The critical target organ after long-term exposure to Cadmium.

• A. The kidney
• B. The liver
• C. The heart
• D. The lungs

Answer: (A)

Long-term cadmium exposure primarily damages the kidney because cadmium accumulates there and causes direct nephrotoxicity in the proximal tubules. The metal binds to metallothionein, and the complex is filtered and reabsorbed by proximal tubular cells, where it builds up and injures cellular structures, impairing reabsorption. This leads to proximal tubule dysfunction with findings such as proteinuria, glycosuria, aminoaciduria, and phosphate wasting, and can progress to chronic tubulointerstitial nephritis and renal failure with continued exposure. While cadmium can affect other organs, the kidney is the main organ impacted in chronic exposure due to its role in cadmium storage and the long biological half-life of cadmium in renal tissue.