIWATE program. Over 90 DBPs were identified; the range in the number of DBPs and their levels reflected the diverse collection sites, different disinfection processes, and the different characteristics of the source waters. For each sampling site, chronic mammalian cell cytotoxicity correlated highly with the numbers of DBPs identified and the levels of DBP chemical classes. Although there was a clear difference in the genotoxic responses among the drinking waters, these data did not correlate as well with the chemical analyses. Thus, the agents responsible for the genomic DNA damage observed in the HIWATE samples may be due to unresolved associations of combinations of identified DBPs, unknown emerging DBPs that were not identified, or other toxic water contaminants. This study represents the first to integrate quantitative in vitro toxicological data with analytical chemistry and human epidemiologic outcomes for drinking water DBPs.

Gas/Solid partitioning of semivolatile organic compounds to model atmospheric solid surfaces as a function of relative humidity. 1. Clean quartz.

Evaluating the relative importance of adsorption to particle surfaces vs absorption into organic material in particles for gas/particle partitioning in the atmosphere requires a comparison of relevant gas/solid partitioning constants with field-determined values. Gas/quartz partitioning constants Kp (m 3 /μg) were measured at 20°C for clean quartz as a function of relative humidity (RH) for 11 semivolatile polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. Increasing RH from ∼30 to ∼70% caused the K p values to decrease by a factor of 10. With adsorption to the quartz surface as the only possible sorption mechanism, surface-area-normalized partition constants (K p,s , m 3 /m 2 ) were calculated. For quartz, correlations of log K p,s with the log of the vapor pressure were found to lie significantly below the corresponding lines for urban particulate matter. We conclude that adsorption to mineral/oxide surfaces like clean quartz is not important in determining K p values in urban air ; such sorption may be important in rural/remote environments.

Inhalable Constituents of Thirdhand Tobacco Smoke: Chemical Characterization and Health Impact Considerations

Tobacco smoke residues lingering in the indoor environment, also termed thirdhand smoke (THS), can be a source of long-term exposure to harmful pollutants. THS composition is affected by chemical transformations and by air-surface partitioning over time scales of minutes to months. This study identified and quantified airborne THS pollutants available for respiratory exposure, identified potential environmental tracers, and estimated health impacts to nonsmokers. In a ventilated 18 m(3) laboratory chamber, six cigarettes were machine-smoked, and levels of particulate matter (PM2.5) and 58 volatile organic compounds (VOCs) were monitored during an aging period of 18 h. Results were compared with field measurements taken in a smokers home 8 h after the last cigarette had been smoked. Initial chamber levels of individual VOCs in freshly emitted secondhand smoke (SHS) were in the range of 1-300 μg m(-3). The commonly used SHS tracers 3-ethenylpyridine (3-EP) and nicotine were no longer present in the gas phase after 2 h, likely due mostly to sorption to surfaces. By contrast, other VOCs persisted in the gas phase for at least 18 h, particularly furans, carbonyls, and nitriles. The concentration ratio of acetonitrile to 3-EP increased substantially with aging. This ratio may provide a useful metric for differentiating freshly emitted (SHS) from aged smoke (THS). Among the 29 VOCs detected in the smokers home at moderate to high concentrations, 18 compounds were also detected in simultaneously sampled outdoor air, but acetonitrile, 2-methyl furan, and 2,5-dimethyl furan appeared to be specific to cigarette smoke. The levels of acrolein, methacrolein, and acrylonitrile exceeded concentrations considered harmful by the State of California. An initial exposure and impact assessment was conducted for a subset of pollutants by computing disability-adjusted life years lost, using available toxicological and epidemiological information. Exposure to PM2.5 contributed to more than 90% of the predicted harm. Acrolein, furan, acrylonitrile, and 1,3-butadiene were considered to be the most harmful VOCs. Depending on which criteria are used to establish the separation between SHS and THS, 5-60% of the predicted health damage could be attributed to THS exposure. Benefits and limitations of this approach are discussed.

Candy Flavorings in Tobacco

An analysis finds that chemicals used to flavor candy and popular drinks are also being used in tobacco products, often at much higher levels. Tobacco products with cherry, grape, and apple flavors contain the same flavorings used in Jolly Rancher candies, Life Savers, and Kool-Aid.

Calculated Cancer Risks for Conventional and “Potentially Reduced Exposure Product” Cigarettes

Toxicant deliveries (by machine smoking) are compiled and associated cancer risks are calculated for 13 carcinogens from 26 brands of conventional cigarettes categorized as “regular” (R), “light” (Lt), or “ultralight” (ULt), and for a reference cigarette. Eight “potentially reduced exposure product” (PREP) cigarettes are also considered. Because agency-to-agency differences exist in the cancer slope factor (CSF) values adopted for some carcinogens, two CSF sets were used in the calculations: set I [U.S. Environmental Protection Agency (EPA)–accepted values plus California EPA–accepted values as needed to fill data gaps] and set II (vice versa). The potential effects of human smoking patterns on cigarette deliveries are considered. Acetaldehyde, 1,3-butadiene, and acrylonitrile are associated with the largest calculated cancer risks for all 26 brands of conventional cigarettes. The calculated risks are proportional to the smoking dose z (pack-years). Using CSF set I and z = 1 pack-year (7,300 cigarettes), the calculated brand-average incremental lifetime cancer risk \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{\mathrm{ILCR}}^{\mathrm{acetaldehyde}}_{1}\) \end{document} values are R, 6 × 10−5; Lt, 5 × 10−5; and ULt, 3 × 10−5 (cf. typical U.S. EPA risk benchmark of 10−6). These values are similar, especially given the tendency of smokers to “compensate” when smoking Lt and ULt cigarettes. \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{\mathrm{ILCR}}^{\mathrm{sub{\Sigma}-lung}}_{1}\) \end{document}is the brand-average per pack-year subtotal risk for the measured human lung carcinogens. Using CSF set I, the \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{\mathrm{ILCR}}^{\mathrm{sub{\Sigma}-lung}}_{1}\) \end{document} values for R, Lt, and ULt cigarettes account for ≤2% of epidemiologically observed values of the all-smoker population average per pack-year risk of lung cancer from conventional cigarettes. RPREP (%) is a science-based estimate of the possible reduction in lung cancer risk provided by a particular PREP as compared with conventional cigarettes. Using CSF set I, all RPREP values are <2%. The current inability to account for the observed health risks of smoking based on existing data indicates that current expressed/implied marketing promises of reduced harm from PREPs are unverified: there is little reason to be confident that total removal of the currently measured human lung carcinogens would reduce the incidence of lung cancer among smokers by any noticeable amount. (Cancer Epidemiol Biomarkers Prev 2007;16(3):584–92)

Gas/particle partitioning of polycyclic aromatic hydrocarbons and alkanes to environmental tobacco smoke.

published in Advance ACS Abstracts, December 15, 1993. Envlron. Sci. Technol., Vol. 28, No. 2, 1994 365

Distribution, quantification and toxicity of cinnamaldehyde in electronic cigarette refill fluids and aerosols

Objective The aim of this study was to evaluate the distribution, concentration and toxicity of cinnamaldehyde in electronic cigarette (e-cigarette) refill fluids and aerosols. Methods The distribution and concentration of cinnamaldehyde were determined in 39 e-cigarette refill fluids plus 6 duplicates using gas chromatography and mass spectrometry (GC/MS). A cinnamaldehyde toxicity profile was established for embryonic and adult cells using a live cell imaging assay, immunocytochemistry, the comet assay and a recovery assay. Results Twenty of the 39 refill fluids contained cinnamaldehyde at concentrations that are cytotoxic to human embryonic and lung cells in the MTT assay. Cinnamon Ceylon aerosol produced in a cartomizer-style e-cigarette was cytotoxic. Cinnamon Ceylon aerosols and refill fluid aerosols (80% propylene glycol or cinnamaldehyde/propylene glycol) made using a tank/boxmod e-cigarette were more cytotoxic at 5 V than 3 V. Using GC/MS, aerosols produced at 5 V contained 10 additional peaks not present in aerosol generated at 3 V. One of these, 2,3-butandione (diacetyl), was confirmed with an authentic standard. Cinnamaldehyde depolymerised microtubules in human pulmonary fibroblasts. At concentrations that produced no effect in the MTT assay, cinnamaldehyde decreased growth, attachment and spreading; altered cell morphology and motility; increased DNA strand breaks; and increased cell death. At the MTT IC50 concentration, lung cells were unable to recover from cinnamaldehyde after 2 hours of treatment, whereas embryonic cells recovered after 8 hours. Conclusions Cinnamaldehyde-containing refill fluids and aerosols are cytotoxic, genotoxic and low concentrations adversely affect cell processes and survival. These data indicate that cinnamaldehyde in e-cigarette refill fluids/aerosols may impair homeostasis in the respiratory system.

Gas-solid retention volumes of organic compounds on styrene-divinylbenzene and ethylvinylbenzene-divinylbenzene co-polymer sorbent beads

Reliable gas sampling with a sorbent requires a good knowledge of the gas-solid retention volumes of the analytes on the sorbent. Literature data on specific retention volumes at 20°C (Vg,293, l/g) are reviewed for a number of styrene-divinylbenzene (Sty-DVB) and ethylvinylbenzene-divinylbenzene (EVB-DVB)sorbents, namely XAD-3, Porapak P, Porapak Q, Chromosorb 101, and Chromosorb 102. New measurements are also made by gas-solid chromatography for a Sty-DVB polymer employed in one variety of Empore membrane extraction filters. For all of the data, the log Vg, 293 values are highly correlated with both log pL0 (log of the liquid vapor pressure at 20°C) and with Tb(pure compound boiling point, K). The correlation equations allow the prediction of log Vg,293 based on either log pL0 or Tb. Equations that can be used for a wide range of compounds and a range of Sty-DVB and EVB-DVB sorbents are: log Vg,293 = 1 .16 log pL0 + 3.51, and log Vg,293 = 0.022Tb − 6.60. Separate equations are recommended for aliphatic acids and alcohols. For the Sty-DVB beads used in one variety of Empore extraction filters, the correlation equations are log Vg,293 = 0.99 log pL0 + 3.04, and log Vg,293 = 0.0175Tb =t- 4.97. Most of the available data support absorption into the resin matrix as the dominant gas-solid partitioning mechanism for organic analytes to Sty-DVB sorbent materials.