Industrial Toxicology — MCQs
Buon's line is seen in: Al 07; Rajasthan 11; NEET 13; JIPMER 13
Brutonian lines on gums are seen in poisoning with which of the following substances?
A person working in a dye factory presented with nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach. Which poisoning do you suspect in this case?
Which of the following causes hypoxic hypoxia?
CO poisoning causes which type of hypoxia?
The gas which produces systemic toxicity without causing local irritation is –
Which of the following poisonings presents with abdominal pain, diarrhea, Mees lines on nails, and myelosuppression?
Mesothelioma is closely associated with which of the following?
Mees' lines and raindrop pigmentation on the hands are seen in which type of poisoning?
What is the Standardized Mortality Ratio (SMR) for the hazardous industry workers (as compared to national population)?
Industrial Toxicology Indian Medical PG Practice Questions and MCQs
Question 1: Buon's line is seen in: Al 07; Rajasthan 11; NEET 13; JIPMER 13
- A. Phosphorus poisoning
- B. Zinc poisoning
- C. Lead poisoning (Correct Answer)
- D. Arsenic poisoning
Explanation: ***Lead poisoning*** - **Buon's line**, also known as a **gingival lead line** or **Burton's line**, is a blue-black line visible on the gums at the junction of the teeth, characteristic of chronic lead poisoning. - This line is formed by the reaction of circulating lead with sulfur ions released by bacterial action in the mouth, forming **lead sulfide** deposits. *Phosphorus poisoning* - **Phosphorus poisoning** can cause widespread organ damage, including gastrointestinal symptoms, liver and kidney failure, and cardiovascular collapse. - It does not typically present with a characteristic gingival line like Buon's line. *Zinc poisoning* - **Zinc poisoning** is relatively rare and can lead to symptoms like nausea, vomiting, abdominal pain, and copper deficiency. - It is not associated with the formation of Buon's line in the gums. *Arsenic poisoning* - **Arsenic poisoning**, particularly chronic exposure, can manifest with skin lesions, neuropathies, and gastrointestinal issues. - A characteristic skin manifestation is **Mee's lines** (transverse white bands on the fingernails), but not Buon's line.
Question 2: Brutonian lines on gums are seen in poisoning with which of the following substances?
- A. Lead (Correct Answer)
- B. Mercury
- C. Zinc
- D. Arsenic
Explanation: ***Lead*** - **Brutonian lines**, also known as **Burton's lines**, are a classic sign of chronic lead poisoning, appearing as a blue or blue-black line along the gum margin. - This discoloration is caused by the reaction of circulating lead with sulfur ions released by oral bacteria, forming lead sulfide deposits in the gingival tissue. *Mercury* - Mercury poisoning can cause **gingivitis**, **stomatitis**, and excessive salivation, but typically not the distinct Burton's lines. - A characteristic feature of chronic mercury poisoning is often **erected tremor** and **erethism** (changes in mood and irritability). *Arsenic* - Chronic arsenic poisoning can lead to **hyperkeratosis** and **hyperpigmentation** of the skin (rain drop pigmentation), as well as **peripheral neuropathy**. - It does not typically cause the specific gingival discoloration seen in lead poisoning. *Zinc* - Zinc intoxication is relatively rare and often results from excessive ingestion of zinc-containing supplements or industrial exposure. - Symptoms usually include **nausea, vomiting, diarrhea**, and sometimes **copper deficiency**, but not gum line discoloration.
Question 3: A person working in a dye factory presented with nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach. Which poisoning do you suspect in this case?
- A. Potassium permanganate (Correct Answer)
- B. Lead
- C. Arsenic
- D. Thallium
Explanation: ***Potassium permanganate*** - The presence of **nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach** is highly indicative of **potassium permanganate poisoning**, which is a caustic agent. - Exposure in a **dye factory** setting further supports this, as potassium permanganate is used as an **oxidizing agent** and **dyeing agent** in various industries. *Lead* - Lead poisoning typically presents with **neurological symptoms** (e.g., foot drop, wrist drop, encephalopathy), **gastrointestinal complaints** (e.g., colic, constipation), and **hematological abnormalities** (e.g., anemia with basophilic stippling). - The acute caustic effects like **burning sensation in the throat and bloody stools** are not characteristic of lead poisoning. *Arsenic* - Acute arsenic poisoning often involves **severe gastroenteritis** ("rice-water stools"), **garlic odor on breath**, **peripheral neuropathy**, and **cardiac arrhythmias**. - While it can cause gastrointestinal distress, the specific caustic burn and conjunctivitis alongside the industrial exposure profile point away from arsenic. *Thallium* - Thallium poisoning is characterized by **rapid hair loss (alopecia)**, **severe peripheral neuropathy**, and **gastrointestinal symptoms** (e.g., abdominal pain, vomiting, diarrhea). - The constellation of symptoms described, particularly the caustic burn and dark bloody stools, does not align with the typical presentation of thallium toxicity.
Question 4: Which of the following causes hypoxic hypoxia?
- A. Pneumonia (Correct Answer)
- B. HCN poisoning
- C. CO poisoning
- D. Circulatory shock
Explanation: ***Pneumonia*** - Pneumonia causes **hypoxic hypoxia** by impairing **gas exchange** in the lungs due to inflammation and fluid accumulation in the alveoli, leading to reduced oxygen uptake. - This results in a **low partial pressure of oxygen (PaO2)** in the arterial blood, even with normal oxygen-carrying capacity and tissue perfusion. *HCN poisoning* - **Hydrogen cyanide (HCN) poisoning** causes **histotoxic hypoxia**, where cells are unable to utilize oxygen despite adequate delivery, by inhibiting **cytochrome c oxidase** in the electron transport chain. - It does not directly reduce the amount of oxygen in the blood or its delivery to tissues. *CO poisoning* - **Carbon monoxide (CO) poisoning** causes **anemic hypoxia** by binding to hemoglobin with a much higher affinity than oxygen, forming **carboxyhemoglobin (COHb)**. - This reduces the **oxygen-carrying capacity** of the blood and shifts the oxygen-hemoglobin dissociation curve to the left, but it is not a direct problem with alveolar gas exchange or oxygen partial pressure. *Circulatory shock* - **Circulatory shock** causes **stagnant or ischemic hypoxia**, characterized by reduced blood flow and oxygen delivery to tissues due to systemic circulatory failure. - While it results in tissue oxygen deprivation, the primary issue is impaired perfusion rather than a defect in the initial oxygenation of blood in the lungs or the blood's capacity to carry oxygen.
Question 5: CO poisoning causes which type of hypoxia?
- A. Anemic hypoxia (Correct Answer)
- B. Hypoxic hypoxia
- C. Stagnant hypoxia
- D. Histotoxic hypoxia
Explanation: ***Anemic hypoxia*** - **Carbon monoxide (CO)** binds to **hemoglobin** with an affinity much higher than oxygen, forming **carboxyhemoglobin**. - This effectively reduces the **oxygen-carrying capacity of the blood**, mimicking a severe anemia, despite normal arterial PO2. *Hypoxic hypoxia* - Occurs when there is **insufficient oxygen delivery to the blood** due to low arterial PO2, as seen in high altitudes or respiratory diseases. - In CO poisoning, **arterial PO2 is typically normal**, distinguishing it from hypoxic hypoxia. *Stagnant hypoxia* - Results from **inadequate blood flow** to tissues, leading to reduced oxygen delivery, as observed in heart failure or shock. - CO poisoning primarily affects oxygen transport by hemoglobin, not the **rate of blood flow**. *Histotoxic hypoxia* - Characterized by the **inability of tissues to utilize oxygen** effectively, even when oxygen delivery is adequate, as seen in cyanide poisoning inhibiting cytochrome oxidase. - In CO poisoning, tissues can utilize oxygen; the problem is the **reduced availability of oxygen** from hemoglobin.
Question 6: The gas which produces systemic toxicity without causing local irritation is –
- A. Carbon monoxide (Correct Answer)
- B. Ammonia
- C. Hydrocyanic acid
- D. Sulfur dioxide
Explanation: ***Carbon monoxide*** - **Carbon monoxide (CO)** is a colorless, odorless, and non-irritating gas, making it difficult to detect by smell or sight. - It exerts its systemic toxicity by binding to **hemoglobin** with high affinity, forming **carboxyhemoglobin (COHb)**, which reduces the oxygen-carrying capacity of blood and impairs oxygen delivery to tissues. *Ammonia* - **Ammonia** is a highly pungent and irritating gas that causes significant local irritation to the **eyes, respiratory tract, and skin** even at low concentrations. - Its toxicity is primarily due to its corrosive effects on mucous membranes and airways, leading to **bronchospasm** and **pulmonary edema**. *Hydrocyanic acid* - **Hydrocyanic acid (HCN)**, or hydrogen cyanide, has a characteristic **"bitter almond" odor** that can be irritating to some individuals, though many cannot smell it. - While it causes rapid systemic toxicity by inhibiting **cellular respiration**, it can also cause **local irritation** to the respiratory tract at sufficient concentrations. *Sulfur dioxide* - **Sulfur dioxide (SO2)** is a sharp, irritating gas that causes immediate and noticeable irritation to the **eyes, nose, throat, and respiratory system**. - Its primary toxic effects are local, leading to **bronchoconstriction** and inflammation of the airways, particularly in individuals with asthma or other respiratory conditions.
Question 7: Which of the following poisonings presents with abdominal pain, diarrhea, Mees lines on nails, and myelosuppression?
- A. Lead
- B. Arsenic (Correct Answer)
- C. Alcohol
- D. Mercury
Explanation: ***Arsenic*** - **Arsenic poisoning** is characterized by gastrointestinal symptoms like severe **abdominal pain** and **diarrhea**, as well as dermatological signs such as **Mees lines** (transverse white bands on fingernails). - It also causes **myelosuppression**, leading to anemia, leukopenia, and thrombocytopenia, and can affect the cardiovascular and nervous systems. *Lead* - **Lead poisoning** typically presents with diffuse **abdominal pain** (lead colic), **constipation** (not diarrhea), and neurological symptoms like **foot drop** and **encephalopathy**. - While it can cause anemia due to impaired heme synthesis, **Mees lines** and significant myelosuppression are not primary features. *Alcohol* - **Alcohol intoxication** or chronic alcoholism primarily affects the central nervous system, liver, and pancreas, leading to symptoms like **ataxia**, **hepatitis**, and **pancreatitis**. - It does not cause **Mees lines** or the specific combination of severe gastrointestinal issues and myelosuppression seen with arsenic. *Mercury* - **Mercury poisoning** typically manifests with neurological symptoms (tremors, emotional lability, **peripheral neuropathy**), stomatitis, and renal dysfunction. - While it can cause gastrointestinal upset, **Mees lines** and **myelosuppression** are not characteristic features of mercury toxicity.
Question 8: Mesothelioma is closely associated with which of the following?
- A. Silicosis
- B. Anthracosis
- C. Byssinosis
- D. Asbestosis (Correct Answer)
Explanation: ***Asbestosis*** - Mesothelioma is a rare but aggressive cancer of the **pleura** or **peritoneum**, and its strongest known etiological link is with **asbestos exposure**. - Asbestos fibers can become lodged in the lungs and pleural lining, leading to chronic inflammation, DNA damage, and eventually oncogenic transformation. *Silicosis* - **Silicosis** is a lung disease caused by inhaling **crystalline silica dust**, primarily affecting miners, construction workers, and foundry workers. - While it can lead to pulmonary fibrosis and an increased risk of tuberculosis and lung cancer, it is not directly associated with mesothelioma. *Anthracosis* - **Anthracosis** is often seen in coal miners and urban dwellers due to the inhalation of **carbon dust**, leading to the accumulation of pigment in the lungs. - This condition is generally benign but can contribute to the development of **coal worker's pneumoconiosis**, which is distinct from mesothelioma. *Byssinosis* - **Byssinosis** is an occupational lung disease caused by the inhalation of **cotton dust** or other textile dusts, typically affecting textile workers. - Symptoms include chest tightness and shortness of breath, particularly after beginning work after a break, and it is unrelated to mesothelioma.
Question 9: 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.
Question 10: What is the Standardized Mortality Ratio (SMR) for the hazardous industry workers (as compared to national population)?
- A. 110
- B. 100
- C. 120 (Correct Answer)
- D. 130
Explanation: ***120*** - To calculate the Standardized Mortality Ratio (SMR), we first need to calculate the **expected deaths** for the hazardous industry workers based on the national death rates. - The formula for expected deaths in each age group is: (National death rate / 1000) × Number of hazardous industry workers - For age group 25-34: Expected deaths = (2.0 / 1000) × 3000 = **6** - For age group 35-44: Expected deaths = (3.5 / 1000) × 2000 = **7** - For age group 45-54: Expected deaths = (6.0 / 1000) × 2000 = **12** - **Total expected deaths** = 6 + 7 + 12 = **25** - **Total observed deaths** = 8 + 9 + 13 = **30** - **SMR formula**: (Total Observed Deaths / Total Expected Deaths) × 100 - **SMR = (30 / 25) × 100 = 1.2 × 100 = 120** - This indicates that the hazardous industry workers have a **20% higher mortality rate** compared to the national population after age-standardization. *100* - An SMR of 100 would indicate that the observed mortality equals the expected mortality (no difference from the national average). - However, the observed deaths (30) exceed the expected deaths (25), so the SMR must be greater than 100. - This option represents the null value where there is no excess mortality. *110* - This option underestimates the actual SMR calculated from the data. - An SMR of 110 would suggest only a 10% excess mortality, which does not match the observed-to-expected ratio of 30:25. - The calculation clearly shows a ratio of 1.2, not 1.1. *130* - This option overestimates the SMR. - An SMR of 130 would require observed deaths to be 1.3 times the expected deaths (32.5 deaths expected for 30 observed). - The actual ratio is 30/25 = 1.2, making this value too high.
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