What is the annual whole-body dose limit for an adult at work, in millisieverts (mSv)?

• A. 5 mSv
• B. 10 mSv
• C. 20 mSv
• D. 50 mSv

Answer: (C)

Occupational exposure limits are set to keep cancer risk from radiation as low as reasonably achievable for workers. For adults working with radiation, the standard limit is 20 millisieverts per year as an effective dose, averaged over a five-year period. This means the total dose over any five-year span should not exceed 100 mSv, so the average per year stays at or below 20 mSv. There is also a safety cap of 50 mSv in any single year to handle unusual spikes in exposure.

So the best choice matches the usual annual occupational limit: 20 mSv. The 50 mSv figure is a per-year ceiling, not the regular average limit, and the other numbers are not the standard occupational annual limit.