A cross-sectional study on school-age children living near a municipal waste incinerator: Urinary metal levels and renal impairment assessment.

To take an insight into the long-term accumulation of chromium (Cr) and cadmium (Cd) in school-age children living near an MWI and to assess their early renal impairment, we conducted a cross-sectional study in 2015. A total of 116 children from the exposure area and 122 from the control area were recruited. We measured the urinary levels of Cr (U-Cr) and Cd (U-Cd) by inductively coupled plasma mass spectrometry (ICP-MS), and detected three classic renal tubule indicators, including N-acetyl-β--glucosaminidase (NAG), β2-microglobulin (BMG), and retinol binding protein (RBP). The U-Cd and U-Cr levels in children living near the MWI were 0.11 and 1.57 μg/g creatinine, respectively. Both the U-Cd and U-Cr levels in the exposure group were lower than those in the control group, although only U-Cd showed a statistical difference (p < 0.01). The U-NAG and U-RBP levels in the exposure group were also statistically lower than those in the control group (0.80 vs. 1.74 IU/g creatinine, 0.26 vs. 0.48 mg/g creatinine, respectively). The U-Cd level in this study was positively correlated with the U-NAG level (r = 0.26, p < 0.01), as the U-Cr level was also positively correlated with the levels of U-NAG, U-RBP, and U-BMG (r = 0.21, 0.33, 0.18, p < 0.01, respectively). This study indicates that children living close to this particular MWI may not suffer considerable long-term accumulation of Cd or Cr, nor early renal impairment.