ABSTRACT
Objective: Cadmium (Cd) is a cumulative poison. Long-term exposure to environmental Cd causes oxidative stress, renal dysfunction and bone defects. The present study aimed to investigate the status of renal impairment and risk of urolithiasis in inhabitants environmentally exposed to Cd in Mae Sot District, Tak Province of Thailand. Methods: A total of 77 non-smoking women were recruited to the study, 40 subjects from high Cd-polluted areas (Group 1), 17 subjects from the vicinity of Cd-polluted areas (Group 2) and 20 control subjects from non Cd-polluted areas living outside the Mae Sot District (Group 3). Blood and 24-hr urine samples were collected. Plasma creatinine (Cr), calcium (Ca), magnesium (Mg) and zinc (Zn) were measured. Levels of Cd, Zn, Mg, Ca, Cr, proteins and N-acetyl-β-glucosaminidase (NAG) activity were determined from urine samples. Results: Group 1 and Group 2 excreted urinary Cd significantly higher than Group 3. The prevalence of urinary Cd \> 2 mg/g Cr in Group 1, Group 2 and Group 3 were 25%, 11.8% and 0%, respectively. Creatinine clearance (CCr) of Group 1 was significantly lower than that of Group 2. Urinary excretions of proteins, Ca and Zn in Group 1 were significantly higher than in Group 2. Urinary levels of NAG activity and proteins in Group 1 were significantly higher than in Group 3. The urinary level of Ca in Group 1 was significantly higher than in Group 3. In contrast, urinary Mg in Group 1 was significantly lower than that in Group 3. In Group 1, urinary Cd was positively correlated with urinary NAG activity, proteins and Zn, but it was inversely correlated with CCr. Conclusion: The residents of high Cd-polluted areas had renal impairment, increased urinary Ca and decreased urinary Mg. Subjects who resided in the vicinity, manifested kidney damage. These local populations are at risk for kidney diseases, particularly urolithiasis.