Progress in cadmium-related health effects in persons with high environmental exposure in northwestern Thailand: A five-year follow-up

Abstract

Food-borne cadmium was the principal source of exposure for persons living in the 12 cadmium-contaminated villages in Mae Sot District, Tak Province, northwestern Thailand. This report presents progress in cadmium-related health effects among persons with high cadmium exposure. The study included 436 persons who had urinary cadmium levels ≥5μg/g creatinine and were screened for urinary cadmium, renal function, hypertension, diabetes and urinary stones in 2005 (baseline) and 2010 (5-year follow-up). Study renal biomarkers included urinary excretion of β2-microglobulin (β2-MG), total protein and calcium, serum creatinine and glomerular filtration rate (GFR). The geometric mean level of urinary cadmium statistically significantly reduced from 9.5±1.6μg/g creatinine in 2005 to 8.8±1.6μg/g creatinine in 2010. Compared to baseline, the follow-up examination revealed significant increases in urinary β2-MG (tubular effect), urinary total protein and serum creatinine, and a decrease in GFR (glomerular effects). Progressive renal dysfunctions were similarly observed in persons both with and without reduction in cadmium intake. Significant increases in prevalence of hypertension, diabetes and urinary stones were also detected at follow-up. These three disorders were found to markedly impair renal functions in the study persons. Our study indicates that in persons with prolonged excessive cadmium exposure, toxic health effects may progress even after exposure reduction. Renal damage from cadmium can be due to its direct nephrotoxic effect and also through the related disorders causing nephropathy.