in both 1998 and 2006 were carried out with the approval of the Ethics Committee of Fudan University and local authorities. All the participants gave written informed con- sent before the study. Results At baseline in 1998, urinary albumin, β2-microglobulin, and NAG levels were all significantly higher in residents of the highly polluted area than in residents of the control area (Table 2; all p < 0.001). BCd decreased among all those surveyed in 2006, especially in the two polluted areas, whereas UCd decreased only in the highly polluted area (Table 2). Although both NAG and β2-microglobulin increased in individuals from all areas (p < 0.01), albumin tended to decrease, with a highly significant decline in the highly polluted area (p < 0.01). In 2006, the serum creatinine concentra- tion was higher in the highly polluted area than in the other two areas (p < 0.01), but there were no differences in estimated GFR (eGFR) between the nonpolluted area and polluted areas (Table 2). The eGFR in 2006 was significantly decreased only in those with the highest UCd in 1998 (> 20 μg/g creatinine) compared with participants who had < 2 gμ/g creatinine UCd (Table 3). The predictivity, on an individual basis, of the different biomarkers of kidney varied (Table 4). The probability of having an ele- vated β2-microglobulin (above the cut point) in 2006 was clearly associated with ele- vated β2-microglobulin in 1998 [odds ratio (OR) = 24.8; 95% confidence interval (CI): 11.2, 55.3). In contrast, much weaker signifi- cant associations were found between elevated albumin and NAG in 1998 and elevated values in 2006. Prevalence curves for kidney dysfunction in 1998 and 2006 in relation to UCd in 1998 are shown in Figure 1. The prevalence curve for elevated NAG in 2006 was slightly below the one for 1998, suggesting some recov- ery of kidney function after exposure was reduced, but the difference was not statisti- cally significant (p = 0.06 for a decrease in the group with UCd > 20 μg/g creatinine). For β2-microglobulin the difference between the prevalence curves was far from statistically sig- nificant (p = 0.29 for a decrease in the group with UCd > 20 gμ/g creatinine). In contrast, the prevalence curve for elevated albumin in 2006 was unrelated to UCd, despite a clear Table 3. Serum creatinine and eGFR in 2006, by 1998 UCd group [median (range)]. 1998 UCd group (μg/g creatinine) Serum creatinine (μmol/L) eGFR (mL/min/1.73 m2) 93 (60–119) 92 (52–118) 92 (55–120) 90 (46–121) 84 (38–109)* Renal function after reduction in Cd exposure association in 1998 (p < 0.05 for a decrease in the three groups with UCd > 5 gμ/g creati- nine), suggesting that effects of exposure on albumin excretion were temporary. T h e t e n d e n c y t o w a r d r e c o v e r y i n β2-microglobulin in 2006 after exposure in 1998 appeared to be driven by recovery in individuals < 50 years of age at baseline, but sample sizes were small and differences were not statistically significant (Figure 2). Stratification by sex (Figure 3) did not indicate any major sex difference for β2-microglobulin or albumin. For NAG, however, the prevalence curve for men tended to be higher in 2006 than in 1998, whereas the opposite pattern appeared for women, suggesting the possibil- ity of impairment in men but improvement in women. We also compared baseline charac- teristics between participants evaluated in 2006 and those lost to follow-up [see Supplemental Material, Table 1 (http://dx.doi.org/10.1289/ ehp.1103699)]. Some differences appeared for age, β2-microglobulin, and albumin, but not in a systematic manner. Mean baseline UCd and BCd levels were comparable, although BCd in the moderately polluted area was sta- tistically significantly lower in those lost to follow-up [GMs (IQRs) were 3.04 (1.88–5.00; see Supplemental Material, Table 1] compared with 3.78 (2.50–6.50) μg/L in the present study (Table 2). We also analyzed data for all subjects evaluated in 2006, including individu- als who were > 80 years of age, had high blood pressure, or were on any physician-prescribed medication. The results were similar to those reported in Table 2 (see also Supplemental Material, Table 2). *p < 0.05 compared with the 0–2 group, by Mann‑Whitney U‑ test. Table 4. The relationship between kidney function in 1998 and in 2006, as reflected by urinary NAG, β2‑microglobulin, and albumin. Kidney function indicator Normal in 2006 (n) Elevated in 2006 (n) Normal in 2006 (n) Elevated in 2006 (n) Normal in 1998 Elevated in 1998 Age‑adjusted cut points were as follows: NAG, 9.8 U/g creatinine in 1998 and 16.6 U/g creatinine in 2006; β2‑microglobulin, 0.890 mg/g creatinine in 1998 and 1.028 mg/g creatinine in 2006; albumin, 14.6 mg/g creatinine in 1998 and 21.7 mg/g creatinine in 2006. 92 12 58 36 23 8 OR (95% CI) 2.6 (1.6, 4.4) 24.8 (11.2, 55.3) 3.0 (1.2, 7.5) NAG β2-Microglobulin Albumin 0–2 2–5 5–10 10–20 > 20 80 70 ) 60 % ( ce 50 n lae 40 v rpe 30 G AN 20 10 0 1998 2006 n 66 125 99 83 39 247 350 331 66 (45–100) 69 (47–112) 68 (31–113) 68 (39–112) 73 (45–130) 37 27 15 80 70 ) 60 % ( ce 50 n lae 40 v rpe 30 Mβ2 20 10 0 80 70 ) (% 60 e nce 50 l vea 40 r inp 30 lbum 20 A 10 0 0 5 10 15 20 25 30 UCd (µg/g creatinine) in 1998 35 0 5 10 15 20 25 30 UCd (µg/g creatinine) in 1998 35 0 5 10 15 20 25 30 UCd (µg/g creatinine) in 1998 35 Figure 1. Prevalence of renal dysfunction in relation to 1998 UCd level shown by increased excretion of NAG (A), β2‑microglobulin (β2M; B), and albumin (C) above the cut points. Environmental Health Perspectives • volume 120 | number 2 | February 2012 225