Caustic Alkali
Commonly caustic alkalis encountered in poisoning include ammonia (usually in the form of ammonium hydroxide), carbonates of sodium and potassium, and hydroxides of sodium, potassium, and calcium. Ammonia is a colourless gas with a pungent odour. It condenses to a liquid at –33.4°C. The chemical formula is NH3. Ammonium hydroxide is a liquid containing about 30 percent ammonia. Other corrosive alkalis occur as a white powder or colourless solution.
Uses
- Ammonia gas is used in Smelling salts.
- Ammonium hydroxide (32.5% ammonia) is used in Paint, oil, and dirt remover, refrigerant.
- Sodium hydroxide (caustic soda) is used in Drain cleaner, oven cleaner.
- Potassium hydroxide (caustic potash) is also used in Drain cleaner as well as hearing aid batteries.
- Sodium carbonate (washing soda) is used as Household cleaning agent, detergent.
- Potassium carbonate is also used as Household cleaning agent.
- Sodium hypochlorite is used as Household bleach.
- Calcium hydroxide (Slaked lime) is used in Paint and industrial purpose.
Fatal Dose
- Sodium carbonate – 30 gm
- Potassium carbonate – 15 gm
- Sodium hydroxide – 5 gm
- Potassium hydroxide – 5 gm
- Ammonia – 30 ml
Fatal Period
The fatal period is 24 hours.
Mechanism of action
- In concentrated form, alkali acts as corrosive and in dilute form they act as irritant.
- Strong alkali produces liquefaction necrosis and causes saponification of fats and dissolves proteins thus causing deep penetration in the tissue resulting in extensive tissue destruction.
- Productions of ulcers are more common.
- Oesophagus is more commonly affected than stomach resulting in stricture formation or perforation.
- Type of material ingested may result in varying degree and location of injury.
Sign and Symptoms
Local
Causes chemical burns of the skin with skin showing grayish, soapy, necrotic areas without charring.
Inhalation
- Irritation of eyes and watering
- Cough
- Breathlessness
- Respiratory tract gets edematous and inflamed.
- Laryngeal edema or spasm may occur causing death.
Ingestion
- Caustic taste
- Burning pain
- Abdominal pain
- Vomiting and vomitus is alkaline in reaction.
- Diarrhea
- Tenesmus
- The lips, mucous membrane of oral cavity, and the tongue appears soft, swollen, bleached and bogy.
- The mucosa of GIT is swollen, soft, grayish or bleached and sloughs easily.
- Esophagus is affected commonly than stomach and results in dysphagia, drooling and hematemesis.
- Alkali induced injury of esophagus.
Management
Local
Wash the affected area with copious water.
Ingestion
- Milk or water may be given to dilute the alkali.
- Induction of Emesis is contraindicated as the procedure may precipitate convulsions.
- Gastric lavage may be carried out after protecting air way.
- Neutralization with acid as it may cause exothermic reaction and increases the risk of perforation.
- Assess the injury of esophagus by esophagoscopy.
- Especially in the case of ammonia, Respiratory distress may require endotracheal intubation, cricothyroidotomy, or tracheostomy, depending on severity.
- Oxygen must be administered if necessary.
- Withhold all oral feeds initially.
- Assess fluid and electrolyte balance.
- Alkali injuries to the eye and skin should be irrigated copiously with water or saline for at least 20 to 30 minutes also Ophthalmologic consultation is mandatory. Topical antibiotics and steroids may be also effective.
- Rest Symptomatic measures should be taken.
Post-mortem findings
- In case of Ammonia characteristics odour may be perceived.
- Mucosa of mouth, tongue, esophagus and stomach is bleached and sodden with areas of necrosis.
- Esophagus may show esophagitis or perforation.
- Pulmonary edema
- Inhalation – laryngeal edema
- Brownish or grayish staining of skin.
- Congestion of respiratory tract and pulmonary oedema (especially in the case of ammonia)
Forensic Examination and Test for Detection
Physical Examination
In stomach contents may be seen:
● White, solid, slimy lumps, flakes, or granules.
● Turns litmus paper blue.
● Becomes warm on addition of water.
● If exposed to air, becomes moist and gets dissolved.
● Soapy or slimy feeling when touched with fingers.
Sharp penetrating odour in the case of ammonia.
● Platinum wire flame Test: Touch platinum wire to the unknown substance and then place it in a flame. Sodium gives an intense persistent yellow flame while Potassium gives a deep purple flame.
● Fume Test for Ammonia: Place an open bottle of concentrate HCL near a sample of stomach contents, aspirate, or vomitus. Copious white fumes of ammonium chloride will indicate if ammonia is present. The test can also be done to detect the presence of ammonia in the atmosphere.
● Titration test
● Gas chromatography
Medico legal Aspects
- Accidental poisoning occurs usually by mistaking an alkali solution for water, lemonade, beer, etc., because of careless storage of these chemicals in inadequately labeled, ordinary looking bottles or jars.
- Industrial accidents involving these substances are reported from time to time.
- Suicidal cases are occasionally encountered.
- Homicides are quite rare but have been reported.
- Ammonia may sometimes be sprayed or thrown on a victim to facilitate robber.
Other Caustics
Potassium permanganate
Nature
- Also known as Condy’s crystals; Chameleon mineral; Purple salt.
- It is dark purple or bronze coloured.
- It is odourless, sweetish, astringent orthorhombic crystals.
Uses
- It is used as bleaching Resins, waxes, fats, oils, cotton, silk and other fibers.
- It is also used as a fungicide; insecticide, miticide; algicide, antiseptic; oxidizer; disinfectant; deodorant; sanitizer.
Fatal Dose
About 5 to 10 grams.
Mode of Action
- In concentrations exceeding 1:5000 (as a solution), potassium permanganate is an irritant, and in highly concentrated form it acts as a corrosive.
- It also exhibits systemic toxicity.
Sign and symptoms
- Intense burning pain with difficulty in swallowing, abdominal pain.
- Vomiting
- Diarrhoea
- Severe thirst
- Vomitus may be purple brown in colour.
- Skin and mucosa become stained deep brown or black.
- Severe inflammatory oedema.
- Dyspnoea
Post mortem findings
- Brownish black staining of tissues.
- Corrosion of oesophagus and stomach.
- Evidence of hepatic and renal damage.
- Congestion of airways
- Pulmonary oedema
Medicolegal aspects
- Accidental poisoning occurs due to Children swallowing the attractive looking crystals, mistaking them for sweets, or out of plain curiosity.
- It is misuse as an abortifacient.
- Industrial exposure.
- Suicidal ingestions have been reported from time to time.
Iodine
Nature
- It is Blue-black in colour and glittering crystals.
- It has peculiar odour.
Uses
- It is used for Antiseptic preparation
- Lugol’s iodine (5% iodine with 10% potassium iodide in water).
- Tincture of iodine (2.5% iodine and 2.5% potassium iodide, or 2% iodine, 2.4% sodium iodide, 47% alcohol, and water).
- Povidone-iodine (5 to 10% iodophor, i.e. mixture of polyvinyl-pyrrolidone and iodine).
- Iodex (iodine with methyl salicylate)
Fatal Dose
- About 2 to 5 grams of free iodine.
- 1 to 2 ounces of strong iodine tincture.
Mode of Action
- Locally, strong iodine solution can be an intense irritant.
- Systemic toxicity is due to combination of free iodine with serum sodium bicarbonate, leading to metabolic acidosis.
Sign and symptoms
- Rhinorrhoea
- Conjunctivitis
- Cough
- Burning pain extending from the mouth to the abdomen
- Salivation
- Metallic taste
- Vomiting
- Diarrhoea.
- Vomitus and stools may appear yellowish.
- Glottic oedema
- Pulmonary oedema
- Delirium
- Hallucinations
- Convulsions
- Tachycardia
- Hypotension
- Metabolic acidosis
- Renal failure.
Post mortem findings
- Brownish or yellowish stains of skin and mucosa.
- Characteristic odour
- Congestion of viscera, especially the kidneys.
Test for Detection
Specific Tests for Iodine
- Yellowish stains of clothing, skin and mucosa.
- Characteristic odour.
- Vomitus or stomach contents when heated in a beaker will cause the iodine to sublime on a cold surface.
- To 10 ml of vomitus or gastric aspirate, add 1 ml of starch solution. A blue-black colour will develop which indicates Iodine .
- Urine Test: Add 5 ml of chloroform and a few drops of nitric acid to 10 ml of urine and allow to stand for 3 minutes. A pinkish-violet chloroform layer forms which indicates Iodine.
Hydrogen peroxide
Nature
Hydrogen peroxide is a clear, colourless liquid with a faint ozone-like odour and has bitter taste.
Uses
- Disinfectant
- Radiology
- Treatment of inspissated meconium, constipation, and faecal impaction.
- Mouth wash/gargle.
- Hair and teeth bleaching.
- Vaginal douche
- Industry purpose
Fatal Dose
- The usual fatal dose is not clear.
- Fatalities are mostly associated with industrial grade solutions.
Mode of Action
- Hydrogen peroxide decomposes to water and oxygen. But when used in closed spaces or under pressure, liberated oxygen cannot escape.
- Systemic oxygen embolisation and surgical emphysema can occur.
Sign and Symptoms
- Irritation caused to mucus membranes.
- Severe burn of GI mucous.
- Respiratory tract obstruction and respiratory failure.
- Metabolic acidosis and convulsions.
Treatment
- Aggressive airway management includes endotracheal intubation, oxygen administration and mechanical ventilation.
- Cautious gastric lavage may be administered with iced saline.
- Supportive measures should be taken with particular reference to control of metabolic acidosis and convulsions.
- Laparotomy may be effective if there is evidence of air in the GI tract.
- Hyperbaric oxygen therapy may help alleviate life threatening gas embolisation.
Post mortem findings
- Froth at the mouth or nose.
- Frothy blood in venous systems.
- “Frosty coating” of GI tract.
- Crepitus of liver.
- Diffuse cerebral oedema with cerebellar and uncaltonsillar notching.
- Visceral congestion.
- Petechiae of thymus, pericardium, and other viscera.
- Organ vacuolisation (gas emboli).
Medicolegal aspects
- Most cases of accidental therapeutic poisoning have been encountered.
- Occasionally suicidal poisoning is seen.
References
- Dr. K.S. Narayan Reddy. The essential of forensic medicine and toxicology.34th edition.
- VV Pillay. Modern medical toxicology.4th edition.
