Forensic Toxicology — MCQs

Forensic Toxicology Indian Medical PG Practice Questions and MCQs

Question 801: Cobra poison is:

A. Vasculotoxic
B. Myotoxic
C. Neurotoxic (Correct Answer)
D. Cardiotoxic

Explanation: ***Neurotoxic*** - Cobra venom contains **alpha-neurotoxins** that block **nicotinic acetylcholine receptors** at neuromuscular junctions, causing flaccid paralysis. - The primary cause of death is **respiratory failure** due to paralysis of respiratory muscles, making neurotoxicity the dominant mechanism. *Vasculotoxic* - Vasculotoxic effects are characteristic of **viper venoms**, causing bleeding, swelling, and tissue necrosis. - Cobra venom's primary action targets the **nervous system**, not blood vessels. *Myotoxic* - Myotoxic venoms directly damage **muscle tissue**, leading to rhabdomyolysis and muscle pain. - While minor muscle effects may occur, **neurotoxicity** remains the predominant and life-threatening mechanism in cobra envenomation. *Cardiotoxic* - Some cobra venoms contain **cardiotoxins**, but these are secondary to the primary neurotoxic effects. - The main cause of cardiovascular collapse is **respiratory paralysis**, not direct cardiac toxicity.

Question 802: The poison that can be detected in hair/bones long after death is:

A. Lead
B. Arsenic (Correct Answer)
C. Mercury
D. Cannabis

Explanation: ***Arsenic*** - **Arsenic** has a high affinity for **keratin-rich tissues** like hair and nails, where it accumulates and can be detected long after exposure or death. - It also deposits in **bones**, allowing for its detection in archaeological remains, making it a classic poison for historical forensic analysis. *Lead* - While **lead** also accumulates in bones and teeth, its primary long-term storage is in these tissues, not predominantly in hair in a way that is easily detectable post-mortem in the same manner as arsenic. - Lead poisoning detection in **hair** is possible but less reliable or common for long-term retrospective analysis compared to arsenic due to varying growth rates and external contamination. *Mercury* - **Mercury**, particularly organic forms, can accumulate in hair, but its detection for very long periods post-mortem tends to be more variable and less definitive for pinpointing chronic poisoning than arsenic in hair and bone. - Its excretion and distribution patterns differ, making it somewhat less persistent in hair/bone over extremely long periods compared to arsenic, which binds strongly to **sulfhydryl groups**. *Cannabis* - **Cannabis** metabolites can be detected in hair for an extended period (months), but typically not "long after death" in the same forensic toxicology context as heavy metals which are incorporated into bone and keratin structures. - As an organic compound, its stability and detectability diminish over time in a way that heavy metals like arsenic, which become part of the mineral matrix, do not.

Question 803: A farmer presented with confusion, increased salivation, fasciculations, miosis, tachycardia and hypertension. Poison that can cause these manifestations:

A. Arsenic
B. Opium
C. Dhatura
D. OPC (Correct Answer)

Explanation: ***OPC*** - The combination of **confusion**, increased salivation, **fasciculations**, **miosis**, and **tachycardia/hypertension** points towards **organophosphate poisoning (OPC)** due to excessive cholinergic stimulation. - Farmers are at high risk for OPC due to exposure to **pesticides**. *Arsenic* - **Arsenic poisoning** typically causes severe gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain, along with **garlic breath** and **neuropathy**. - It does not commonly present with prominent salivation, fasciculations, or miosis. *Opium* - **Opioid overdose** characteristically leads to **CNS depression**, **respiratory depression**, **pinpoint pupils (miosis)**, and **bradycardia** and **hypotension**. - It does not cause increased salivation, fasciculations, or tachycardia. *Dhatura* - **Dhatura poisoning** is characterized by **anticholinergic symptoms** such as **dry mouth**, dilated pupils (mydriasis), blurred vision, warm dry skin, **tachycardia**, and **agitation/delirium**. - It would not cause increased salivation, fasciculations, or miosis.

Question 804: The triad of "saturnine" gout, hypertension and renal insufficiency is seen in poisoning with which of the following metals?

A. Arsenic
B. Lead (Correct Answer)
C. Copper
D. Iron

Explanation: ***Lead*** - **Lead poisoning** is classically associated with the triad of **"saturnine" gout**, **hypertension**, and **renal insufficiency** - Lead interferes with **heme synthesis** and **renal tubular function**, and elevates **uric acid levels** leading to gout - The term "saturnine" derives from Saturn, the alchemical name for lead, and specifically refers to lead-related pathology - Chronic lead nephropathy causes progressive renal damage leading to hypertension and renal insufficiency *Arsenic* - Arsenic poisoning typically presents with **gastrointestinal symptoms** (acute watery diarrhea), skin lesions (**hyperkeratosis, melanosis, Mees' lines**), and **peripheral neuropathy** - Not primarily associated with the specific triad of gout, hypertension, and renal insufficiency *Copper* - Copper toxicity, as seen in **Wilson's disease**, manifests with hepatic dysfunction, neurological symptoms (tremor, dysarthria), and **Kayser-Fleischer rings** - Does not typically present with this specific combination of gout, hypertension, and renal insufficiency *Iron* - Acute iron poisoning causes **gastrointestinal distress**, metabolic acidosis, and shock - Chronic iron overload (**hemochromatosis**) leads to widespread organ damage (liver cirrhosis, cardiomyopathy, diabetes mellitus) but not the specific triad of saturnine gout, hypertension, and renal insufficiency

Question 805: Most sensitive test for sanguinarine is

A. Nitric Acid (Correct Answer)
B. Paper chromatography
C. FeCl3
D. HCl

Explanation: ***Nitric Acid*** - **Nitric acid test** is the **most sensitive and classical test** for detecting sanguinarine in forensic toxicology. - When nitric acid is added to sanguinarine, it produces a **characteristic blood-red color** that gradually fades to yellow-brown, which is highly specific for this alkaloid. - This colorimetric reaction is rapid, sensitive, and routinely used in the **forensic investigation of argemone oil poisoning** (epidemic dropsy). - The test can detect even small quantities of sanguinarine in biological samples and contaminated oils. *Paper chromatography* - While paper chromatography is a useful **confirmatory technique** for separating and identifying alkaloids, it is not considered the most sensitive primary test for sanguinarine. - Chromatographic methods are more time-consuming and typically used for **detailed analysis** rather than as screening tests in forensic practice. - The nitric acid test remains the preferred initial screening method due to its simplicity and sensitivity. *FeCl3* - **Ferric chloride (FeCl3)** is primarily used to detect **phenolic compounds** by forming colored complexes. - Sanguinarine does not produce a characteristic reaction with FeCl3 that would be useful for its specific identification. - This reagent is not employed in the standard forensic detection of sanguinarine. *HCl* - **Hydrochloric acid (HCl)** can dissolve alkaloids by forming their corresponding salts, but it does not produce any **characteristic color change** specific to sanguinarine. - HCl is used for extraction purposes but not as a sensitive detection method for this particular alkaloid. - It lacks the specificity required for forensic identification of sanguinarine.

Question 806: Ramesh, 30 yrs old male, diagnosed case of CO poisoning presented with syncope or coma with intermittent convulsions, rapid respirations, tachycardia with a weak pulse and pink or red discolouration of the skin; estimated percentage of COHb:-

A. 40 to 50 %
B. 30 to 40 %
C. 60 to 70 %
D. 50 to 60 % (Correct Answer)

Explanation: ***50 to 60 %*** - A COHb saturation of 50-60% typically leads to severe symptoms like **syncope**, **coma**, convulsions, and the characteristic **pink/red skin discoloration** due to highly saturated COHb. - At this level, **tissue hypoxia** is profound, affecting critical organs and causing systemic manifestations. *40 to 50 %* - While 40-50% COHb levels can cause significant symptoms such as **confusion**, collapse, and cardiac arrhythmias, **coma** and **convulsions** are more characteristic of higher levels. - The distinctive **pink skin** is also less consistently present or as pronounced at this saturation range compared to 50-60%. *30 to 40 %* - COHb levels between 30-40% commonly result in symptoms like **headache**, **nausea**, **vomiting**, **dizziness**, and **visual disturbances**. - **Syncope** and **coma** are generally not observed at these lower levels of COHb saturation. *60 to 70 %* - COHb levels in the 60-70% range are considered **fatal**, often resulting in rapid death, rather than the described symptom complex of syncope, coma with intermittent convulsions, and pink skin. - While these symptoms would certainly be present, it's a more critically life-threatening, often terminal, stage.

Question 807: Following is a contact poison –

A. BaSO4
B. BHC
C. Paris green
D. DDT (Correct Answer)

Explanation: ***DDT*** - **DDT (dichlorodiphenyltrichloroethane)** is the classic **organochlorine insecticide** that acts primarily as a **contact poison**. - It is absorbed through the **insect cuticle** upon direct contact and disrupts the **nervous system** by interfering with sodium channel function. - DDT is the most well-known example of a contact poison used in pest control and public health. *BHC* - **Benzene hexachloride (BHC/Lindane)** is an **organochlorine insecticide** but acts primarily as a **stomach poison** rather than a contact poison. - While it has some contact activity, its main mechanism involves ingestion and systemic absorption through the gastrointestinal tract. - It is not classified primarily as a contact poison in forensic toxicology. *BaSO4* - **Barium sulfate (BaSO4)** is a **radiocontrast agent** used in medical imaging and is generally **insoluble** and non-toxic when ingested. - It does not act as a poison and has no insecticidal properties. - It is medically safe and used routinely for diagnostic purposes. *Paris green* - **Paris green (copper(II) acetoarsenite)** is an **arsenical compound** that acts primarily as a **stomach poison** when ingested by pests. - Its toxicity is due to **arsenic content** absorbed from the digestive tract, not through direct contact. - Historically used as both a pigment and insecticide, but toxic via ingestion route.

Question 808: Which type of poisoning occurs due to ingestion of Linseed plant -

A. Hydrocyanic acid (Correct Answer)
B. Atropine
C. Pilocarpine
D. Aconite

Explanation: ***Hydrocyanic acid*** - Linseed (flaxseed) plants contain **cyanogenic glycosides**, which, when ingested, are hydrolyzed to release **hydrocyanic acid (HCN)**, also known as cyanide. - Cyanide poisoning is rapid and severe, leading to **cellular hypoxia** by inhibiting cytochrome oxidase in the electron transport chain, resulting in bright cherry-red coloration of blood and mucous membranes, metabolic acidosis, and potentially rapid death. - **Clinical features** include headache, dizziness, confusion, dyspnea, seizures, and cardiovascular collapse. *Atropine* - **Atropine** is an anticholinergic alkaloid found in plants like deadly nightshade (**Atropa belladonna**) and Jimsonweed (**Datura stramonium**), not in linseed. - It causes symptoms such as **dilated pupils**, dry mucous membranes, **tachycardia**, hyperthermia, and gastrointestinal stasis. *Pilocarpine* - **Pilocarpine** is a cholinergic alkaloid found in the **Pilocarpus** genus of plants, not in linseed. - Ingestion leads to signs of parasympathetic overstimulation, including **salivation**, lacrimation, miosis, and diarrhea (muscarinic effects). *Aconite* - **Aconite** is a highly toxic plant containing **aconitine alkaloids**, primarily found in species like monkshood (Aconitum napellus), not in linseed. - Poisoning typically results in **cardiac arrhythmias**, neurological signs (paresthesias, weakness), and can lead to death due to **cardiac or respiratory arrest**.

Question 809: A 70-year-old male patient with a history of consuming traditional medicine regularly presents with exertional chest pain, episodic tachycardia, and extra systoles. He also has hyperpigmentation and keratosis on palms and soles. What is the probable cause?

A. Chronic nicotine poisoning
B. Cocaine poisoning
C. Cannabis ingestion
D. Arsenophagia (Correct Answer)

Explanation: ***Arsenophagia*** - **Arsenic poisoning**, particularly chronic exposure, can lead to **cardiovascular complications** such as **cardiomyopathy**, arrhythmias (tachycardia, extrasystoles), and **angina-like chest pain**. - The presentation of exertional chest pain, episodic tachycardia, and extrasystoles in an elderly patient is consistent with the cardiac effects of chronic arsenic toxicity, which can mimic **ischemic heart disease**. *Chronic nicotine poisoning* - While chronic nicotine use and smoking can contribute to **cardiovascular disease** and *arrhythmias*, it is less likely to directly cause exertional chest pain in the specific context of "poisoning" without clear evidence of overdose. - Nicotine's primary cardiovascular effects are often related to its role in accelerating **atherosclerosis** and increasing **myocardial oxygen demand**, rather than direct toxic cardiomyopathy mimicking arsenic. *Cocaine poisoning* - **Cocaine toxicity** typically presents with acute and severe cardiovascular effects, including **myocardial infarction**, **severe hypertension**, **tachycardia**, and *arrhythmias*, often in a younger population or with acute exposure. - The term "poisoning" usually implies acute or subacute overdose, and while chronic use has effects, the clinical picture here is more suggestive of a slower-onset, cumulative toxic effect. *Cannabis ingestion* - Acute cannabis use can cause **tachycardia** and mild **hypotension**, but it is generally not associated with exertional chest pain or significant *arrhythmias* that would lead to this specific constellation of symptoms, especially in an elderly patient. - Chronic cannabis use has not been definitively linked to the type of chronic progressive cardiac damage seen with arsenic and is unlikely to be the primary cause of these severe symptoms.

Question 810: Postmortem caloricity is seen in

A. Datura poisoning
B. Strychnine poisoning (Correct Answer)
C. Ergot poisoning
D. Organophosphorus poisoning

Explanation: ***Strychnine poisoning*** - **Postmortem caloricity**, an abnormal persistence of body heat after death, is a classic sign associated with **strychnine poisoning**. - This symptom arises due to intense **muscular spasms** and convulsions caused by strychnine, leading to excessive heat generation. *Datura poisoning* - **Datura poisoning** typically presents with symptoms related to **anticholinergic effects**, such as dry mouth, dilated pupils, tachycardia, and delirium. - It does not characteristically cause postmortem caloricity, as muscle rigidity is not a primary feature. *Ergot poisoning* - **Ergot poisoning**, or **ergotism**, is characterized by symptoms like gangrene of the extremities (St. Anthony's Fire) due to **vasoconstriction** and neurological effects such as seizures and hallucinations. - It does not typically lead to postmortem caloricity. *Organophosphorus poisoning* - **Organophosphorus poisoning** primarily manifests with **cholinergic overstimulation** symptoms, including salivation, lacrimation, urination, defecation, gastrointestinal upset, emesis (SLUDGE syndrome), bradycardia, miosis, and muscle fasciculations. - It is not associated with postmortem caloricity; rather, the body temperature may remain normal or decrease postmortem.

Practice by Chapter

General Principles of Toxicology

Practice Questions

Corrosive Poisons

Practice Questions

Metallic Poisons

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Non-Metallic Poisons

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Organic Irritant Poisons

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Neurotic Poisons

Practice Questions

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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