Carbolic Acid Synonyms: Phenol, Hydroxy-Benzene Propeies * Colourless, prismatic, needle-like crystals that turns pink and liquefies when exposed to air * Has sweetish burning taste and phenol like smell * Concentrated phenol is a dark brown liquid and contains impurities like cresol * Lysol is 50% solution of cresol in saponified vegetable oil. However, phenol is 8 times more toxic than Lysol * Dettol is chlorinated phenol with turpineol * Household phenol (sold as phenyle) contains five percent phenol in water. * Derivatives of phenol 1. Cresol 2. Thymol 3. Creosate (coal tar) 4. Menthol 5. Tannic acid 6. Napthol 7. Resorcinol. Uses 1. Antiseptic and disinfectant 2. Manufacture of plastic Absorption, Metabolism and Excretion * Phenol is absorbed from skin, gastric mucosa, per rectum, per vagina and respiratory tract * Phenol is conveed into hydroquinone and pyrocatechol and excreted in urine. Traces are excreted by lungs, salivary glands, and skin. Fatal dose: * 2 gm crystals * 25 to 50 ml of household phenol Fatal period: 3 to 4 hours. Mechanism of Action * Phenol has local as well as systemic action * Locally it acts as corrosive agent and when absorbed, it causes CNS depression, metabolic acidosis and renal failure. * Carbolic acid has great penetrating power and it coagulates protein. * Phenols have a powerful antipyretic effect similar to that of salicylates. * Phenols and derivatives of phenols cause methemoglobinemia Clinical Features Local: When applied to skin or mucosa, it causes burning pain, numbness, tingling and anesthesia. It causes corrosion and produce white eschar (scar), which falls off in few days leaving brown stained area. Systemic: 1. GIT: Burning pain followed by tingling numbness and anesthesia. Nausea and vomiting. 2. RS: Respiration is slow and labored. 3. CNS: Headache, giddiness, unconsciousness, convulsions, coma. 4. Oliguria and hepatic failure. 5. Urine: May be colorless but on exposure to air turns green due to oxidation of phenol metabolites (hydroquinone and pyrocatechol). It is known as carboluria. 6. The hydroquinone and pyrocatechol may cause pigmentation in the cornea and various cailages, a condition known as oochronosis. Management * Skin: Wash with undiluted polyethylene glycol. * Oxygen/ventilatory suppo * Intravenous fluids and vasopressors to suppo blood pressure * Ingestion: Cautious stomach wash with sodium or magnesium sulfate solution * Lidocaine for ventricular arrhythmias * Benzodiazepines for seizures * Treat methemoglobinemia - if methemoglobinemia is > 30%, ingest Methylene blue (1-2 mg/kg). Exchange transfusion may be needed if methemoglobinemia is > 70%. REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO300