General Toxicology PDF

# General Toxicology - Study of poisoning (Source, properties, mechanism of action, signs & symptoms, diagnosis and management). - Significance: - Acute: medical emergency - Leading cause of morbidity & mortality in India and major health problem worldwide. - Most lethal cause of suicid...

# General Toxicology - Study of poisoning (Source, properties, mechanism of action, signs & symptoms, diagnosis and management). - Significance: - Acute: medical emergency - Leading cause of morbidity & mortality in India and major health problem worldwide. - Most lethal cause of suicide. ## Basic Terms | Term | Description | | ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Forensic toxicology | Medicolegal aspects of poisoning: medicolegal reporting, gastric lavage, Post mortem (Pm) findings, Samples to be preserved. | | Occupational toxicology | Study of poisons in relation to specific occupation. | | Eco-toxicology | Study of poisons in relation to environment. | | Poison | Any substance given in any form (Solid/liquid/gas), any route (oral/injectable/inhalation/direct contact) causing ill health or death by its local or remote action. Rapid absorption: Inhalational > Intravenous > Intramuscular. | ### Drug vs Poison: - **"Sola dosis facit venenum"** (Given by Paracelsus): **The dose makes the poison.** - **Drug:** - **Medical significance:** Low dose, intention to heal - **Legal significance:** - **Poison:** - **High dose** - **Intention to cause harm** ### Toxin vs Venom: | Category | Description | | -------- | ----------------------------------------------------------------------------------------------------------------------------- | | Toxin | Any biological substance produced by a living organism (Plant/animal) | | Venom | Toxin produced by an animal, proteinaceous substance injected into the body, causing ill effects. | ## Classification of Poisons **Mnemonic: CINCAM** | Poison Type | Features & Examples | | ---------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Corrosives | Causes corrosion, Maximum tissue destruction. Eg: Acids and alkalis | | Irritants | Causes inflammation, Types: Non metallic: Phosphorous, iodine, chlorine, bromine. Metallic : Lead, iron, copper, arsenic, cadmium, thallium, mercury. Plant sources: Ricinus communis, Abrus precatorius, calotropis, Croton tiglium, Capsicum annuum, Semecarpus anacardium. Animal sources: Snake bite, scorpion sting, spider bite. | | Neurotoxins | Acting on brain (Cerebral poison): Somniferous (Induces sleep): Opioids. Deliriants (Cause delirium): Datura, cannabis, cocaine. Inebriants (Cause intoxication): Alcohol, chloral hydrate. Stimulant (Cause excitation): Caffeine, cocaine, amphetamine. Psychoactive: Cannabis, phencyclidine (Angel's dust). Acting on spinal cord (Spinal poisons): Strychnos nux vomica: Excitation. Gelsemium Inhibition. Acting on peripheral nervous system: Conium maculatum (Hemlock), Curare. | | Cardiotoxins | Cardiac poisons mnemonic Car DONA: Cardiac poisons: Digitalis (Fox glove), Oleander (Pink or yellow), Nicotine (Tobacco), Aconite (Sweet poison). | | Asphyxiants | Induce asphyxia, Most are gases: Simple/inert: Carbon dioxide, nitrogen, helium. Chemical (Interact with cells): Carbon monoxide, cyanide, hydrogen sulphide. Irritant: Chlorine, methyl isocyanate, ammonia. | | Miscellaneous poisons | Agricultural poisons: Insecticides, mosquito repellents (Pyrethroids), Rodenticides, Food poisoning agents. | ## Diagnosis of Poisoning ### In Living People - **History:** - **Onset:** Sudden/insidious. - **Progression:** Worsens uniformly. - **Clinical Features:** - **Toxicodromes:** Collection of signs for type of poisoning? - **Cholinergic (Organophosphates, carbamates).** - **Anticholinergic (Datura, tricyclic antidepressants, anti-psychotics).** - **Opioids (morphine).** - **Sedative-hypnotics.** - **Sympathomimetics (cocaine, amphetamine, theophylline).** - **H/o recent food/drink intake.** - **Similar features in family members.** | Feature | Cholinergic | Anticholinergic | Opioids/Sedative-hypnotics | Sympathomimetics | | ------------------ | -------------- | ---------------- | ------------------------- | ------------------- | | HR | ↓ | ↑ | ↓ (Dry) | ↑ | | BP | ↓ | ↓ | ↓ | ↓ | | Sweating | ↑ | ↑ | No effect | ↑ | | Temperature | ↓ | ↑ | ↓ | ↑ | | Pupils | Pinpoint | Dilated | Pinpoint | Dilated | | CNS Features | Convulsions, Coma | Delirium, Hallucinations, Coma | Coma | Hyperalert- Convulsions | | Other Features | Bowel sounds & GI motility ↑, All secretions ↑ | Urinary retention, Bowel sounds ↑, All secretions ↑ | Respiratory depression | Tremors | | **Toxidromes of opioid and sedative-hynotics : Similar to each other.** | **Triad of pinpoint pupils + Coma + Respiratory depression : morphine poisoning.** ### Lab Investigations - **Blood:** - **Urine:** Oxalate casts/crystals in urine → Suggestive of oxalic acid/ Ethylene glycol poisoning. - **Note:** Proximal convoluted tubule (PCT) necrosis → Phenol. ## Ideal Homicidal vs Suicidal Poison | Property | Ideal Homicidal Poison | Ideal Suicidal Poison | | ----------------- | ------------------------------------------------------------------------------ | ------------------------------------------------------- | | Cost | Colorless, odorless & tasteless, Cheap | Pleasant taste, Unimportant | | Onset of symptoms | Delayed | Immediate | | Nature of symptoms | Resembles natural disease, Non specific (Difficult to identify) | Painless death, Unimportant | | PM findings | Unimportant | Unimportant | | Lab test | Undetectable, No ideal homicidal poison, Nearly ideal homicidal poison: Thallium (Poisoner's poison), Arsenic, Aconite | Unimportant, Cyanide, Organophosphates, Aluminium phosphate (commonly used in North India), Opioids | | Examples | Thallium (Poisoner's poison), Arsenic, Aconite | Cyanide, Organophosphates, Aluminium phosphate, Opioids | ## In Dead People | Category | Description | | --------- | ------------------------------------------------------------------------- | | Physical | Odour of poison, Color of hypostasis, Stomach mucosa: Color, Nature | | Chemical | AKA toxicological analysis/poison detection in tissues. | ### Odor of poison - **To perceive smell → Open cranial cavity.** | Poison | Odor | | ---------------- | --------------------------------------------------------------- | | Cyanide | Oil of bitter almonds | | Cannabis | Burnt rope | | Hydrogen sulphide | Rotten egg | | Disulfiram | Fruity | | Alcohol | Acrid pear | | Chloral hydrate | Kerosene (D/t addition of aromax, a petroleum product) or garlic | | Paraldehyde | Acrid pear | | Organophosphates | Garlic | | Phosphorous | Garlic | | Arsenic | Garlic | | Conium maculatum | Mousy | | Salicylates | Oil of winter green | ### Color of hypostasis - **Normal color: Blue.** | Poison | Skin Color | | ---------------- | ------------------ | | Carbon monoxide | Cherry red | | Cyanide | Brick/bright red | | Phosphorous | Dark brown | | mneumonics BAN: | | | Bromide | Chocolate brown | | Aniline | Deep blue | | Nitrites | Bluish green | | Aniline | Black | | Hydrogen sulphide | Purple | | Carbolic acid | Black necrotic, charring | | Nitric acid | Yellow or brown d/t altered blood | | Arsenic | Buff white & leathery, Red velvety mucosa, white particles on the mucosa | | Mercury | Slate grey | | Copper sulphate | Bluish | | Sodium amytal | Yellow or dark brown | ### Stomach mucosa: | Poison | Nature/Color | | ---------------- | ------------------------------------------------------------------------------- | | Sulphuric acid | Black necrotic, charring | | Nitric acid | Yellow or brown d/t altered blood | | Carbolic acid | Buff white & leathery | | Arsenic | Red velvety mucosa, white particles on the mucosa. | | Mercury | Slate grey | | Copper sulphate | Bluish | | Sodium amytal | Yellow or dark brown | ### Preserved gastric content: - Can be used to detect poison. ### Chemical analysis: - Identification of poison in tissues is an absolute proof of poisoning. ### Organs to be sent for analysis: | Poison | Stomach | Small Intestine | Liver | Kidney | | ------ | ------------------------ | ----------------- | -------- | ----------- | | | (Food storage) | (Absorption) | (Metabolism) | (Organ of excretion) | | | ingesting | | | | | | Mnemonic: Bloody Silk. | | | | ### Quantity to be preserved | Organ | Quantity to be preserved | | :--------------------------------------- | :-------------------------- | | Blood (most reliable) & urine sample | Entire stomach | | Stomach | Proximal 30cm | | Small intestine | 500g | | Liver | Half of each kidney | | Kidney | | ### Target organs to be preserved for suspected poisonings: | Organ to be preserved | Suspected poison | | :----------------------- | :------------------------------------------- | | Heart | Digitalis, Aconite | | Brain | Cerebral poisons: Alcohol, Cocaine | | Spinal cord | Spinal poisons: Strychnos nux vomica, Gelsemium | | CSF | Alcohol | | Vitreous sample (Particularly if body is decomposed) | Volatile/gaseous (Eg: Asphyxiants) | | Lungs | | | Abdominal fat | | | Bone | Metallic poisons: Arsenic, Antimony, Thallium | | Hair | Metallic poisons: Arsenic, Antimony, Thallium | | Nails | Metallic poisons: Arsenic, Antimony, Thallium | | Skin | Metallic poisons: Arsenic, Antimony, Thallium | | Spleen | Carbon monoxide, Cyanide | ## Preservatives - To be added in glass container containing the organ. ### For Chemical Analysis 1. Saturated solution of sodium chloride: - Cheaper, m/c used. 2. **Rectified spirit: 95% alcohol, ideal preservative.** | Saturated solution of sodium chloride | Rectified spirit | | :-------------------------------------- | :--------------------------- | | Aconite | Alcohol (False positive reaction) | | Corrosives (Except phenol) | Formalin | | | Phosphorous (Luminescent property is lost) | | | Kerosene | | | Chloroform | | | Acetone | ## Preservatives Used for Specific Organs/Tissues - **Note:** | Organ/Sample | Preservative used | | ------------- | ----------------------------------------------------------------------------------------- | | Blood | Sodium fluoride + Potassium oxalate | | | Sodium fluoride: 10mg/ml of blood stops bacterial growth. | | | Potassium oxalate: 3mg/ml of blood, anticoagulant.) | | Urine | Thymol > Sodium fluoride > Toluene | | Virology | Glycerol | **Note:** - No preservatives are needed in: - Analysis of bone, hair, and nails. - Analysis < 24 hours. - Deeply frozen samples. - Formalin: - **Never** used in chemical analysis (Destroys the poison). - Used only in histopathological examinations.