Prospective associations between environmental heavy metal exposure and renal outcomes in adults with chronic kidney disease.

Abstract

In Taiwan, Changhua County residents were exposed to high heavy metal pollution and exhibited high heavy metal levels in blood and urine. We examined associations between heavy metals in residential soil and renal outcomes of residents with chronic kidney disease (CKD). From 1 January 2003 to 30 June 2015, we retrospectively identified CKD patients with an estimated glomerular filtration rate of <60mL/min per 1.73m2 at one tertiary care centre. We linked data displaying heavy metal concentrations from farm soil adjacent to the patients' residences to clinical outcomes. We included 2343 CKD patients (533 with progression to end-stage renal disease [ESRD] and 1810 without]. We followed these patients for 3.49±2.27years, until death or initiation of maintenance dialysis. There were high correlations among the concentrations of the eight metals: arsenic, cadmium, chromium, mercury, copper, lead, nickel, and zinc. After factor analysis, chromium, copper, nickel, and zinc were grouped and labelled Factor 1. High Factor 1 concentration near the patients' residences was associated with diagnoses of hypertension, diabetes mellitus, and cerebral vascular accident. Patients living in areas with high Factor 1 concentrations were at higher risk of ESRD. After multivariate adjustment [adjusted hazard ratio: 1.08, 95% Confidence interval: 1.01-1.14, P=0.02], only zinc and nickel were risk factors for progression to ESRD. Patients with CKD, with long-term exposure to soil-based heavy metals, had rapid progression to ESRD. Groups of minerals from the same source of contamination may accumulate and lead to additional harm.