Table 3.

Sample-weighted multiple linear regression model for blood nitromethane (ng/L), where tobacco smoke exposure is represented by measured serum cotinine (ng/mL). The geometric mean of blood nitromethane used for computing ΔY [95%CI] is 646 ng/L for non-users and 789 ng/L for exclusive smokers. NHANES 2007–2012 (N=6,730)

	Non-users (N=5,345)			Exclusive Smokers (N=1,385)
Predictor	Slope [95%CI]a	p-Valuea	ΔY[95%CI]b	Slope [95%CI]a	p-Valuea	ΔY[95%CI]b
Serum cotinine (ng/mL)	0.0166 [0.0056, 0.0276]	0.0039	10.8 [3.81, 18.0]	0.0005 [0.0003, 0.0007]	<.0001	0.402 [0.251, 0.552]
Sex
Female	0.0626 [0.0372, 0.0880]	<.0001	41.7 [24.9, 58.9]	0.0362 [−0.0253, 0.0976]	0.2423	29.1 [−18.5, 79.6]
Male	Ref.c	.	Ref.	Ref.	.	Ref.
Age (years)
12–19	−0.0619 [−0.0974, −0.0264]	0.0010	−38.8 [−59.4, −17.4]	−0.0652 [−0.1313, 0.0008]	0.0527	−49.8 [−95.9, −0.663]
20–39	Ref.	.	Ref.	Ref.	.	Ref.
40–59	0.0388 [0.0014, 0.0762]	0.0421	25.6 [1.52, 50.5]	0.0143 [−0.0225, 0.0511]	0.4383	11.4 [−16.8, 40.6]
≥60	0.1480 [0.1038, 0.1922]	<.0001	103 [71.4, 136]	0.1335 [0.0602, 0.2067]	0.0006	113 [50.5, 179]
Race/Ethnicity
Mexican American	0.1193 [0.0553, 0.1834]	0.0005	81.9 [37.8, 129]	0.0794 [0.0012, 0.1575]	0.0466	65.2 [2.51, 133]
Non-Hispanic Black	0.1422 [0.0978, 0.1866]	<.0001	98.7 [67.1, 132]	0.0994 [0.0416, 0.1572]	0.0011	82.4 [34.7, 133]
Non-Hispanic White	Ref.	.	Ref.	Ref.	.	Ref.
Other Race	0.1523 [0.0985, 0.2061]	<.0001	106 [67.8, 147]	−0.0002 [−0.0548, 0.0544]	0.9937	−0.169 [−41.1, 43.0]
BMI
Healthy weight	Ref.	.	Ref.	Ref.	.	Ref.
Overweight/Obese	0.0614 [0.0362, 0.0867]	<.0001	40.9 [24.2, 58.0]	0.0711 [0.0339, 0.1084]	0.0004	58.2 [28.0, 89.5]
Underweight	−0.0944 [−0.1843, −0.0046]	0.0397	−58.2 [−107, −4.39]	−0.0822 [−0.1894, 0.0251]	0.1301	−62.2 [−134, 17.9]
Poverty Status
No	Ref.	.	Ref.	Ref.	.	Ref.
Yes	−0.0372 [−0.0901, 0.0157]	0.1638	−23.6 [−54.9, 9.36]	0.0341 [−0.0092, 0.0774]	0.1204	27.4 [−6.42, 62.6]
NHANES Cycle
2007–2008	0.0316 [−0.0365, 0.0997]	0.3556	20.7 [−22.1, 66.5]	−0.0319 [−0.0903, 0.0266]	0.2784	−24.8 [−67.1, 20.1]
2009–2010	Ref.	.	Ref.	Ref.	.	Ref.
2011–2012	0.0162 [−0.0382, 0.0706]	0.5526	10.5 [−23.4, 46.3]	−0.0233 [−0.0821, 0.0355]	0.4298	−18.2 [−61.2, 27.3]
Fasting time (hrs)	−0.0011 [−0.0036, 0.0015]	0.3996	−0.694 [−2.29, 0.907]	−0.0008 [−0.0056, 0.0040]	0.7361	−0.638 [−4.32, 3.06]
Food group (kg/day)
Milk products	−0.0210 [−0.0732, 0.0312]	0.4224	10.5 [−23.4, 46.3]	−0.0235 [−0.0991, 0.0521]	0.5350	−18.3 [−73.1, 40.7]
Meat, poultry	0.0655 [0.0107, 0.1202]	0.0201	−13.4 [−44.8, 19.6]	0.1353 [0.0284, 0.2421]	0.0141	114 [24.9, 213]
Eggs	0.0341 [−0.2005, 0.2688]	0.7713	43.7 [7.84, 81.5]	−0.2002 [−0.3833, −0.0171]	0.0328	−143 [−249, −16.9]
Legumes, nuts, seeds	0.2056 [0.0491, 0.3622]	0.0111	22.4 [−114, 194]	0.0834 [−0.2653, 0.4321]	0.6330	68.6 [−179, 416]
Grain products	0.0572 [0.0094, 0.1049]	0.0199	147 [35.1, 278]	0.0562 [−0.0284, 0.1408]	0.1878	45.6 [−20.5, 117]
Fruits	0.0389 [−0.0192, 0.0970]	0.1846	38.0 [6.88, 70.6]	0.0447 [−0.0373, 0.1267]	0.2788	36.1 [−27.4, 105]
Vegetables	0.2067 [0.1299, 0.2836]	<.0001	25.6 [−11.4, 64.7]	0.0780 [−0.0229, 0.1788]	0.1267	64.0 [−15.9, 152]
Fats, oils, salad dressings	0.1314 [−0.2932, 0.5561]	0.5367	148 [91.0, 210]	0.6345 [−0.1907, 1.4596]	0.1287	699 [−124, 2.54E+03]
Sugars, sweets, beverages	−0.0137 [−0.0239, −0.0036]	0.0091	90.7 [−159, 469]	−0.0171 [−0.0337, −0.0006]	0.0431	−13.4 [−25.9, −0.758]
Cured meat	0.3438 [−0.0125, 0.7001]	0.0582	−8.80 [−15.1, −2.46]	0.4363 [−0.6751, 1.5478]	0.4340	432 [−376, 2.82E+03]
Luncheon meat and hot dogs	−0.0133 [−0.2451, 0.2186]	0.9090	265 [−2.37, 643]	0.2733 [−0.0931, 0.6397]	0.1403	248 [−63.6, 693]
Tap water	−0.0093 [−0.0231, 0.0045]	0.1817	−8.51 [−137, 153]	−0.0193 [−0.0422, 0.0036]	0.0974	−15.0 [−32.1, 2.43]

^aThe dependent variable, blood nitromethane (ng/L), was natural log-transformed for the regression model.

^bΔY is the expected change in nitromethane concentration in ng/L associated with a unit-increase in the predictor at the overall geometric mean, controlling for other predictors in the model.

^cReference group