Table 5.

Serum Zn, Cu, Se, and whole blood Cd and Se concentrations in the pooled black shale and reference areas

Black shale areas					Reference areas
Concentration	Median	Mean SD	Range	n	Median	Mean SD	Range	n	p-valuea
Serum Ca mg/l	91.40	91.55 ± 4.12	78.3–102.6	103	93.6	93.53 ± 3.85	85.50–103.3	82	p < 0.001b
Serum Zn mg/l	0.82	0.86 ± 0.16	0.55–1.53	104	0.87	0.87 ± 0.12	0.61–1.21	82	p = 0.122
Serum Cu mg/l	1.15	1.20 ± 0.26	0.79–2.28	104	1.15	1.17 ± 0.24	0.60–1.90	82	p = 0.610
Serum Se µg/l	92.25	91.53 ± 10.53	69.50–113.0	104	91.50	92.26 ± 15.18	48.50–148.0	80	p = 0.975
cB-Se µg/l	102.00	101.47 ± 10.73	76.00–125.0	97	98.50	101.12 ± 21.53	67.50–210.0	82	p = 0.180
cB-Cd µg/l	0.25	0.37 ± 0.42	0–2.73	98	0.21	0.41 ± 0.73	0.03–5.00	82	p = 0.425

^aMann–Whitney U-test: between black shale and reference areas (pooled data of Sotkamo and Kaavi)

^bT-test: between black shale and reference areas (pooled data of Sotkamo and Kaavi)

^cB-Se = whole blood Se, ^bB-Cd = whole blood Cd