TABLE 3.

Models^* Evaluating Predictors of VOC Blood Levels in Sampled USAF Personnel (n = 69)

	Ethylbenzene (μg/L)†		Toluene (μg/L)†		o-xylene (μg/L)†		m-/p-xylene (μg/L)†
Model/Variables	β (SE)	P Value	β (SE)	P Value	β (SE)	P Value	β (SE)	P Value
Model 1
Intercept	−4.28 (0.42)	<0.0001	−3.83 (0.49)	<0.0001	−5.18 (0.41)	<0.0001	−4.40 (0.42)	<0.0001
JP-8 exposure (yes/no)	0.31 (0.22)	0.16	0.43 (0.26)	0.10	0.52 (0.22)	0.02	0.58 (0.22)	0.01
Shift cigarette smoking (yes/no)	0.43 (0.21)	0.05	1.13 (0.25)	<0.0001	0.48 (0.21)	0.03	0.73 (0.21)	0.001
USAF base A	Ref		Ref		Ref		Ref
USAF base B	3.44 (0.26)	<0.0001	1.65 (0.31)	<0.0001	1.45 (0.25)	<0.0001	1.59 (0.26)	<0.0001
USAF base C	−0.05 (0.58)	0.93	−0.97 (0.68)	0.16	−0.41 (0.57)	0.47	−1.04 (0.59)	0.08
Mean relative humidity	0.03 (0.02)	0.09	0.03 (0.02)	0.09	0.04 (0.02)	0.006	0.05 (0.02)	0.001
Summary Adjusted R2	0.74		0.50		0.5/		0.55
Model 2
Intercept	−3.57 (0.37	<0.0001	−3.24 (0.45)	<0.0001	−4.26 (0.34)	<0.0001	−3.54 (0.38)	<0.0001
8-h TWA THC (mg/m3)	0.04 (0.01)	<0.0001	0.03 (0.01)	<0.0001	0.04 (0.01)	<0.0001	0.04 (0.01)	<0.0001
2,5-dimethylfuran (μg/L)	3.76 (1.78)	0.04	13.32 (2.17)	<0.0001	0.45 (1.67)	0.79	4.65 (1.86)	0.02
USAF base A	Ref		Ref		Ref		Ref
USAF base B	3.36 (0.22)	<0.0001	1.55 (0.26)	<0.0001	1.38 (0.20)	<0.0001	1.50 (0.23)	<0.0001
USAF base C	0.44 (0.46)	0.34	−0.77 (0.56)	0.17	0.12 (0.43)	0.79	−0.64 (0.48)	0.19
Mean relative humidity	0.003 (0.01)	0.81	0.02 (0.02)	0.13	0.02 (0.01)	0.13	0.03 (0.01)	0.03
Summary Adjusted R2	0.82		0.63		0.69		0.67

JP-8, jet propulsion fuel 8; Ref, referent; SE, standard error; THC, total hydrocarbons; TWA, time-weighted average; USAF, US Air Force; VOC, volatile organic compounds.

Model 1: with self-reported cigarette use (shift cigarette smoking [yes/no]) and day 5 JP-8 exposure (yes/no).

Model 2: with measured JP-8 (8-h TWA THC [mg/m³]) and cigarette smoke exposure (2,5-dimethylfuran [μg/L]).

^*Multiple linear regression.

^†Natural log-transformed.