Demographic characteristics of study participants, and smoking/vaping history and use
| Smokers (n=10) M (SD) or per cent | 2nd Generation (n=9) M (SD), per cent, [range] | 3rd Generation (n=11) M (SD), per cent, [range] | p Value | |
|---|---|---|---|---|
| Age (years) | 36.4 (13.0) | 35.1 (12.1) | 30.8 (7.9) | NS |
| Male (%) | 60% | 45% | 81% | NS |
| Non-Hispanic white (%) | 40% | 44% | 55% | NS |
| Age started smoking (years) | 15.2 (3.6) | 14.6 (3.2) | 15.7 (3.5) | NS |
| Cigs per day (current/previous*) | 18.4 (9.2) | 15.8 (6.8)* | 17.3 (11.4)* | NS |
| Former smoker (%) | − | 100% | 100% | − |
| Years vaping | − | 2.2 (0.83) | 3.0 (2.24) | NS |
| Self-reported e-liquid consumption/week (mL) | − | 22.0 (13.7) | 54.8 (25.0) | <0.0001 |
| E-liquid nicotine concentration (mg/mL) | − | 22.3 (7.5) [11–36] | 4.1 (2.9) [1.5–6] | <0.00001 |
| E-cig voltage (V) | − | 4.1 (0.5) [3.4–4.7] | 4.0 (0.4) [3.4–4.7] | NS |
| E-cig resistance (Ω) | − | 2.0 (0.3) [1.6–2.6] | 0.4 (0.2) [0.1–0.6] | <0.001 |
| E-cig power (W) | − | 8.6 (1.9) [6.6–12.6] | 71.6 (50.0) [18.6–162.4] | 0.001 |
| Number of heating coils | − | 1.8 (0.5) [1–2] | 1.6 (0.7) [1–3] | NS |
| eCO (ppm) | 13.9 (11.1) | 2.3 (1.0) | 3.4 (1.2) | <0.0001 |
| NNAL (pmol/mL)† | 1.47 (0.82) | 0.17 (0.19) | 0.21 (0.47) | <0.01 |
| Cotinine (ng/mL) | 331.1 (179.3) | 316.6 (235.8) | 430.5 (225.4) | NS |
*Previous level of cigarettes smoked per day for G2 and G3 users.
†Total NNAL was below the LOD (0.015 pmol/mL) in 6 EC users (30%).
E-cig, electronic cigarette; eCO, exhaled carbon monoxide; LOD, limit of detection.