COHN Toxicology and Biohazards 3 — Questions and Answers
Question 1: Which route of exposure is the MOST common pathway for occupational chemical poisoning?
- Ingestion
- Inhalation (Correct answer)
- Skin absorption
- Injection
Correct answer: Inhalation
Inhalation is the most common occupational exposure route because workers breathe contaminated air continuously, providing direct access to the large surface area of the lungs.
Question 2: A healthcare worker receives a needlestick injury from a patient with unknown HIV status. According to CDC guidelines, post-exposure prophylaxis (PEP) should be initiated within:
- 72 hours (Correct answer)
- 24 hours
- 1 week
- 48 hours
Correct answer: 72 hours
CDC guidelines recommend initiating HIV PEP as soon as possible, ideally within hours of exposure, but no later than 72 hours for maximum effectiveness.
Question 3: Hydrogen sulfide (H₂S) is particularly dangerous because at high concentrations it:
- Causes methemoglobin formation that prevents oxygen delivery
- Paralyzes the olfactory nerve, eliminating the warning odor (Correct answer)
- Displaces oxygen by filling lungs with heavy gas molecules
- Binds to hemoglobin 200 times more strongly than carbon monoxide
Correct answer: Paralyzes the olfactory nerve, eliminating the warning odor
At high concentrations, H₂S rapidly paralyzes the olfactory nerve so workers lose the rotten-egg warning odor and can be overcome without realizing the danger.
Question 4: The concept of 'skin notation' (Sk) on a chemical's TLV indicates that:
- The chemical causes dermatitis in all exposed workers
- Significant absorption through intact skin can contribute to total body burden (Correct answer)
- Skin contact must be avoided because dermal TLVs are more restrictive
- PPE is not required because the air limit is already protective
Correct answer: Significant absorption through intact skin can contribute to total body burden
Skin notation alerts occupational health professionals that dermal absorption of the chemical can be significant enough to add to systemic toxicity, even when air levels are controlled.
Question 5: A construction worker is found unconscious in a confined space where fuel combustion equipment was used. The FIRST priority action is:
- Immediately enter and drag the worker out
- Put on supplied-air SCBA before entering to rescue (Correct answer)
- Lower a rope and have the worker self-rescue
- Ventilate the space for 10 minutes before entering without PPE
Correct answer: Put on supplied-air SCBA before entering to rescue
Confined space rescuers must use supplied-air SCBA because entering without respiratory protection leads to multiple fatalities — the majority of confined space deaths are untrained would-be rescuers.
Question 6: Which biological monitoring specimen is BEST for assessing recent (within 24-48 hours) organic solvent exposure?
- Hair sample
- Nail clippings
- End-exhaled breath or urine sample (Correct answer)
- Whole blood sample collected 1 week post-exposure
Correct answer: End-exhaled breath or urine sample
End-exhaled breath captures volatile organic solvents directly, and urine collected at end of shift detects rapidly-cleared metabolites that reflect recent exposure.
Question 7: Under SARA Title III, what is the primary purpose of Tier II chemical inventory reporting?
- To establish permissible exposure limits for hazardous chemicals
- To inform local emergency planners and fire departments about hazardous chemical storage (Correct answer)
- To create a national registry of worker compensation claims for toxic exposures
- To require employers to reduce chemical inventories below threshold quantities
Correct answer: To inform local emergency planners and fire departments about hazardous chemical storage
SARA Title III Tier II reports notify local emergency planning committees (LEPCs) and fire departments about hazardous chemicals stored on-site to facilitate emergency response planning.
COHN Toxicology and Biohazards 3
Which route of exposure is the MOST common pathway for occupational chemical poisoning?