Heavy metals and pesticides in chronic kidney disease - Results from a matched case-control study from a rural population in Shivamogga district in South India

Abstract

Introduction: There is a high prevalence of chronic kidney disease (CKD) in the rural agrarian population of South India and it often appears unrelated to major known causes such as diabetes or glomerulonephritis. Methods: In a matched case-control study conducted in a rural population in Shivamogga district in South India, the association of heavy metals - lead (Pb), arsenic (As), cadmium (Cd) - and pesticides in CKD was studied. Blood and spot urine samples were tested quantitatively for heavy metals and qualitatively for pesticides. Results: In all, 69 matched pairs (40 female, 58%) were recruited. The mean estimated glomerular filtration rate (mL/min/1.73 m2) was 60.1 (14.2) in cases and 83.4 (13.4) in controls. Elevated blood lead level >5 μg/dL was seen in 15 cases and 25 controls, respectively [P = 0.035, matched odds ratio (MOR) 0.5, 95% confidence interval (CI) 0.22-1.05]. Urinary Pb was elevated in 16 cases and 13 controls, respectively (P = 0.28, MOR 1.25, 95% CI 0.58-2.73). There was no significant association with As and Cd, while pesticide residues were undetectable in cases as well as controls. These results did not change even after excluding CKD cases with diabetes, stage 2 hypertension, and significant proteinuria. Conclusions: There was no statistical significant association between any of the studied heavy metals and CKD, although there was a significant burden of heavy metals in the studied subjects.