Corrosive Poisons: Acids

• This chapter discusses corrosive poisons, specifically mineral/inorganic acids and strong alkalis

Mineral/Inorganic Acids

• Mineral acids cause coagulative necrosis by precipitating proteins, resulting in a hard eschar or scab that may protect underlying tissue
• They have no remote action
• Act as irritants when slightly diluted
• Act as stimulants when well diluted
• Acids typically cause second-degree, deep partial thickness burns that are clearly demarcated, dry, hard, and mildly edematous
• The stomach is the most commonly involved organ in acid ingestion due to some natural protection of the esophageal squamous epithelium
• Common mineral/inorganic acids include sulphuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl)

Sulphuric Acid (H2SO4)

• Colorless, odorless, oily, and non-fuming with a burning taste
• Locally corrosive
• Indirectly causes shock, asphyxia, perforation of the stomach, chemical peritonitis, and esophageal stricture
• Fatal dose (concentrated): 5-10 ml
• Fatal period: 12-18 hours
• Symptoms include oropharyngeal burns, burning pain in throat/epigastrium, dysphagia, dysphonia, dyspnea, eructation, vomiting, and thirst
• Drinking more causes more vomiting
• Vomitus is strongly acidic with altered blood and mucous shreds
• Teeth appear chalky white and brittle
• Constipation is usually present
• Urination is suppressed
• Tenesmus is present
• Stool contains mucus and blood
• Tenderness present over the abdomen
• Stiffness of the abdomen and peritonitis occur
• No usual abdominal distension
• Skin erosion over mouth angles/lips/fingers with blackening and excoriation
• Causes stomach perforation
• Leads to death by shock, stomach perforation, peritonitis, laryngeal spasm, or malnutrition due to esophageal stricture
• Postmortem findings: Skin erosion of the mouth angles/lips, corrosion of the trachea/larynx, blackish charring/peppery feel of the stomach, stomach perforation, and toxic swelling of the liver/kidneys
• Often accidental (mistaken for glycerin or suicidal
• Rarely used for homicide or as an abortifacient

Nitric Acid (HNO3)

• Colorless, pungent, choking, fuming with a burning taste
• Locally corrosive causing respiratory distress
• Fatal dose (concentrated): 10-15 ml
• Fatal period: 12-24 hours
• Symptoms include oropharyngeal burns, burning pain in throat/epigastrium, dysphagia, dysphonia, dyspnea, eructation, vomiting, and thirst
• Yellowish coating on teeth
• Constipation, urination, tenesmus and stool are the same as with sulphuric acid
• Present tenderness over the abdomen
• Abdominal stiffness and abdominal distension due to gas in the stomach occur
• Yellow discoloration over mouth angles/lips/fingers
• Causes stomach perforation
• Leads to death by shock, stomach perforation, peritonitis, laryngeal spasm, or respiratory distress
• Postmortem findings: Yellow discoloration/corrosion of skin, congested larynx/trachea, soft/friable/ulcerated stomach wall
• Accidentally or suicidally consumed, homicide is rare

Hydrochloric Acid (HCl)

• Colorless, pungent, sour, fuming with a burning taste
• Locally corrosive causing respiratory tract inflammation
• Fatal dose (concentrated): 15-20 ml
• Fatal period: 18-30 hours
• Symptoms include oropharyngeal burns, burning pain in throat/epigastrium, dysphagia, dysphonia, dyspnea, eructation, vomiting, and thirst
• Teeth show no change
• Same constipation, urination and tenesmus
• Stool may be present
• Present tenderness over the abdomen
• Abdominal stiffness and abdominal distension due to gas in the stomach occur
• No erosion, the epidermis may fall off after a few days
• Causes stomach perforation
• Leads to death by shock, laryngeal spasm, or pulmonary edema (due to vapor inhalation)
• Postmortem findings: Not much skin corrosion, brownish parchmentization, inflammation of respiratory passages, and brownish fluid in the stomach
• Mostly suicidal, or accidental
• Rarely used for homicide or as an abortifacient

Treatment for Mineral/Inorganic Acid Poisoning

• Avoid gastric lavage and emetics
• Dilute the acid immediately using milk or water, followed by aluminum hydroxide gel
• Provide a demulcent like olive oil, milk, egg white, starch water, or butter
• Do not give bicarbonate or other neutralizing agents
• Administer prednisolone
• Correct circulatory shock with IV fluids/blood products, and antibiotics for perforation
• Tracheostomy for glottis edema
• Give nutrient substances intravenously, then progress to liquids, soft foods, and a regular diet
• Use morphine for pain
• Wash skin burns with copious water
• Do not use chemical antidotes
• For hydrofluoric acid, use benzalkonium chloride solution or calcium gluconate gel
• Complications: Delayed perforation, delayed upper GI bleeding, or gastric outlet obstruction

Additional Information

• Viscera and skin should be preserved in absolute alcohol or rectified spirit, and clothes sent without preservatives
• Neutralizing agents should no longer be given
• Magenstrasse refers to the pathway of corrosive agents in the stomach

Vitriolage (Vitriol Throwing)

• Throwing a corrosive substance on a person with malicious intent
• Sulphuric acid is most commonly used
• Other substances include nitric acid, carbolic acid, caustic soda/potash, iodine, marking nut juice, or calotropis
• Causes discoloration/staining of skin and clothing (brown/black with sulphuric acid, yellow with nitric acid), trickle marks, painless burns, presence of chemical substance, slow repair, and scar tissue contractures
• Treatment involves washing with water/soap, applying MgO paste, and covering with antibiotic ointment
• For eye exposure, anesthetize and irrigate
• Results in grievous hurt
• Punishable under IPC sections 326-A and 326-B

Chemical Colitis – Inflammation of the Colon

• Caused by exposure of colonic mucosa to toxic chemicals
• Agents involved: Sulphuric/hydrochloric/acetic acids, sodium hydroxide, hydrogen peroxide, alcohol, radiocontrast agents, glutaraldehyde, formalin, ergotamine, hydrofluoric acid, household disinfectants, ammonia, soap, herbal medicines and potassium permanganate
• Symptoms include intermittent abdominal pain, fecal incontinence, diarrhea, and hematochezia
• Severe mucosal injury may show peritonitis
• Treat by discontinuing toxic agents, with fluid resuscitation, broad-spectrum antibiotics, steroids, and bowel rest
• Medico-legal Aspects: Can be accidental, deliberate (suicidal, homicidal or sexual), or iatrogenic

Boric Acid

• High-risk individuals include those with mental illness, depression, Munchausen's syndrome, learning difficulties, and those using enemas regularly.
• Boric acid is a weak acid of boron that acts as an antiseptic, insecticide, flame retardant, and neutron absorber.
• Signs and symptoms include nausea, vomiting, diarrhea with blue-green emesis/diarrhea, generalized erythema creating 'boiled lobster' appearance, rash on palms, soles, and buttocks, irritability, seizures, delirium, coma, oliguria, renal tubular damage, elevated serum creatinine, tachycardia, hypotension, hepatic injury, and hyperthermia
• Death from circulatory collapse
• Treat with supportive measures, hemodialysis, or exchange transfusion
• Accidental intake is common in children

Oxalic Acid

• Colorless, transparent, prismatic crystals
• Used for removing blood, rust stains, cleaning metals, and removing signatures from documents.
• Acts as a corrosive locally and remotely
• Causes shock, electrolyte imbalance (hypocalcemia), renal tubular necrosis, and uremia.
• Fulminating Poisoning: >15 g ingested, burning taste, constriction, nausea, vomiting, eructation, altered blood with coffee-ground appearance, thirst, diarrhea, electrolyte imbalance, and death.
• Acute Poisoning: Hypocalcemia leads to tingling/numbness, weakness, parasthesia, carpopedal spasm, hyperirritability, tetany, convulsions, coma, dilatedpupils, metabolic acidosis, ventricular fibrillation, and renal failure.
• Delayed Poisoning: Nephritis-uremia, scanty urine, hematuria, albuminuria, and oxaluria
• Treat with gastric lavage with calcium lactate, limewater, calcium lactate/gluconate/chloride, parathyroid extracts, demulcents, bowel washes, hemodialysis, and symptomatic treatment

Carbolic Acid (Phenol, C6H4OH)

• Colorless, prismatic needle-shaped crystals that turn pink and liquefy on air exposure
• Used as an antiseptic/disinfectant
• Attacks the nervous system, causing paralysis and death
• Local symptoms include damaged nerve endings, coagulation necrosis, and grayish white slough
• GIT symptoms include burning/tingling, anesthesia, diarrhea, and abdominal pain
• RS symptoms include phenol odor in breath, laryngeal/pulmonary edema, and stertorous breathing
• MS symptoms include muscular spasms/convulsions
• CNS symptoms include headache, giddiness, tinnitus, and contracted pupils
• CVS symptoms include rapid/feeble/irregular pulse, cold/clammy/sweating skin, collapse, unconsciousness, and coma
• Chronic poisoning (carbol marasmus) causes anorexia, weight loss, excessive saliva, headache, vertigo, dark urine, and ochronosis
• Treat with stomach washing, demulcents, saline administration, cleaning skin, and applying oil/methylated spirit

Strong Alkalis (Caustic Alkalis)

• Common poisons are ammonia, potassium hydroxide, sodium hydroxide, and carbonates of ammonia, potassium and sodium
• Cause more severe injury than acids due to water absorption, protein precipitation, liquefaction necrosis, and saponification of fats
• Lesions are the same as acids
• There is a caustic taste and burning heat, alkaline vomitus, purging, mucus and blood in motions, blisters/brownish discoloration on lips/skin, soft/swollen digestive tract, and esophageal stricture
• Ammonia vapor leads to congestion/watering of eyes, sneezing, coughing, choking, collapse, and suffocation
• Do not use gastric lavage or emetics
• Dilute with water, give demulcents, and support breathing
• Accidental poisoning is more common in children