Anant Babu Marahatta
Ph.D.student in Chemistry
Quantum Chemistry group, Department of chemistry, Tohoku University, Sendai,Japan

There is no doubt that common salt or sodium chloride (NaCl) is indeed essential to all life. It is the basic milieu of mammals. It occurs as colorless cubic crystals or as white crystalline powder. It is available at everyone’s home as well as in laboratory. No one suspect that it is a poison. One who studied biochemistry must have learnt that salt is a poison and can be used to kill infants. It is indeed a rather safe poison because one doesn’t need to buy anything when salt is administered in larger quantities than required, it can cause death too.

One teaspoonful of salt weighs about 5gms. Normal uptake by adults is about 5 to 15gm daily or about 1-3 teaspoonfuls. Children consume less salt is even necessary for normal growth. The sodium needed for growth is 0.5 mEq/kg from birth to 3 months of age, which decreases to 0.1mEq/kg at 6 months. The average content of sodium in human milk is 7mEq/L and that in cow milk is 21mEq/L.

Since, chemists and biochemists find it easier to talk in terms of equivalent weights. Equivalent weights are actually measures of the characteristic proportions in which the given elements combine .As we all know that 1mEq.sodium equals 23 mg and that of NaCl equals 58.5mg, and 1mEq would be equal to 1/1000 Equivalent weight. Thus, when one says that sodium needed for growth is 0.5 mEq/kg from birth to three months of age; he simply means that for every kg of baby’s weight, 0.5mEq of sodium is needed. Thus if the infant weighs, say, 4kg he would need 4 x 0.5 or about 2mEq of sodium. Since 1mEq of sodium is 23 mg, it would mean that the infant would need about 46mg of sodium daily. This much sodium would be available from about 117 mg of salt. Similarly we can convert other values given above.

Most people will not believe that common salt is a deadly poison. The only difference between this and other commonly known poisons is that one has to administer rather large quantities. One or two tea spoonfuls of salt would not kill an adult but can easily kill a 6 month old baby. About 40 teaspoons of common salt would kill an adult human being too. The toxic oral dose of salt is 0.5 to 1.0 gm/kg. For a 70 kg man this amount is about 35-70 gm. That means if an adult consumes about 70 gm of salt [or about 14 teaspoons], he would be severely poisoned. The estimated fatal amount, i.e. amount sufficient to kill, is about 1 to 3 gm /kg [remember that weight of one teaspoon common salt is about 5 gm.]. This amounts to about 70 to 210 gm. [about 40 teaspoonfuls] of salt for a 70 kg man.

Interestingly, the Chinese used saturated salt solution for suicide. Salt intoxication and death have occurred when it is used to induce vomiting as well. When some body has consumed a poison, it is imperative to remove as much poison from his stomach as possible. One of the best ways to do this is to make the person vomit. It has been known from the ancient times that a strong solution of common salt induces vomiting and that is why for centuries, it was a favorite method of doctors to induce vomiting for poisoned patients. But now it is known that saturated solution of salt itself can cause salt poisoning, so it is rarely used these days. Thus accidental poisoning and death takes place due to the common salt if the person consuming less harmful poison is induced vomiting by injecting saturated salt solution orally. This is the most common accident frequently observed in the society.



The stomach contents and the blood analysis of the person poisoned by common salt tell the doctor that salt has been administered to the patient. While examining the brain tissue under the microscope, it has been found the capillaries of the brain are damaged and they are full of blood. There are innumerable bleeding points- technically known as hemorrhages in the brain. Many venous channels of the brain called dural sinuses are blocked. All these findings are strongly in favor of salt poisoning.

No comments: