Forensic Toxicology — MCQs
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Which of the following poisonings will lead to the skin appearance shown below?
Effects of which poisoning are shown below?
An unconscious patient was brought to the casualty. ABG reveals metabolic acidosis with hypocalcemia. The urine specimen from this patient is shown below. Identify the substance:
Identify the flowers shown below:
The following presentation occurs due to? (AIIMS Nov 2018)
The seeds of this plant produce which toxin?
Which of the following insecticides is a natural contact poison?
Which of the following is the least toxic organophosphorus compound?
Beta oxalyl amino alanine (BOAA) is found in:
Mees' lines and raindrop pigmentation on the hands are seen in which type of poisoning?
Forensic Toxicology Indian Medical PG Practice Questions and MCQs
Question 781: Which of the following poisonings will lead to the skin appearance shown below?
- A. Mercury poisoning
- B. Cadmium poisoning
- C. Antimony poisoning
- D. Arsenic poisoning (Correct Answer)
Explanation: ***Arsenic poisoning*** - Chronic arsenic exposure can lead to characteristic **rain-drop hyperpigmentation** (scattered spots of hyperpigmentation on a hypopigmented background), and **keratoses** on the palms and soles, as seen in the image. - This **skin manifestation** is a strong indicator of arsenic toxicity and can progress to skin cancers like squamous cell carcinoma and basal cell carcinoma. *Mercury poisoning* - **Mercury poisoning** typically manifests with neurological symptoms like tremors, ataxia, and psychological disturbances, as well as kidney damage. - Dermatological signs are less common but can include acrodynia (pink disease) in children, characterized by a **diffuse red rash**, swelling, and pain in the extremities, which is not depicted. *Cadmium poisoning* - Chronic exposure to **cadmium** primarily affects the kidneys (leading to renal dysfunction), bones (causing osteomalacia and osteoporosis), and lungs (emphysema). - While skin pigmentation changes can occur in some heavy metal poisonings, they are not a prominent or pathognomonic feature of cadmium toxicity. *Antimony poisoning* - **Antimony poisoning**, often from occupational exposure or specific medications, can cause gastrointestinal symptoms (nausea, vomiting), cardiac abnormalities (arrhythmias), and liver dysfunction. - Skin manifestations are not a common or characteristic feature of antimony toxicity.
Question 782: Effects of which poisoning are shown below?
- A. Arsenic poisoning (Correct Answer)
- B. Mercury poisoning
- C. Cadmium poisoning
- D. Antimony poisoning
Explanation: ***Arsenic poisoning*** - The image depicts severe **hyperkeratosis** and **hyperpigmentation** of the palms and soles, which are classic cutaneous manifestations of chronic arsenic poisoning. - Chronic exposure to arsenic often leads to these skin changes, along with other systemic effects like **neuropathy** and increased cancer risk. *Mercury poisoning* - Chronic mercury poisoning (e.g., Minamata disease) primarily affects the **nervous system**, causing **ataxia**, **paresthesias**, and psychiatric disturbances. - While skin changes can occur (e.g., acrodynia in children), they are typically not characterized by this specific pattern of palmar/plantar hyperkeratosis and hyperpigmentation. *Cadmium poisoning* - Cadmium poisoning mainly affects the **kidneys** (proximal tubular dysfunction), **bones** (osteomalacia, osteoporosis, "itai-itai" disease), and lungs. - Skin manifestations similar to those shown in the image are not typical features of cadmium toxicity. *Antimony poisoning* - Acute antimony poisoning typically causes **gastrointestinal symptoms** (nausea, vomiting, diarrhea) and cardiac effects. - Chronic exposure can lead to irritation of the skin and mucous membranes, but the prominent palmar/plantar hyperkeratosis and hyperpigmentation shown are not characteristic.
Question 783: An unconscious patient was brought to the casualty. ABG reveals metabolic acidosis with hypocalcemia. The urine specimen from this patient is shown below. Identify the substance:
- A. Ethylene glycol (Correct Answer)
- B. Methyl alcohol
- C. Formaldehyde
- D. Paraldehyde
Explanation: ***Ethylene glycol*** - The image shows **calcium oxalate crystals** (both monohydrate, "dumbbell" shapes, and dihydrate, "envelope" shapes), classical findings in **ethylene glycol poisoning**. - Ethylene glycol is metabolized into **oxalic acid**, which precipitates with calcium, leading to **hypocalcemia** and metabolic acidosis due to accumulating organic acids. *Methyl alcohol* - Methyl alcohol poisoning is characterized by metabolites like **formic acid**, causing severe **metabolic acidosis** and visual disturbances, but does not typically lead to calcium oxalate crystalluria. - While it causes profound acidosis, the diagnostic urine crystals seen in the image are not associated with methyl alcohol intoxication. *Formaldehyde* - Formaldehyde poisoning is generally due to ingestion or inhalation, leading to immediate toxicity, often with severe gastrointestinal and respiratory symptoms. - It does not typically metabolize into substances that form **calcium oxalate crystals** in the urine or cause hypocalcemia in this manner. *Paraldehyde* - Paraldehyde is an older sedative/hypnotic that can cause **metabolic acidosis** due to its metabolism into acetic acid, especially in large doses. - However, it does not lead to the formation of **calcium oxalate crystals** in the urine or associated hypocalcemia as seen in the image.
Question 784: Identify the flowers shown below:
- A. Aconite (Correct Answer)
- B. Datura
- C. Nerium Odorum
- D. Cerbera Thevetia
Explanation: ***Aconite*** - The image displays characteristics consistent with **Aconite** (monkshood) flowers, which are typically **dark purple to blue** and have a distinctive **hooded shape**. - Aconite is known for its **highly toxic** alkaloids, especially **aconitine**, which can cause rapid and severe symptoms upon ingestion or skin contact. *Cerbera Thevetia* - **Cerbera Thevetia** (yellow oleander) flowers are typically **yellow or orange** and are bell-shaped, which differs significantly from the flowers shown. - Poisoning from *Cerbera Thevetia* is primarily due to **cardiac glycosides**, leading to symptoms like bradycardia, nausea, and vomiting. *Datura* - **Datura** flowers are typically **large, trumpet-shaped**, and vary in color from white to purple, but lack the distinctive hooded appearance seen in the image. - *Datura* species contain **tropane alkaloids** (e.g., scopolamine, atropine), which cause anticholinergic effects like mydriasis, delirium, and tachycardia. *Nerium Odorum* - **Nerium Odorum** (pink oleander) flowers are typically **pink, red, or white** and have a pinwheel shape with five petals, which does not match the flowers in the image. - Like *Thevetia*, *Nerium Odorum* is toxic due to **cardiac glycosides**, causing similar cardiovascular and gastrointestinal symptoms.
Question 785: The following presentation occurs due to? (AIIMS Nov 2018)
- A. Chronic Copper sulfate poisoning
- B. Long term ingestion of arsenic in drinking water (Correct Answer)
- C. Application of mercury ointment
- D. Application of Calotropis
Explanation: ***Long term ingestion of arsenic in drinking water*** - The image shows **hyperpigmentation and hyperkeratosis** on the palms, often described as "raindrop pigmentation" or diffuse darkening with scattered paler lesions (leukomelanosis). This is a classical dermatological manifestation of **chronic arsenic poisoning**, particularly from contaminated drinking water. - **Arsenicosis** can also cause palmar and plantar keratoses, which can progress to malignant skin lesions over time. *Chronic Copper sulfate poisoning* - Chronic copper poisoning is rare and typically affects the liver, leading to conditions like **cirrhosis** and **hepatitis**, as seen in Wilson's disease. - Skin manifestations from copper poisoning are not typically characterized by the diffuse hyperpigmentation and hyperkeratosis seen in the image. *Application of mercury ointment* - Topical mercury exposure can cause localized skin irritation, dermatitis, or systemic toxicity with features like **acrodynia** (pink disease) in children, characterized by a pink rash, irritability, and hypertension. - It does not typically lead to the described pattern of diffuse hyperpigmentation and hyperkeratosis on the palms. *Application of Calotropis* - **Calotropis** (such as *Calotropis gigantea* or *procera*) is a plant known for its toxic latex, which can cause intense local irritation, vesication, or ulceration upon skin contact. - Its effects are primarily acute irritant or allergic reactions and do not produce the chronic skin changes of hyperpigmentation and hyperkeratosis seen in the image.
Question 786: The seeds of this plant produce which toxin?
- A. BOAA
- B. Pyrrolizidine
- C. Hydrocyanic acid
- D. Sanguinarine (Correct Answer)
Explanation: ***Sanguinarine*** - **Sanguinarine** is the primary and most clinically significant alkaloid found in *Argemone mexicana* seeds, responsible for **epidemic dropsy** syndrome. - It causes **oxidative stress**, **capillary damage**, and **generalized edema** by inhibiting various cellular enzymes, particularly Na-K-ATPase and protein kinases. - Epidemic dropsy presents with bilateral leg edema, breathlessness, erythema, and gastrointestinal symptoms, making sanguinarine the predominant toxin associated with this plant. *BOAA* - **BOAA (β-N-oxalylamino-L-alanine)** is the neurotoxin found in *Lathyrus sativus* (grass pea/khesari dal), NOT in *Argemone mexicana*. - BOAA causes **neurolathyrism**, characterized by irreversible spastic paraplegia, which is a completely different condition from epidemic dropsy. - This option is incorrect as it is associated with a different plant toxin syndrome. *Pyrrolizidine* - **Pyrrolizidine alkaloids** are found in *Senecio* species (ragwort), *Crotalaria* species, and *Heliotropium* species. - They cause **hepatic veno-occlusive disease** (Budd-Chiari syndrome) with hepatomegaly, ascites, and liver failure. - They are not associated with *Argemone mexicana* and do not cause the epidemic dropsy syndrome. *Hydrocyanic acid* - **Hydrocyanic acid (cyanide)** is found in stone fruit pits (apricot, peach, cherry), cassava, and bitter almonds. - It causes rapid **cellular hypoxia** by inhibiting **cytochrome c oxidase** in the mitochondrial electron transport chain. - Clinical features include sudden collapse, cherry-red discoloration, and smell of bitter almonds - completely different from the gradual edema of epidemic dropsy.
Question 787: Which of the following insecticides is a natural contact poison?
- A. Propoxur
- B. Rotenone (Correct Answer)
- C. Carbaryl
- D. Lindane
Explanation: ***Rotenone*** - **Rotenone** is a naturally occurring plant-derived insecticide, traditionally used as a **contact poison** and **stomach poison**. - It is effective against a broad spectrum of insects and works by inhibiting **electron transport** in the mitochondria, disrupting cellular respiration. *Propoxur* - **Propoxur** is a **synthetic carbamate insecticide**, not a natural one. - It acts primarily as a **cholinesterase inhibitor**, interfering with nervous system function. *Carbaryl* - **Carbaryl** is a **synthetic carbamate insecticide**, derived from carbamic acid, not a natural product. - Its mechanism of action involves **reversible inhibition of acetylcholinesterase**, leading to nerve overstimulation. *Lindane* - **Lindane** is an **organochlorine insecticide**, which is a synthetic compound, not naturally occurring. - It acts as a **neurotoxin**, primarily by interfering with **GABA-gated chloride channels** in the insect's nervous system.
Question 788: Which of the following is the least toxic organophosphorus compound?
- A. Parathion
- B. Malathion
- C. Fenitrothion
- D. Abate (Correct Answer)
Explanation: ***Abate (Temephos)*** - **Abate** is specifically designed for use in water as a mosquito larvicide and has a notably **lower mammalian toxicity** compared to other organophosphates. - Its chemical structure and metabolic breakdown in mammals make it less potent in inhibiting **acetylcholinesterase**. *Malathion* - While generally considered less toxic than some other organophosphates like parathion, **malathion** still poses significant toxicity, especially with **high or prolonged exposure**. - It is metabolically activated to **malaoxon**, a more potent acetylcholinesterase inhibitor. *Fenitrothion* - **Fenitrothion** is an organophosphate insecticide with moderate to high toxicity, similar to malathion, but often considered more toxic for some species. - It works by inhibiting **cholinesterase enzymes**, leading to a buildup of acetylcholine. *Parathion* - **Parathion** is one of the most highly toxic organophosphorus compounds, historically used as a powerful insecticide but now restricted or banned in many countries due to its severe toxicity. - It is readily absorbed and metabolically converted to **paraoxon**, a very potent cholinesterase inhibitor.
Question 789: Beta oxalyl amino alanine (BOAA) is found in:
- A. Argemone mexicana
- B. Crotalaria medicaginea
- C. Aspergillus flavus
- D. Lathyrus sativus (Correct Answer)
Explanation: ***Lathyrus sativus*** - **Lathyrus sativus**, also known as **grass pea**, is a legume that contains the neurotoxin **beta-oxalyl-amino-alanine (BOAA)**. - Consumption of **Lathyrus sativus** in large quantities over a prolonged period can lead to **lathyrism**, a neurological disorder causing paralysis. *Argemone mexicana* - **Argemone mexicana**, or **prickly poppy**, contains **sanguinarine** and **dihydrosanguinarine** alkaloids, which can cause **epidemic dropsy**. - Its oil is sometimes used as an adulterant in mustard oil, leading to symptoms like **edema** and **cardiac issues**. *Crotalaria medicaginea* - Species of **Crotalaria** (e.g., Crotalaria retusa, Crotalaria medicaginea) are known to contain **pyrrolizidine alkaloids**, which can be **hepatotoxic** and **pneumotoxic**. - Consumption can lead to **liver damage** and **pulmonary hypertension** in livestock and humans. *Aspergillus flavus* - **Aspergillus flavus** is a fungus that produces **aflatoxins**, potent **carcinogens** and **hepatotoxins**. - Aflatoxins are often found in contaminated food products like peanuts, corn, and tree nuts, causing **liver cancer** and **immunosuppression**.
Question 790: Mees' lines and raindrop pigmentation on the hands are seen in which type of poisoning?
- A. Arsenic (Correct Answer)
- B. Thallium
- C. Cadmium
- D. Lead
Explanation: **Arsenic** - **Mees' lines** (transverse white bands on fingernails) and **raindrop pigmentation** (hyperpigmentation with scattered hypopigmented spots) are classic dermatological manifestations of chronic arsenic poisoning. - Arsenic interferes with cellular respiration and DNA repair, leading to systemic effects including characteristic skin changes. *Thallium* - Thallium poisoning is often associated with diffuse **hair loss (alopecia)**, sensory neuropathy, and gastrointestinal symptoms. - It does not typically cause Mees' lines or raindrop pigmentation. *Cadmium* - Chronic cadmium exposure is primarily associated with **renal dysfunction** (Fanconi syndrome), **osteomalacia**, and lung disease. - It does not cause the specific nail or skin pigmentation described. *Lead* - Lead poisoning typically manifests with **gastrointestinal symptoms** (colic), neurological deficits (foot drop), and **anemia**. - While it can cause some dermatological changes, **Mees' lines** and **raindrop pigmentation** are not characteristic features.
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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