Electronic Cigarette Solvents, JUUL E-Liquids, and Biomarkers of Exposure: In Vivo Evidence for Acrolein and Glycidol in E-Cig-Derived Aerosols.

Despite the increasing popularity of e-cigarettes, their long-term health effects remain unknown. In animal models, exposure to e-cigarette has been reported to result in pulmonary and cardiovascular injury, and in humans, the acute use of e-cigarettes increases heart rate and blood pressure and induces endothelial dysfunction. In both animal models and humans, cardiovascular dysfunction associated with e-cigarettes has been linked to reactive aldehydes such as formaldehyde and acrolein generated in e-cigarette aerosols. These aldehydes are known products of heating and degradation of vegetable glycerin (VG) present in e-liquids. Here, we report that in mice, acute exposure to a mixture of propylene glycol:vegetable glycerin (PG:VG) or to e-cigarette-derived aerosols significantly increased the urinary excretion of acrolein and glycidol metabolites─3-hydroxypropylmercapturic acid (3HPMA) and 2,3-dihydroxypropylmercapturic acid (23HPMA)─as measured by UPLC-MS/MS. In humans, the use of e-cigarettes led to an increase in the urinary levels of 23HPMA but not 3HPMA. Acute exposure of mice to aerosols derived from PG:13C3-VG significantly increased the 13C3 enrichment of both urinary metabolites 13C3-3HPMA and 13C3-23HPMA. Our stable isotope tracing experiments provide further evidence that thermal decomposition of vegetable glycerin in the e-cigarette solvent leads to generation of acrolein and glycidol. This suggests that the adverse health effects of e-cigarettes may be attributable in part to these reactive compounds formed through the process of aerosolizing nicotine. Our findings also support the notion that 23HPMA, but not 3HPMA, may be a relatively specific biomarker of e-cigarette use.

Biomonitoring occupational sevoflurane exposure at low levels by urinary sevoflurane and hexafluoroisopropanol.

This study aimed to correlate environmental sevoflurane levels with urinary concentrations of sevoflurane (Sev-U) or its metabolite hexafluoroisopropanol (HFIP) in order to assess and discuss the main issues relating to which biomarker of sevoflurane exposure is best, and possibly suggest the corresponding biological equivalent exposure limit values. Individual sevoflurane exposure was measured in 100 healthcare operators at five hospitals in north-east Italy using the passive air sampling device Radiello(®), and assaying Sev-U and HFIP concentrations in their urine collected at the end of the operating room session. All analyses were performed by gas chromatography-mass spectrometry. Environmental sevoflurane levels in the operating rooms were also monitored continuously using an infrared photoacoustic analyzer. Our results showed very low individual sevoflurane exposure levels, generally below 0.5 ppm (mean 0.116 ppm; range 0.007-0.940 ppm). Sev-U and HFIP concentrations were in the range of 0.1-17.28 µg/L and 5-550 µg/L, respectively. Both biomarkers showed a statistically significant correlation with the environmental exposure levels (Sev-U, r=0.49; HFIP, r=0.52), albeit showing fairly scattered values. Sev-U values seem to be influenced by peaks of exposure, especially at the end of the operating-room session, whereas HFIP levels by exposure on the previous day, the data being consistent with the biomarkers' very different half-lives (2.8 and 19 h, respectively). According to our results, both Sev-U and HFIP are appropriate biomarkers for assessing sevoflurane exposure at low levels, although with some differences in times/patterns of exposure. More work is needed to identify the best biomarker of sevoflurane exposure and the corresponding biological equivalent exposure limit values.

Study of the metabolism of estragole in humans consuming fennel tea.

The metabolism of the potent carcinogen estragole was investigated in humans after consumption of fennel tea by analyses of its metabolites in blood plasma and urine. Stable isotope dilution assays based on LC-MS/MS detection revealed that 1'-hydroxylation of estragole happened very fast as the concentration of conjugated 1'-hydroxyestragole in urine peaked after 1.5 h, whereas it was no longer detectable after 10 h. Besides the formation of less than 0.41% conjugated 1'-hydroxyestragole of the estragole dose administered, the further metabolite p-allylphenol was generated from estragole in a higher percentage (17%). Both metabolites were also detected in blood plasma in less than 0.75-2.5 h after consumption of fennel tea. In contrast to this, no estragole was present in these samples above its detection limit. From the results, it can be concluded that an excess of the major fennel odorant trans-anethole principally does not interfere with estragole metabolism, whereas influences on the quantitative composition of metabolites cannot be excluded. The presence of a sulfuric acid conjugate of estragole could not be confirmed, possibly due to its high reactivity and lability.

Automated solid phase extraction and quantitative measurement of 2,3-dibromo-1-propanol in urine using gas chromatography-mass spectrometry.

2,3-Dibromo-1-propanol (DBP) was used as an active flame retardant in the 1970s. It was also used as an intermediate in the preparation of insecticide formulations, pharmaceuticals and the flame retardants tris(2,3-dibromopropyl) phosphate (Tris-BP) and tetrabromobisphenol A bis (2,3-dibromopropyl ether). DBP is also produced in vivo as a metabolic product of Tris-BP in humans. In 1977, sleepwear containing DBP and Tri-BP was banned because of evidence of carcinogenicity animal studies. Although the production of DBP was reduced after 1977, studies show that DBP is still detected in indoor air and dust; hence, the U.S. population may be exposed potentially to DBP. Only a few methods have been reported in the literature for assessing exposure to DBP or Tris-BP by measuring DBP in urine. These methods are based on a labor-intensive and time-consuming liquid-liquid extraction for the isolation of DBP from the urine matrix. To measure urinary DBP in humans, a fast, accurate, and sensitive method was developed with a limit of detection of 0.1 ng/mL and extraction recovery of 96%. This method involves enzymatic cleavage of the DBP-glucuronide or sulfate conjugate, automated solid phase extraction, and analysis by gas chromatography-mass spectrometry using 1,4-dibromo-2-butanol as the internal standard.

Simultaneous determination of unmodified sevoflurane and of its metabolite hexafluoroisopropanol in urine by headspace sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry.

Unmodified sevoflurane and its metabolite, hexafluoroisopropanol (HFIP), have both been proposed as biomarkers of exposure in post-shift urine for operating room personnel exposed to inhalation anaesthetic sevoflurane. We used headspace sorptive extraction (HSSE) and thermal desorption-capillary GC-MS to assess sensitively both compounds in the urine matrix (after a HFIP deconjugation step). In GC-MS splitless mode, calibration plots (approximately 15-650 microg/L) were linear (r2 > 0.9910) and the limits of detection (1 microg/L for both biomarkers) showed increased sensitivity for HFIP with respect to the previously described headspace GC-MS method. The method was suitable for biological monitoring of both biomarkers of exposure to sevoflurane.

[Urinary hexafluoroisopropanol in the assessment of occupational exposure to sevoflurane: methodologic features and critical points]. / L'esafluoroisopropanolo urinario nella valutazione dell'esposizione professionale a sevofluorano: aspetti metodologici e punti critici.

The increasing use of sevoflurane as anaesthetic leads to the need for finding a biological index to evaluate the occupational exposure in surgical activity. Several studies indicate that Hexafluoroisopropanol (HFIP) is a specific sevoflurane metabolite quickly glucuronidated and excreted as HFIP-glucuronide in the urine (HFIPu). Therefore the HFIP removal kinetics in occupational exposure and the correlation between sevoflurane exposure and HFIPu are poorly understood. We studied no. 86 operating room workers of Novara Hospital to evaluate the correlation between the sevoflurane individual exposure (SE) and the HFIPu at the end of the shift expressed in microgram/L (A-HFIPu) and in microgram/g creat. (C-HFIPu). Therefore, in the same group of subjects we evaluated the HFIPu in the urine sampled at 8.00 a.m. before the work. The correlation coefficient was R2 = 0.782 (p < 0.0001) for SE/A-HFIPu and R2 = 0.862 (p < 0.0001) for SE/C-HFIPu; HFIPu normalized for urinary creatinine (C-HFIPu) is an index more suitable than the A-HFIPu. Furthermore we concluded for the usefulness of pre-shift HFIPu.

Determination of hexafluoroisopropanol, a sevoflurane urinary metabolite, by 9-fluorenylmethyl chloroformate derivatization.

A reversed-phase HPLC method with fluorescence detection for the quantification of hexafluoroisopropanol (HFIP) in urine is presented. HFIP, a metabolite of the inhalation anesthetic sevoflurane, is excreted mainly in urine as glucuronic acid conjugate. After enzymatic hydrolysis of the glucuronate, primary amino groups of interferent urinary compounds are blocked by reaction with o-phthalic dicarboxaldehyde and 3-mercaptopropionic acid, followed by labeling of HFIP with 9-fluorenylmethyl chloroformate. The derivatization reaction proceeds in a water-acetonitrile (1:1) solution at room temperature with a borate buffer of pH 12.5 as a catalyst. A stable fluorescent derivative of HFIP is formed within 5 min. The HFIP-FMOC derivative is separated by reversed-phase chromatography with isocratic elution on an octadecyl silyl column (33x4.6 mm, 3 microm) and guard column (20x4.0 mm, 40 microm), at 35 degrees C, and detected by fluorescence detection at an excitation wavelength of 265 nm and an emission wavelength of 311 nm. The method detection limit is 40 pg, per 10-microl injection volume, corresponding to 16 microg/l of HFIP in urine. The among-series relative standard deviation is <6% at 200 microg/l (n=6). As a preliminary application, the method was used to detect HFIP concentration in the urine of two volunteers exposed for 3 h to an airborne concentration of sevoflurane in the order of 2 ppm.

Disposition of propargyl alcohol in rat and mouse after intravenous, oral, dermal and inhalation exposure.

1. The disposition of propargyl alcohol (PAL) radiolabelled with carbon-14 ([2,3-14C]PAL) was determined in the F344 rat and B6C3F1 mouse following intravenous (i.v.), oral, inhalation and dermal exposure. 2. By 72h following an i.v. (1 mg kg(-1) or oral (50 mg kg(-1) dose, 76-90% of the dose was excreted. Major routes of excretion by rat were urine (50-62%), CO2 (19-26%) and faeces (6-14%). Major routes of exerection by mouse were urine (30-40%), CO2 (22-26%) and faeces (10-20%). Less than 6% of the dose remained in tissues at 72 h. Biliary exeretion of radioactity by rat (62% in 4 h) was much greater than elimination in faeces (6% in 72 h), indicating that PAL metabolites underwent extensive enterohepatic recycling. 3. Dermal exposure studies demonstrated that dermal absorption of PAL was minimal due to its inherent volatility. 4. In the inhalation studies (1, 10 or 100 ppm for 6 h), 23-68% of the radioactivity to which animals were exposed was absorbed. The primary route of excretion was urine (23-53%), and significant portion was exhaled as volatile organics (15-30%). 5. PAL was extensively metabolized by both species. One metabolite was identified as 3,3-bis[(2-(acetylamino)-2-carboxyethyl)thio]-1-propanol, which is consistent with Banijamali et al. (1999).

Identification of metabolites of [1,2,3-(13)C]Propargyl alcohol in mouse urine by (13)C NMR and mass spectrometry and comparison to rat.

Species differences in the metabolism of acetylenic compounds commonly used in the formulation of pharmaceuticals and pesticides have not been investigated. To better understand the in vivo reactivity of this bond, the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, was examined in rats and mice. An earlier study (Banijamali, A. R.; Xu, Y.; Strunk, R. J.; Gay, M. H.; Ellis, M. C.; Putterman, G. J. J. Agric. Food Chem. 1999, 47, 1717-1729) in rats revealed that PA undergoes extensive metabolism primarily via glutathione conjugation. The current research describes the metabolism of PA in CD-1 mice and compares results for the mice to those obtained for rats. [1,2,3-(13)C;2,3-(14)C]PA was administered orally to the mice. Approximately 60% of the dose was excreted in urine by 96 h. Metabolites were identified, directly, in whole urine by 1- and 2-D (13)C NMR and HPLC/MS and by comparison with the available reference compounds. The proposed metabolic pathway involves glucuronide conjugation of PA to form 2-propyn-1-ol-glucuronide as well as oxidation of PA to the proposed intermediate 2-propynal. The aldehyde undergoes conjugation with glutathione followed by further metabolism to yield as final products 3,3-bis[(2-acetylamino-2-carboxyethyl)thio]-1-propanol, 3-[(2-acetylamino-2-carboxyethyl)thio]-3-[(2-amino-2-carboxyethyl)thi o]-1-propanol, 3,3-bis[(2-amino-2-carboxyethyl)thio]-1-propanol, 3-[(2-amino-2-carboxyethyl)thio]-2-propenoic acid, and 3-[(2-formylamino-2-carboxyethyl)thio]-2-propenoic acid. A small portion of 2-propynal is also oxidized to result in the excretion of 2-propynoic acid. On the basis of urinary metabolite data, qualitative and quantitative differences are noted between rats and mice in the formation of the glucuronide conjugate of PA and in the formation of 2-propynoic acid and metabolites derived from glutathione. These metabolites represent further variation on glutathione metabolism following its addition to the carbon-carbon triple bond compared to those described for the rat.

Identification of metabolites of [1,2,3-(13)C]Propargyl alcohol in rat urine by (13)C NMR and mass spectrometry.

Little is known about the metabolism of acetylenic (C&tbd1;C) compounds commonly used in the formulation of pesticides. To better understand the in vivo reactivity of this bond, we examined the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, used extensively in the chemical industry. [1,2,3-(13)C, 2,3-(14)C]PA was administered orally to male Sprague-Dawley rats. Approximately 56% of the dose was excreted in urine by 96 h. Major metabolites were characterized, directly, in the whole urine by one- and two-dimensional (13)C NMR. To determine the complete structures of metabolites of PA, rat urine was also subjected to TLC followed by purification of separated TLC bands on HPLC. The purified metabolites were identified by (13)C NMR and mass spectrometry and by comparison with available synthetic standards. The proposed metabolic pathway involves oxidation of propargyl alcohol to 2-propynoic acid and further detoxification via glutathione conjugation to yield as final products: 3, 3-bis[(2-(acetylamino)-2-carboxyethyl)thio]-1-propanol, 3-(carboxymethylthio)-2-propenoic acid, 3-(methylsulfinyl)-2-(methylthio)-2-propenoic acid, 3-[[2-(acetylamino)-2-carboxyethyl]thio]-3-[(2-amino-2-carboxyethyl)t hio]-1-propanol and 3-[[2-(acetylamino)-2-carboxyethyl]sulfinyl]-3-[2-(acetylamino)-2-car boxyethyl]thio]-1-propanol. These unique metabolites have not been reported previously and represent the first example of multiple glutathione additions to the carbon-carbon triple bond.