ABT Occupational Toxicology 1 — Questions and Answers
Question 1: Which organization establishes Threshold Limit Values (TLVs) for occupational chemical exposures?
- OSHA
- ACGIH (Correct answer)
- NIOSH
- EPA
Correct answer: ACGIH
The ACGIH (American Conference of Governmental Industrial Hygienists) establishes TLVs as voluntary guidelines for occupational chemical exposures.
Question 2: OSHA Permissible Exposure Limits (PELs) are typically expressed as what type of measurement?
- 15-minute short-term exposure limit
- 8-hour time-weighted average (TWA) (Correct answer)
- Ceiling value that must never be exceeded
- 30-minute excursion limit
Correct answer: 8-hour time-weighted average (TWA)
OSHA PELs are expressed as 8-hour time-weighted averages reflecting exposures over a standard workday.
Question 3: For volatile organic compounds (VOCs) in the workplace, which route of exposure is generally most significant?
- Dermal absorption
- Oral ingestion
- Inhalation (Correct answer)
- Ocular absorption
Correct answer: Inhalation
Inhalation is the primary route of exposure for VOCs because their high vapor pressure results in significant airborne concentrations in occupational settings.
Question 4: Under OSHA's lead standard for general industry, at what blood lead concentration must a worker be medically removed from exposure?
- 20 µg/dL
- 40 µg/dL
- 60 µg/dL (Correct answer)
- 80 µg/dL
Correct answer: 60 µg/dL
OSHA's lead standard (29 CFR 1910.1025) requires mandatory medical removal when a worker's blood lead level reaches 60 µg/dL.
Question 5: The 'skin' notation on an ACGIH TLV primarily indicates that:
- The substance causes dermatitis as its primary toxic effect
- Significant dermal absorption can contribute to the total body burden (Correct answer)
- Skin contact with the substance is strictly prohibited
- The substance is a confirmed skin carcinogen
Correct answer: Significant dermal absorption can contribute to the total body burden
The 'skin' notation indicates that dermal absorption is significant enough to contribute appreciably to overall exposure and potential systemic toxicity.
Question 6: Red blood cell (erythrocyte) cholinesterase activity is the preferred biomarker for monitoring occupational exposure to which class of pesticides?
- Pyrethroids
- Organophosphates (Correct answer)
- Organochlorines
- Neonicotinoids
Correct answer: Organophosphates
Organophosphates irreversibly inhibit cholinesterase; red blood cell cholinesterase reflects cumulative inhibition over the approximately 120-day lifespan of the erythrocyte.
Question 7: In the hierarchy of occupational health controls, which control method is most preferred because it completely removes the hazard?
- Engineering controls
- Administrative controls
- Elimination (Correct answer)
- Personal protective equipment
Correct answer: Elimination
Elimination is the highest priority in the hierarchy of controls because it completely removes the hazard from the workplace, providing the greatest level of worker protection.
ABT Occupational Toxicology 1
Which organization establishes Threshold Limit Values (TLVs) for occupational chemical exposures?