CIH Hazards & Exposures 4 — Questions and Answers
Question 1: What is the primary mechanism by which asbestos fibers cause mesothelioma?
- Long, thin, biopersistent fibers penetrate the pleura and cause chronic inflammation and DNA damage (Correct answer)
- Fibers dissolve in lung fluid releasing iron that generates free radicals only in the bronchi
- Asbestos fibers act as a chemical carcinogen through metabolic activation in the liver
- Short fibers are phagocytized and cleared, while only soluble fibers reach the pleura
Correct answer: Long, thin, biopersistent fibers penetrate the pleura and cause chronic inflammation and DNA damage
Amphibole and chrysotile fibers that are long (>5 µm), thin (<3 µm), and biopersistent reach the pleura and cause persistent inflammation leading to mesothelioma.
Question 2: A worker is exposed to hydrogen sulfide (H₂S) at 50 ppm for 15 minutes. What health effect is most expected at this concentration?
- Rapid olfactory fatigue and eye/respiratory irritation (Correct answer)
- Immediate loss of consciousness and death
- Mild headache with no olfactory impairment
- No detectable health effect at this level
Correct answer: Rapid olfactory fatigue and eye/respiratory irritation
At 50 ppm, H₂S causes rapid olfactory paralysis (olfactory fatigue) along with eye and upper respiratory tract irritation; unconsciousness occurs at much higher concentrations.
Question 3: Which parameter is used in industrial hygiene to describe the fraction of an inhaled aerosol that deposits in the gas-exchange region of the lung?
- Respirable fraction (Correct answer)
- Inhalable fraction
- Thoracic fraction
- Total suspended particulate (TSP)
Correct answer: Respirable fraction
The respirable fraction captures particles that penetrate to the alveolar region, defined by an aerodynamic diameter convention with a 50% cutpoint at approximately 4 µm.
Question 4: A worker's urine sample after a shift shows elevated mandelic acid and phenylglyoxylic acid. Which solvent was the worker most likely exposed to?
- Styrene (Correct answer)
- Benzene
- Toluene
- Ethylbenzene
Correct answer: Styrene
Mandelic acid and phenylglyoxylic acid are the primary urinary metabolites of styrene and are used as biological exposure indices (BEI) by ACGIH.
Question 5: Under the OSHA Hazard Communication Standard (HCS 2012), which GHS signal word indicates a LESS severe hazard category?
- Warning (Correct answer)
- Danger
- Caution
- Notice
Correct answer: Warning
'Warning' is used for less severe hazard categories (e.g., Category 2 or 3), while 'Danger' is reserved for more severe hazards (e.g., Category 1).
Question 6: Which of the following best defines the term 'ceiling value' (C) in the context of occupational exposure limits?
- A concentration that should not be exceeded at any time during the work shift (Correct answer)
- An 8-hour time-weighted average that must not be exceeded
- A 15-minute short-term exposure limit averaged over a 15-minute period
- A target concentration that represents best available technology
Correct answer: A concentration that should not be exceeded at any time during the work shift
A ceiling value is an instantaneous limit that must not be exceeded at any moment during a work shift, unlike TWA limits that are averaged over time.
Question 7: A worker develops hand-arm vibration syndrome (HAVS). Which early symptom is most characteristic of the vascular component?
- Episodic finger blanching triggered by cold (Raynaud's phenomenon) (Correct answer)
- Persistent burning pain in all five fingers
- Carpal tunnel syndrome with thenar muscle wasting
- Loss of temperature discrimination in the palm
Correct answer: Episodic finger blanching triggered by cold (Raynaud's phenomenon)
The vascular component of HAVS presents as episodic Raynaud's phenomenon — finger blanching on cold exposure — caused by vibration-induced vasospasm.
CIH Hazards & Exposures 4
What is the primary mechanism by which asbestos fibers cause mesothelioma?