Barium is an alkaline earth metal found in ores principally as sulphates and carbonates (barite and witherite respectively). The commercial use ranges from getters in electrical tubes, rodenticides, and colourants in paint and as a contrast medium in medical imaging. It is also found in oil and gas drilling muds, stabilizers for plastics, case hardening steels, bricks, tiles and lubricating oils and jet fuel. Barium occurs naturally in food and drinking water. Most exposure occurs through oral ingestion or inhalation of barium containing dust. Foods such as Brazil nuts, seaweed, fish and certain plants may contain high levels of barium. The toxicity of barium is related to the solubility and hence availability of the salt. Barium sulphate (medical contrast) being very insoluble is non-toxic as very little is absorbed. Barium carbonate which dissolves in the stomach acids is readily absorbed, as are barium hydroxide and nitrate, and these compounds are more toxic. Barium has the potential to bio-concentrate. Occupational exposure is generally in the barium mining or processing industries.
Barium exerts its toxicity through its effects on potassium channels; it is a competitive potassium channel antagonist, blocking the passive efflux of potassium from the intracellular compartment, resulting in hypokalaemia. This in turn leads to ventricular tachycardia, unstable blood pressure, muscle weakness and paralysis. Local gastrointestinal effects include abdominal cramps, vomiting and diarrhoea. Nephropathy is considered the most sensitive measure of toxicity with a clear dose response curve in animal studies.
Approximately 90% of the body burden of barium is contained in the bones and teeth; the primary route for excretion is through the faeces.
There is no data correlating exposure levels with blood or urine barium levels.
Lipids/Trace Metals
UBA
Recommended sampling time is POST SHIFT - the last 2 hours to immediately following the end of the working week.
Aliquot to Core laboratory for UCRN
14 days
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