Heavy metal poisoning: the effects of cadmium on the kidney

Abstract

The heavy metal cadmium (Cd) is known to be a widespread environmental contaminant and a potential toxin that may adversely affect human health. Exposure is largely via the respiratory or gastrointestinal tracts; important non-industrial sources of exposure are cigarette smoke and food (from contaminated soil and water). The kidney is the main organ affected by chronic Cd exposure and toxicity. Cd accumulates in the kidney as a result of its preferential uptake by receptor-mediated endocytosis of freely filtered and metallothionein bound Cd (Cd-MT) in the renal proximal tubule. Internalised Cd-MT is degraded in endosomes and lysosomes, releasing free Cd(2+) into the cytosol, where it can generate reactive oxygen species (ROS) and activate cell death pathways. An early and sensitive manifestation of chronic Cd renal toxicity, which can be useful in individual and population screening, is impaired reabsorption of low molecular weight proteins (LMWP) (also a receptor-mediated process in the proximal tubule) such as retinol binding protein (RBP). This so-called 'tubular proteinuria' is a good index of proximal tubular damage, but it is not usually detected by routine clinical dipstick testing for proteinuria. Continued and heavy Cd exposure can progress to the clinical renal Fanconi syndrome, and ultimately to renal failure. Environmental Cd exposure may be a significant contributory factor to the development of chronic kidney disease, especially in the presence of other co-morbidities such as diabetes or hypertension; therefore, the sources and environmental impact of Cd, and efforts to limit Cd exposure, justify more attention.

Electrochemical Determination of the Levels of Cadmium, Copper and Lead in Polluted Soil and Plant Samples from Mining Areas in Zamfara State, Nigeria

“…The kidney is the main organ affected by the chronic Cd exposure and toxicity. Cadmium accumulates in the kidney which may result in renal failure [25].…”

Harmful Interactions of Non-Essential Heavy Metals with Cells of the Innate Immune System

“…Cd is also present in tobacco, with each cigarette containing 1-3 µg of the metal, predisposing both active and passive smokers to the toxic effects of Cd inhalation [11]. In welders, acute exposure to Cd may lead to pneumonitis, pulmonary edema and death, with a Parkinsonism-like neurological disorder being a late effect of acute toxicity [1].…”

The Non-carcinogenic Risk of Cadmium in Bottled Water in Different Age Groups Humans: Bandar Abbas City, Iran

“…Cadmium's biological half-life in bone and kidney is 38 and 10 years, respectively (16). Chronic exposure to cadmium causes kidney failure and itai-itai disease (osteoporosis and severe pain) (17,18). The standard limit of WHO and EPA for Cd in bottled drinking water is 3 and 5 µg/lrespectively (19,20).…”