Forensic Toxicology Practice Questions

Q: Gastric lavage is contraindicated in?

Hydrocarbons. ***Hydrocarbons*** - Gastric lavage is contraindicated in **hydrocarbon poisoning** due to the high risk of **aspiration** [2]. - Aspiration of hydrocarbons can lead to severe **chemical pneumonitis**, which is often more life-threatening than the systemic toxicity from ingestion [2]. *Bicarbonate* - Ingesting a large amount of bicarbonate can cause **alkalosis** and electrolyte imbalances. - While gastric lavage is not typically the primary treatment for mild bicarbonate overdose, it is not absolutely contraindicated in cases of massive ingestion where there is a clear benefit to removing unabsorbed substance, especially if performed with proper airway protection [1], [3]. *Organo-Phosphosphate poisoning* - Gastric lavage is generally recommended for **organophosphate poisoning** if the patient presents within 1-2 hours of ingestion and is awake with an intact gag reflex, or with a protected airway [2]. - This helps remove unabsorbed poison and can reduce the systemic absorption of these highly toxic compounds. *PCM toxicity* - For **paracetamol (PCM) toxicity**, gastric lavage can be considered if the patient presents within 1-2 hours of ingestion and has ingested a potentially toxic dose, especially when activated charcoal is not immediately available or contraindicated [4]. - The primary treatment for PCM toxicity involves **N-acetylcysteine (NAC)**, but gastric emptying can play a role in reducing initial absorption [4].

Q: Ochronosis is seen in poisoning with:

Carbolic acid. ***Carbolic acid (Phenol)*** - Carbolic acid causes **blackish-brown discoloration** of skin and tissues at the site of contact due to its **corrosive action and protein denaturation**. - This characteristic **dark staining of tissues** is a forensic marker of phenol poisoning and is sometimes referred to in forensic literature as "ochronosis-like" changes. - Phenol is absorbed through skin and mucous membranes and can cause **CNS depression, convulsions, and metabolic acidosis**. *Boric acid* - Boric acid poisoning manifests with **"boiled lobster" appearance** of skin (erythematous desquamation). - Causes **gastrointestinal symptoms** (vomiting, diarrhea) and **CNS effects** in severe cases. - Does not cause blackish tissue discoloration. *HCl (Hydrochloric acid)* - HCl is a **strong corrosive acid** causing severe chemical burns. - Produces **white or gray coagulated necrosis** of tissues on contact. - Does not produce the dark discoloration characteristic of phenol. *Oxalic acid* - Oxalic acid poisoning causes **hypocalcemia** by chelating calcium ions. - Leads to **cardiac arrhythmias, tetany, and renal toxicity** (calcium oxalate crystal deposition). - Does not cause tissue discoloration or ochronosis.

Q: A patient was found to have pink coloured skin and mucosa, bitter almond smell from breath and frothy discharge. Cause of death in this patient;

Cyanide poisoning. ***Cyanide poisoning*** - **Pink/cherry-red skin and mucosa** occur because cyanide **inhibits cytochrome oxidase** in the mitochondrial electron transport chain, preventing cellular oxygen utilization. This results in **high venous oxyhemoglobin levels** as oxygen remains in the blood but cannot be used by tissues. - The characteristic **bitter almond smell** is pathognomonic for cyanide, though only detectable by 40-60% of the population due to genetic variations in odor perception. - **Frothy discharge** indicates pulmonary edema, common in acute cyanide toxicity. *H2S poisoning* - **Hydrogen sulfide** poisoning typically presents with a characteristic **rotten egg smell**, not bitter almonds. - It causes cellular hypoxia by **inhibiting cytochrome oxidase**, similar to cyanide, but the clinical presentation, odor, and skin coloration (may be greenish) differ. *Datura poisoning* - **Datura poisoning** is characterized by an **anticholinergic toxidrome**: hot, dry, red skin (flushed from vasodilation, not hypoxia), dilated pupils, delirium, and urinary retention. - It does not cause a bitter almond smell or the characteristic pink coloration seen in cyanide poisoning. *CO poisoning* - **Carbon monoxide (CO) poisoning** is associated with a **cherry-red skin color** due to **carboxyhemoglobin** formation, where CO binds hemoglobin with 200-250x greater affinity than oxygen. - While it also causes cellular hypoxia, there is **no bitter almond smell**, and the mechanism differs (oxygen cannot bind vs. oxygen cannot be utilized).

Q: Vitreous humor is preserved in suspected poisoning with:

Alcohol. ***Alcohol*** - **Vitreous humor** is an ideal sample for postmortem alcohol analysis due to its **sequestration** from other body fluids, which minimizes postmortem production or degradation of alcohol. - Its **avascular nature** and **slow diffusion** rates ensure that the alcohol concentration in the vitreous humor closely reflects the ante-mortem blood alcohol concentration. *Cyanide* - Sampling **vitreous humor** is generally not the primary choice for detecting cyanide because cyanide is rapidly absorbed and metabolized, making its detection more reliable in other tissues. - Cyanide can degrade in biological samples, and its concentration in the vitreous humor may not accurately reflect the lethal dose or recent exposure. *Morphine* - While **vitreous humor** can be used for opiate detection, **blood and urine** are generally preferred for initial screening and quantitative analysis of morphine. - Morphine undergoes metabolism during its elimination, and its distribution into the vitreous humor might not always accurately reflect the **pharmacodynamics** or precise time of exposure compared to blood. *Carbon monoxide* - **Carbon monoxide (CO) poisoning** is primarily diagnosed by measuring **carboxyhemoglobin levels** in blood, as CO binds avidly to hemoglobin. - The vitreous humor is not a suitable sample for detecting carbon monoxide or carboxyhemoglobin as it lacks red blood cells and hemoglobin, which are the targets of CO toxicity.

Q: CSF sample is preserved for which poisoning?

Heavy metal. ***Heavy metal*** - CSF samples can be used for the detection of certain heavy metals, such as **lead** or **mercury**, particularly in cases of suspected neurological toxicity or chronic exposure. - While blood or urine are more common for initial screening, CSF may be analyzed to understand direct CNS involvement or when other samples are inconclusive. *Organophosphates* - Diagnosis of organophosphate poisoning primarily relies on measuring **cholinesterase activity** in the blood (red blood cell acetylcholinesterase or plasma cholinesterase). - CSF is generally not used for the diagnosis of organophosphate poisoning as these compounds primarily act peripherally and at the neuromuscular junction, with systemic distribution. *Alcohol* - Alcohol poisoning is typically diagnosed by measuring **blood ethanol levels**, which directly reflect acute intoxication. - While alcohol can cross the blood-brain barrier, CSF testing for alcohol is not a standard or necessary procedure for diagnosing acute or chronic alcohol poisoning. *Alphos* - Alphos (aluminum phosphide) poisoning is diagnosed by clinical presentation and detection of phosphine gas or its metabolites in **blood, gastric lavage, or urine samples**. - CSF is not a primary sample type for the diagnosis of Alphos poisoning, as its toxic effects are systemic and primarily on cellular respiration.

Q: Cobra poison is:

Neurotoxic. ***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.

Q: A farmer with pinpoint pupils, increased secretions and urination. What is the most likely diagnosis?

Organophosphate poisoning. ***Organophosphate poisoning*** - **Pinpoint pupils (miosis)**, **increased secretions** (salivation, lacrimation, bronchial secretions), and **urination** are classic signs of cholinergic crisis caused by organophosphate toxicity [1]. - The patient's profession as a **farmer** increases the likelihood of exposure to pesticides, which often contain organophosphates [1], [2]. *Alcohol poisoning* - While alcohol poisoning can cause CNS depression, it does not typically present with **pinpoint pupils** or **increased secretions** like salivation and urination. - Common signs include **ataxia**, **slurred speech**, **nausea**, and **vomiting**. *Opioid poisoning* - Opioid poisoning also causes **pinpoint pupils** and **CNS depression**, but it typically leads to **decreased secretions** and **urinary retention**, not increased urination [2]. - **Respiratory depression** is a hallmark feature, which is not highlighted here as a primary symptom. *Atropine poisoning* - Atropine is an anticholinergic agent, meaning it would cause the opposite effects of organophosphate poisoning [2]. - Symptoms would include **dilated pupils (mydriasis)**, **dry mouth**, **decreased secretions**, and **urinary retention**.

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

Arsenic. ***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.

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

OPC. ***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.

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

Lead. ***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 1

Gastric lavage is contraindicated in?

Accepted Answer

Hydrocarbons

Answer

Bicarbonate

Answer

Organo-Phosphosphate poisoning

Answer

PCM toxicity

Question 2

Ochronosis is seen in poisoning with:

Accepted Answer

Carbolic acid

Answer

Boric acid

Answer

HCl

Answer

Oxalic acid

Question 3

A patient was found to have pink coloured skin and mucosa, bitter almond smell from breath and frothy discharge. Cause of death in this patient;

Accepted Answer

Cyanide poisoning

Answer

H2S poisoning

Answer

Datura poisoning

Answer

CO poisoning

Question 4

Vitreous humor is preserved in suspected poisoning with:

Accepted Answer

Alcohol

Answer

Cyanide

Answer

Morphine

Answer

Carbon monoxide

Question 5

CSF sample is preserved for which poisoning?

Accepted Answer

Heavy metal

Answer

Organophosphates

Answer

Alcohol

Answer

Alphos

Question 6

Cobra poison is:

Accepted Answer

Neurotoxic

Answer

Vasculotoxic

Answer

Myotoxic

Answer

Cardiotoxic

Question 7

A farmer with pinpoint pupils, increased secretions and urination. What is the most likely diagnosis?

Accepted Answer

Organophosphate poisoning

Answer

Alcohol poisoning

Answer

Opioid poisoning

Answer

Atropine poisoning

Question 8

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

Accepted Answer

Arsenic

Answer

Lead

Answer

Mercury

Answer

Cannabis

Question 9

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

Accepted Answer

OPC

Answer

Arsenic

Answer

Opium

Answer

Dhatura

Question 10

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

Accepted Answer

Lead

Answer

Arsenic

Answer

Copper

Answer

Iron

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

On this page

Practice by Chapter

Want unlimited practice?