Factors affecting the variability in the observed levels of cadmium in blood and urine among never smoker adults aged ≥ 20–64 years and senior citizens aged ≥ 65 years

Figures & data

Table 1. Weighted frequency distribution of blood and urine cadmium by gender, race/ethnicity, and exposure to environmental tobacco smoke (ETS) at work and home

	Age 20–64 years*			Age≥65 years**
	N	Weighted N	Weighted %	N	Weighted N	Weighted %
Blood Cadmium
Total	11,644	51,932,0784	100.0	3,576	101,212,243	100.0
Males	4,545	219,593,901	42.3	1,230	29679711	29.3
Females	7,099	299,726,883	57.7	2,346	71,532,532	70.7
Non-Hispanic White	4,452	335,549,622	64.6	2,158	83,226,837	82.2
Non-Hispanic Black	2,468	61,329,369	11.8	515	6,926,633	6.8
Mexican American	2,806	52,582,937	10.1	517	3373283	3.3
Other Race/Ethnicity	1,918	69,858,856	13.5	386	7,685,489	7.6
Exposed to ETS at work	1,104	51,349,002	9.9	34	802,018	0.8
Not exposed to ETS at work	10,536	467,810,594	90.1	3,542	10,041,0225	99.2
Exposed to ETS at home	662	28,062,253	5.4	137	3,452,711	3.4
Not exposed to ETS at home	10,900	488,126,358	94.6	3,423	97,406,513	96.6
Urine Cadmium
Total	3,791	515,295,814	100.0	1,150	95,693,296	100.0
Males	1,494	214,039,662	41.5	407	28,501,477	29.8
Females	2,297	301,256,152	58.5	743	67,191,819	70.2
Non-Hispanic White	1,445	333,183,435	64.7	668	77,466,259	81.0
Non-Hispanic Black	821	63,038,499	12.2	178	7,463,397	7.8
Mexican American	906	50,810,460	9.9	172	3,055,246	3.2
Other Race/Ethnicity	619	68,263,420	13.2	132	7,708,394	8.1
Exposed to ETS at work	389	55,205,011	10.7	9	699,008	0.7
Not exposed to ETS at work	3,402	460,090,803	89.3	1,141	94,994,288	99.3
Exposed to ETS at home	219	27,480,541	5.4	36	2,380,557	2.5
Not exposed to ETS at home	3,542	483,803,672	94.6	1,103	92,629,955	97.5

Source: Data from National Health and Nutrition Examination Survey 1999–2010.

* Observations at or above the limit of detection for blood cadmium was 71.1% and for urine cadmium 92.4%.

** Observations at or above the limit of detection for blood cadmium was 88.4% and for urine cadmium 97.5%.

Table 2. Unadjusted geometric means with 95% confidence intervals for blood cadmium in μg/L and urine cadmium in μg/L by survey year by age for never smokers

	Blood cadmium		Urine cadmium
	Age: 20–64 years	Age: ≥65 years	Age: 20–64 years	Age: ≥ 65 years
1999–2000	0.324 (0.299–0.351)	0.445 (0.4–0.495)	0.192 (0.166–0.222)	0.282 (0.229–0.347)
2001–2002	0.284 (0.272–0.296)	0.398 (0.382–0.414)	0.208 (0.188–0.229)	0.281 (0.244–0.322)
2003–2004	0.228 (0.212–0.246)	0.374 (0.34–0.411)	0.197 (0.175–0.221)	0.259 (0.22–0.305)
2005–2006	0.236 (0.226–0.247)	0.359 (0.339–0.381)	0.173 (0.156–0.192)	0.286 (0.241–0.34)
2007–2008	0.243 (0.234–0.253)	0.345 (0.323–0.369)	0.179 (0.159–0.201)	0.239 (0.214–0.267)
2009–2010	0.235 (0.228–0.243)	0.352 (0.332–0.374)	0.166 (0.151–0.182)	0.297 (0.244–0.363)
2011–2012	0.219 (0.208–0.23)	0.325 (0.301–0.35)	0.14 (0.128–0.153)	0.236 (0.199–0.28)
β	−0.0225184	−0.0192928	−0.0241651	−0.0076994
p	< 0.01	< 0.01	< 0.01	0.29
% change each NHANES cycle	−5.3	−4.5	−5.7	−1.8
Ratio in % (2011–2012)/(1999–2000)	67.6	73.0	72.9	83.7

Table 3. Unadjusted geometric means with 95% confidence intervals for blood cadmium in μg/L and urine cadmium in μg/L by gender, race/ethnicity, and exposure to environmental tobacco smoke (ETS) by age for never smokers

	Blood cadmium		Urine cadmium		Pairwise comparison between adults and seniors
	Age: 20–64 years	Age:≥65 years	Age: 20–64 Years	Age: ≥ years	pBCd	pUCd
Males (M)	0.208 (0.203–0.213)	0.31 (0.298–0.323)	0.164 (0.156–0.173)	0.249 (0.229–0.272)	< 0.01	< 0.01
Females (F)	0.283 (0.277–0.29)	0.393 (0.38–0.405)	0.184 (0.174–0.195)	0.273 (0.253–0.296)	< 0.01	< 0.01
Non-Hispanic White (NHW)	0.234 (0.228–0.24)	0.364 (0.352–0.377)	0.158 (0.15–0.166)	0.254 (0.238–0.271)	< 0.01	< 0.01
Non-Hispanic Black (NHB)	0.264 (0.257–0.272)	0.346 (0.329–0.363)	0.247 (0.227–0.269)	0.322 (0.29–0.358)	< 0.01	< 0.01
Mexican American (MA)	0.253 (0.242–0.264)	0.35 (0.332–0.37)	0.19 (0.175–0.205)	0.245 (0.203–0.294)	< 0.01	< 0.01
Other Race/Ethnicity (OTH)	0.312 (0.298–0.326)	0.416 (0.378–0.457)	0.205 (0.185–0.227)	0.364 (0.29–0.457)	< 0.01	< 0.01
Exposed to ETS at work (ETSW_Yes)	0.235 (0.225–0.245)	0.325 (0.273–0.387)	0.163 (0.147–0.182)	0.321 (0.248–0.415)	< 0.01	< 0.01
Not exposed to ETS at work (ETSW_No)	0.25 (0.245–0.255)	0.367 (0.356–0.378)	0.177 (0.169–0.185)	0.266 (0.25–0.283)	< 0.01	< 0.01
Exposed to ETS at home (ETSH_Yes)	0.257 (0.243–0.273)	0.346 (0.31–0.386)	0.194 (0.166–0.227)	0.298 (0.215–0.415)	< 0.01	< 0.01
Not exposed to ETS at home (ETSH_No)	0.248 (0.243–0.253)	0.367 (0.356–0.378)	0.175 (0.167–0.182)	0.265 (0.249–0.283)	< 0.01	< 0.01
Statistically significant differences	M < F (p < 0.01), NHB > MA > NHW (p<0.01), ETSW_Yes < ETSW_No (p < 0.01)	M < F (p < 0.01)	M < F (p < 0.01), NHB > MA > NHW (p < 0.01)	NHB > NHW (p<0.01), NHB > MA (p<0.01)

Table 4. Adjusted geometric means with 95% confidence intervals for blood cadmium in μg/L and urine cadmium in μg/L by gender, race/ethnicity, and exposure to environmental tobacco smoke (ETS) by age for never smokers

	Blood cadmium		Urine cadmium
	Age: 20–64 years	Age: ≥65 years	Age: 20–64 years	Age: ≥65 years
Males (M)	0.216 (0.185–0.254)	0.37 (0.306–0.448)	0.169 (0.109–0.261)	0.238 (0.17–0.332)
Females (F)	0.288 (0.245–0.338)	0.447 (0.373–0.536)	0.263 (0.172–0.405)	0.362 (0.255–0.513)
Non-Hispanic White (NHW)	0.22 (0.187–0.259)	0.385 (0.322–0.46)	0.172 (0.111–0.269)	0.262 (0.186–0.37)
Non-Hispanic Black (NHB)	0.239 (0.203–0.281)	0.383 (0.317–0.463)	0.196 (0.127–0.303)	0.272 (0.195–0.379)
Mexican American (MA)	0.25 (0.211–0.297)	0.403 (0.332–0.49)	0.239 (0.155–0.37)	0.28 (0.191–0.41)
Other Race/Ethnicity (OTH)	0.295 (0.245–0.354)	0.461 (0.376–0.567)	0.244 (0.158–0.375)	0.371 (0.25–0.55)
Exposed to ETS at work (ETSW_Yes)	0.245 (0.204–0.293)		0.21 (0.135–0.326)
Not exposed to ETS at work (ETSW_No)	0.255 (0.218–0.297)		0.212 (0.138–0.326)
Exposed to ETS at home (ETSH_Yes)	0.233 (0.186–0.292)	0.453 (0.314–0.652)	0.234 (0.141–0.389)	0.316 (0.16–0.624)
Not exposed to ETS at home (ETSH_No)	0.267 (0.238–0.3)	0.366 (0.349–0.384)	0.19 (0.128–0.283)	0.272 (0.251–0.296)
Statistically significant differences	M < F (p < 0.01), NHW < NHB (p = 0.01), NHW < MA (p < 0.01)	M < F (p < 0.01)	M < F (p < 0.01), MA > NHB > NHW (p < 0.01)	M < F (p < 0.01)

Figure 1. Adjusted geometric means in μg/L with 95% confidence intervals for blood cadmium for adults aged 20–64 years by (A) race/ethnicity and exposure to environmental tobacco smoke (ETS) at home (NHW = Non-Hispanic White, NHB = Non-Hispanic Black, MA = Mexican American, OTH = other unclassified race/ethnicities, ETSH_Yes = exposed to ETS at home, ETS_No = not exposed to ETS at home, and (B) exposure to ETS at home and exposure to ETS at work (ETSW_Yes = exposure to ETS at work, ETSW_No = no exposure to ETS at work).

Figure 2. Adjusted geometric means in μg/L with 95% confidence intervals for (A) blood cadmium for adults aged 20–64 years by gender (M = male, F = female) and race/ethnicity (NHW = Non-Hispanic White, NHB = Non-Hispanic Black, MA = Mexican American, OTH = other unclassified race/ethnicities) and (B) urine cadmium for seniors aged ≥ 65 years by gender and race/ethnicity.

Table 5. Regression slopes and percent change in the values of blood and urine cadmium with a unit change* in the values of independent variables for those aged 20–64 years

Independent variable	Blood cadmium			Urine cadmium
	β	p	% change in blood cadmium with a unit change in independent variable	β	p	% change in urine cadmium with a unit change in independent variable
Age	0.00567	< 0.01	1.314	0.02572	< 0.01	6.102
Age^2	−0.00001	0.76	−0.001	−0.00016	< 0.01	−0.037
Log10(Body Mass Index)	−0.26251	< 0.01	−2.534	−0.26865	< 0.01	−2.594
Poverty Income Ratio	0.00091	0.62	0.209	−0.00660	0.09	1.531
Number of cigarette smokers living at home	0.03910	0.15	9.420	−0.08682	0.15	22.131
Number of cigarettes smoked inside home every day	−0.00108	0.40	−0.249	0.00332	0.20	−0.767
Survey year	−0.02457	< 0.01	−5.820	−0.01605	< 0.01	−3.765
Number of hours inhaling other people’s smoke	−0.00379	0.13	−0.876	−0.00856	0.23	−1.990
Consumption of nuts and seeds in grams	0.00023	0.01	0.052	0.00020	0.35	0.045
Consumption of white bread in grams	−0.00002	0.50	−0.004	−0.00007	0.42	−0.015
Consumption of cereals in grams	−0.00011	0.12	−0.025	−0.00045	0.05	−0.103
Consumption of white potatoes in grams	−0.00003	0.36	−0.008	0.00009	0.30	0.020
Consumption of fried potatoes in grams	−0.00001	0.79	−0.003	−0.00010	0.40	−0.023
Consumption of lettuce based salads in grams	0.00008	0.17	0.018	0.00022	0.19	0.050
Consumption of red meat in grams	−0.00002	0.63	−0.004	0.00008	0.35	0.017
Urine creatinine	Not in model			0.00343	< 0.01	0.794
R^2	23.3%			48.9%

* For 10% change in the values of body mass index.

Table 6. Regression slopes and percent change in the values of blood and urine cadmium with a unit change* in the values of independent variables for those aged ≥ 65 years

Independent variable	Blood cadmium			urine cadmium
	β	p	% change in blood cadmium with a unit change in independent variable	β	p	% change in urine cadmium with a unit change in independent variable
Age	0.00444	0.82	1.027	−0.09013	0.04	−23.065
Age^2	0.00002	0.85	0.005	0.00063	0.03	0.146
Log10(Body Mass Index)	−0.16454	< 0.01	−1.581	−0.36357	0.03	−3.526
Poverty Income Ratio	0.00411	0.26	0.951	−0.00029	0.97	−0.067
Number of cigarette smokers living at home	−0.05244	0.55	−12.835	−0.16436	0.28	−46.003
Number of cigarettes smoked inside home every day	−0.00459	0.10	−1.063	0.00185	0.84	0.426
Survey year	−0.01845	< 0.01	−4.341	−0.00787	0.27	−1.828
Consumption of nuts and seeds in grams	−0.00007	0.82	−0.016	−0.00020	0.70	−0.046
Consumption of white bread in grams	0.00003	0.76	0.006	−0.00028	0.16	−0.064
Consumption of cereals in grams	0.00008	0.50	0.019	0.00065	0.20	0.150
Consumption of white potatoes in grams	0.00003	0.67	0.006	0.00013	0.49	0.030
Consumption of fried potatoes in grams	0.00006	0.66	0.013	0.00075	0.04	−0.173
Consumption of lettuce based salads in grams	−0.00003	0.82	−0.007	−0.00024	0.34	−0.056
Consumption of red meat in grams	−0.00008	0.57	−0.018	−0.00001	0.97	−0.001
Urine creatinine	Not in model			0.00436	< 0.01	1.010
R^2	13.8%			45.7%

* For a 10% change in value of body mass index.