Question 1: Which of the following heavy metals is most commonly associated with chronic poisoning due to its presence in drinking water and industrial exposure?
- A. Lead (Pb)
- B. Mercury (Hg)
- C. Arsenic (As)
- D. Cadmium (Cd)
Answer
Answer: C. Arsenic (As)
Explanation: Arsenic is commonly associated with chronic poisoning due to its presence in contaminated drinking water, particularly in regions with natural geological deposits of arsenic. Chronic exposure can lead to skin lesions, cancer, and cardiovascular diseases. While lead, mercury, and cadmium are also toxic, arsenic is particularly notorious for its widespread impact through water contamination.
Question 2: Which analytical technique is considered the gold standard for detecting trace amounts of heavy metals in biological samples?
- A. Atomic absorption spectroscopy (AAS)
- B. Inductively coupled plasma mass spectrometry (ICP-MS)
- C. X-ray fluorescence (XRF)
- D. Gas chromatography-mass spectrometry (GC-MS)
Answer
Answer: B. Inductively coupled plasma mass spectrometry (ICP-MS)
Explanation: ICP-MS is considered the gold standard for detecting trace amounts of heavy metals in biological samples due to its high sensitivity, precision, and ability to analyze multiple elements simultaneously. AAS is also widely used but lacks the multi-element capability of ICP-MS. XRF is non-destructive but less sensitive, and GC-MS is not typically used for heavy metal analysis.
Question 3: Which of the following heavy metals is known to bioaccumulate in the food chain, particularly in fish, and can cause Minamata disease?
- A. Lead (Pb)
- B. Mercury (Hg)
- C. Cadmium (Cd)
- D. Chromium (Cr)
Answer
Answer: B. Mercury (Hg)
Explanation: Mercury is known to bioaccumulate in the food chain, particularly in fish, and can cause Minamata disease, a neurological syndrome caused by severe mercury poisoning. Methylmercury, the organic form of mercury, is highly toxic and accumulates in aquatic organisms, leading to human exposure through consumption of contaminated fish.
Question 4: What is the primary mechanism of toxicity for lead (Pb) in the human body?
- A. Disruption of calcium metabolism
- B. Inhibition of heme synthesis
- C. Binding to sulfhydryl groups in enzymes
- D. Generation of reactive oxygen species (ROS)
Answer
Answer: B. Inhibition of heme synthesis
Explanation: Lead primarily exerts its toxicity by inhibiting heme synthesis, which is essential for the production of hemoglobin. Lead interferes with enzymes such as δ-aminolevulinic acid dehydratase (ALAD) and ferrochelatase, leading to anemia and the accumulation of heme precursors like δ-aminolevulinic acid (ALA) in the blood and urine.
Question 5: Which of the following heavy metals is most likely to cause Itai-Itai disease, characterized by severe bone pain and kidney damage?
- A. Cadmium (Cd)
- B. Arsenic (As)
- C. Mercury (Hg)
- D. Chromium (Cr)
Answer
Answer: A. Cadmium (Cd)
Explanation: Cadmium is most likely to cause Itai-Itai disease, a condition characterized by severe bone pain, fractures, and kidney damage. Chronic exposure to cadmium, often through contaminated rice or water, leads to its accumulation in the kidneys and bones, disrupting calcium metabolism and causing osteomalacia.
Question 6: Which of the following is a common biomarker for arsenic exposure in humans?
- A. Urinary arsenic metabolites
- B. Blood lead levels
- C. Hair mercury content
- D. Serum cadmium levels
Answer
Answer: A. Urinary arsenic metabolites
Explanation: Urinary arsenic metabolites, such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), are common biomarkers for arsenic exposure. Arsenic is rapidly metabolized and excreted in urine, making it a reliable indicator of recent exposure. Blood, hair, and serum are not typically used for arsenic biomonitoring.
Question 7: Which of the following heavy metals is known to cause “blue line” on the gums, a condition called Burton’s line, in cases of chronic poisoning?
- A. Mercury (Hg)
- B. Lead (Pb)
- C. Arsenic (As)
- D. Cadmium (Cd)
Answer
Answer: B. Lead (Pb)
Explanation: Chronic lead poisoning can cause a “blue line” on the gums, known as Burton’s line. This is due to the deposition of lead sulfide in the gum tissue, resulting from the reaction of lead with hydrogen sulfide produced by oral bacteria. It is a classic clinical sign of chronic lead exposure.
Question 8: Which of the following heavy metals is most likely to cause lung cancer when inhaled as a particulate in occupational settings?
- A. Chromium (Cr)
- B. Cadmium (Cd)
- C. Nickel (Ni)
- D. All of the above
Answer
Answer: D. All of the above
Explanation: Chromium, cadmium, and nickel are all known to cause lung cancer when inhaled as particulate matter in occupational settings. These metals are classified as human carcinogens by the International Agency for Research on Cancer (IARC) due to their ability to induce oxidative stress, DNA damage, and mutations in lung tissue.
Question 9: Which of the following is a common chelating agent used to treat acute heavy metal poisoning?
- A. Dimercaprol (BAL)
- B. Penicillamine
- C. EDTA (ethylenediaminetetraacetic acid)
- D. All of the above
Answer
Answer: D. All of the above
Explanation: Dimercaprol (BAL), penicillamine, and EDTA are all common chelating agents used to treat acute heavy metal poisoning. These agents bind to heavy metals in the bloodstream, forming stable complexes that are excreted in urine, thereby reducing the toxic effects of the metals.
Question 10: Which of the following heavy metals is most likely to cause peripheral neuropathy and “wrist drop” in cases of chronic exposure?
- A. Lead (Pb)
- B. Mercury (Hg)
- C. Arsenic (As)
- D. Cadmium (Cd)
Answer
Answer: A. Lead (Pb)
Explanation: Chronic lead exposure is most likely to cause peripheral neuropathy and “wrist drop,” a condition characterized by weakness or paralysis of the extensor muscles of the wrist. This is due to lead’s neurotoxic effects on the peripheral nervous system, particularly the motor nerves.