The recommended standards for Yucca Mountain are illustrative of the unusual attention and concern surrounding risks from man-made ionizing radiation. Many reasons have been advanced for this concern, including the connection between radiation and nuclear weapons and the fact that human senses cannot detect radiation.

Ironically, however, it has also been very difficult to detect adverse effects from low-level radiation. The search for radiation effects among populations exposed to moderately elevated radiation levels–inhabitants of regions with high natural levels of radiation, nuclear industry workers (excluding miners), and residents of houses with high radon levels–has not provided any conclusive evidence of excess cancer rates. In a push of the pendulum far to the skeptical side, this creates a temptation to dismiss entirely the hazards of low doses.

It is difficult to find a firmly based middle ground. The available information, taken as a whole, provides no conclusive evidence as to the nature of the consequences at low doses and low dose rates. However, proponents of the linearity hypothesis and of hormesis –as well as believers in a near-zero effect–can find support from individual studies (see Appendix F). Under these circumstances, adopting the linearity hypothesis for purposes of setting radiation limits may be a prudent regulatory expedient. However, it should be recognized that the scientific validity of the hypothesis is not well established.

The current uncertainties highlight the importance of continued studies of the effects of low-level radiation. A better scientific understanding of radiation risks is crucial to the formulation of appropriate protective standards and, more broadly, to the achievement of a responsible balance in assessing the use of nuclear technologies in industry, medicine, and energy production.