Table 3: Reference values for the United States population (in μg/L), NHANES 2005-2006 [110].

MetalAges (years)SpecimenGeometric mean (95% CI)50th percentile (95% CI)95th percentile (95% CI)

Arsenic6–11U7.19 (5.81–8.90)6.96 (5.32–8.88)34.1 (19.6–58.5)
UCC8.88 (7.05–11.2)7.87 (6.19–9.42)45.4 (22.9–80.9)
12–19U8.19 (6.87–9.77)7.92 (6.37–9.50)41.9 (32.7–48.0)
UCC6.30 (5.56–7.14)5.19 (4.80–6.19)28.0 (21.9–33.2)

Cadmium1–5 WBNA*NA0.230 (0.210–0.250)
6–11WBNANA0.260 (0.230–0.280)
12–19WBNANA0.960 (0.820–1.08)
6–11
U0.066 (0.056–0.078)0.060 (0.050–0.080)0.240 (0.160–0.290)
UCC0.081 (0.072–0.092)0.080 (0.070–0.090)0.200 (0.180–0.240)
12–19 U0.099 (0.090–0.109)0.110 (0.100–0.120)0.310 (0.250–0.430)
UCC0.076 (0.071–0.081)0.080 (0.070–0.090)0.210 (0.160–0.240)

Lead1–5 WB1.46 (1.36–1.57)1.43 (1.34–1.55)3.80 (3.49–4.54)
6–11 WB1.02 (0.948–1.10)0.970 (0.890–1.01)3.00 (2.26–3.81)
12–19 WB0.797 (0.746–0.852)0.740 (0.690–0.790)2.23 (1.98–2.46)

Mercury1–5 WBNANA1.43 (1.25–1.59)
6–11 WBNA0.410 (0.330–0.460)2.34 (1.53–3.42)
12–19 WB0.513 (0.461–0.570)0.460 (0.390–0.530)2.41 (2.12–2.90)
6–11
U0.333 (0.267–0.416)0.320 (0.250–0.390)2.18 (1.28–3.40)
UCC0.411 (0.323–0.524)0.390 (0.290–0.500)2.55 (1.38–3.50)
12–19 U0.372 (0.286–0.486)0.350 (0.270–0.470)2.59 (1.40–4.45)
UCC0.286 (0.230–0.356)0.260 (0.200–0.320)1.76 (1.11–2.67)

U: urine; UCC: urine, creatinine corrected (in μg/g of creatinine); WB: whole blood.
Lead measurements reported in μg/dL.
*NA: not available or not calculated due to low detection frequency.