TABLE 2.
Biomarkers of Nicotine, Tobacco-Specific Nitrosamine, and Volatile Organic Toxicants in Exclusive E-Cigarette–Only Users Versus Dual Users and Controls
| Variable | E-Cigarette–Only Users,a n = 67 | Dual Users,b n = 16 | Controls,c n = 20 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mediand | IQR | Range | Mediane | IQR | Range | Mediane | IQR | Range | |
| Saliva cotinine (ng/mL) | 0 | 3.8 | 0–864.6 | 99.4** | 139.0 | 36.2–302.8 | 0* | 0 | 0 |
| Urine NNAL (pg/mL of creatinine) | 0.3 | 0.7 | 0–0.9 | 68.1** | 68.7 | 32.7–299.3 | 0** | 0 | 0 |
| PMA (ng/mg of creatinine; benzene) | 0 | 0.1 | 0–2.0 | 0.2** | 0.7 | 0–2.4 | 0 | 0 | 0–0.1 |
| MHBMA (ng/mg of creatinine; 1,3-butadiene) | 0 | 0 | 0–2.2 | 0 | 0.1 | 0–0.2 | 0* | 0.5 | 0–1.1 |
| HEMA (ng/mg of creatinine; ethylene oxide) | 0.5 | 1.1 | 0–7.6 | 1.0* | 1.4 | 0–8.2 | 1.3 | 2.3 | 0–4.0 |
| CNEMA (ng/mg of creatinine; acrylonitrile) | 1.3 | 3.2 | 0–108.4 | 59.4** | 81.3 | 3.7–142.6 | 0** | 1.1 | 0–1.6 |
| 3-HPMA (ng/mg of creatinine; acrolein) | 254.3 | 191.4 | 0–2311.6 | 439.7* | 224.1 | 153.6–814.4 | 192.8* | 261.6 | 0–1416.4 |
| 2-HPMA (ng/mg of creatinine; propylene oxide) | 28.8 | 25 | 0–1382.6 | 40.2 | 27.9 | 10.2–310.9 | 15.2** | 14.4 | 0–34.5 |
| AAMA (ng/mg of creatinine; acrylamide) | 67.3 | 69 | 0–581.2 | 235.6** | 239.8 | 41.4–574.7 | 34.5** | 41.6 | 0–182.0 |
| HMPMA (ng/mg of creatinine; crotonaldehyde) | 148.7 | 99 | 0–793.4 | 185.4 | 156.6 | 110.0–437.9 | 100.4* | 129.9 | 0–522.1 |
All comparisons were made with e-cigarette–only users as a comparison group. IQR, interquartile range; MHBMA, 4-hydroxy-2-buten-1-yl-mercapturic acid.
Used an e-cigarette product in the past 24 h and had NNAL levels <1 pg/mL of creatinine.
Used an e-cigarette product in the past 24 h, smoked a cigarette in the past 30 d, and had NNAL levels ≥30 pg/mL of creatinine.
No use of tobacco or e-cigarette in the past 30 d, with NNAL levels <1 pg/mL of creatinine and cotinine levels <1 ng/mL.
The median (IQR) was reported for cotinine, NNAL (pg/mL of creatinine), and VOCs (ng/mg of creatinine) because of non-normal distribution.
Tests were based on regression models of log-transformed values, including planned covariates (sex and race and/or ethnicity) with contrasts for e-cigarette–only users versus controls and for e-cigarette–only users versus dual users.
P < .05; ** P < .001.