Radiation Benefit and Risk Assessment

How much radiation does it take to cause our risk for an observable health effect to increase? Is there a level of radiation that is safe? How is radiation beneficial? The question of an effect occurring because of radiation exposure and the question of whether low‐ level radiation is safe are much‐debated topics. There are many thoughts on the answers to these questions, and suggested answers lie along a continuum, especially when the topic is low‐level radiation. Answers range from " radiation is good for you " (this is the hormesis hypothesis) to " low levels of radiation are safe " (they do not measurably increase your risk of disease) to " any amount of radiation exposure carries some risk " (this is the linear no‐threshold hypothesis). According to the American Cancer Society, the average natural incidence of cancer in the United States is 42 percent (42 out of 100 people will get cancer in their lifetime). Diagnostic medical radiation exposures may or may not increase this risk. It is important to note that radiation exposure does not create a unique cancer risk situation, nor is the risk directly measurable or distinguishable from the cancer risk caused by other sources (environmental, chemical, biological, etc.). When we discuss radiation risks, the effects are probabilistic in nature—like the odds of getting a heads when we flip a coin. First, we lack the scientific data to determine a precise risk of cancer in the future from radiation exposure today, but we estimate the increase in the cancer incidence rate is about 0.17 percent per rem of radiation dose; this is based on the effects we see with high doses. However, it is impossible to say with certainty that any single person will get a radiation‐induced cancer. Second, it may be impossible to even demonstrate that additional cancers have occurred, since the normal incident rate of cancer is about 42 percent plus or minus some natural variation. What this means is that out of a group of 100 people, it is estimated that about 42 will get a cancer in their lifetime. If we expose each of them to one rem of radiation, still about 42 out of 100 will get a cancer in their lifetime. If we expose each to five rem of radiation, we estimate now that about 43 out of 100 will get a cancer in their lifetime. What we cannot …