TABLE 1.
Concentrations of mercapturic acid metabolites of volatile organic compounds (VOCs) measured in 24-hour urine collected during cigarette smoking, e-cigarette use, and abstention.
| Exposure (Biomarker) (ng/mg creatinine) |
Cigarette (Mean, SD) |
E-cigarette (Mean, SD) |
Abstention (Mean, SD) |
CC to EC ratio (GM, 95% CI) |
Ratio of EC to Abstention (GM, 95% CI) |
||
|---|---|---|---|---|---|---|---|
| All subjects | CC at Arm 2* | EC at Arm 2** | |||||
| Acrolein (3-HPMA) | 965.7 (674.3) | 258.8 (195.2) | 279.9 (140.0) | 3.70 (2.85-4.79) a | 0.82 (0.67-1.01) | 0.81 (0.62-1.04) | 0.83 (0.61-1.14) |
| Acrylamide (AAMA) | 190.2 (72.8) | 112.9 (50.8) | 92.8 (37.2) | 1.70 (1.50-1.92) a | 1.21 (1.03-1.43) b | 1.15 (0.93-1.43) | 1.27 (1.01-1.61) |
| Acrylonitrile (CNEMA) | 140.9 (95.5) | 21.8 (19.7) | 32.9 (27.6) | 7.09 (5.88-8.54) a | 0.64 (0.56-0.74) c | 0.50 (0.42-0.59) | 0.81 (0.71-0.92) |
| 1,3-Butadiene (MHBMA-1+2) | 3.43 (3.23) | 0.51 (0.42) | 0.70 (0.40) | 5.80 (3.73-9.00) a | 0.63 (0.48-0.82) c | 0.47 (0.32-0.68) | 0.83 (0.61-1.13) |
| 1,3-Butadiene (MHBMA-3) | 0.21 (0.12) | 0.17 (0.13) | 0.15 (0.10) | 1.31 (1.06-1.61) a | 1.05 (0.84-1.30) | 0.92 (0.66-1.29) | 1.18 (0.91-1.53) |
| Benzene (PMA) | 1.77 (1.52) | 0.48 (0.31) | 0.42 (0.48) | 3.21 (2.53-4.07) a | 1.46 (1.13-1.90) b | 0.94 (0.64-1.37) | 2.18 (1.71-2.77) |
| Crotonaldehyde (HPMMA) | 489.9 (297.7) | 168.1 (95.36) | 145.6 (55.3) | 2.77 (2.34-3.29) a | 1.08 (0.94-1.25) | 1.23 (0.99-1.54) | 0.97 (0.82-1.14) |
| Ethylene oxide (HEMA) | 4.28 (3.82) | 1.47 (1.06) | 1.84 (1.64) | 2.55 (2.10-3.10) a | 0.82 (0.71-0.95) c | 0.78 (0.66-0.93) | 0.86 (0.69-1.08) |
| Methylating agent (MMA) | 15.51 (12.84) | 17.30 (20.32) | 18.0 (17.5) | 1.01 (0.85-1.20) | 0.94 (0.77-1.15) | 1.18 (0.97-1.44) | 0.77 (0.57-1.04) |
| Propylene oxide (2-HPMA) | 82.7 (43.5) | 53.6 (41.1) | 41.7 (22.9) | 1.69 (1.33-2.16) a | 1.17 (0.98-1.39) | 1.08 (0.88-1.33) | 1.24 (0.95-1.64) |
Notes: * CC at Arm 2 = participants who were assigned to smoke combustible cigarettes during Arm 2 immediately before the abstention days;
EC at Arm 2 = participants who were assigned to vape e-cigarettes during Arm 2, immediately before the abstention days;
= significant difference between combustible cigarettes and e-cigarettes;
= significantly higher during e-cigarette use compared to abstention;
= significantly lower during e-cigarette use compared to abstention; 2-HPMA = 2-hydroxypropylmercapturic acid; 3-HPMA = 3-hydroxypropylmercapturic acid; AAMA = 2-carbamoylethylmercapturic acid; CNEMA = 2-cyanoethylmercapturic acid; HEMA = 2-hydroxyethylmercapturic acid (acrylonitrile, vinyl chloride, ethylene oxide); HPMMA = 3-hydroxy-1-methyl-propylmercapturic acid; MHBMA-1+2 = sum of isomers 1-hydroxy-3-buten-2-yl-mercapturic acid and 2-hydroxy-3-buten-1-yl-mercapturic acid; MHBMA-3 = 4-hydroxy-2-buten-1-yl-mercapturic acid; MMA = methylmercapturic acid; and, PMA = phenylmercapturic acid. During Day 2 of the cigarette arm, per cent below the limit of quantitation (LOQ) for each metabolite was as follows: 3-HPMA (0%); AAMA (0%); CNEMA (0%); MHBMA-1+2 (2.8%); MHBMA-3 (58.3%); PMA (0%); HPMMA (0%); HEMA (0%); MMA (36.1%); 2-HPMA (0%). Per cent below LOQ on Day 2 of the e-cigarette arm were as follows: 3-HPMA (0%); AAMA (0%); CNEMA (0%); MHBMA-1+2 (41.7%); MHBMA-3 (83.3%); PMA (22.2%); HPMMA (0%); HEMA (0%); MMA (33.3%); 2-HPMA (0%). Per cent below LOQ during abstinence were as follows: 3-HPMA (0%); AAMA (0%); CNEMA (0%); MHBMA-1+2 (80.6%); MHBMA-3 (97.2%); PMA (30.6%); HPMMA (0%); HEMA (25.0%); MMA (33.3%); 2-HPMA (0%).