Table 5.

Multivariate linear regression models for 1,4-BQ-Alb.^a,^b

	< 1 ppm (n = 205)c		≥ 1 ppm (n = 179)c
	β (SE)	p-Value	β (SE)	p-Value
Intercept	7.78 (0.196)	< 0.001	8.07 (0.245)	< 0.001
Benzene (ppm)a	0.030 (0.011)	0.010	0.391 (0.040)	< 0.001
Blood-collection media		< 0.001		< 0.001
Plasma EDTA	1.55 (0.100)	< 0.001	1.32 (0.145)	< 0.001
Plasma heparin	−0.052 (0.101)	0.608	0.230 (0.107)	0.033
Serum	Reference		Reference
Age (years)	−0.005 (0.004)	0.144	−0.008 (0.004)	0.078
BMI (kg/m2)	−0.013 (0.008)	0.134	−0.025 (0.010)	0.014
Smoke cigarettes	0.456 (0.068)	< 0.001	0.242 (0.081)	0.003
R2 (adjusted R2)	0.62 (0.61)		0.60 (0.59)

^aLog-transformed.

^bFor the sake of comparison, nonsignificant covariates were also retained in the model.

^cBecause of missing adduct determinations, five observations were excluded from the group exposed to < 1 ppm benzene and one observation was excluded from the group exposed to ≥ 1 ppm.