Barium toxic action

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. 

The Canadian Council of Ministers of the Environment recommends an interim soil quality criterion of 750 mg kg for agricultural use (Anonymous 1999). The toxic action of barium compounds is determined by their solubility, and the only risk deriving from near-insoluble barium sulfate is that of soluble barium salts present as impurities. Hence, the concentration of acid-soluble substances in barium sulfate for pharma-... 

Mattila MJ, Anyos K, Puisto EL. 1986. Cardiotoxic actions of doxepin and barium chloride in conscious rabbits. Arch Toxicol, Suppl, Toxic Interfaces Neurones, Smoke Genes 9 205-208. 

The bicarbonates of sodium and potassium are very weak bases and their concentrated solutions are not corrosive to the skin. Beryllium and magnesium hydroxides are only slightly soluble in water and are very weakly basic. While the corrosive actions of the alkalies can be predicted from their basicity strength, their toxicity is governed by the metal ions (especially for the alkaline-earth metal hydroxides). For example, while caustic soda is a stronger base, and more corrosive than barium hydroxide, the latter is toxic in a manner similar to other barium salts. 

Calcium ions also can precipitate sulfate. Barium is quite toxic and not as readily available as calcium. Barium has the added disadvantage of attacking anode coatings and can destroy their action. Calcium compounds are cheaper on a unit cost basis, but higher excess concentrations are necessary to achieve a given residual sulfate concentration. As a result, calcium precipitation often costs more than barium precipitation [60,88]. Another disadvantage of calcium is the fact that two brine clarifiers are required. The sulfate must be precipitated first after removal of the precipitate, calcium itself must be removed. It will be seen below that the clarifiers are large pieces of equipment that can dominate the process-plant layout. 

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