It is commonly stated that “any radiation dose, no matter how small, can cause cancer.” The basis for that statement is the linear no-threshold theory (LNT) of radiation carcinogenesis. According to LNT, if 1 Gy (100 rad) of exposure gives a cancer risk R, the risk from 0.01 Gy (1 rad) of exposure is R/100, the risk from 0.00001 Gy (1 mrad) is R/100,000, and so on. Thus the cancer risk is not zero regardless of how small the exposure. However, in recent years, a strong sentiment has developed in the community of radiation health scientists to regard risk estimates in the low-dose region based on LNT as being grossly exaggerated or completely negligible. For example, the 6000-member Health Physics Society, the principal organization for radiation protection scientists, issued a position paper (Health Physics Society 1996) stating “Below 10 rad ... risks of health effects are either too small to be observed or are non-existent.” A similar position statement was issued by American Nuclear Society.