Table 2.

Summary of the linear mixed models for predicting natural log-transformed, post-exposure urinary HDA concentrations in the spray-painters using unadjusted (BZC, Models 1 and 3) or APF adjusted BZC levels (BZC-APF, Models 2 and 4). The starting Models 1 and 2 originate from our previously published work³ and include only exposure variables and creatinine. The final Models 3 and 4 include exposure variables, creatinine, and statistically significant individual and workplace factors.^a

Model	Variable	Estimate	Standard error	p-value	AIC	R2
1. Starting model with BZC	InBZC	0.08	0.09	0.38	1038	0.25
	Indermal	0.11	0.07	0.12
	Increatinine	1.25	0.17	<0.0001
	worker var	0.99	0.07
	residual var	1.78	0.15
2. Starting model with BZC-APF	InBZC-APF	0.14	0.06	0.03	1035	0.28
	Indermal	0.08	0.07	0.24
	Increatinine	1.28	0.17	<0.0001
	worker var	0.93	0.07
	residual var	1.76	0.15
3. Final model with BZCb	Indermal	0.16	0.06	0.01	1025	0.29
	Increatinine	1.35	0.17	<0.0001
	Half-face	0.62	0.39	0.11
	Full-face	1.33	0.70
	Monday	−0.16	0.26	0.10
	Tuesday	0.57	0.20
	Wednesday	−0.06	0.20
	Thursday	−0.02	0.24
	worker var	1.00	0.10
	residual var	1.11	0.15
4. Final model with BZC-APF	InBZC-APF	0.19	0.06	0.001	1025	0.29
	Increatinine	1.34	0.17	<0.0001
	Monday	−0.20	0.25	0.05
	Tuesday	0.64	0.20
	Wednesday	−0.03	0.19
	Thursday	−0.11	0.24
	coverall	−0.48	0.29	0.09
	worker var	1.01	0.09
	residual var	1.68	0.15

^aInBZC = natural log-transformed breathing zone concentration; InBZC-APF = natural log-transformed respirator adjusted breathing zone concentration; Indermal = natural log-transformed dermal exposure; Increatinine = natural log-transformed creatinine concentration; AIC = Akaike's Information Criterion; var = variance.

^bBZC was removed from the final model since it was not statistically significant.