Feces cadmium

Biological half-times of cadmium in humans are lengthy. Based on body burden and excretion data, cadmium may remain in the human body for 13-47 years. Although cadmium is excreted primarily in urine and feces, cadmium tends to increase in concentration with age of the organism and eventually acts as a cumulative poison. These phenomena have not been documented adequately in wildlife species. 

Severe illness and death can occur from exposure to many cadmium compounds. It is absorbed in the gastrointestinal tract. However, it can be eliminated in the urine and feces in young, healthy people. 

Gregus and Klaassen carried out a comparative study of fecal and urinary excretion and tissue distribution of eighteen metals in rats after intravenous injection. Total (fecal + urinary) excretion was relatively rapid (over 50% of the dose in 4 days) for cobalt, silver and manganese between 50 and 20% for copper, thallium, bismuth, lead, cesium, gold, zinc, mercury, selenium and chromium and below 20% for arsenic, cadmium, iron, methylmercury and tin. Feces was the predominant route of excretion for silver, manganese, copper, thallium, lead, zinc, cadmium, iron and methylmercury whereas urine was the predominant route of excretion of cobalt, cesium, gold, selenium, arsenic and tin. Most of the metals reached the highest concentration in liver and kidney. However, there was no... 

Saliva is not an important route of excretion since most of the chemicals present in saliva will eventually reach the gastrointestinal tract to be reabsorbed or eliminated in the feces. The unbound fraction of several therapeutic drugs may diffuse passively from plasma into saliva. This provides a noninvasive means of indirectly monitoring plasma concentrations of drugs like lithium, phenytoin, and theophylline. Metals like lead, cadmium, and mercury are also present in saliva. 

Kjellstrom, T., Borg, K. and Lind. B. (1978). Cadmium in feces as estimation of daily cadmium intake in Sweden. Environ. Res. 15. 242-251. 

FIG. 6.26 Atomic-force microscopy 3-D topography image (20 pm x 20 pm x 200 nm) of the sur-fece-relief grating on 100-layer mixed LBK film of polymer 44 and cadmium stearate deposited on glass (reproduced from reference 121 with permission. Copyright (1American Chemical Society). 

The major route of excretion of cadmium is via feces and bile. Approximately 95% of oral cadmium dose is excreted in the feces due to the poor absorption of cadmium from the GI tract. Urinary excretion of cadmium may become significant after the onset of renal damage. 

The excretion of cadmium via the urine and feces is very low in normal human beings and the biological half-life is probably between 10 and 30 yr for the total body. ... 

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