Environmental epidemiological study and estimation of benchmark dose for renal dysfunction in a cadmium-polluted area in China

Abstract

We have performed a study aimed at investigating the critical concentration of urinary cadmium (UCd) required for the development of renal dysfunction. We studied population groups (totally 790 persons) living in two cadmium exposed areas and one control area in China. UCd, was determined as an indicator of cadmium exposure and accumulation, while the concentrations of N-acetyl-beta-D-glucosaminidase (NAG), its iso-form B (NAG-B), beta2-microglobulin (B2M), retinol binding protein (RBP), and albumin (ALB) in urine were measured as indicators of the renal effects caused by cadmium. There was a significantly increased prevalence of hyperNAGuria, hyperNAG-Buria, hyperB2Muria, hyperRBPuria and hyperALBuria with increasing levels of Cd excretion in urine. We used the benchmark dose (BMD) procedure to estimate the critical concentration of urinary cadmium in this general population. The lower confidence limit of the BMD (LBMD-05) of urinary cadmium for a 5% level of risk above the background level was estimated for each of the renal effect indicators. The BMD-05/LBMD-05 were estimated to be 4.46/3.99, 6.70/5.87, 8.36/7.31, 7.98/6.98 and 15.06/12.18 microg/g creatinine for urinary NAG-B, NAG, B2M, RBP and ALB, respectively. Our findings suggest, based on the present study, that the Lower Confidence Limit of the Population Critical Concentration of UCd (LPCCUCd-05) of tubular dysfunction for 5% excess risk level above the background may be ca. 3-4 microg/g creatinine, and that cadmium concentration in urine should be kept below this level to prevent renal tubular damage. This report is the first to use the BMD method in this field and to define the concept of critical concentration in urine.

Application of Cloud Point Extraction for Cadmium in Biological Samples of Occupationally Exposed Workers: Relation Between Cadmium Exposure and Renal Lesion

“…Also, urinary β 2 M was correlated with urine Cd (r=0.43, p<0.05). These findings which indicate tubular damage of the exposed workers are in agreement with other studies [39,40]. Also, we can suggest that the exposure to Cd in the soldering iron workers is not intense enough to produce glomerular injur y as indicated by the normal albuminuria.…”

Heavy metal poisoning: the effects of cadmium on the kidney

“…Calculated bMD varies in each study, because of differences in the populations studied, the marker of proteinuria used (RBP, NAG or b 2 M), and the threshold chosen for bMD: 5% or 10% above 'background' prevalence of tubular proteinuria. bMD calculated in these studies varies from 0.71 lg/g creatinine (de Burbure et al 2006) in children to 3-4 lg/g creatinine in adults (Jin et al 2004).…”

“…There is a good correlation between increasing levels of urinary Cd and increased urinary excretion of RBP (Jin et al 2004), b 2 M (Hong et al 2004, and NAG (Uno et al 2005); serum urea or creatinine, and albuminuria, are too insensitive. The Cadmibel study in Belgium was the first to link urinary Cd with tubular proteinuria in a population study, demonstrating a dose-effect relationship between urinary Cd and tubular proteinuria.…”

Cadmium reduces adipocyte size and expression levels of adiponectin and Peg1/Mest in adipose tissue

“…The sources of Cd exposure are foods, including rice, fish, and shellfish, and cigarette smoke. As Cd has a long biological half-life (15-20 years) in man (Jin et al, 2004;Swiergosz-Kowalewska, 2001), studies on the adverse effects of chronic Cd exposure on various tissues are required.…”