Table 2.

Blood BTEXS concentrations (ng/L).

Population	Compound	N	LOD	%>LOD	GM	P95	NHANES 2005–08 Values*		GuLF STUDY Spearman Correlation Coefficients
							GM	P95	Benzene	Toluene	Ethylbenzene	o-Xylene	m/p-Xylene	Styrene
Tobacco Smoke-Unexposed**	Benzene	142	24	35	25	84	22	56	1	0.36	0.28	0.18	0.25	0.27
	Toluene	144	25	99	88	314	86	329		1	0.54	0.47	0.63	0.29
	Ethylbenzene	105	24	39	26	104	26	75			1	0.70	0.77	0.62
	o-Xylene	142	24	39	25	99	28	84				1	0.84	0.27
	m/p-Xylene	146	34	74	61	390	85	259					1	0.36
	Styrene	141	30	59	52	882	25	55						1
Tobacco Smoke-Exposed***	Benzene	241	24	75	91	526	188	561	1	0.88	0.79	0.59	0.74	0.56
	Toluene	244	25	100	262	1170	478	1393		1	0.83	0.75	0.86	0.55
	Ethylbenzene	182	24	77	56	199	83	210			1	0.86	0.92	0.69
	o-Xylene	237	24	71	37	113	54	135				1	0.93	0.55
	m/p-Xylene	241	34	93	127	426	226	585					1	0.55
	Styrene	234	30	87	98	1110	92	233						1

Abbreviations: GuLF STUDY, Gulf Long-term Follow-up Study, NHANES, National Health and Nutrition Examination Survey; LOD, Limit of Detection; GM, Geometric Mean; P95, 95th percentile.

^*NHANES values for Tobacco Unexposed reflect adult NHANES participants (≥ 21 years) with blood 2,5-DMF concentrations less than 14 ng/mL; values for Tobacco Exposed reflect NHANES participants with blood 2,5-DMF concentrations greater than or equal to 14 ng/L.

^**Tobacco smoke-unexposed participants reported no primary tobacco use, less than 30 minutes of passive smoke exposure, and had blood 2,5-DMF concentrations less than 14 ng/L.

^***Tobacco smoke-exposed participants reported primary tobacco use, 30 or more minutes of passive smoke exposure, or had blood 2,5-DMF concentrations greater than or equal to 14 ng/L.