Table 6. Prevalence of hyper-U-β₂M and hyper-U-NAG corresponding to U-Cd intervals among subjects from county A (CA) and county B (CB) at different cadmium exposure levels¹.

U-Cd intervals (µg/g cr) 2	CA					CB
		Hyper-U-NAG		Hyper-U-β2M			Hyper-U-NAG		Hyper-U-β2M
	Median of U-Cd (µg/g cr)	+/−	%	+/−	%	Median of U-Cd (µg/g cr)	+/−	%	+/−	%
<Q1	1.44	8/59	11.94	3/64	4.08	0.72	2/53	3.64	2/53	3.64
Q1–Q2	3.43	5/63	7.35	6/62	6.67	1.72	6/49	10.91	8/47	14.55
Q2–Q3	5.97	11/56	16.42	10/57	17.39	3.80	3/53	5.36	8/48	14.28
>Q3	13.80	24/43	35.82	12/55	15.09	12.36	12/43	21.82	27/28	49.10
Total	4.47	48/221	17.84	31/238	11.52	2.86	23/198	10.41	45/176	20.36
Linear trend test		χ2 = 14.876, P<0.001		χ2 = 7.055, P = 0.008			χ2 = 7.015, P = 0.008		χ2 = 31.194, P<0.001

¹The 90^th percentiles of U-β₂M and U-NAG of the control group were assumed as the thresholds of hyper-U-β2M and hyper-U-NAG, respectively.

²U-Cd intervals were divided according to the three corresponding quartiles (i.e., Q₁ = 2.38 µg/g cr_, Q₂ = 4.47 µg/g cr, and Q₃ = 8.59 µg/g cr in CA; and Q₁ = 1.16 µg/g cr_, Q₂ = 2.86 µg/g cr, and Q₃ = 6.88 µg/g cr in CB).

U-β2M, urinary level of β2-microglobulin; U-NAG, urinary level of N-acetyl-β-D-glucosaminidase; U-Cd, urinary level of cadmium.