[en] This report contains a preliminary assessment of the radiation dose and potential health impact of the accident on March 28, 1979 at the Three Mile Island Nuclear Station. This assessment was prepared by a task group composed of technical staff members from The Environmental Protection Agency, The Department of Health, Education and Welfare, and The Nuclear Regulatory Commission. The estimated dose that might have been received by an individual is less than 100 mrem. The collective dose received by the 2,164,000 people estimated to live within 50 miles of the reactor site is calculated to be 3,300 person-rem (with a range of 1600 to 5300 person-rem). This corresponds to an average dose of approximately 1.5 mrem. The potential number of fatal cancers that is projected to occur as a result of the accident is less than 1. This potential impact would be undetectable compared to the 325,000 cancer deaths that would normally be expected to occur in a population of 2,164,000. The estimated total health impact, including fatal and non-fatal cancers and genetic effects to all future generations is approximately 2 health effects