Barium intake

Humans can be exposed to barium in the air, water, or food. Numerous studies exist that discuss the distribution of barium in the human body, but they do not always specify route of exposure. It is presumed that the majority of the barium intake is from the oral route. Barium occurs mostly (over 93%) in the bones and teeth of humans. Very little is found in blood plasma or soft tissues but, when it is detected in the organs, it is found in the eye, lungs, skin, and adipose tissue in humans at less than 1 % of total body weight (Schroeder et al. 1972). This information is supported by a number of studies (Bauer et al. 1957 Losee etal. 1974 Miller et al. 1985 Moloukhia and Ahmed 1979 Sowden 1958 Sowden and Stitch 1957 Sowden and Pirie 1958). 

All barium salts, especially the water and acid-soluble compounds, are highly toxic. Barium ion can cause death through ventricular fibrillation of the heart. It is a stimulant to the heart muscle. Intake of a few grams of barium salt can be lethal to humans. The insoluble salts such as barium sulfate, however, have little toxic action. 

No chronic-duration oral MRL was established for barium, despite the observation of a NOAEL and a LOAEL for blood pressure effects in a chronic rat study by Perry et al. (1983,1985,1989), because the resulting MRL would have been approximately 19-50-fold lower than the estimated daily intake of barium from air, water, and dietary sources combined. 

The American Conference of Governmental Industrial Hygienists threshold limit value — time-weighted average is 0.5 mg ml for soluble barium compounds and lOmgmH for barium sulfate. The permissible exposure limit is 0.5 mg m for barium in soluble compounds. The reference dose for barium is 0.07 mg kg day and the tolerable daily intake... 

Animal foodstuffs deliver 74% of iodine, 72% selenium, and 62% lithium intake in humans, while vegetables supply the highest amounts of cadmium (74%), molybdenum (70%), aluminum (70%), potassium (62%), strontium (58%), barium (57%), arsenic (57%), and the lowest amounts of iodine (16%) and lithium (25%). 

In humans, the dietary intake of barium occurs largely from drinking water. For example, German drinking water was found to contain barium levels of between 18 and 614 pg (mean 73 pg L Schulz... 

The untreated poisoning of humans with 3-4g soluble barium is inevitably fatal, though toxic effects may be expected after an oral intake of only 200-500 mg (Reeves... 

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