Forensic Toxicology Practice Questions

Q: In which of the following poisonings does silver nitrate impregnated filter paper turn black when exposed to gastric lavage contents?

Aluminium phosphide. ***Aluminium phosphide*** - Aluminium phosphide ($AlP$) reacts vigorously with water or gastric acid to release highly toxic **phosphine gas** ($PH_3$). - Phosphine gas is a strong reducing agent that reacts with **silver nitrate ($AgNO_3$)** impregnated paper, reducing it to black **metallic silver ($Ag$)** and thus turning the paper black, a method known as the field test for Celphos. ***Malathion*** - Malathion is an **organophosphate insecticide**, and its poisoning is diagnosed primarily by clinical features of cholinergic crisis (SLUDGE syndrome) and measuring depressed **serum/RBC cholinesterase levels**. - Organophosphates do not release phosphine gas and therefore do not produce a positive reaction with silver nitrate filter paper. ***Barbiturates*** - Barbiturate poisoning is confirmed using tests like the **Dille-Koppanyi test** (for color change) or advanced **chromatographic methods** on blood or urine samples. - The barbiturate structure does not produce a reducing gas like phosphine upon reaction, so the silver nitrate paper test would remain negative. ***Opium*** - Opium poisoning (due to alkaloids like **morphine**) is confirmed by detecting the drug or its metabolites in urine or blood using **immunoassays** or gas/liquid chromatography. - Opium alkaloids are not detected by this specific qualitative test, as it is designed to detect the highly reducing nature of phosphine gas.

Q: A patient is brought to the emergency department with acute onset of severe abdominal pain, throat irritation followed by vomiting that contains blood and bile, and diarrhea that initially appears bloody but later becomes colorless, odorless, and rice-water-like. On examination, a distinct garlicky odor is noted in the breath. Which of the following is the most likely agent responsible for the poisoning?

Arsenic. ***Arsenic*** - The combination of **acute severe gastroenteritis** (bloody, then "rice-water" diarrhea) and a distinct **garlicky odor** on the breath is pathognomonic for **acute arsenic poisoning**. - Arsenic is a potent cytotoxin causing widespread capillary damage, leading to severe fluid loss and shock, mimicking cholera. *Phosphorus* - **Phosphorus poisoning** typically presents with a **garlicky odor** (similar to arsenic) and severe gastroenteritis, but the characteristic diarrhea is often described as **smoky or luminous** in the dark, not the rice-water stools seen here. - The main toxicity is hepatotoxicity, leading to acute liver failure (jaundice, coagulation defects) in the second phase after an asymptomatic period. *Aluminium phosphide* - Poisoning from **aluminium phosphide** (often used as a rodenticide/fumigant, marketed as 'Celphos') produces a distinctive, strong odor of **phosphine gas**, usually described as **'rotten fish' or 'carbide'**, not garlicky. - Its main effect is **myocardial toxicity** and refractory hypotension. *Croton seeds* - **Croton seed poisoning** is characterized by intense localized irritation of the GI tract due to the toxin **crotin**, leading to severe **vomiting and purging** (diarrhea). - This poisoning **does not produce a garlicky odor** or the characteristic **rice-water stools** described in this presentation.

Q: All are causes of wrist drop (condition shown in the image below) except:

Zinc poisoning. ***Zinc poisoning*** - **Zinc poisoning** is not a characteristic cause of **wrist drop**, which is typically associated with **radial nerve palsy**. - While excessive zinc can cause copper deficiency and neurological issues, it does not directly lead to **radial nerve entrapment** or damage causing wrist drop. *Arsenic toxicity* - **Chronic arsenic poisoning** can lead to **peripheral neuropathy**, which may include motor weakness such as **wrist drop**. - The neurological damage is often dose-dependent and can affect various peripheral nerves. *Lead poisoning* - **Lead poisoning** is a well-known cause of **radial nerve palsy**, leading to **wrist drop**. - This is often seen in occupational exposures and can be quite specific to the **radial nerve**. *Use of crutches* - Prolonged or improper use of **crutches** can cause compression of the **radial nerve** in the axilla, leading to **crutch palsy**. - **Crutch palsy** manifests as weakness of the **forearm and hand extensors**, resulting in **wrist drop**.

Q: The appearance of lines in nails as shown below is seen in? (Recent NEET Pattern 2016-17)

Arsenic poisoning. ***Arsenic poisoning*** - The image shows **Mees' lines (leuconychia striata)**, which are transverse white bands across the nail plate. - These lines are a **classic and pathognomonic sign of chronic arsenic poisoning** in medical education and competitive exams. - Mees' lines appear 4-6 weeks after arsenic exposure and move distally as the nail grows. - Other conditions like chemotherapy, carbon monoxide poisoning, and severe systemic illness can rarely cause similar findings, but arsenic remains the most important association. *Copper poisoning* - Copper poisoning (Wilson's disease) causes **azure lunulae**, which are blue discoloration of the nail lunula, not transverse white lines. - It primarily affects the **liver, brain, and eyes** with symptoms like Kayser-Fleischer rings. *Mercury poisoning* - Chronic mercury poisoning (acrodynia or Pink Disease in children) typically causes **pink discoloration of the nails, excessive sweating, and rash**. - It does not manifest as transverse white lines. *Thallium poisoning* - The hallmark feature of thallium poisoning is **alopecia (hair loss)**, which is the most characteristic finding. - Other features include painful neuropathies, gastrointestinal symptoms, and neurological manifestations. - Mees' lines are **not a characteristic feature** of thallium poisoning in standard medical teaching.

Q: The toxin shown in the image will lead to the development of: (Recent NEET Pattern 2016-17)

Danbury tremor. ***Danbury tremor*** - The image displays **elemental mercury**, identifiable by its silvery metallic liquid appearance. Mercury poisoning, also known as mercurialism, characteristically manifests as **Danbury tremor** (also called "hatter's shakes"), a fine tremor affecting the hands and fingers due to chronic mercury exposure. - This neurological manifestation is named after **Danbury, Connecticut**, a historical hat-making center where workers developed tremors from mercury exposure used in felt hat production, giving rise to the phrase "**mad as a hatter**." *Burtonian line* - The **Burtonian line** (Burton's line) is a **blue-black gingival discoloration** specifically associated with **chronic lead poisoning**, not mercury toxicity. - This clinical sign results from **lead sulfide deposition** along the gum margin and is not observed in mercury poisoning. *Basophilic stippling of RBC* - **Basophilic stippling** is a microscopic finding on blood smear showing **ribosomal RNA aggregates** in red blood cells, characteristic of **lead poisoning** due to inhibition of pyrimidine-5'-nucleotidase. - This hematological finding is **not associated with mercury toxicity**, which primarily affects the nervous system and kidneys. *Clapton line* - The term "**Clapton line**" is **not a recognized medical sign** in standard medical literature or toxicology references. - This appears to be a **distractor option** with no established association with mercury or any other heavy metal poisoning.

Q: Identify the plant shown in the image:

Calotropis. ***Calotropis*** - The image distinctly shows the **thick, milky white latex** oozing from a broken stem or leaf of a plant, which is a characteristic feature of **Calotropis** species (e.g., *Calotropis procera* or *Calotropis gigantea*). - These plants are common in arid and semi-arid regions and are known for their **toxic latex** containing cardenolides. *Plumbago* - This plant does not produce a significant amount of **milky white latex** when damaged. - *Plumbago* species are known for their distinct flower clusters and root extracts used in traditional medicine. *Croton* - While some *Croton* species do produce latex, it is often **reddish or clear**, not typically the thick, milky white consistency seen in the image. - *Croton* plants vary widely in appearance, but the latex type helps differentiate them. *Abrus* - *Abrus precatorius* (Rosary Pea) is known for its highly **toxic seeds** and does not produce milky latex from its leaves or stems. - It is a vine with characteristic pinnate leaves and brightly colored seeds.

Q: The toxin shown below will lead to the development of:

Basophilic stippling of RBC. ***Basophilic stippling of RBC*** - The image depicts **lead powder**, a known cause of **lead poisoning** - **Lead inhibits pyrimidine 5'-nucleotidase**, leading to accumulation of ribosomal RNA aggregates in red blood cells - These aggregates appear as **basophilic stippling** on peripheral blood smear - a characteristic hematological finding - This is the **most direct and consistent laboratory marker** of lead poisoning *Burtonian line* - The **Burtonian line** (Burton's line or lead line) is a **blue-black line on the gingival margin** due to lead sulfide deposition - While this IS associated with lead poisoning, it is a **clinical sign requiring poor oral hygiene** and is less consistently present - **Basophilic stippling is the more specific hematological finding** directly caused by lead's effect on RBC metabolism *Clapton line* - **Clapton's line** is a **greenish-blue gingival line** seen in **copper poisoning**, not lead poisoning - This is a distractor referring to a sign of a different heavy metal toxicity *Danbury tremor* - **Danbury tremor** (also called "hatter's shakes") refers to tremors associated with **mercury poisoning**, not lead poisoning - Historically seen in hat-makers who used mercury in felt production - While lead can cause neurological symptoms including tremors, this specific term refers to mercury toxicity

Q: Identify the toxin shown below which causes the given ECG changes. (Recent NEET Pattern 2016-17)

Yellow Oleander. ***Yellow Oleander*** - The image displays the **yellow oleander plant** (*Thevetia peruviana*), which contains cardiac glycosides like **thevetin, neriifolin, and thevetoxin**. - These toxins inhibit the **Na+/K+ ATPase pump**, leading to increased intracellular calcium and characteristic ECG changes similar to **digitalis toxicity** (e.g., **bradycardia**, **AV block**, scooping ST-segment depression, ventricular arrhythmias, and T-wave changes). - Yellow oleander is a common cause of poisoning in **tropical regions** and presents with gastrointestinal symptoms followed by life-threatening cardiac arrhythmias. *Aconite* - Aconite (*Aconitum* species) is a cardiotoxic plant but causes toxicity through **sodium channel activation** rather than cardiac glycoside effects. - Presents with **paresthesias, ventricular arrhythmias**, but ECG shows different patterns (polymorphic VT, not typical digitalis-like changes). - The plant morphology is distinct from yellow oleander, with characteristic hood-shaped flowers. *Dhatura* - Dhatura (*Datura stramonium*) is an **anticholinergic poison** containing tropane alkaloids (atropine, scopolamine, hyoscyamine). - Causes **tachycardia** (not bradycardia), mydriasis, dry mouth, hallucinations, and hyperthermia. - ECG shows sinus tachycardia, not the bradycardia and AV blocks seen with cardiac glycosides. *Abrus precatorius* - Abrus precatorius (rosary pea, jequirity bean) contains **abrin**, a **ribosome-inactivating protein toxin**. - Causes severe **gastroenteritis, hepatotoxicity**, and multiorgan failure, not primarily cardiac toxicity. - Does not produce the characteristic digitalis-like ECG changes shown in the image.

Question 1

In which of the following poisonings does silver nitrate impregnated filter paper turn black when exposed to gastric lavage contents?

Accepted Answer

Aluminium phosphide

Answer

Malathion

Answer

Opium

Answer

Barbiturates

Question 2

In a suspected case of poisoning, gastric lavage fluid combined with silver nitrate solution gives rise to a black color in which poisoning?

Accepted Answer

Aluminium phosphide poisoning

Answer

Cocaine poisoning

Answer

Organophosphorus poisoning

Answer

Opium poisoning

Question 3

Match the following substances with their type of poisoning:
Substance:
A. Lead
B. Croton
C. Opium
D. Cocaine
Type of Poisoning:
1. Metallic irritant
2. Organic irritant
3. CNS depressant
4. Deliriant

Accepted Answer

A-1, B-2, C-3, D-4

Answer

A-2, B-1, C-3, D-4

Answer

A-4, B-3, C-2, D-1

Answer

A-3, B-4, C-1, D-2

Question 4

A patient is brought to the emergency department with acute onset of severe abdominal pain, throat irritation followed by vomiting that contains blood and bile, and diarrhea that initially appears bloody but later becomes colorless, odorless, and rice-water-like. On examination, a distinct garlicky odor is noted in the breath. Which of the following is the most likely agent responsible for the poisoning?

Accepted Answer

Arsenic

Answer

Aluminium phosphide

Answer

Phosphorus

Answer

Croton seeds

Question 5

All are causes of wrist drop (condition shown in the image below) except:

Accepted Answer

Zinc poisoning

Answer

Arsenic toxicity

Answer

Lead poisoning

Answer

Use of crutches

Question 6

The appearance of lines in nails as shown below is seen in? (Recent NEET Pattern 2016-17)

Accepted Answer

Arsenic poisoning

Answer

Copper poisoning

Answer

Mercury poisoning

Answer

Thallium poisoning

Question 7

The toxin shown in the image will lead to the development of: (Recent NEET Pattern 2016-17)

Accepted Answer

Danbury tremor

Answer

Clapton line

Answer

Basophilic stippling of RBC

Answer

Burtonian line

Question 8

Identify the plant shown in the image:

Accepted Answer

Calotropis

Answer

Plumbago

Answer

Croton

Answer

Abrus

Question 9

The toxin shown below will lead to the development of:

Accepted Answer

Basophilic stippling of RBC

Answer

Burtonian line

Answer

Clapton line

Answer

Danbury tremor

Question 10

Identify the toxin shown below which causes the given ECG changes. (Recent NEET Pattern 2016-17)

Accepted Answer

Yellow Oleander

Answer

Aconite

Answer

Dhatura

Answer

Abrus precatorius

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

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