COHN COHN-S 4 — Questions and Answers
Question 1: Which toxicological concept describes the dose below which no adverse effect is observed in a study population?
- Threshold limit value (TLV)
- No-observed-adverse-effect level (NOAEL) (Correct answer)
- Permissible exposure limit (PEL)
- LD50
Correct answer: No-observed-adverse-effect level (NOAEL)
The NOAEL is the highest dose in a toxicology study at which no statistically significant adverse effects are observed.
Question 2: A manufacturing employee reports that a co-worker has threatened to 'settle the score' after a disciplinary action. A COHN-S should FIRST:
- Document the report and wait for further incidents
- Advise the employee to confront the co-worker directly
- Notify security and management immediately (Correct answer)
- Reassign the threatened employee without investigation
Correct answer: Notify security and management immediately
Workplace violence threats require immediate notification of security and management to assess risk and protect employee safety.
Question 3: The ACGIH Threshold Limit Value-Short Term Exposure Limit (TLV-STEL) is defined as the concentration to which workers can be exposed for up to:
- 5 minutes without adverse effects
- 15 minutes without adverse effects (Correct answer)
- 30 minutes without adverse effects
- 60 minutes without adverse effects
Correct answer: 15 minutes without adverse effects
The TLV-STEL is a 15-minute time-weighted average concentration that should not be exceeded during any 15-minute period in the workday.
Question 4: In occupational health program evaluation, which metric measures the ratio of benefits gained to program costs?
- Return on investment (ROI) (Correct answer)
- Incidence rate
- Severity rate
- Net promoter score
Correct answer: Return on investment (ROI)
ROI calculates the financial return relative to the cost of a program, expressed as a percentage, and is key to demonstrating program value.
Question 5: A COHN-S is reviewing noise dosimetry results. A worker's full-shift dose reads 105%. Per OSHA 29 CFR 1910.95, which action is REQUIRED?
- Recommend hearing protection on a voluntary basis
- Enroll the worker in a hearing conservation program (Correct answer)
- Remove the worker from the noisy environment immediately
- Repeat monitoring within 6 months only
Correct answer: Enroll the worker in a hearing conservation program
OSHA requires enrollment in a hearing conservation program when an employee's noise exposure equals or exceeds an 8-hour TWA of 85 dBA (50% dose = 85 dBA, so 105% = well above action level).
Question 6: Which type of epidemiological study is BEST suited for investigating a rare occupational disease with a long latency period?
- Randomized controlled trial
- Cross-sectional study
- Case-control study (Correct answer)
- Prospective cohort study
Correct answer: Case-control study
Case-control studies are efficient for rare diseases because they start with cases (disease present) and match them with controls, allowing retrospective exposure assessment.
Question 7: Under OSHA's bloodborne pathogen standard, hepatitis B vaccination must be offered to at-risk employees:
- Within 10 working days of initial assignment (Correct answer)
- After the first needlestick exposure
- Only if the employee requests it in writing
- At the annual occupational health exam
Correct answer: Within 10 working days of initial assignment
OSHA 29 CFR 1910.1030 requires employers to offer hepatitis B vaccination to at-risk workers within 10 working days of initial assignment at no cost.
COHN COHN-S 4
Which toxicological concept describes the dose below which no adverse effect is observed in a study population?