DEATH BY OXALIC ACID

Anant Babu Marahatta
Tohoku University
Japan
Oxalic acid is a constituent of many house hold products. It is found in many disinfectants, household bleach, metal cleaning liquids, antirust products and furniture polishes. Oxalic acid is a crystalline, colorless substance and is efflorescent. This means it tends to become powdery on account of loss of water of crystallization. It has got its name from the Greek word Oxalis, which means sorrel. It occurs in sorrel plant and because of this the French chemist Lavoiser in 1787 named it as Oxalic acid. It occurs in the leaves and young stalk of Rhubarb, Spinach and even Cabbage. Sorrel is succulent acid herb used in salads.

Accidental poisoning has been known to occur after a hearty meal of rhubarb or sorrel .Food rich in oxalate can also lead to kidney stones because kidney stones are generally made up of oxalates. Crystals of oxalic acid are similar in appearance to those of magnesium sulphate (Epsom salt) and zinc sulphate. Because of this similarity, cases of accidental poisoning have occurred. Magnesium sulphate in doses of 15g is used as a laxative (to facilitate the evacuation of Bowels) and is non toxic. Since oxalic acid, a dangerous poison is so similar looking to Epsom salt-a commonly used drug as laxative medicine-it is necessary to be able to differentiate between the two. If the doctor or nurse fails to differentiate between the two, accidental poisonings may occur. Two patients at the mental hospital in Scotland had died in 1956 after receiving doses of oxalic acid which was mistaken for Epsom salts. Similarly zinc sulphate is also commonly used drug and looks very similar to the dangerous poison, oxalic acid. Thus in order to remain in the safe side, it is very much essential to be able to differentiate between them.

HOW DO DOCTORS DIFFERENTIATE BETWEEN THE TWO?

Since if we taste a small amount of crystal of each, oxalic acid is sour in taste and magnesium sulphate is nauseatingly bitter and zinc sulphate is metallic bitter. But surely, this is not the best method to find out the poison. The reaction of oxalic acid is strongly acidic but that of zinc sulphate is slightly acidic and magnesium sulphate is neutral. On application of heat, Oxalic acid sublimes while the rest of the two salts remain fixing. When each salt is allowed to react with sodium carbonate, oxalic acid shows effervescence but no precipitate while the other two salts show no effervescence but a give white precipitate of metal carbonates. But perhaps the easiest test is to see whether stains of ink will disappear by a solution of one of these salts or not. Since, a solution of oxalic acid makes the stain disappear ,the other two salts can not do that That is why oxalic acid is used in products like ink removers and furniture polishes. It is also used in households as a “bleach” to remove stains or to clean metals notably brass or leather and also used in calico-printing (cotton cloth especially plain white and unbleached).


CAN OXALIC ACID BE USED FOR HOMICIDE?

No that is not possible .because of its sour taste; it has not been used for homicide. Oxalates have however been used to procure abortion by vaginal injection.

HOW DOES OXALIC ACID AFFECT THE HUMAN BODY?

Oxalic acid has both a local and systemic action on the body. By local action, i.e. the action on stomach and intestinal walls with which it comes in contact. By systemic effect i.e. remote effects on organs with which it does not really come in contact. Oxalic acid readily corrodes the mucus membrane of the digestive tract. Unlike corrosive mineral acids and alkalis, oxalates do not lose their poisonous properties when diluted. On the contrary, dilute solution of oxalates can cause grave systemic effects. Oxalic acid however rarely damages the skin.

As far as systemic effects are concerned, large doses of oxalic acid can cause death due to shock. Oxalates can readily combine with the Calcium ion in the body tissues, causing a precipitous fall in the level of ionized calcium. This can cause muscle irritability, tetany and convulsions and irregular action and slowing of the heart. Since all muscle cells in the body are very much dependent on calcium for their proper functioning and it includes heart muscle too.

WHAT ARE THE SIGNS AND SYMPTOMS OF OXALIC ACID POISONING?

The symptoms of the oxalic acid poisoning depend on the size and concentration of the dose. A large concentrated dose would kill with in a couple of hours by shock or hypocalcaemia (lowering of calcium levels in the blood).A large dilute dose would cause kidney failure. There is immediate sour or bitter taste associated with a burning sensation in the mouth, throat and food pipe because of the corrosive action of the oxalic acid. There is eructation (formal belching-emit wind noisily through the mouth), distension(Swell out by pressure) of abdomen, thirst, nausea and vomiting. The vomit has a coffee ground appearance because the oxalic acid badly corrodes the stomach walls. There may be bloody vomiting for the same reason. Finally shock supervenes and death occurs. Acute poisoning occurs when the moderately large dose is taken and in such cases, the person survives up to 48 hrs. The symptoms are muscle irritability, tenderness, tetany, convulsions, numbness (paralyzed) and tingling (feel a slight stinging) of the finer tips and legs, cardiac irregularity, slowing of the heart, ventricular fibrillation (irregular and fast beating of the ventricles of the hearts).Delayed poisoning may occur when a smaller dose is taken. This may lead to renal failure and uremia. Death occurs with in 5-14 days.

HOW EXACTLY DID THE DOCTOR MAKE OUT THAT IT WAS THE CASE OF OXALIC ACID POISONING?

The person poisoned with the oxalic acid runs down the strange streaks from the angles of the mouth. Due to corrosion, there is whitening or yellow-white discoloration of the lips, lining of the mouth and upper surface of the tongue. The lining of the stomach in oxalic acid poisoning is blackened by the production of acid haematin. There may be superficial corrosion. The stomach may contain fresh or altered blood. Furthermore crystals of calcium oxalate can be demonstrated in scrapings of the stomach mucosa. The kidneys of a person dying of oxalic acid poisoning are congested and swollen with oedema (accumulation of excess fluid in body tissues). The renal tubules even contain the oxalate crystals. Thus doctors may sure it is the case of oxalic acid poisoning.

DEATH BY POTASSIUM PERMANGANATE [KMnO4]

ANANT BABU MARAHATTA
Ph.D. student
Tohoku University, Japan

Potassium permanganate is not a new chemical for the chemists as well as for other scientists. It is generally used in even very simple lab. It is a crystalline, colored substance and soluble in water. Its salts are normally stable in crystalline form but Zinc permanganate can become explosive. In fact, storing it in tightly stopper bottles is highly dangerous.

KMnO4 Solution

The color of the solution of KMnO4 is differed depending upon its concentration. If the concentration is about one part per million (1 PPm), the solution has a faint pink color. When the concentration is one part in 76000 (65mg/4.5dm3), the fluid becomes purple. Because of its color, solution has been used for staining purpose too. Those who use the chemical as a stain for flooring and woodwork and work with the concentrated solution must exercise with great care.

DEATH BY COMMON SALT [NaCl]

Anant Babu Marahatta
Ph.D.student in Chemistry
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.

THUS, THIS IS OUR WORK TO MAKE THE SOCIETY AWARE ABOUT THE SALT POISONING. SALT SOLUTION INFACT INDUCES VOMITTING BUT ITS HIGH CONCENTRATION ACTS AS FATAL.


DOCTORAL EVIDENCES OF COMMON SALT POISONING

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.