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

AimIn 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). MethodFrom 1 January 2003 to 30 June 2015, we retrospectively identified CKD patients with an estimated glomerular filtration rate of <60mL/min per 1.73m(2) 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 3.492.27years, until death or initiation of maintenance dialysis. ResultsThere 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. ConclusionPatients 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. Summary at a Glance In this study, researchers from Taiwan examined associations between heavy metal concentrations in soil and the clinical outcomes in a cohort of patients with CKD. Higher heavy metal concentrations in farms nearby patients' residences were associated with a higher risk of progression to end-stage kidney disease. However, the mechanisms underlying this association are unclear and further study is required.