Forensic Toxicology Practice Questions

Q: Poisoning with which of the following retards putrefaction:

Arsenic. ***Arsenic*** - **Arsenic** is a known **preservative** of tissues due to its ability to inhibit bacterial growth and enzyme activity, thereby retarding putrefaction. - In cases of arsenic poisoning, the decomposition of a body may be noticeably slower, and the tissues can appear unusually well-preserved. *Lead* - While **lead** is a heavy metal and can have toxic effects, it is not primarily known for its ability to significantly **retard putrefaction**. - Its toxic mechanisms do not involve direct inhibition of bacterial and enzymatic processes in a way that typically preserves tissues post-mortem. *Aluminium phosphide* - **Aluminium phosphide** is a highly toxic pesticide that can cause rapid death, but it does not have properties that actively **retard the process of putrefaction**. - Its mechanism of toxicity primarily involves the release of phosphine gas, which causes cellular damage, rather than tissue preservation. *Copper* - **Copper**, another heavy metal, has antimicrobial properties but is not recognized as an agent that significantly **retards putrefaction** in the same manner as arsenic. - Its acute and chronic toxic effects do not typically lead to the preservation of tissues after death.

Q: Which of the following is not a feature of Organophosphate poisoning?

Mydriasis. ***Mydriasis*** - Organophosphate poisoning leads to **cholinergic crisis**, which causes **miosis** (pinpoint pupils) due to excessive parasympathetic stimulation of the pupillary constrictor muscles. - **Mydriasis** (pupil dilation) is characteristic of **anticholinergic poisoning** or sympathetic overactivity, which is the opposite effect. *Lacrimation* - Organophosphates inhibit **acetylcholinesterase**, leading to an accumulation of **acetylcholine** at cholinergic synapses. - This excess acetylcholine stimulates muscarinic receptors, causing an increase in gland secretions, including **lacrimation** (tearing). *Vomiting* - The muscarinic effects of organophosphate poisoning stimulate the **gastrointestinal tract**, leading to symptoms like nausea, abdominal cramps, diarrhea, and **vomiting**. - This is a common and significant feature of the cholinergic syndrome. *Salivation* - Similar to lacrimation, the excess acetylcholine due to organophosphate poisoning causes increased stimulation of salivary glands. - This results in excessive **salivation**, often manifesting as hypersalivation or drooling.

Q: Acrodynia, or Pink disease, occurs in poisoning with which of the following substances?

Mercury. ***Mercury*** - **Acrodynia**, also known as **Pink disease**, is a rare and severe form of **mercury poisoning**, primarily affecting infants and young children. - Key symptoms include **pinkish-red rash** on the hands and feet, hypertension, irritability, profuse sweating, and muscle weakness. *Lead* - **Lead poisoning** typically presents with symptoms such as **abdominal pain**, constipation, developmental delay, and a **lead line on the gums**. - It does not cause the characteristic rash or other symptoms associated with acrodynia. *Thallium* - **Thallium poisoning** is known for causing **hair loss (alopecia)**, excruciating neuropathic pain, gastrointestinal disturbances, and neurological symptoms. - While it is a neurotoxic heavy metal, its clinical picture is distinct from acrodynia. *Arsenic* - **Arsenic poisoning** can manifest with dermatological signs like **hyperpigmentation** and **hyperkeratosis**, as well as gastrointestinal and neurological symptoms. - It does not produce the pinkish rash, irritability, or hypertension typical of acrodynia.

Q: Percentage of COHb that usually causes death:

> 80%. ***> 80%*** - While significant symptoms occur at lower levels, **COHb levels above 80%** typically cause profound central nervous system depression leading to **cardiac arrest and death**. - This level indicates almost complete displacement of oxygen from hemoglobin, leading to severe **tissue hypoxia**. *> 70%* - At **COHb levels above 70%**, individuals are often in a **coma**, experiencing severe **cardiac dysfunction** and respiratory failure. - Death is highly probable at this level, though it is not the universally accepted threshold for lethality as higher percentages are more definitive for causing death. *> 60%* - At **COHb levels above 60%**, patients typically experience **coma, convulsions**, and significant **cardiovascular compromise**. - While extremely dangerous and often fatal, **COHb levels above 80%** are more reliably associated with death. *> 50%* - At **COHb levels above 50%**, individuals often experience **coma, seizures**, and severe **metabolic acidosis**. - While critical and life-threatening, death is less common at this percentage compared to those above 70% or 80%, as aggressive medical intervention may still be effective.

Q: Barium carbonate poisoning causes -

Muscular weakness. ***Correct: Muscular weakness*** - **Soluble barium salts** (barium chloride, barium nitrate, barium sulfide) are highly toxic when ingested, releasing Ba²⁺ ions - Barium blocks **potassium channels** in cell membranes, causing **intracellular shift of potassium** leading to profound **hypokalemia** - This results in **flaccid paralysis** and severe **muscular weakness**, which is the **hallmark feature** of barium poisoning - Can progress to **paralysis of respiratory muscles**, making it life-threatening - **Note:** Barium carbonate itself is **insoluble** and relatively non-toxic; toxicity occurs when converted to soluble forms in stomach acid *Incorrect: Gastrointestinal irritation* - While mild GI symptoms (nausea, vomiting, diarrhea) may occur, they are **not the dominant feature** - The primary toxicity is **neuromuscular** rather than gastrointestinal - GI irritation, when present, is overshadowed by the dramatic muscular manifestations *Incorrect: Cyanosis* - Cyanosis is not a primary feature of barium poisoning - May occur **secondarily** if respiratory muscle paralysis is severe enough to cause hypoxemia - Not a characteristic or early sign *Incorrect: Respiratory distress* - Respiratory distress occurs due to **paralysis of respiratory muscles** from hypokalemia - This is a **complication** of the muscular weakness, not the primary manifestation - While serious and potentially fatal, it represents progression of the neuromuscular toxicity

Q: Knockout drops are:

Chloral hydrate. ***Chloral hydrate*** - **Chloral hydrate** is a sedative-hypnotic substance historically used as "knockout drops" due to its quick action in inducing sleep or unconsciousness. - Its use has largely been replaced by safer alternatives due to its narrow therapeutic index and potential for respiratory depression and cardiac arrhythmias. *Kerosene* - **Kerosene** is a flammable hydrocarbon liquid primarily used as fuel or solvent, not as a sedative or hypnotic agent. - Ingestion of kerosene is highly toxic and can cause chemical pneumonitis and gastrointestinal irritation. *Paraldehyde* - **Paraldehyde** is an older sedative and hypnotic drug, but it is not typically referred to as "knockout drops." - It has a very pungent odor and taste, which would make surreptitious administration difficult, and is generally avoided in modern medical practice. *Turpentine* - **Turpentine** is a distillate of pine resin used as a solvent or cleaner, and historically as a liniment or anthelminthic. - It is highly toxic if ingested and can cause severe gastrointestinal distress, kidney damage, and central nervous system depression, but it is not a sedative-hypnotic.

Q: Yellow discoloration of skin and mucosa is seen in poisoning with:

Nitric acid. ***Nitric acid*** - **Nitric acid** causes a characteristic **yellow discoloration** of the skin and mucous membranes due to the formation of **xanthoproteic acid**. - This reaction occurs when nitric acid comes into contact with proteins, nitrating the aromatic amino acids (tyrosine, tryptophan, and phenylalanine). *Phosphoric acid* - **Phosphoric acid** burns, if severe, can cause skin irritation with redness and blistering, but typically do not result in a distinct yellow discoloration. - While corrosive, its mechanism of tissue damage differs from nitric acid's specific reaction with proteins. *Sulphuric acid* - **Sulphuric acid** is a potent dehydrating agent and corrosive acid that causes severe burns, often appearing **black or brown (eschar)** due to tissue coagulation and carbonization. - It does not produce the specific yellow discoloration seen with nitric acid. *Nitrous oxide* - **Nitrous oxide** is an inhalational anesthetic and analgesic, and its overdose can lead to **hypoxia**, dizziness, and potential bone marrow suppression with chronic abuse. - It does not cause any form of skin or mucosal discoloration; its effects are systemic and neurological.

Q: Green colored urine is seen after ingestion of:

Phenol. ***Phenol*** - Ingestion of **phenol** can lead to green-colored urine due to the formation of oxidation products, such as **hydroquinone** and **catechol**, which are excreted in the urine. - The green discoloration is a distinct toxicological sign associated with systemic phenol absorption. *Organophosphorus* - **Organophosphorus** poisoning primarily causes cholinergic symptoms like miosis, bradycardia, bronchorrhea, and muscle fasciculations. - It does not typically lead to a change in urine color; the urine usually remains clear or amber. *Copper sulphate* - **Copper sulfate** poisoning can cause symptoms like vomiting, abdominal pain, diarrhea, and potentially kidney damage. - While it can cause renal dysfunction, it does not typically result in green urine discoloration. *Cyanide* - **Cyanide** poisoning is characterized by rapid onset of symptoms affecting the cardiovascular, respiratory, and central nervous systems, leading to cellular hypoxia. - Urine color is not a characteristic feature of cyanide poisoning; it usually remains normal or slightly discolored due to other complications like rhabdomyolysis in severe cases.

Q: Acts both as poison and antidote:

Copper sulfate. ***Copper sulfate*** - **Copper sulfate** acts both as a **poison and antidote**, demonstrating dual properties. - In **large doses**, it is toxic, causing **gastrointestinal distress**, **hepatotoxicity**, **nephrotoxicity**, and potentially death. - Historically, it was used in **small controlled doses as an emetic** (to induce vomiting) in cases of poisoning, acting as an antidote by expelling ingested toxins. - **Note**: Its use as an emetic is now **outdated** due to safety concerns, but it remains the classic example of a substance with both toxic and therapeutic properties. *Mercuric chloride* - **Mercuric chloride** is a highly toxic compound acting primarily as a **corrosive poison**, causing severe damage to the **gastrointestinal tract** and kidneys. - It does not possess any antidote properties and requires aggressive **chelation therapy** for treatment. *Silver chloride* - **Silver chloride** is of **low toxicity** due to its insolubility in water and biological fluids. - While chronic exposure can cause **argyria** (bluish skin discoloration), it has no antidote properties. *Thallium arsenate* - **Thallium arsenate** contains two highly toxic elements (**thallium** and **arsenic**), both potent poisons affecting multiple organ systems. - Used in **pesticides** and **rodenticides** due to its toxicity, it has no beneficial or antidote properties.

Q: Which of the following is used in the second-line management of strychnine poisoning?

Barbiturates. ***Barbiturates*** - As a **second-line treatment**, barbiturates like phenobarbital are used to control **refractory seizures** and muscle spasms in strychnine poisoning when benzodiazepines are insufficient. - They enhance the effect of **GABA**, leading to central nervous system depression and muscle relaxation. *Physostigmine* - This is an **acetylcholinesterase inhibitor** and is primarily used to reverse the anticholinergic effects of certain poisonings, not strychnine. - It would worsen seizures by increasing **acetylcholine**, which can cause tremors and convulsions. *Naloxone* - Naloxone is an **opioid antagonist** used to reverse opioid overdose, which presents with respiratory depression and pinpoint pupils. - It has no role in treating strychnine poisoning, which primarily causes **muscle spasms** and seizures. *Diazepam* - Diazepam, a **benzodiazepine**, is the **first-line treatment** for seizures and muscle spasms in strychnine poisoning. - It works by enhancing the effects of **GABA** at the GABA-A receptor, thereby reducing neuronal excitability.

Question 1

Poisoning with which of the following retards putrefaction:

Accepted Answer

Arsenic

Answer

Lead

Answer

Aluminium phosphide

Answer

Copper

Question 2

Which of the following is not a feature of Organophosphate poisoning?

Accepted Answer

Mydriasis

Answer

Lacrimation

Answer

Vomiting

Answer

Salivation

Question 3

Acrodynia, or Pink disease, occurs in poisoning with which of the following substances?

Accepted Answer

Mercury

Answer

Lead

Answer

Thallium

Answer

Arsenic

Question 4

Percentage of COHb that usually causes death:

Accepted Answer

> 80%

Answer

> 70%

Answer

> 60%

Answer

> 50%

Question 5

Barium carbonate poisoning causes -

Accepted Answer

Muscular weakness

Answer

Gastrointestinal irritation

Answer

Cyanosis

Answer

Respiratory distress

Question 6

Knockout drops are:

Accepted Answer

Chloral hydrate

Answer

Kerosene

Answer

Paraldehyde

Answer

Turpentine

Question 7

Yellow discoloration of skin and mucosa is seen in poisoning with:

Accepted Answer

Nitric acid

Answer

Phosphoric acid

Answer

Sulphuric acid

Answer

Nitrous oxide

Question 8

Green colored urine is seen after ingestion of:

Accepted Answer

Phenol

Answer

Organophosphorus

Answer

Copper sulphate

Answer

Cyanide

Question 9

Acts both as poison and antidote:

Accepted Answer

Copper sulfate

Answer

Mercuric chloride

Answer

Silver chloride

Answer

Thallium arsenate

Question 10

Which of the following is used in the second-line management of strychnine poisoning?

Accepted Answer

Barbiturates

Answer

Physostigmine

Answer

Naloxone

Answer

Diazepam

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

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