Table 2.

Biomarker concentrations by sampling times, adjusted for covariates, for all subjects (n = 55), “noncigarette smokers” (n = 47), and “suspected cigarette smokers” (n = 8)

Sampling time
BiomarkerPreexposurePostexposurePost- to preexposure ratioP-value
Cotinine (ng/mg creatinine)
 All subjects14.4 (9.70–21.3)59.3 (40.0–87.7)4.13 (2.93–5.81)<0.001
 Non-CS11.8 (7.21–19.2)55.3 (33.9–90.1)4.70 (3.23–6.83)<0.001
 Suspected CS55.7 (27.8–111)107 (53.6–215)1.93 (1.04–3.56)0.04
Nicotine (ng/mg creatinine)
 All subjects3.12 (1.74–5.60)227 (126–407)72.9 (37.8–140)<0.001
 Non-CS2.59 (1.32–5.12)262 (132–516)101 (52.8–193)<0.001
 Suspected CS14.8 (4.01–54.4)158 (42.9–581)10.7 (1.03–111)0.047
NNAL (pg/mg creatinine)
 All subjects1.32 (0.83–2.11)2.84 (1.79–4.51)2.14 (1.44–3.20)<0.001
 Non-CS1.24 (0.758–2.03)2.87 (1.76–4.69)2.32 (1.55–3.46)<0.001
 Suspected CS3.23 (0.879–11.9)4.38 (1.19–16.1)1.36 (0.28–6.67)0.85
2-OH-propyl (ng/mg creatinine)
 All subjects38.5 (22.9–64.8)49.1 (29.2–82.5)1.27 (0.95–1.70)0.10
 Non-CS52.0 (27.0–100)66.9 (34.8–128)1.29 (0.92–1.80)0.14
 Suspected CS33.6 (19.0–59.0)40.2 (22.7–71.3)1.20 (0.76–1.87)0.38
3-OH–propyl (ng/mg creatinine)
 All subjects309 (203–471)437 (287–666)1.41 (1.21–1.65)<.001
 Non-CS281 (169.7–466)398 (240–661)1.42 (1.19–1.68)<.001
 Suspected CS390.0 (173–878)543 (241–1,223)1.39 (0.89–2.18)0.12
2-Carbamoylethyl (ng/mg creatinine)
 All subjects89.3 (66.5–120)101 (75.6–136)1.14 (1.03–1.26)0.01
 Non-CS93.5 (66.2–132)107 (76.3–152)1.15 (1.03–1.29)0.01
 Suspected CS133 (67.9–261)140 (71.4–275)1.05 (0.85–1.30)0.59
Cyanoethyl (ng/mg creatinine)
 All subjects5.68 (3.14–10.3)9.69 (5.36–17.5)1.71 (1.43–2.04)<.001
 Non-CS5.22 (2.55–10.7)9.30 (4.54–19.1)1.78 (1.46–2.18)<.001
 Suspected CS17.5 (3.01–102.1)23.1 (3.97–134)1.32 (0.84–2.08)0.19
2-Hydroxy-3-buten-1-yl (or MHBMA) (ng/mg creatinine)
 All subjects0.18 (0.11–0.28)0.25 (0.16–0.40)1.42 (1.08–1.85)0.01
 Non-CS0.15 (0.10–0.24)0.21 (0.13–0.32)1.35 (1.03–1.77)0.03
 Suspected CS0.17 (0.06–0.51)0.33 (0.11–0.96)1.89 (0.61–5.87)0.22
OH-ethyl (ng/mg creatinine)
 All subjects2.98 (2.31–3.85)3.68 (2.85–4.75)1.23 (1.10–1.39)<.001
 Non-CS3.03 (2.22–4.15)3.75 (2.74–5.13)1.24 (1.09–1.41)0.002
 Suspected CS3.65 (2.53–5.26)4.45 (3.09–6.42)1.22 (0.88–1.69)0.192
Phenyl (ng/mg creatinine)
 All subjects0.18 (0.12–0.27)0.34 (0.22–0.53)1.91 (1.48–2.47)<.001
 Non-CS0.19 (0.11–0.31)0.35 (0.21–0.58)1.87 (1.40–2.49)<.001
 Suspected CS0.25 (0.08–0.79)0.54 (0.17–1.74)2.21 (1.15–4.24)0.02
Sampling time
BiomarkerPreexposureNext dayNext day topreexposure ratioP-value
Cotinine (ng/mg creatinine)
 All subjects14.4 (9.70–21.3)45.9 (31.0–67.9)3.20 (2.27–4.50)<0.001
 Non-CS11.8 (7.21–19.2)45.2 (27.7–73.7)3.84 (2.64–5.59)<0.001
 Suspected CS55.7 (27.8–111.7)60.2 (30.0–120.6)1.08 (0.58–2.00)0.76
Nicotine (ng/mg creatinine)
 All subjects3.12 (1.74–5.60)32.3 (18.0–58.0)10.4 (5.37–20.0)<0.001
 Non-CS2.59 (1.32–5.12)38.1 (19.3–75.1)14.7 (7.68–28.1)<0.001
 Suspected CS14.8 (4.01–54.4)19.8 (5.37–72.7)1.34 (0.13–13.9)0.93
NNAL (pg/mg creatinine)
 All subjects1.32 (0.83–2.11)2.88 (1.81–4.59)2.18 (1.46–3.25)<0.001
 Non-CS1.24 (0.76–2.03)2.96 (1.81–4.84)2.39 (1.60–3.57)<0.001
 Suspected CS3.23 (0.88–11.9)4.08 (1.11–15.0)1.26 (0.26–6.21)0.91

NOTES: Smoking status determined by urine cotinine cut-point of 30 ng/mL; non-CS, noncigarette smoker; suspected CS, suspected cigarette smoker; adjusted for covariates: sex, age, BMI, hookah use category, prior SHS (yes/no), marijuana use (yes/no), time spent smoking hookah, average bowls, and bar SHS (yes/no); NNAL, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; VOC mercapturic acid metabolites and parent compounds: 2-hydroxypropyl (propylene oxide), 3-hydroxypropyl (acrolein), 2-carbamoylethyl (acrylamide), cyanoethyl (acrylonitrile), 2-hydroxy-3-buten-1-yl or isomer(s) [abbrev. MHBMA] (1,3-butadiene), 2-hydroxyethyl (ethylene oxide), and phenyl (benzene).