Answer to Question #87 Submitted to "Ask the Experts"

Q

Do studies (like the Hiroshima survivors) show a beneficial effect of exposure to low (<10 rem) amounts of radiation?

A

Evidence showing that exposure to radiation (less than 10 rem) is beneficial to human health has been very difficult to demonstrate. Current scientific knowledge suggests that the effect is unlikely. The data from the Japanese survivors of the atomic bombs show statistically significant health effects (primary cancer) at dose levels in excess of 20 rem. Below this dose, the probability of health effects (including detrimental and beneficial effects) is so small that statistically significant observations are almost impossible to make. Some scientists have reported beneficial effects in Japanese survivors but demonstration of the effect depends on how the analysis of the data is done. Using the same database, other scientists have shown that at low doses there appears to be a threshold dose below which no radiation effect is observed. Still other scientists report that small doses may cause cancer. The problem is further complicated by the lack of clearly established biological mechanism(s) to explain beneficial effects. Kenneth L. Mossman, Ph.D. Professor of Health Physics Director, Office of Radiation Safety Arizona State University