Soluble barium salts are most toxic. These are barium chloride, nitrate, sulphide, carbonate, hydrate etc. Barium sulphate is insoluble and not toxic.
Source and uses – Barium carbonate is used as a rodenticidal agent. Other soluble salts are used in industries and laboratories. The insoluble barium sulphate being radio-opaque and non-toxic is used in radio-diagnosis. Barium sulphide has been taken for barium sulphate by mistake. Old stock of barium sulphate may change to barium sulphide in small amount and cause poisoning.
Absorption, distribution and excretion – The soluble salts of barium are well-absorbed through the G.I. tract. After absorption, it is distributed to all tissues. In comparison with other tissues, in bones it stays deposited for a longer period. Absorbed salts are excreted mainly through the bowel (G.I. tract) and to some extent through urine. Excretion of the metal from tissues other than bones is complete in two or three days after absorption.
Fatal dose – Barium chloride, Barium sulphide and Barium nitrate-1 gm; Barium carbonate-5 gm.
Fatal period – Death occurs within 12 hours.
Actions, signs and symptoms – The soluble salts are locally irritant. After absorption they act as stimulants, both for voluntary and involuntary muscles including heart muscles, which are lastly paralysed.
On ingestion, there is burning colicky abdominal pain with vomiting and motion. There are tingling sensation and tremor of muscles. Pulse – irregular, B.P. – raised. There is contraction of muscles. Voluntary muscles may have fasciculations. There are cardiac arrhythmia, ectopic beats, forceful systolic contraction and lastly ventricular fibrillation. In surviving patients paralysis of muscles occurs with loss of deep reflexes. Paralysis of respiratory muscles at this stage may be the cause of death. Thus, death may occur due to shock from abdominal pain at the initial phase, then due to ventricular fibrillation and lastly due to paralysis of respiratory muscles.
Treatment – Sodium sulphate 15 gm or magnesium sulphate 15 gm. is given orally to convert the ingested soluble barium compound to insoluble barium sulphate, to prevent absorption. To lower the raised blood pressure 30 – 60 mg, sodium nitrite works better. To prevent or counter ventricular fibrillation, quinidine sulphate 100 to 200 mg, orally or procaineamide 500 mg. by very slow I.V. injection may be given. The danger (stoppage of heart) of I.V. procaineamide injection should be kept in mind. Anti-spasmodic may be useful to combat colicky spasm of the intestine and the vessels.
Postmortem findings – Nothing specific. Submucosal haemorrhage in the G.I. tract occurs, often due to excessive spasm.
Medicolegal aspects – Barium sulphide causes accidental poisoning when it is taken by mistake for barium sulphate, for X’ray examination. Exposure may occur in chemical industries. Accidental poisoning has occurred due to contamination of food grains with grains treated with barium carbonate for rat killing. Suicidal consumption of barium carbonate may happen. Homicidal poisoning is not expected.