TABLE 4.

Final Models of 8-Hour TWA THC in Air (μg/m³) and Postshift Urinary Metabolites

	Ln (Postshift Urinary 1-Naphthol)		Ln (Postshift Urinary 2-Naphthol)		Ln (Postshift Urinary 2-Hydroxyfluorene)
	β (SE)	P	β (SE)	P	β (SE)	P
Intercept	4.59 (0.45)	<0.0001	4.83 (0.46)	<0.0001	3.53 (0.35)	<0.0001
Ln preshift urine concentration	0.33 (0.05)	<0.0001	0.34 (0.05)	<0.0001	0.29 (0.06)	<0.0001
Base		0.17		0.40		0.32
1	−0.29 (0.17)		−0.46 (0.15)		−0.25 (0.16)
2	−0.23 (0.17)		−0.39 (0.15)		−0.10 (0.16)
3	Ref		Ref		Ref
Sex
Female	−0.007 (0.19)	0.97	0.14 (0.17)	0.40	0.01 (0.18)	0.95
Male	Ref		Ref		Ref
Cigarettes during work shift		0.0009		0.006		0.002
1/2 pack	0.92 (0.30)		0.65 (0.24)		0.67 (0.24)
1/4 pack	0.78 (0.15)		0.49 (0.13)		0.61 (0.13)
None	Ref		Ref		Ref
Postshift urinary creatinine	0.005 (0.0006)	<0.0001	0.005 (0.0005)	<0.0001	0.005 (0.0004)	<0.0001
Ln 8-hr TWA THC (mg/m3)	0.17 (0.04)	<0.0001	0.09 (0.03)	0.005	0.08 (0.03)	0.006
Random effects
σ2bw (intercept only)	1.23		0.89		0.90
σ2ww (intercept only)	0.67		0.42		0.41
σ2bw (full model)	0.19		0.19		0.25
σ2ww (full model)	0.54		0.28		0.25
Variability explained by model, %
Between-worker	85		79		72
Within-worker	19		33		39

SE, standard error; THC, total hydrocarbon; TWA, time-weighted average.