Arsenic

Arsenic exists as both organic and inorganic forms, neither has any known biological function. Inorganic and organic arsenic salts are well absorbed when ingested and are rapidly distributed to the skin, nails, and hair where it binds to keratin. Arsenic exists as a number of species and oxidation states having marked differences in toxicity. If taken acutely, arsenic can cause diarrhoea and acute renal failure. If exposure is chronic, then abdominal pain, upper respiratory tract difficulty can develop. Organic forms of arsenic are relatively non-toxic. Arsenic can be measured in both urine and whole blood; however urine is the preferred sample. Organic arsenic is present in seafood and therefore it should be excluded from the diet for 5 days before a sample is taken.