Pesticide Exposure — MCQs
All of the following statements about pralidoxime in organophosphate poisoning are true except:-
Which drug is the specific antidote for organophosphorus poisoning?
Atropine is not an antidote in:
Which of the following substances is a toxin but has also been historically used as a therapeutic emetic in poisoning management?
Which of the following statements about DDT is false?
A woman died within 5 years of marriage under suspicious circumstances. Her parents complained that her in-laws used to frequently demand dowry. Under which of the following sections can a magistrate authorize an autopsy of the case?
Pralidoxime is not useful in poisoning with which of the following?
Mechanism of action of atropine in treatment of organophosphate poisoning is?
Which of the following is the least toxic organophosphorus compound?
In toxicology, viscera are typically stored in which of the following solutions?
Pesticide Exposure Indian Medical PG Practice Questions and MCQs
Question 1: All of the following statements about pralidoxime in organophosphate poisoning are true except:-
- A. It does not cross blood brain barrier
- B. It should be started after 24 hours of poisoning (Correct Answer)
- C. Reactivates the AChE enzyme
- D. It is given intravenously
Explanation: ***It should be started after 24 hours of poisoning*** - **Pralidoxime (2-PAM)** is most effective when administered **early** in organophosphate poisoning, ideally within minutes to a few hours of exposure. - Delaying administration beyond **24-48 hours** significantly reduces its efficacy because the bond between the organophosphate and **acetylcholinesterase (AChE)** becomes **irreversible** (a process called "aging"). *It does not cross blood brain barrier* - **Pralidoxime** is a **quaternary ammonium compound**, which makes it highly polar and unable to readily cross the **blood-brain barrier**. - Therefore, it primarily reactivates **acetylcholinesterase** in the **peripheral nervous system** but has limited effect on central nervous system symptoms. *Reactivates the AChE enzyme* - **Pralidoxime** works by **reactivating the acetylcholinesterase enzyme** that has been inhibited by organophosphates. - It does this by binding to the organophosphate molecule, thereby freeing the active site of the **AChE enzyme** to metabolize **acetylcholine** again. *It is given intravenously* - **Pralidoxime** is typically administered via **intravenous (IV) infusion** to achieve rapid and sustained therapeutic concentrations. - Due to its poor oral absorption, oral administration is not a suitable route for treating acute organophosphate poisoning.
Question 2: Which drug is the specific antidote for organophosphorus poisoning?
- A. EDTA
- B. BAL
- C. Atropine
- D. Pralidoxime (PAM) (Correct Answer)
Explanation: ***Pralidoxime (PAM)*** - **Pralidoxime (PAM)** reactivates the enzyme **acetylcholinesterase** by detaching the organophosphate from the enzyme's active site. - It is most effective when administered early, ideally within a few hours of exposure, to prevent **aging** of the enzyme-inhibitor complex. *EDTA* - **EDTA** (ethylenediaminetetraacetic acid) is a chelating agent primarily used in the treatment of **heavy metal poisoning**, such as lead poisoning. - It is not effective against organophosphorus compounds, which act by inhibiting acetylcholinesterase. *BAL* - **BAL** (British Anti-Lewisite, or dimercaprol) is another chelating agent used to treat poisoning by **heavy metals** such as arsenic, mercury, and gold. - It does not have a mechanism of action that addresses the enzyme inhibition caused by organophosphates. *Atropine* - **Atropine** is used in organophosphorus poisoning, but it is not a specific antidote as it does not address the cause of poisoning. - It acts to counteract the **muscarinic effects** of excessive acetylcholine, such as bradycardia, bronchospasm, and excessive secretions, but does not reactivate acetylcholinesterase.
Question 3: Atropine is not an antidote in:
- A. Baygon
- B. Parathion
- C. Endrin (Correct Answer)
- D. Tik 20
Explanation: ***Endrin*** - Endrin is an **organochlorine insecticide**, and its toxicity is primarily mediated through the central nervous system, causing seizures and neurological symptoms. - Atropine is an **anticholinergic drug** and is ineffective because organochlorines do not act on cholinergic receptors; therefore, it is not an antidote for endrin poisoning. *Baygon* - Baygon is a **carbamate insecticide**, which inhibits acetylcholinesterase, leading to cholinergic crisis. - Atropine is an appropriate antidote for Baygon poisoning, as it blocks the effects of excess acetylcholine at muscarinic receptors. *Parathion* - Parathion is an **organophosphate insecticide**, known for irreversible inhibition of acetylcholinesterase, resulting in severe cholinergic toxicity. - Atropine is a crucial antidote for parathion poisoning, used to counteract the muscarinic effects of acetylcholine accumulation. *Tik 20* - Tik 20 typically contains **organophosphate compounds** such as malathion or parathion, which are acetylcholinesterase inhibitors. - As an effective anticholinergic, atropine is indicated in the treatment of poisoning by organophosphates found in products like Tik 20.
Question 4: Which of the following substances is a toxin but has also been historically used as a therapeutic emetic in poisoning management?
- A. Thallium
- B. Copper sulphate (Correct Answer)
- C. Arsenic oxide
- D. Mercuric chloride
Explanation: ***Copper sulphate*** - **Copper sulphate** is a **potent toxin** that causes gastrointestinal irritation, hemolysis, hepatotoxicity, and acute renal failure upon ingestion. - It was **historically used as an emetic** to induce vomiting in certain poisoning cases for gastric decontamination, though this practice has been largely abandoned due to its own significant toxicity and the availability of safer alternatives. - This represents its dual nature: a poison itself, yet paradoxically used in poisoning management (not as an antidote, but as a gastric evacuant). *Thallium* - **Thallium** is a highly toxic heavy metal causing severe multi-organ failure, alopecia, peripheral neuropathy, and potentially fatal systemic toxicity. - It has **no therapeutic use** in poisoning management and is purely a toxicological concern. *Arsenic oxide* - **Arsenic oxide** (arsenic trioxide) is a well-known carcinogen and potent cellular poison that disrupts oxidative phosphorylation. - While it has modern therapeutic use in acute promyelocytic leukemia, it has **never been used in poisoning management** as an emetic or therapeutic agent. *Mercuric chloride* - **Mercuric chloride** is highly corrosive and causes severe gastrointestinal burns, acute tubular necrosis, and systemic mercury toxicity. - It is a **potent toxin with no therapeutic application** in poisoning management.
Question 5: Which of the following statements about DDT is false?
- A. It is contact poison
- B. Residual effect lasts for 18 months (Correct Answer)
- C. Is lipophilic in nature
- D. Belongs to organochlorine group
Explanation: ***Residual effect lasts for 18 months*** - **DDT's residual insecticidal effect** typically lasts only **3-12 months** when applied as an indoor residual spray, making 18 months definitively **FALSE**. - While DDT persists in the environment for years due to bioaccumulation, its **active insecticidal residual effect** on treated surfaces is much shorter than 18 months. - This is the **FALSE statement** among the options. *It is contact poison* - **TRUE**: DDT acts as a **contact poison**, being absorbed through the insect's **cuticle** upon direct contact. - It disrupts **sodium channels** in the nervous system, causing neurological overstimulation, tremors, and paralysis. *Is lipophilic in nature* - **TRUE**: DDT is highly **lipophilic** (fat-soluble), which explains its bioaccumulation in fatty tissues. - This lipophilicity leads to **biomagnification** through the food chain, causing environmental and health concerns. *Belongs to organochlorine group* - **TRUE**: DDT (Dichlorodiphenyltrichloroethane) is a classic example of an **organochlorine insecticide**. - Other organochlorines include lindane, aldrin, and dieldrin.
Question 6: A woman died within 5 years of marriage under suspicious circumstances. Her parents complained that her in-laws used to frequently demand dowry. Under which of the following sections can a magistrate authorize an autopsy of the case?
- A. Section 302 IPC
- B. Section 174 Cr Pc
- C. Section 304 IPC
- D. Section 176 Cr Pc (Correct Answer)
Explanation: ***Section 176 Cr PC*** - This section empowers a **Magistrate to hold an inquiry into the cause of death** in cases of suspicious circumstances, including deaths within seven years of marriage where dowry harassment is alleged. - The magistrate can **order a post-mortem examination** or even a second post-mortem if there are doubts about the initial findings, making it the appropriate section for **magisterial authorization** of autopsy. - In dowry death cases, Section 176 provides judicial oversight and ensures an independent inquiry beyond police investigation. *Section 174 Cr PC* - This section deals with **police inquiry** and report on suicide and suspicious deaths, empowering the **police officer** (not magistrate) to investigate and order an autopsy. - While Section 174 is used for initial police investigation in suspicious deaths, the question specifically asks about **magistrate authorization**, which falls under Section 176. - Section 174 is the procedural provision for police-initiated investigation, whereas magisterial inquiry requires Section 176. *Section 304 IPC* - This section pertains to **punishment for culpable homicide not amounting to murder**. It is a substantive penal provision, not a procedural law. - It deals with the legal consequence of an act after investigation and trial, not with the investigative procedure for conducting an autopsy. - Charges under Section 304 IPC may result from findings after the autopsy, but it doesn't authorize the autopsy itself. *Section 302 IPC* - This section specifies the **punishment for murder**. Like Section 304 IPC, it is substantive criminal law defining a crime and its penalty. - It would be invoked *after* the investigation reveals evidence of murder, not during the initial phase of ordering an autopsy for a suspicious death. - An autopsy authorized under Cr PC sections might lead to charges under Section 302 IPC, but it doesn't authorize the autopsy procedure.
Question 7: Pralidoxime is not useful in poisoning with which of the following?
- A. Parathion
- B. Malathion
- C. Carbamate (Correct Answer)
- D. DFP
Explanation: ***Carbamate*** - Pralidoxime (2-PAM) is an **acetylcholinesterase reactivator** that works by detaching organophosphates from the active site of the enzyme. - Carbamates bind **reversibly** to acetylcholinesterase, and the enzyme-carbamate complex dissociates spontaneously within hours, making pralidoxime **unnecessary**. - Since the enzyme reactivates on its own, pralidoxime offers no therapeutic benefit in carbamate poisoning and is therefore **not indicated**. *Malathion* - Malathion is an **organophosphate insecticide** that inhibits acetylcholinesterase irreversibly. - Pralidoxime is effective in reactivating acetylcholinesterase inhibited by malathion, especially if administered early. *Parathion* - Parathion is an **organophosphate insecticide** that causes irreversible inhibition of acetylcholinesterase. - Pralidoxime is indicated for parathion poisoning to restore enzyme function and reverse cholinergic symptoms. *DFP* - DFP (Diisopropylfluorophosphate) is a potent **organophosphate nerve agent** that irreversibly inhibits acetylcholinesterase. - Pralidoxime is used in the treatment of DFP poisoning to reactivate the enzyme.
Question 8: Mechanism of action of atropine in treatment of organophosphate poisoning is?
- A. It inhibits secretion of acetylcholine
- B. It has antimuscarinic activity (Correct Answer)
- C. It is reactivator of acetylcholine esterase enzyme
- D. It is agonist of acetylcholine receptors
Explanation: ***It has antimuscarinic activity*** - **Organophosphate poisoning** leads to **excessive acetylcholine** at muscarinic receptors, causing symptoms like miosis, bradycardia, and increased secretions. - **Atropine** is a **competitive antagonist** at these muscarinic receptors, thereby blocking the effects of excess acetylcholine. *It inhibits secretion of acetylcholine* - Atropine does not directly inhibit the secretion of **acetylcholine** from nerve terminals. - Its action is postsynaptic, specifically at the **receptor level**. *It is reactivator of acetylcholine esterase enzyme* - **Pralidoxime (2-PAM)** and other **oximes** are the drugs that reactivate **acetylcholinesterase**. - Atropine does not reactivate the enzyme; it only blocks the effects of acetylcholine. *It is agonist of acetylcholine receptors* - An **agonist** would mimic the effects of acetylcholine, which would worsen the symptoms of organophosphate poisoning. - Atropine is an **antagonist**, meaning it blocks the receptors.
Question 9: 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 10: In toxicology, viscera are typically stored in which of the following solutions?
- A. Glycerine
- B. Rectified spirit
- C. Formalin
- D. Saturated salt solution (Correct Answer)
Explanation: ***Saturated salt solution*** - **Saturated salt solution** is the **standard preservative** for viscera in forensic toxicology, used specifically for **medicolegal purposes**. - It acts as a **preservative** by inhibiting bacterial growth and enzymatic activity through its **high osmotic pressure**, which prevents degradation of toxins, drugs, and poisons present in the viscera. - It **does not interfere** with subsequent toxicological analysis and helps maintain the **concentration of toxic substances** by avoiding dilution or chemical reactions. - This is the method prescribed in forensic practice for preserving stomach contents, liver, kidney, spleen, and other viscera for chemical analysis. *Glycerine* - **Glycerine** is typically used as a **mounting medium** in histology or as a cryoprotectant, not for forensic toxicological preservation of viscera. - It can interfere with chemical analysis due to its **viscosity** and chemical properties. *Rectified spirit* - **Rectified spirit** (ethyl alcohol) may be used for preserving some specimens, but it can **alter the chemical composition** of certain drugs and volatile toxins. - It can **extract lipophilic substances** from tissues and may cause **protein denaturation**, affecting accurate toxicological analysis. - It is specifically **avoided in alcohol poisoning cases** as it would interfere with blood alcohol estimation. *Formalin* - **Formalin** is used for **histopathological tissue fixation**, not for toxicological analysis. - Formaldehyde **chemically reacts** with many drugs, alkaloids, and toxins, forming complexes that make their detection and quantification **impossible**. - It is **contraindicated** for forensic toxicology specimens as it destroys the evidence of poisoning.
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