Carbolic Acid (Phenol)

1} When pure, the acid consists of short, colowebsiteess, prismatic, needle-like crystals, which have a burning sweetish taste, are hygroscopic and which turn pink and liquefy when exposed to air.
2} It has a characteristic ‘carbolic’ or phenolic smell.
3} It is slightly soluble in water but freely soluble in glycerine, ether, alcohol and benzene.
4} The commercial carbolic acid is a dark brown liquid containing several impurities, chiefly cresol.

Route :
Ingestion, Contact
Fatal Dose :
2 grams of pure phenol
Fatal Period :
3 to 4 hours.
Mechanism of action :
1} Corrosion, necrosis anaesthesia and gangrene of the local area.
2} Action on medulla and kidney.

Actions:
1} Local action: tingling? numbness? coagulation necrosis? white eschar? necrosis and gangrene? sloughing
2} Remote action:
a} On CNS – shock
b} On kidney – carboluria

Clinical Picture :
Poisoning due to carbolic acid is known as carbolism.
1} Skin: It causes burning and numbness. Superficial burn is pale grey but deep burns are black. It produces a white opaque eschar which is painless and falls off in a few days leaves a brown stain. There may be necrosis and gangrene of the tissue which becomes green-white or brown-white` the dead tissue sloughs readily.
2} Digestive tract: Hot burning pain extends from the mouth to the stomach, which is followed by tingling and later anaesthesia. Deglutition {swallowing} and speech become painful and difficult. The lips, mouth and tongue are corroded, which soon become white and hardened. Nausea and vomiting are present in about 20 percent of cases.
3} Respiratory tract: Pulmonary oedema and laryngeal oedema develop due to irritation. Breathing is slow and laboured progressing to respiratory failure. When vomiting occurs, the poison may be aspirated into the lungs causing bronchitis and bronchopneumonia.
4} Systemic Effects: Phenol is a depressant of the nervous system especially the respiratory centre. Headache, giddness, unconsciousness and coma occur. The temperature is subnormal` the pupils are contracted` breathing is stertorous` pulse is rapid, feeble and irregular` face covered with cold sweat` and there is dusky cyanosis, respiratory alkalosis and metabolic acidosis. Liver may be damaged. In severe cases, haemolysis and methaemoglobinaemia are characteristic features. There is a strong odour of phenol in breath. Convulsions and lock-jaw sometimes occur.
5} Urine: It is scanty and contains albumin and free haemoglobin, suppression may follow. It may be colowebsiteess or slightly green at first, but turns green or even black on exposure to air. This is known as carboluria and is diagnostic.

Treatment :
1} An emetic often fails due to the anaesthetic effect.
2} The stomach should be washed carefully with plenty of lukewarm water containing activated charcoal, olive oil, castor oil, magnesium or sodium sulphate, or saccharated lime with which phenol combines and forms harmless products. Soap solution or 10 percent glycerine may be used and the washing continued till the washings are clear and colowebsiteess.
3} When lavage is completed, 30 g. of magnesium sulphate or a quantity of medicinal liquid paraffin should be left in the stomach.
4} Demulcents
5} Saline containing 7 g. of sodium bicarbonate per litre is given i.v. to combat circulatory depression, to dilute carbolic acid content of blood and to encourage excretion by producing diuresis.
6} Haemodialysis, if there is renal failure.
7} Methylene blue i.v. if there is severe methaemoglobinaemia.
8} If phenol falls on the body, contaminated clothing should be removed at once, skin cleaned, and the area washed with soap and water. Olive oil, methylated spirit or 10 percent solution of ethyl alcohol act as solvents.

Carbolic Acid (Phenol)

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