Table 4.

Median values and ranges (2%–max) for Mn and Ni concentrations in hair and water from Quaternary deposit and bedrock wells in the black shale and reference areas of this study (pooled) and median Mn and Ni concentrations in well water for the whole of Finland (Lahermo et al., 2002)

	Black shale area		Reference area		Well water in Finlandd
	Quaternary deposit wells (n = 49)	Bedrock wells (n = 15)	Quaternary deposit wells (n = 11)	Bedrock wells (n = 17)	Quaternary deposit wells (n = 739)	Bedrock wells (n = 263)
Water Mn µg/l
Median	5.07a, b	24.9b	1.77a, c	7.84c	4.36	16.3
2%–maximum	0.34–1620	0.28–172	0.42–12.90	0.94–289	0.1–5330	0.2–4140
Hair Mn mg/kg
Median	0.94	2.03	0.83c	1.37c
2%–maximum	0.20–11.1	0.27–9.04	0.25–9.83	0.21–36.44
Water Ni µg/l
Median	3.83b	0.65b	4.55c	1.17c	0.84	0.595
2%– maximum	0.32–51.0	0.15–8.15	1.10–8.87	0.03–9.15	0.06–277	< 0.06–67.50
Hair Ni mg/kg
Median	0.85b	0.49b	0.86	0.77
2%–maximum	0.15–12.3	0.15–2.2	0.44–4.3	0.15–8.0

^aMann–Whitney U-test: difference in Mn concentrations in water between Quaternary deposit wells of black shale and reference areas, p = 0.018

^bMann–Whitney U-test: difference in Mn and Ni concentrations between Quaternary deposit and bedrock wells in the black shale areas, Mn in water p = 0.002, Ni in water p < 0.001, Ni in hair p = 0.007

^cMann–Whitney U-test: difference in Mn and Ni concentrations between Quaternary deposit and bedrock wells of the reference areas, Mn in water p = 0.006, Mn in hair p = 0.047, Ni in water p = 0.003

^dLahermo et al. (2002)