. Author manuscript; available in PMC: 2012 Jan 1.

Published in final edited form as: J Expo Sci Environ Epidemiol. 2010 Jun 30;21(4):355–364. doi: 10.1038/jes.2010.19

Table 1.

ICP-MS measured element concentrations in blank filter paper by lot (ng/spot).

	W-031¹				W-041¹				W-051¹
Variable	Median	Mean	Std Dev	%CV	Median	Mean	Std Dev	%CV	Median	Mean	Std Dev	%CV	p-value²
Al	105.78	112.57	57.54	51%	20.35	23.67	6.88	29%	25.81	56.95	70.25	123%	0.0376
Ba	14.76	14.84	2.51	17%	11.66	11.39	1.07	9%	3.14	3.06	1.02	33%	0.0002
Ca	7 338.50	7 445.68	495.36	7%	6 846.11	6 686.19	748.40	11%	4 892.98	4 733.23	647.97	14%	0.0002
Cd	0.14	0.15	0.02	14%	0.13	0.13	0.01	10%	0.02	0.02	0.01	57%	0.0002
Ce	0.21	0.22	0.03	13%	0.16	0.16	0.03	18%	0.02	0.04	0.05	152%	0.0002
Co	1.48	1.61	0.23	14%	1.17	1.26	0.28	22%	1.89	1.90	0.28	15%	0.0376
Cr	0.27	0.36	0.22	61%	0.28	0.30	0.11	38%	0.26	0.36	0.25	70%	0.8145
Cs³	3.22	5.41	4.83	89%	1.55	2.33	1.86	80%	2.52	10.51	29.07	277%	0.2921
Cu	13.19	14.53	3.93	27%	3.43	4.17	1.29	31%	3.14	3.70	2.06	56%	0.0376
Fe	79.65	84.10	16.86	20%	76.61	77.95	6.09	8%	49.41	53.27	23.30	44%	0.0029
K	67.51	71.86	10.81	15%	111.65	110.74	61.83	56%	256.93	259.56	54.06	21%	0.0006
Li	0.06	0.12	0.08	69%	0.09	0.09	0.03	35%	0.21	0.27	0.13	48%	0.0376
Mg	1 095.89	1 072.89	98.17	9%	1 322.12	1 300.07	104.43	8%	1501.26	1 523.28	72.37	5%	0.0006
Mn	34.07	34.36	3.13	9%	21.40	21.35	1.36	6%	5.37	5.82	1.10	19%	0.0002
Mo	0.06	0.16	0.17	106%	0.02	0.06	0.13	227%	0.19	0.22	0.24	110%	0.2921
Na	1 919.67	1 921.40	100.31	5%	2 497.40	2 385.04	382.10	16%	3 321.83	3 116.59	809.64	26%	0.0006
Ni	0.89	0.90	0.14	15%	0.62	0.60	0.15	24%	0.57	0.55	0.36	67%	0.0376
P	314.67	309.09	38.59	12%	373.30	386.53	58.43	15%	45.82	50.22	80.98	126%	0.0002
Pb	0.75	24.81	53.33	3%	0.51	0.57	0.33	57%	0.21	0.86	1.23	142%	0.2921
Rb	0.09	0.08	0.04	46%	0.11	0.11	0.04	33%	0.26	0.27	0.05	19%	0.0006
S	317.47	317.55	49.99	16%	355.16	363.54	65.65	18%	646.41	649.67	85.90	13%	0.0006
Sb³	3.94	44.90	100.07	223%	−1.31	1.16	21.95	1900%	6.82	8.53	36.72	430%	0.8145
Sr	13.67	13.46	1.04	8%	11.08	11.36	1.41	12%	7.26	7.95	1.64	21%	0.0029
Ti	1.31	1.32	0.83	63%	0.50	0.64	0.75	117%	0.63	2.86	7.16	250%	0.1749
Tl³	0.00	0.81	2.11	260%	1.14	1.55	1.76	113%	1.44	1.88	1.76	93%	0.2921
U³	9.70	10.35	1.71	17%	5.59	5.90	0.78	13%	4.19	4.64	2.93	63%	0.0174
V	0.08	0.09	0.03	32%	0.09	0.09	0.02	24%	0.12	0.15	0.10	66%	0.2921
Zn	18.81	17.76	5.17	29%	13.95	0.24	25.50	10836%	6.30	7.08	37.38	528%	0.0174

The number of samples for each of the three lots: W-031, W-041, and W-051, was 5, 5, and 15 respectively.

Calculated by Brown-Mood median test

Expressed as picograms/spot