Forensic Toxicology Practice Questions

Q: What is the characteristic colour of urine in carbolic acid poisoning?

Dark green. **Explanation:** The characteristic finding in carbolic acid (phenol) poisoning is **Carboluria**. When phenol is ingested or absorbed, it is metabolized in the liver and excreted in the urine as **quinol (hydroquinone) and pyrocatechol**. While the urine may appear normal when freshly voided, upon exposure to atmospheric oxygen, these metabolites undergo oxidation, turning the urine a characteristic **dark green or smoky green** color. **Analysis of Options:** * **A. Dark yellow:** This is typically seen in concentrated urine or dehydration and is not specific to phenol poisoning. * **B. Reddish:** Red urine (hematuria or hemoglobinuria) is common in conditions like viper bites or mercury poisoning, but not characteristic of phenol. * **C. Black:** While carboluria can progress to a very dark, near-black shade if left standing for a long duration, "Dark green" is the classic medical description used in forensic literature and examinations. **Clinical Pearls for NEET-PG:** * **Odor:** Phenol has a characteristic "phenolic" or "hospital-like" antiseptic odor. * **Local Action:** It causes **corrosive whitening** of the mucous membranes (painless due to its anesthetic effect). * **Systemic Effect:** It is a potent CNS depressant and can cause rapid death due to respiratory failure. * **Antidote:** Gastric lavage with lukewarm water or olive oil is used (avoid glycerin). Magnesium sulfate or Sodium sulfate can be used as a chemical antidote to form non-toxic sulfoconjugates.

Q: Hemodialysis is used in all the following poisonings, except:

Kerosene oil. **Explanation** The effectiveness of hemodialysis in toxicology depends on specific pharmacokinetic properties: the toxin must have a **low molecular weight**, **low volume of distribution (Vd)**, **low lipid solubility**, and **low protein binding**. **1. Why Kerosene oil is the correct answer:** Kerosene (a hydrocarbon) is highly **lipid-soluble**, has a **high volume of distribution**, and is extremely large/complex in molecular structure. These properties make it inaccessible to the dialysis membrane. Furthermore, the primary clinical danger of kerosene is **aspiration pneumonitis**, not systemic toxicity that can be cleared via the blood. Hemodialysis is strictly contraindicated as it provides no benefit and delays supportive care. **2. Analysis of other options:** * **Barbiturates:** Long-acting barbiturates (e.g., Phenobarbital) have low protein binding and small Vd, making them highly dialyzable. * **Alcohol:** Ethanol, Methanol, and Ethylene glycol are small, water-soluble molecules with low Vd. Hemodialysis is the gold standard for severe methanol or ethylene glycol poisoning to remove both the parent compound and toxic metabolites (formic acid). * **Cocaine:** While not a first-line treatment (supportive care is primary), cocaine has a relatively small Vd and low molecular weight. In extreme cases of life-threatening toxicity, it *can* be removed via hemodialysis, unlike hydrocarbons. **Clinical Pearls for NEET-PG:** * **Mnemonic for Dialyzable poisons (BLAST-M):** **B**arbiturates, **L**ithium, **A**lcohols, **S**alicylates, **T**heophylline, **M**ethanol. * **Hydrocarbon Contraindication:** Never induce vomiting (emesis) or perform gastric lavage in kerosene poisoning due to the high risk of fatal aspiration. * **Vd Rule:** If the Volume of Distribution is **>1 L/kg**, hemodialysis is generally ineffective (e.g., Digoxin, TCAs, Organophosphates).

Q: You are performing an autopsy on a person suspected to have died from arsenic poisoning. Which of the following tissues will hold the maximum concentration of arsenic?

Liver. **Explanation:** **1. Why Liver is Correct:** In cases of acute or sub-acute arsenic poisoning, the **liver** is the primary site of accumulation. Arsenic has a high affinity for sulfhydryl (-SH) groups, which are abundant in hepatic enzymes. After absorption, arsenic is rapidly cleared from the blood and sequestered in parenchymatous organs. The liver, being the largest metabolic organ and the first major site of portal circulation, retains the **highest absolute concentration** of arsenic during the initial period following exposure. **2. Why Other Options are Incorrect:** * **Kidney & Spleen:** While arsenic is found in these vascular organs, the concentration is significantly lower than in the liver. The kidney is the primary route of excretion, but not the primary site of storage. * **Bone:** Arsenic does deposit in bones (replacing phosphorus), but this occurs in the **chronic stage** or long after death. In the context of a standard autopsy for suspected poisoning, the liver remains the gold standard for toxicological yield. **3. NEET-PG High-Yield Pearls:** * **Chronic Poisoning:** In chronic cases, arsenic is best detected in **keratinized tissues** (Hair, Nails, and Skin) because it binds to the keratin's disulfide bonds. * **Nail Finding:** Look for **Aldrich-Mees lines** (transverse white bands). * **Post-mortem finding:** Arsenic is known for its **preservative effect** on the body, leading to delayed putrefaction (mummification). * **Stomach Appearance:** Classically described as a **"Red Velvet"** appearance due to sub-mucosal extravasation. * **Fatal Dose:** 100–200 mg of Arsenic Trioxide.

Q: In snake envenomation, what is the standard initial dose of antivenom?

10 vials. **Explanation:** In the management of snake envenomation (particularly in the Indian subcontinent), the standard protocol follows the **WHO and National Health Guidelines**. The initial dose of Polyvalent Anti-Snake Venom (ASV) is **10 vials**, administered as an infusion [1]. **Why 10 vials is the correct answer:** The rationale is based on the average amount of venom injected by a venomous snake (like a Cobra or Russell’s Viper) during a "full" bite, which is approximately **63 mg to 150 mg** [3]. Since each vial of polyvalent ASV is manufactured to neutralize a specific amount of venom (e.g., 6 mg of Cobra venom or 6 mg of Russell’s Viper venom), **10 vials** are required to neutralize the average maximum venom load injected in a single strike. **Analysis of Incorrect Options:** * **A & B (2 or 4 vials):** These doses are sub-therapeutic. Administering too little ASV fails to neutralize the circulating toxins, leading to the progression of neurotoxicity or coagulopathy. * **D (20 vials):** While 20 vials may be the *total* dose required in severe cases or if symptoms do not improve after 1–2 hours, it is not the standard *initial* dose. **Clinical Pearls for NEET-PG:** * **ASV Administration:** It should be given only when there are systemic signs (coagulopathy, neurotoxicity) or severe local swelling [1]. It is **not** given for "dry bites." * **ASV in India:** It is **Polyvalent**, covering the "Big Four": Spectacled Cobra, Common Krait, Russell’s Viper, and Saw-scaled Viper [1]. * **Test Dose:** Routine skin sensitivity testing before ASV is **not recommended** as it is unreliable and delays treatment. * **Neurotoxicity:** If a patient shows signs of neurotoxicity (ptosis, respiratory distress), the **Neostigmine (Atropine-Neostigmine) test** is indicated [2].

Q: Which of the following is incorrect regarding Dhatura seed?

Is pale yellow in color. ### Explanation The correct answer is **D (Is pale yellow in color)** because Dhatura seeds are actually **brownish-black** or **dark brown** in color. This is a classic "distractor" question in Forensic Toxicology, as Dhatura seeds are frequently compared with **Capsicum (Chilli) seeds**, which are pale yellow. #### Analysis of Options: * **A. Has small numerous depressions:** This is a correct feature. Dhatura seeds have a **pitted/reticulated** surface with numerous small depressions, whereas Capsicum seeds are smooth. * **B. Is kidney-shaped:** This is a correct feature. Dhatura seeds are **reniform (kidney-shaped)** and larger than Capsicum seeds. * **C. Tastes bitter:** This is a correct feature. Dhatura seeds contain tropane alkaloids (Atropine, Hyoscine, Hyoscyamine) which impart a **bitter taste**. In contrast, Capsicum seeds are pungent (hot). * **D. Is pale yellow in color:** This is **incorrect** for Dhatura. As mentioned, Dhatura is dark brown/black, while Capsicum is pale yellow. #### High-Yield Clinical Pearls for NEET-PG: * **The "Double Edge" Rule:** Dhatura seeds have a **double-layered convex border**, whereas Capsicum seeds have a single edge. * **Embryo Shape:** On cross-section, the embryo of Dhatura is **curved**, while in Capsicum, it is **peripheral**. * **Clinical Presentation:** Dhatura poisoning presents with the "Dry as a bone, Red as a beet, Blind as a bat, Hot as a hare, and Mad as a hatter" syndrome (Anticholinergic toxidrome). * **Antidote:** **Physostigmine** is the specific antidote for central anticholinergic symptoms.

Q: Which of the following is NOT a cardiac poison?

Opioids. **Explanation:** In forensic toxicology, poisons are classified based on their primary site of action. **Opioids** (Option A) are primarily classified as **Somniferous poisons** (a subtype of Cerebral Neurotic poisons). Their main mechanism of action involves binding to mu-opioid receptors in the Central Nervous System, leading to CNS depression, respiratory depression, and miosis. While they can cause secondary bradycardia, they are not categorized as primary cardiac poisons. **Analysis of Incorrect Options:** * **Digitalis (Option B):** A classic cardiac poison derived from *Digitalis purpurea* (Foxglove). It inhibits the Na+/K+-ATPase pump, increasing vagal tone and myocardial contractility. * **Oleander (Option C):** Both Pink Oleander (*Nerium oleander*) and Yellow Oleander (*Thevetia peruviana*) contain cardiac glycosides (like oleandrin and thevetin) that act similarly to Digoxin, causing profound arrhythmias and heart block. * **Aconite (Option D):** (Often misspelled as 'Ollala' or 'Aconite' in various question banks). Aconite is a potent cardiac poison that acts on sodium channels, leading to "dreadful arrhythmias" and death by ventricular fibrillation or asphyxia. **High-Yield Clinical Pearls for NEET-PG:** * **Cardiac Poisons Mnemonic:** Remember **"D-A-O"** (Digitalis, Aconite, Oleander) + **Nicotine** and **Quinine**. * **Yellow Oleander:** The most common cardiac poison used for suicide in India; it contains **Thevetin A & B**. * **Aconite:** Known as "Sweet Poison" or "Blue Rocket"; it causes a characteristic tingling and numbness of the tongue (Hippocratic sign). * **Opioid Triad:** Pinpoint pupil, respiratory depression, and coma. Treatment of choice is **Naloxone**.

Q: Priapism occurs in which of the following poisoning?

Cantharide poisoning. **Explanation:** **Cantharides (Spanish Fly)** is the correct answer. It contains **Cantharidin**, a potent irritant derived from the beetle *Cantharis vesicatoria*. When ingested or absorbed, cantharidin is excreted through the urinary tract. Its mechanism involves intense irritation and inflammation of the urethral mucosa, which leads to reflex pelvic vascular congestion. This results in **priapism** (persistent, painful erection) and is the reason for its historical, albeit dangerous, reputation as an aphrodisiac. Other classic features include "burning from mouth to anus," hematuria, and potential renal failure. **Analysis of Incorrect Options:** * **Snakebite:** While certain elapid bites (like Cobras) cause neurological symptoms and some viper bites cause coagulopathy, priapism is not a characteristic feature. (Note: *Phoneutria* spider bites can cause priapism, but not common snakebites). * **Ratti (Abrus precatorius):** Known for containing **Abrin** (a toxalbumin similar to ricin). It primarily causes severe gastroenteritis or local necrosis (Sui sores) but does not affect the urogenital system to cause priapism. * **Arsenic:** A heavy metal that acts as a protoplasmic poison. Acute poisoning presents with "rice-water stools" and chronic poisoning with hyperpigmentation (Raindrop pigmentation) and hyperkeratosis, but not priapism. **High-Yield Clinical Pearls for NEET-PG:** * **Cantharides** is also known as a "Blister Beetle" because it causes skin vesication on contact. * **Other causes of Priapism in Toxicology:** Carbon monoxide poisoning, Chlorpromazine, and certain spider venoms. * **Post-mortem finding in Cantharides:** Intense congestion of the bladder and kidneys (Urogenital inflammation).

Q: What is the chemical constituent of cigarette lighters commonly used for volatile substance abuse?

Butane. **Explanation:** **Correct Answer: B. Butane** Volatile substance abuse (VSA), often referred to as "solvent sniffing" or "huffing," involves the inhalation of vaporous substances to achieve a psychoactive effect. **Butane** is a highly volatile aliphatic hydrocarbon used as the primary propellant and fuel in cigarette lighters and refill canisters. It is a popular agent for abuse because it is inexpensive, legal, and produces rapid euphoria by acting as a central nervous system (CNS) depressant. **Analysis of Incorrect Options:** * **A. Fluorocarbon:** These are typically found in aerosol propellants (like hairsprays) and refrigerants (Freon). While also abused, they are not the constituent of lighter fluid. * **C. Acetone:** A common solvent found in nail polish removers and certain glues. It is a ketone, not the primary gas in lighters. * **D. Toluene:** An aromatic hydrocarbon found in "model airplane glue," spray paints, and paint thinners. It is one of the most commonly abused solvents but is a liquid at room temperature, unlike the pressurized gas in lighters. **High-Yield Clinical Pearls for NEET-PG:** * **Sudden Sniffing Death Syndrome (SSDS):** The most feared complication of butane/solvent abuse. It occurs due to **myocardial sensitization** to endogenous catecholamines, leading to fatal ventricular arrhythmias (V-fib) upon sudden exertion or fright. * **"Huffer’s Rash":** Perioral eczematous dermatitis seen in chronic abusers due to the drying effect of the solvents. * **Organ Toxicity:** Chronic abuse of toluene is specifically associated with **renal tubular acidosis (RTA)** and white matter encephalopathy. * **Treatment:** Avoid epinephrine in acute intoxication (due to myocardial sensitization); use beta-blockers if arrhythmias occur.

Q: Treatment of opium poisoning includes all of the following except?

Digitalis. **Explanation:** The management of Opium (Opioid) poisoning focuses on preventing further absorption, maintaining the airway, and using specific pharmacological antagonists. **Why Digitalis is the Correct Answer (The "Except"):** Digitalis is a cardiac glycoside used to increase myocardial contractility in heart failure or to control ventricular rate in atrial fibrillation. It has **no role** in the treatment of opium poisoning. In fact, opium poisoning typically causes respiratory depression and bradycardia; administering digitalis could potentially worsen certain cardiac arrhythmias or provide no therapeutic benefit to the primary pathology of respiratory failure. **Analysis of Other Options:** * **Stomach Wash (Gastric Lavage):** This is a mainstay of treatment. Even if the drug was taken hours ago, gastric lavage is performed using **Potassium Permanganate (1:5000)** because opioids undergo **entero-gastric circulation** (they are secreted back into the stomach from the blood). * **Purgatives:** Sodium sulfate or magnesium sulfate is administered to hasten the excretion of the drug from the gastrointestinal tract and prevent further systemic absorption. * **Naloxone:** This is the **specific antidote** of choice. It is a pure opioid antagonist that reverses respiratory depression, sedation, and hypotension by competing for mu, kappa, and delta receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Opioid Poisoning:** Pinpoint pupils (miosis), respiratory depression, and coma. * **Antidote Dosage:** Naloxone is usually given as 0.4 mg to 2 mg IV, repeated every 2-3 minutes if no response occurs. * **Exception to Miosis:** Pethidine (Meperidine) poisoning causes **mydriasis** (dilated pupils) due to its atropine-like action. * **Potassium Permanganate:** Acts by oxidizing the alkaloids in the stomach, rendering them inactive.

Question 1

What is the characteristic colour of urine in carbolic acid poisoning?

Accepted Answer

Dark green

Answer

Dark yellow

Answer

Reddish

Answer

Black

Question 2

Gastric lavage is NOT indicated in which of the following poisoning cases?

Accepted Answer

Corrosive acid poisoning

Answer

Arsenic poisoning

Answer

Dhatura poisoning

Answer

Organophosphorus poisoning

Question 3

Hemodialysis is used in all the following poisonings, except:

Accepted Answer

Kerosene oil

Answer

Barbiturates

Answer

Alcohol

Answer

Cocaine

Question 4

You are performing an autopsy on a person suspected to have died from arsenic poisoning. Which of the following tissues will hold the maximum concentration of arsenic?

Accepted Answer

Liver

Answer

Kidney

Answer

Spleen

Answer

Bone

Question 5

In snake envenomation, what is the standard initial dose of antivenom?

Accepted Answer

10 vials

Answer

2 vials

Answer

4 vials

Answer

20 vials

Question 6

Which of the following is incorrect regarding Dhatura seed?

Accepted Answer

Is pale yellow in color

Answer

Has small numerous depressions

Answer

Is kidney-shaped

Answer

Tastes bitter

Question 7

Which of the following is NOT a cardiac poison?

Accepted Answer

Opioids

Answer

Digitalis

Answer

Oleander

Answer

Ollala

Question 8

Priapism occurs in which of the following poisoning?

Accepted Answer

Cantharide poisoning

Answer

Snakebite

Answer

Ratti poisoning

Answer

Arsenic poisoning

Question 9

What is the chemical constituent of cigarette lighters commonly used for volatile substance abuse?

Accepted Answer

Butane

Answer

Fluorocarbon

Answer

Acetone

Answer

Toluene

Question 10

Treatment of opium poisoning includes all of the following except?

Accepted Answer

Digitalis

Answer

Stomach wash

Answer

Purgatives

Answer

Naloxone

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

On this page

Practice by Chapter

Want unlimited practice?