Forensic Toxicology Practice Questions

Q: Corn picker's pupil is seen in poisoning by which plant?

Datura. **Explanation:** **Corn picker’s pupil** refers to unilateral or bilateral **mydriasis** (dilated pupil) caused by the accidental contact of *Datura* alkaloids with the eye. The name originates from agricultural workers who, while picking corn or crops, accidentally brush against *Datura* plants (often found as weeds in fields). The plant contains belladonna alkaloids like **atropine, hyoscine, and hyoscyamine**, which act as potent muscarinic antagonists, causing pupillary dilation and paralysis of accommodation (cycloplegia). **Analysis of Options:** * **A. Datura (Correct):** It is the classic cause. The sap or pollen of the plant contains anticholinergic alkaloids that cause topical mydriasis upon contact. * **B. Cannabis:** Typically causes conjunctival injection (red eyes) and occasionally miosis or no significant pupillary change, but never the classic "Corn picker’s" mydriasis. * **C. Datura stramonium:** While this is a species of Datura, in the context of standard forensic textbooks and NEET-PG patterns, "Datura" (Option A) is the broader, preferred clinical term for the poisoning syndrome. * **D. Nicotine:** Initially causes transient stimulation (miosis) followed by persistent depression (mydriasis) due to its action on nicotinic receptors, but it is not associated with the "Corn picker" phenomenon. **High-Yield Clinical Pearls for NEET-PG:** * **Datura Poisoning (Roadside Poison):** Characterized by the "9 Ds": Dryness of mouth, Dysphagia, Dilated pupil, Dry hot skin, Drunken gait, Delirium, Drowsiness, Death, and Distended bladder. * **Diagnostic Test:** Instillation of **pilocarpine**; if the pupil fails to constrict, it confirms pharmacological blockade by atropine/datura. * **Antidote:** **Physostigmine** (a tertiary amine that crosses the blood-brain barrier).

Q: In acute organophosphorous poisoning, which of the following is seen?

Edematous lungs. **Explanation:** In acute **Organophosphorous (OP) poisoning**, the primary mechanism is the irreversible inhibition of the enzyme **Acetylcholinesterase**. This leads to an accumulation of Acetylcholine (ACh) at the synapses, resulting in overstimulation of muscarinic and nicotinic receptors. **Why "Edematous lungs" is correct:** The hallmark of OP poisoning is a "cholinergic crisis." Stimulation of muscarinic receptors ($M_2$ and $M_3$) in the respiratory system causes two major effects: 1. **Profuse Bronchorrhea:** Excessive secretion of bronchial glands. 2. **Bronchoconstriction:** Narrowing of the airways. On autopsy, the lungs are found to be heavy, congested, and **edematous** (pulmonary edema). When the lungs are squeezed, a characteristic frothy, blood-stained fluid exudes from the bronchi. This is often the immediate cause of death due to respiratory failure. **Why other options are incorrect:** * **A. Dry lungs:** OP poisoning causes "wet" symptoms (SLUDGE: Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis). Dry lungs are more characteristic of Atropine (anti-cholinergic) overdose. * **C. Pneumonia:** While aspiration pneumonia can be a late complication, it is not a primary feature of *acute* poisoning. * **D. Pleural rub:** This is a clinical sign of pleurisy (inflammation), not a feature of acute toxic lung congestion. **High-Yield Pearls for NEET-PG:** * **Odor:** Pungent, **Garlic-like** or Kerosene-like odor (due to the solvent). * **Pupils:** Pin-point pupils (**Miosis**). * **Antidotes:** **Atropine** (reverses muscarinic effects) and **Pralidoxime/PAM** (reverses nicotinic effects by regenerating AChE). * **Post-mortem finding:** Presence of frothy secretions at the mouth and nose, similar to drowning.

Q: Death caused by suicide using household items in Japan is due to the production of which of the following?

H2S. **Explanation:** The correct answer is **H2S (Hydrogen Sulfide)**. This question refers to a specific phenomenon known as **"Detergent Suicide,"** which gained notoriety in Japan in the late 2000s before spreading globally. **Why H2S is correct:** Hydrogen sulfide suicide involves mixing common household chemicals—typically an **acidic toilet bowl cleaner** (containing hydrochloric acid) and a **sulfur-containing pesticide or bath salt** (lime sulfur). When combined in a confined space (like a bathroom or car), they undergo a chemical reaction that releases high concentrations of H2S gas. H2S is a potent cellular asphyxiant that inhibits **cytochrome c oxidase** in the mitochondrial electron transport chain, leading to rapid respiratory failure and death. **Why the other options are incorrect:** * **Acidic solution:** While an acidic solution is a *reactant* used to trigger the process, it is the resulting gas (H2S), not the liquid acid, that causes death via inhalation. * **HCN gas:** Hydrogen cyanide is also a cellular asphyxiant, but it is not typically produced from simple household detergent mixtures in this specific epidemiological context. * **CO:** Carbon monoxide is a common cause of suicidal death (e.g., charcoal burning), but it is not the specific "household detergent" method associated with the Japanese trend. **High-Yield NEET-PG Pearls:** * **Rotten Egg Odor:** H2S is characterized by a distinct rotten egg smell; however, at high concentrations, it causes **olfactory fatigue**, making it undetectable to the victim. * **Greenish Discoloration:** On autopsy, H2S poisoning may show a characteristic greenish-purple discoloration of the viscera and blood (sulfhaemoglobin). * **Safety Hazard:** These cases pose a significant risk to first responders due to secondary inhalation toxicity. * **Mechanism:** Similar to Cyanide, it causes **histotoxic hypoxia**.

Q: Yellow Phosphorus is preserved in what substance?

Water. **Explanation:** **Correct Answer: D. Water** Yellow Phosphorus (also known as White Phosphorus) is a highly reactive substance used in the manufacturing of fireworks, matches, and rodenticides. The primary reason it is preserved in **water** is its extreme pyrophoric nature; it has a very low ignition temperature (about 30°C to 34°C). When exposed to air, it undergoes spontaneous oxidation and catches fire, emitting dense white fumes of phosphorus pentoxide (garlic-like odor). Since it is insoluble in water and heavier than water, submerging it prevents contact with atmospheric oxygen, thereby preventing spontaneous combustion. **Analysis of Incorrect Options:** * **A. Alcohol:** Phosphorus is slightly soluble in alcohol. More importantly, alcohol does not provide a sufficient airtight seal to prevent oxidation as effectively as water. * **B. Kerosene:** This is a common distractor. **Sodium and Potassium** metals are stored in kerosene because they react violently with water. Yellow phosphorus, conversely, does not react with water but is highly soluble in organic solvents and oils. * **C. Formalin:** This is a preservative for biological tissues (to fix proteins). It is not used for storing reactive inorganic elements. **High-Yield Clinical Pearls for NEET-PG:** * **Garlic Odor:** A classic sign of phosphorus poisoning is a garlic-like odor in the breath and vomitus. * **Luminous Vomit:** Vomitus and stools may be phosphorescent (glow in the dark). * **Phossy Jaw:** Chronic exposure leads to "Phossy Jaw" (bony necrosis of the mandible). * **Post-mortem:** "Smoking Stool Syndrome" is characteristic. During autopsy, the stomach contents should be collected in **saturated salt solution** (not formalin) to prevent combustion and preserve the toxin for chemical analysis.

Q: A 52-year-old male presented with muscular stiffness and painful cramps. The face was drawn into a forced grimace (risus sardonicus). Strychnine poisoning was suspected. Strychnine competitively antagonizes which of the following?

Glycine. **Explanation:** **1. Why Glycine is Correct:** Strychnine is a potent spinal poison derived from the seeds of *Strychnos nux-vomica*. Its primary mechanism of action is the **competitive antagonism of Glycine**, which is the major inhibitory neurotransmitter in the postsynaptic receptors of the motor neurons in the spinal cord and brainstem. By blocking glycine, strychnine removes the normal inhibitory control over motor neurons, leading to unchecked sensory stimulation. This results in generalized muscle spasms, opisthotonus (arch-like bowing of the body), and the characteristic **risus sardonicus** (a fixed, grimacing expression due to spasm of facial muscles). **2. Why Other Options are Incorrect:** * **Glutamate:** This is the primary *excitatory* neurotransmitter in the CNS. Strychnine does not interact with glutamate receptors. * **Succinylcholine:** This is a depolarizing neuromuscular blocker used in anesthesia. It acts on nicotinic receptors at the neuromuscular junction, causing paralysis, not the spasticity seen in strychnine poisoning. * **Acetylcholine:** This is the neurotransmitter at the neuromuscular junction and autonomic ganglia. While related to muscle contraction, it is not the target of strychnine. **3. High-Yield Clinical Pearls for NEET-PG:** * **Fatal Dose:** Approximately 30–100 mg (one crushed seed). * **Post-mortem findings:** Rigor mortis appears very early and disappears early. * **Differential Diagnosis:** Tetanus. (Distinction: In strychnine poisoning, muscles relax completely between convulsions; in tetanus, muscle rigidity is persistent). * **Management:** Benzodiazepines (Diazepam) are the first-line treatment to control convulsions by enhancing GABAergic inhibition.

Q: Black tongue is a side effect of the abuse of which substance?

Cocaine. **Explanation:** **Cocaine (Option D)** is the correct answer. The phenomenon of a "black tongue" (melanoglossia) in cocaine abusers is primarily attributed to the inhalation of smoke from "crack" cocaine or the practice of applying the drug topically to the tongue. The discoloration results from the deposition of carbonaceous combustion products and the drug's intense vasoconstrictive effect, which can lead to superficial tissue ischemia and the trapping of debris on the filiform papillae. **Analysis of Incorrect Options:** * **Heroin (Option A):** Chronic use typically presents with "track marks" (intravenous use) or "snort sores." It does not cause specific tongue discoloration, though it may cause dry mouth (xerostomia). * **Dhatura (Option B):** As a deliriant with anticholinergic properties, Dhatura causes a **"dry as a bone"** mouth. The tongue appears dry, red, and swollen, but not black. * **Smoking (Option C):** While chronic tobacco smoking can cause a "hairy tongue" (lingua villosa) or brownish staining due to tar, it is not the classic forensic association for "black tongue" in the context of acute substance abuse questions. **Clinical Pearls for NEET-PG:** * **Cocaine:** Known as the "Great Mimicker" of cardiovascular emergencies. Look for **Magnan’s Symptom** (cocaine bugs/formication)—the feeling of insects crawling under the skin. * **Pupillary Findings:** Cocaine causes **Mydriasis** (dilated pupils), whereas Heroin causes **Miosis** (pinpoint pupils). * **Dhatura:** Remember the "Dry as a bone, red as a beet, blind as a bat, hot as a hare, and mad as a hatter" mnemonic.

Q: DDT is a:

Contact poison. **Explanation:** **DDT (Dichloro-Diphenyl-Trichloroethane)** is a chlorinated hydrocarbon insecticide. It is classified as a **Contact Poison** because it can be absorbed through the intact skin, respiratory tract, or gastrointestinal tract. Once in contact with the organism, it acts primarily as a neurotoxin by altering the sodium channels in nerve membranes, leading to repetitive firing of action potentials. **Analysis of Options:** * **A. Contact Poison (Correct):** DDT is highly lipid-soluble, allowing it to penetrate the chitinous exoskeleton of insects or the integument of mammals upon physical contact. This is its primary mode of action in toxicology. * **B. Hemolytic Poison:** These are substances like snake venom (Viper) or certain chemicals (e.g., Arsine gas) that cause the destruction of red blood cells. DDT does not have a primary hemolytic effect. * **C. Muscle Poison:** While DDT causes tremors and convulsions (due to CNS stimulation), it is not a direct muscle poison (like ryanodine). The muscular effects are secondary to its action on the nervous system. * **D. Stomach Poison:** While DDT can be toxic if ingested, the term "stomach poison" specifically refers to insecticides that must be eaten to be effective (e.g., Arsenic). DDT’s ability to kill via surface contact makes "Contact Poison" the more accurate toxicological classification. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Prolongs the opening of sodium channels (similar to Pyrethroids). * **Storage:** Being highly lipophilic, it accumulates in the **adipose tissue** (Bioaccumulation). * **Clinical Feature:** Characterized by "DDT jitters" (tremors) and seizures. * **Treatment:** No specific antidote; management is symptomatic (Diazepam for seizures). * **Environmental Note:** It is a persistent organic pollutant with a very long half-life.

Q: What is the active principle of the jequirity bean?

Abrin. **Explanation:** The **jequirity bean** (also known as *Abrus precatorius*, Ratti, or Gunchi) contains the potent toxalbumin **Abrin**. **1. Why Abrin is correct:** Abrin is a highly toxic protein that acts as a **Ribosome-Inactivating Protein (RIP)**. It consists of two chains (A and B); the B-chain facilitates cell entry, while the A-chain inhibits protein synthesis by inactivating the 28S ribosomal RNA. This leads to cell death. In forensic practice, the seeds are often used to make "Sui" (needles) for cattle poisoning or homicidal purposes. **2. Why the other options are incorrect:** * **Nicotine:** The active alkaloid found in *Nicotiana tabacum* (Tobacco). It acts on nicotinic acetylcholine receptors and is not associated with *Abrus precatorius*. * **Curare:** A generic term for various South American arrow poisons (e.g., *Chondrodendron tomentosum*). Its active principle is **D-tubocurarine**, which acts as a non-depolarizing neuromuscular blocker. * **Pilocarpine:** A parasympathomimetic alkaloid obtained from the leaves of *Pilocarpus* plants. It is used clinically to treat glaucoma and dry mouth. **Clinical Pearls for NEET-PG:** * **Fatal Dose:** 1–2 crushed seeds (ingesting whole seeds is usually harmless due to the tough, indigestible coat). * **Fatal Period:** 3–5 days. * **Post-mortem Finding:** Presence of a "Sui" (needle) at the injection site with surrounding edema, necrosis, and fragmenting of the seed. * **Treatment:** Primarily symptomatic; there is no specific antidote for Abrin. * **Resemblance:** Abrin is biochemically similar to **Ricin** (from Castor beans) but is significantly more toxic.

Q: Mercury poisoning is characterized by all EXCEPT:

Kayser-Fleischer ring. **Explanation:** The correct answer is **Kayser-Fleischer (KF) ring** because it is a pathognomonic sign of **Wilson’s Disease (Copper poisoning)**, not Mercury poisoning. It represents the deposition of copper in the Descemet’s membrane of the cornea. **Analysis of Options:** * **Tremor (Option A):** This is a classic feature of chronic mercury poisoning. It typically begins as "Intentional Tremors" (Danbury tremors) affecting the hands, progressing to the tongue and eyelids. When associated with behavioral changes, it is known as **Erethism**. * **Anterior lens capsule deposits (Option C):** Also known as **Mercuria Lentis**, this is a characteristic finding in chronic mercury exposure where a brownish-rose discoloration appears on the anterior capsule of the lens due to mercury deposition. * **Pink disease (Option D):** Also called **Acrodynia**, this is a hypersensitivity reaction to mercury seen primarily in children. It presents with pinkish discoloration of the hands and feet, irritability, and profuse sweating. **High-Yield Clinical Pearls for NEET-PG:** * **Minamata Disease:** Caused by Methyl-mercury (organic mercury) consumption via contaminated fish. * **Hatters’ Shakes:** Tremors seen in felt-hat industry workers due to mercury exposure. * **Hydrargyrum:** The Latin name for Mercury; chronic poisoning is termed **Hydrargyrism**. * **Chelation:** Dimercaprol (BAL) is used for inorganic mercury, while Succimer (DMSA) is preferred for organic mercury. *Note: BAL is contraindicated in organic mercury poisoning.*

Question 1

Corn picker's pupil is seen in poisoning by which plant?

Accepted Answer

Datura

Answer

Cannabis

Answer

Datura stramonium

Answer

Nicotine

Question 2

In acute organophosphorous poisoning, which of the following is seen?

Accepted Answer

Edematous lungs

Answer

Dry lungs

Answer

Pneumonia

Answer

Pleural rub

Question 3

Death caused by suicide using household items in Japan is due to the production of which of the following?

Accepted Answer

H2S

Answer

Acidic solution

Answer

HCN gas

Answer

CO

Question 4

Yellow Phosphorus is preserved in what substance?

Accepted Answer

Water

Answer

Alcohol

Answer

Kerosene

Answer

Formalin

Question 5

A 52-year-old male presented with muscular stiffness and painful cramps. The face was drawn into a forced grimace (risus sardonicus). Strychnine poisoning was suspected. Strychnine competitively antagonizes which of the following?

Accepted Answer

Glycine

Answer

Glutamate

Answer

Succinyl choline

Answer

Acetyl choline

Question 6

Regarding alcoholic gaze nystagmus, which of the following statements is false?

Accepted Answer

Horizontal gaze nystagmus is pathognomic of alcohol intoxication

Answer

It appears at blood alcohol levels of 50 - 100 mg %

Answer

Positional alcohol nystagmus I occurs 30 minutes after ingestion

Answer

Positional alcohol nystagmus II occurs 5 - 6 hours after ingestion

Question 7

Black tongue is a side effect of the abuse of which substance?

Accepted Answer

Cocaine

Answer

Heroin

Answer

Dhatura

Answer

Smoking

Question 8

DDT is a:

Accepted Answer

Contact poison

Answer

Hemolytic poison

Answer

Muscle poison

Answer

Stomach poison

Question 9

What is the active principle of the jequirity bean?

Accepted Answer

Abrin

Answer

Nicotine

Answer

Curare

Answer

Pilocarpine

Question 10

Mercury poisoning is characterized by all EXCEPT:

Accepted Answer

Kayser-Fleischer ring

Answer

Tremor

Answer

Anterior lens capsule deposits

Answer

Pink disease

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

On this page

Practice by Chapter

Want unlimited practice?