Forensic Toxicology — MCQs
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Yellow/fatty liver is characteristically seen in which type of poisoning?
What is used for stomach wash in cases of phenol poisoning?
Magnan syndrome is seen in which poisoning?
Which cause of death would lead to an elevated level of cyanide?
Arsenophagists are:
Aldrich-Mee's lines are characteristic of poisoning by which heavy metal?
Green coloured urine is seen in:
What substance is commonly used in 'sin needles' for animal poisoning?
An ECG of a patient with snake bite is shown below. What is the abnormality seen?
What toxic substance is responsible for floppy baby syndrome?
Forensic Toxicology Indian Medical PG Practice Questions and MCQs
Question 701: Yellow/fatty liver is characteristically seen in which type of poisoning?
- A. Datura poisoning
- B. Cocaine poisoning
- C. Phosphorus poisoning (Correct Answer)
- D. Opium poisoning
Explanation: **Explanation:** **Phosphorus poisoning** (specifically white/yellow phosphorus) is a potent hepatotoxin. It causes **acute yellow atrophy** of the liver, characterized by massive periportal fatty infiltration and necrosis. The liver becomes enlarged, soft, and yellow due to the accumulation of triglycerides, as phosphorus interferes with the synthesis of lipoproteins required to export fats from hepatocytes. This leads to a clinical picture of fulminant hepatic failure and jaundice. **Analysis of Incorrect Options:** * **Datura poisoning:** This is a deliriant poison containing alkaloids like atropine and hyoscine. It primarily affects the central and autonomic nervous systems (causing "dry as a bone, mad as a hatter" symptoms) but does not cause fatty liver. * **Cocaine poisoning:** Cocaine is a CNS stimulant and sympathomimetic. While chronic use can cause various organ damages, its acute toxicity is characterized by cardiovascular events (arrhythmias, MI) and seizures, not fatty liver. * **Opium poisoning:** Opium is a CNS depressant. Death usually occurs due to respiratory failure. Post-mortem findings are non-specific, typically showing visceral congestion and pulmonary edema. **High-Yield Clinical Pearls for NEET-PG:** * **Phossy Jaw:** Chronic phosphorus poisoning leads to osteomyelitis of the mandible. * **Garlic Odor:** The breath and vomitus in phosphorus poisoning typically smell of garlic. * **Luminous Vomitus:** Phosphorus exhibits phosphorescence; the vomitus may glow in the dark. * **Other causes of fatty liver in toxicology:** Alcohol (most common), Carbon tetrachloride ($CCl_4$), and Arsenic.
Question 702: What is used for stomach wash in cases of phenol poisoning?
- A. 10% glycerin (Correct Answer)
- B. Potassium permanganate (KMnO4)
- C. Alkaline water solution
- D. Saline water
Explanation: **Explanation:** In cases of **phenol (carbolic acid) poisoning**, the primary goal of gastric lavage is to neutralize and dissolve the corrosive substance before it causes extensive systemic absorption or deep tissue damage. **Why 10% Glycerin is the Correct Answer:** Phenol is highly soluble in organic solvents but poorly soluble in water. **10% Glycerin** (or liquid paraffin) is the preferred choice for stomach wash because phenol is more soluble in glycerin than in the gastric mucosa. This helps in dissolving the phenol and preventing its further absorption into the systemic circulation. It also acts as a demulcent, providing a protective coating to the irritated esophageal and gastric linings. **Analysis of Incorrect Options:** * **B. Potassium Permanganate (KMnO4):** This is a powerful oxidizing agent used for alkaloids (like opium) or phosphorus poisoning. It is not effective against the corrosive action of phenol. * **C. Alkaline water solution:** While phenol is a weak acid, using strong alkalis is contraindicated as it may lead to exothermic reactions or worsen the corrosive injury. * **D. Saline water:** Phenol has low solubility in water. Using plain saline or water may actually hasten the absorption of phenol by spreading it over a larger surface area of the gastric mucosa (the "solvent effect"). **Clinical Pearls for NEET-PG:** * **Antidote:** There is no specific systemic antidote for phenol; management is supportive. * **Odor:** Phenol poisoning is characterized by a distinctive **"carbolic acid" or "hospital-like" odor** in the breath. * **Urine:** A classic sign is **"Carboluria"**—the urine turns dark green or black on standing due to the oxidation of hydroquinone and pyrocatechol. * **Contraindication:** While gastric lavage is generally done with care, it must be performed using a soft, small-bore tube because phenol acts as a local anesthetic, potentially masking the pain of a perforation.
Question 703: Magnan syndrome is seen in which poisoning?
- A. Morphine
- B. Alcohol
- C. Cannabis
- D. Cocaine (Correct Answer)
Explanation: **Explanation:** **Magnan’s Syndrome** (also known as Cocaine Bugs or Formication) is a classic clinical feature of chronic **Cocaine** toxicity. It is a tactile hallucination where the patient feels as if insects, ants, or grains of sand are crawling under or over their skin. This often leads to "cocaine sores" due to the patient excessively scratching or picking at their skin to remove the imaginary parasites. **Why the other options are incorrect:** * **Morphine:** Chronic use typically leads to miosis (pinpoint pupils), constipation, and drowsiness. Withdrawal may cause "gooseflesh" (piloerection), but not the specific tactile hallucinations of Magnan’s syndrome. * **Alcohol:** While alcohol withdrawal can cause *Delirium Tremens* (which includes visual and tactile hallucinations), Magnan’s syndrome is specifically associated with the stimulant effects of cocaine. * **Cannabis:** Toxicity is generally characterized by conjunctival injection, increased appetite, and distortions in time and space perception (Run-Amok is a rare associated psychiatric phenomenon), rather than specific tactile hallucinations. **High-Yield Clinical Pearls for NEET-PG:** * **Cocaine:** Also causes **Mydriasis** (dilated pupils) and is known as the "Greatest Energizer." It can lead to sudden cardiac death due to coronary vasospasm. * **Pseudohallucination:** Magnan’s syndrome is technically a tactile hallucination, but the patient may sometimes retain partial insight. * **Differential:** Formication can also be seen in amphetamine use and severe alcohol withdrawal, but in the context of Forensic Medicine exams, it is the hallmark of Cocaine.
Question 704: Which cause of death would lead to an elevated level of cyanide?
- A. Hypothermia
- B. Starvation
- C. Thermal burns (Correct Answer)
- D. Poisoning
Explanation: **Explanation:** The correct answer is **Thermal burns**. In the context of forensic toxicology, elevated cyanide levels are a hallmark finding in victims of house fires or enclosed-space conflagrations. This occurs because the incomplete combustion of synthetic materials—such as polyurethane foam (furniture), plastics, wool, and silk—releases **hydrogen cyanide (HCN) gas**. Victims inhale this toxic smoke, leading to rapid absorption into the bloodstream. In forensic pathology, detecting cyanide in the blood of a fire victim is a vital indicator that the person was **alive at the time the fire started** (inhaling smoke), rather than being a victim of post-mortem burning. **Analysis of Incorrect Options:** * **Hypothermia:** Death from cold exposure typically shows "cherry-red" post-mortem staining (due to oxyhemoglobin) and Wischnewski spots in the stomach, but not cyanide elevation. * **Starvation:** This leads to ketosis and muscle wasting; it has no physiological link to cyanide production or accumulation. * **Poisoning:** While acute cyanide poisoning (e.g., ingestion of KCN) obviously raises levels, in the context of this specific MCQ, "Thermal burns" is the classic forensic association tested to differentiate between ante-mortem and post-mortem burns. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Cyanide inhibits **Cytochrome Oxidase a3**, halting the electron transport chain and causing cellular hypoxia (histotoxic hypoxia). * **Antidote:** The preferred modern antidote is **Hydroxocobalamin** (Cyanokit), which binds cyanide to form Vitamin B12. * **Smell:** Cyanide is famously associated with a **bitter almond odor**, though the ability to smell it is genetically determined (absent in ~20-40% of the population). * **Post-mortem finding:** Bright "cherry-red" or "brick-red" discoloration of skin and viscera.
Question 705: Arsenophagists are:
- A. Criminals using arsenic for homicidal purposes.
- B. Persons using arsenic as an abortifacient.
- C. Persons who can tolerate high doses of arsenic after taking arsenic in low doses at frequent intervals. (Correct Answer)
- D. Persons using arsenic as a cattle poison.
Explanation: **Explanation:** **Arsenophagists** (literally "arsenic eaters") are individuals who have developed a high degree of tolerance to arsenic. This phenomenon occurs through the ingestion of small, sub-lethal doses of arsenic over a prolonged period. Gradually, the body adapts, allowing these individuals to consume doses that would be fatal to a non-habituated person (sometimes up to 0.3 to 0.4 grams in a single dose). This is a classic example of **acquired tolerance** in toxicology. **Analysis of Options:** * **Option C (Correct):** This accurately describes the mechanism of habituation. The tolerance is primarily due to increased excretion and the sequestration of arsenic in less vital tissues like hair and nails. * **Option A:** While arsenic is a notorious homicidal poison (the "King of Poisons"), the term for the user is simply a "homicide" or "poisoner," not an arsenophagist. * **Option B:** Arsenic is rarely used as an abortifacient; more common agents for this purpose include Calotropis or Lead. * **Option D:** Arsenic is indeed used as a cattle poison (often mixed with oil or flour), but the term for the person administering it is not arsenophagist. **High-Yield Clinical Pearls for NEET-PG:** * **Fatal Dose:** 100–200 mg of Arsenic Trioxide. * **Mee’s Lines:** White transverse bands on nails seen in chronic arsenic poisoning. * **Raindrop Pigmentation:** Hyperpigmentation of the skin, a hallmark of chronic exposure. * **Garlic Odor:** Breath and stools of the patient smell distinctly of garlic. * **Antidote:** BAL (British Anti-Lewisite/Dimercaprol) is the specific chelating agent. * **Post-mortem:** Sub-endocardial hemorrhages (flame-shaped) are a characteristic finding.
Question 706: Aldrich-Mee's lines are characteristic of poisoning by which heavy metal?
- A. Lead
- B. Mercury
- C. Arsenic (Correct Answer)
- D. Copper
Explanation: **Explanation:** **Aldrich-Mee’s lines** (often simply called Mee’s lines) are transverse white bands or striae that appear across the fingernails and toenails. They are a classic sign of **Chronic Arsenic Poisoning**. **Why Arsenic is Correct:** Arsenic has a high affinity for sulfhydryl (-SH) groups found in keratin. During episodes of poisoning, arsenic is deposited in the nail matrix, disrupting normal keratinization. As the nail grows (approximately 0.1 mm per day), these white bands move distally. Because they are within the nail substance itself and not the vascular bed, the lines do not blanch under pressure and move outward as the nail grows. **Why Other Options are Incorrect:** * **Lead:** Characterized by the **Burtonian line** (a blue-purple line on the gums/gingival margin) and basophilic stippling of RBCs. * **Mercury:** Associated with **Pink disease (Acrodynia)** and "Mercurialentis" (discoloration of the lens), but not specific transverse nail lines. * **Copper:** Classically associated with the **Kayser-Fleischer (KF) ring** in the cornea (Wilson’s Disease) and "Green hair" in industrial exposure. **High-Yield Clinical Pearls for NEET-PG:** * **Raindrop Pigmentation:** Hyperpigmentation of the skin interspersed with small pale spots (leukoderma) seen in chronic arsenicosis. * **Hyperkeratosis:** Thickening of the skin on palms and soles is a hallmark of arsenic exposure. * **Specimen of Choice:** For chronic arsenic poisoning, **hair and nails** are the preferred samples because arsenic remains fixed in keratin long after it has cleared from blood and urine. * **Mnemonic:** "Mee's" lines = "Arsenic" (Both have 2 'e's or 's' sounds).
Question 707: Green coloured urine is seen in:
- A. Copper sulphate
- B. Opium
- C. Nitric acid
- D. Phenol (Correct Answer)
Explanation: **Explanation:** **Phenol (Carbolic Acid)** poisoning is classic for causing **Carboluria**. When phenol is absorbed, it is metabolized in the liver into hydroquinone and pyrocatechol. These metabolites are excreted in the urine and, upon standing and exposure to air (oxidation), they turn the urine a characteristic **dark green or blackish-green** color. Phenol also acts as a corrosive and a systemic toxin, causing a "bleached" appearance of the oral mucosa and a characteristic "phenolic" odor. **Analysis of Incorrect Options:** * **A. Copper Sulphate:** Poisoning typically leads to **blue or blue-green** colored vomitus and feces due to the color of the salt itself. However, it does not typically cause green urine; instead, it may cause hemoglobinuria (red/brown urine) due to acute intravascular hemolysis. * **B. Opium:** Opium poisoning presents with pinpoint pupils and respiratory depression. It does not significantly alter urine color. * **C. Nitric Acid:** This is a strong corrosive. It causes **yellowish discoloration** of the skin and tissues (Xanthoproteic reaction) due to the nitration of aromatic amino acids, but it does not produce green urine. **High-Yield Clinical Pearls for NEET-PG:** * **Green Urine:** Phenol, Resorcinol, Methylene blue, Propofol, and Amitriptyline. * **Black Urine:** Phenol (on standing), Alkaptonuria (Homogentisic acid), and Quinine. * **Red/Pink Urine:** Rifampicin, Beetroot (Anthocyanin), and Laxatives containing Phenolphthalein. * **Musty/Mousy Odor:** Phenylketonuria. * **Rotten Egg Odor:** Hydrogen Sulphide.
Question 708: What substance is commonly used in 'sin needles' for animal poisoning?
- A. Dhatura seeds
- B. Rati seeds (Correct Answer)
- C. Lead peroxide
- D. Arsenic
Explanation: **Explanation:** **Why Rati Seeds are Correct:** 'Sui' or 'Sin' needles are small, handmade spikes (1.5 to 2 cm long) prepared from the paste of **Rati seeds (*Abrus precatorius*)**. These seeds contain **Abrin**, a potent toxalbumin that inhibits protein synthesis (similar to Ricin). In veterinary forensic practice, these needles are surreptitiously driven into the hide of cattle to cause slow, agonizing death, usually for the purpose of skinning the animal for its hide. The needles are often disguised by being smeared with animal fat or cow dung. **Why Other Options are Incorrect:** * **Dhatura seeds:** These contain tropane alkaloids (Atropine, Hyoscine) and are primarily used as "stupefying agents" in road robberies or for accidental poisoning in children. They are not used to manufacture needles. * **Lead peroxide:** While used in the manufacture of matches and explosives, it has no role in the preparation of traditional 'sin' needles. * **Arsenic:** Although a common cattle poison (usually mixed with fodder), it is a chemical irritant and is not used to form solid mechanical needles like Rati paste. **High-Yield Clinical Pearls for NEET-PG:** * **Active Principle:** Abrin (one of the most lethal toxins known; more toxic than Ricin). * **Mechanism of Action:** Ribosome-inactivating protein (RIP) that halts protein synthesis. * **Clinical Presentation:** If injected (Sui), it causes local edema, necrosis, and painful swelling resembling **Malignant Edema or Anthrax**. * **Post-mortem Finding:** Fragment of the 'Sui' needle may be found at the site of injection. * **Fatal Dose:** 1–2 seeds (if chewed/crushed); **Fatal Period:** 3–5 days.
Question 709: An ECG of a patient with snake bite is shown below. What is the abnormality seen?
- A. Hyperkalemia (Correct Answer)
- B. Hypokalemia
- C. Myocarditis
- D. Bigemini
Explanation: ***Hyperkalemia*** - Snake bite, particularly **viper envenomation**, causes **rhabdomyolysis** leading to **acute kidney injury** and subsequent **hyperkalemia**. - Classic ECG features include **peaked T waves**, **widened QRS complexes**, and **prolonged PR intervals** as potassium levels rise. *Hypokalemia* - ECG shows **flattened T waves**, **prominent U waves**, and **ST depression**, which are opposite to hyperkalemia findings. - Snake bite typically causes **hyperkalemia** due to muscle breakdown and kidney dysfunction, not potassium loss. *Myocarditis* - ECG typically shows **ST elevation**, **T wave inversions**, and **arrhythmias** resembling myocardial infarction patterns. - While snake venom can cause **direct cardiotoxicity**, the predominant ECG abnormality is related to **electrolyte imbalance**. *Bigeminy* - Refers to **alternating normal and premature beats** creating a coupled rhythm pattern on ECG. - Snake bite-induced ECG changes are primarily due to **hyperkalemia** affecting cardiac conduction, not ectopic beat patterns.
Question 710: What toxic substance is responsible for floppy baby syndrome?
- A. Lithium (Correct Answer)
- B. Cadmium
- C. Antimony
- D. Barium
Explanation: **Explanation:** **Floppy Baby Syndrome (Neonatal Hypotonia)** in the context of toxicology is a classic manifestation of **Lithium** toxicity in neonates. Lithium is a common mood stabilizer used for Bipolar Affective Disorder. It readily crosses the placental barrier. When a mother takes lithium near the time of delivery, the neonate may present with symptoms including severe muscle hypotonia (floppiness), cyanosis, lethargy, and a poor suck reflex. This occurs because lithium interferes with neuromuscular transmission and electrolyte balance. **Analysis of Options:** * **Lithium (Correct):** Beyond floppy baby syndrome, lithium is also a known teratogen associated with **Ebstein’s Anomaly** (tricuspid valve displacement). * **Cadmium:** Chronic exposure leads to **Itai-Itai disease** (osteomalacia and renal failure). It does not cause acute neonatal hypotonia. * **Antimony:** Primarily causes gastrointestinal irritation and "antimony spots" (pustular eruptions). It is chemically similar to arsenic but does not cause floppy baby syndrome. * **Barium:** Soluble barium salts cause severe **hypokalemia**, leading to muscular paralysis in adults (Pa-Ping disease), but it is not the classic cause of neonatal floppy baby syndrome. **High-Yield NEET-PG Pearls:** 1. **Ebstein’s Anomaly:** The most specific teratogenic effect of Lithium (Right ventricular atrialization). 2. **Therapeutic Index:** Lithium has a very narrow therapeutic index (0.6–1.2 mEq/L). 3. **Other causes of Floppy Baby:** Apart from Lithium, consider **Infant Botulism** (due to honey ingestion containing *C. botulinum* spores) and maternal use of **Benzodiazepines** or **Magnesium Sulfate** during labor.
Practice by Chapter
General Principles of Toxicology
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Corrosive Poisons
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Metallic Poisons
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Non-Metallic Poisons
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Organic Irritant Poisons
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Neurotic Poisons
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Cardiac Poisons
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Asphyxiant Poisons
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Food Poisoning
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Drug Abuse and Dependence
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Analytical Toxicology Methods
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Interpretation of Toxicology Results
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