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Barium poisonings are uncommon and usually result from accidental contamination of food sources, suicidal ingestion, or occupational inhalation exposure. Accidental mass poisoning has occurred from the addition of barium carbonate to flour and the contamination of table salt. The incidence of barium poisoning in developing countries is much higher than in developed countries.
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Barium is a dense alkaline earth metal that exists in nature as a divalent cation in combination with other elements. The water-soluble barium salts (acetate, chloride, fluoride, hydroxide, nitrate, and sulfide) are highly toxic. The solubility of barium carbonate is low at physiologic pH, but increases considerably as the pH is lowered (such as in the presence of gastric acid). Soluble barium salts are found in depilatories, ceramic glazes, and rodenticides and are used in the manufacture of glass and in dyeing textiles. Barium chlorate is a common ingredient in fireworks, producing a green color on ignition. Barium sulfide and polysulfide may also produce hydrogen sulfide toxicity. Barium may also enter the air during mining and refining processes, the burning of coal and gas, and the production of barium compounds. The oil and gas industries use barium compounds to make drilling mud, which lubricates the drill while it passes through rocks.
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The insoluble salts, such as barium sulfate, are poorly absorbed. However, intravasation from a radiologic study has occurred, where barium sulfate administered under pressure leaked into the peritoneal cavity or portal venous system. Cardiovascular collapse has been reported although it is unclear if this was directly from the barium or from overwhelming sepsis.
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MECHANISM OF TOXICITY
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Systemic barium poisoning is characterized by profound hypokalemia, leading to respiratory and cardiac arrest. Barium is a competitive blocker of potassium channels, interfering with the efflux of intracellular potassium out of the cell. Barium ions may also have a direct effect on either skeletal muscle or neuromuscular transmission. In the GI tract, barium stimulates acid and histamine secretion and peristalsis.
Inhalation of insoluble inorganic barium salts can cause baritosis, a benign pneumoconiosis. One death resulted from barium peroxide inhalation. Detonation of barium styphnate caused severe poisoning from inhalation and dermal absorption.
Pharmacokinetics. After ingestion, soluble barium salts are rapidly absorbed by the digestive mucosa. A rapid redistribution phase is followed by a slow decrease in barium levels, with a half-life ranging from 18 hours to 3.6 days. The predominant route of elimination is the feces, with renal elimination accounting for 10–28%. Barium is irreversibly stored in bone.
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The minimum oral toxic dose of soluble barium salts is undetermined but may be as low as 200 mg. Lethal doses range from 1 to 30 g for various barium salts because absorption is influenced by gastric pH and foods high in sulfate. Patients have survived ingestions of 129 and 421 g of barium sulfide. The US Environmental Protection agency ...