What is the stated limit for accumulated dose?

• A. 125 rad
• B. 100 rad
• C. 250 rad
• D. 500 rad

Answer: (A)

Accumulated dose refers to the total amount of ionizing radiation a person has received over their entire career, not just in a single exposure. The limit is set to keep lifetime risk of stochastic effects, like cancer, within an acceptable range by preventing someone from crossing a long-term exposure cap.

In this material, the stated limit for accumulated dose is 125 rad. That means the sum of all whole-body exposures over a person’s working life should not exceed about 125 rad (roughly 125 rem for gamma/x-ray exposures, since the weighting factor is about 1). To put it in perspective, if a worker were at the annual occupational limit of 5 rem each year, they would reach a 125 rem lifetime cap after about 25 years, illustrating why a lifetime (accumulated) limit is set separate from annual limits.

The other numbers don’t represent this lifetime cap for accumulated dose; they would correspond to different, non-lifetime limits (such as other organ-specific or annual limits).