EMPCO Health Surveillance & Monitoring 3 — Questions and Answers
Question 1: Which agency publishes the Threshold Limit Values (TLVs) used as occupational exposure benchmarks in health surveillance?
- OSHA
- NIOSH
- ACGIH (Correct answer)
- EPA
Correct answer: ACGIH
The American Conference of Governmental Industrial Hygienists (ACGIH) publishes TLVs, which are widely used as occupational health exposure benchmarks.
Question 2: What does the term 'specificity' mean when evaluating a health surveillance screening test?
- The proportion of truly diseased individuals who test positive
- The proportion of truly non-diseased individuals who test negative (Correct answer)
- The overall accuracy of the test across all populations
- The cost-effectiveness ratio of the test
Correct answer: The proportion of truly non-diseased individuals who test negative
Specificity is the ability of a test to correctly identify those without the disease (true negative rate), minimizing false positives.
Question 3: In audiometric surveillance, a Standard Threshold Shift (STS) is defined as an average shift in hearing threshold of how many decibels?
- 5 dB averaged over 500, 1000, and 2000 Hz
- 10 dB averaged over 2000, 3000, and 4000 Hz (Correct answer)
- 15 dB at any single frequency
- 25 dB at 4000 Hz only
Correct answer: 10 dB averaged over 2000, 3000, and 4000 Hz
OSHA defines STS as a change in hearing threshold averaging 10 dB or more at 2000, 3000, and 4000 Hz in either ear.
Question 4: Which hazard category most commonly necessitates blood lead level (BLL) surveillance in an occupational health program?
- Ionizing radiation exposure
- Heavy metal (lead) exposure in smelting or battery manufacturing (Correct answer)
- Solvent inhalation in painting operations
- Biological pathogen exposure in healthcare
Correct answer: Heavy metal (lead) exposure in smelting or battery manufacturing
Blood lead level surveillance is mandated for workers exposed to lead during operations like smelting, battery manufacturing, and lead abatement.
Question 5: What is the role of a 'control biopsy' or baseline sample in longitudinal health surveillance?
- To serve as a legal document in case of injury claims
- To establish an individual's pre-exposure health status for future comparisons (Correct answer)
- To replace periodic medical examinations
- To satisfy insurance underwriting requirements
Correct answer: To establish an individual's pre-exposure health status for future comparisons
Baseline samples establish a worker's pre-exposure health status so that future results can be compared to detect any deterioration attributable to work.
Question 6: When a health surveillance program detects a cluster of similar illnesses among workers in one department, the next appropriate step is to:
- Immediately terminate all workers in that department
- Conduct an exposure assessment and epidemiological investigation of that department (Correct answer)
- Issue bonuses to compensate affected workers
- Transfer the workers to another department without investigation
Correct answer: Conduct an exposure assessment and epidemiological investigation of that department
A disease cluster warrants an exposure assessment and epidemiological investigation to identify the causative workplace hazard and implement controls.
Question 7: Which of the following best describes 'passive surveillance' in occupational health?
- Routine testing of all employees on a fixed schedule
- Collection of health data through existing records such as workers' compensation claims or sick leave logs (Correct answer)
- Direct observation of workers performing tasks
- Employer-sponsored annual wellness screenings
Correct answer: Collection of health data through existing records such as workers' compensation claims or sick leave logs
Passive surveillance uses routinely collected administrative data—such as workers' compensation claims, OSHA logs, or absenteeism records—rather than active testing.
EMPCO Health Surveillance & Monitoring 3
Which agency publishes the Threshold Limit Values (TLVs) used as occupational exposure benchmarks in health surveillance?