[en] Naturally-occurring radionuclides are ubiquitous in the environment. Under various circumstances these radionuclides, primarily from the uranium and thorium decay series, can contaminate the environment to the extent that they pose real or potential public health risks. The investigation and regulatory control of the impacts of most of these sources have been greatly overlooked by Federal and State agencies in the past. This report provides an initial assessment of the scope of the contamination problems, the priorities for radiation control efforts, and recommendations for problem resolution and implementation of effective control measures. This report is intended to assist those persons or agencies interested in the protection of public health from naturally-occurring radionuclide contamination