. 2015 Sep 15;124(4):468–476. doi: 10.1289/ehp.1409551

Table 2.

The variance apportionment of log₁₀-transformed creatinine-corrected metal concentrations in the three sample types collected from 11 adults during a 3-month period.

Type of sample	As	Cd	Co	Cu	Pb	Mo	Ni
Spot sample (n = 529)
ICC	0.19	0.53	0.29	0.08	0.05	0.02	0.01
Between persons σ² (%)^a	0.012 (19)	0.046 (53)	0.027 (29)	0.010 (8)	0.009 (5)	0.002 (2)	0.001 (1)
(95% CI)^b	(0.000, 0.025)	(0.010, 0.082)	(0.004, 0.050)	(0.000, 0.021)	(–0.003, 0.021)	(–0.004, 0.008)	(–0.005, 0.007)
Within person, between day σ² (%)^c	0.026 (39)	0.016 (18)	0.022 (24)	0.020 (17)	0.023 (13)	0.038 (34)	0.163 (36)
(95% CI)^b	(0.018, 0.034)	(0.011, 0.021)	(0.014, 0.030)	(0.011, 0.031)	(0.010, 0.036)	(0.025, 0.051)	(0.111, 0.217)
Within person, within day σ² (%)^d	0.028 (42)	0.025 (29)	0.043 (47)	0.088 (75)	0.149 (82)	0.071 (64)	0.281 (63)
(95% CI)^b	(0.025, 0.031)	(0.022, 0.028)	(0.038, 0.048)	(0.078, 0.098)	(0.132, 0.165)	(0.063, 0.079)	(0.248, 0.310)
First morning sample (n = 88)^e
ICC	0.28	0.68	0.55	0.20	0.14	0.02	0.01
Between person σ² (%)^a	0.016 (28)	0.059 (68)	0.059 (55)	0.015 (20)	0.011 (14)	0.002 (2)	0.001 (1)
(95% CI)^b	(0.001, 0.031)	(0.014, 0.102)	(0.011, 0.107)	(–0.001, 0.032)	(–0.004, 0.026)	(–0.009, 0.013)	(–0.007, 0.011)
Within person σ² (%)^c	0.041 (72)	0.027 (32)	0.049 (45)	0.059 (80)	0.069 (86)	0.094 (98)	0.220 (99)
(95% CI)^b	(0.030, 0.052)	(0.020, 0.034)	(0.036, 0.062)	(0.043, 0.075)	(0.051, 0.087)	(0.069, 0.119)	(0.166, 0.274)
24-hr collection (n = 88)^e
ICC	0.29	0.70	0.50	0.12	0.07	0.02	0.01
Between person σ² (%)^a	0.013 (29)	0.048 (70)	0.034 (50)	0.009 (12)	0.006 (7)	0.001 (2)	0.001 (1)
(95% CI)^b	(–0.112, 0.138)	(0.012, 0.087)	(0.006, 0.062)	(–0.004, 0.022)	(–0.006, 0.018)	(–0.056, 0.059)	(–0.067, 0.070)
Within person σ² (%)^c	0.032 (71)	0.021 (30)	0.034 (50)	0.065 (88)	0.079 (93)	0.049 (98)	0.153 (91)
(95% CI)^b	(0.024, 0.040)	(0.016, 0.026)	(0.024, 0.044)	(0.047, 0.083)	(0.058, 0.100)	(0.036, 0.062)	(0.115, 0.191)
σ² = variance. ^aThe proportion of between-person variance to the total variance. ^bConfidence intervals for the variance components. ^cThe proportion of within-person between-day variance to the total variance. ^dThe proportion of within-person within-day variance to the total variance. ^eFor first morning and 24-hr urine collections, the distinction between within-day vs. between-day variability is not applicable with only one measurement per day.