Which of the following is the lens dose limit for occupational exposure?

• A. 100 mSv/year
• B. 50 mSv/year
• C. 150 mSv/year
• D. 500 mSv/year

Answer: (C)

Protecting the eyes from radiation is crucial because the lens is highly sensitive to ionizing damage, and cataracts can develop with relatively small doses. The dose limit for the lens during occupational work is set per year to keep exposure to this tissue below the level where cataracts become likely. The value commonly used in many safety standards for this purpose is 150 mSv per year, making it the upper cap you should not exceed in any single year of work.

That’s why 150 mSv/year is the best answer here: it reflects the established annual limit for the lens under traditional occupational exposure guidelines. Exposures at or above this level raise the risk of radiation-induced cataracts, so the limit is designed to prevent that outcome.

For context, modern recommendations in some guidelines have moved toward different phrasing—favoring a lower average over multiple years (and no single year exceeding a smaller cap)—but this question aligns with the older standard of 150 mSv per year for the lens. The other numbers do not represent the recognized lens limit: 100 mSv/year is below the traditional threshold, 50 mSv/year is not the lens limit in these standards, and 500 mSv/year would greatly exceed it and would pose a clear safety violation.