The remainder of this document contains a brief explanation of radiation and its effects on humans. As you will read, some radiation is present everywhere and the levels of radiation most employees of the NRC and BRC licensees receive, are not much larger than these natural levels. Because the radiation levels are required by law and good practice to be kept quite low, there is not considered to be a significant health risk to individual adult employees. The average person in the United States gets a dose of two rems from external natural sources in about 12 years. A tabulation of these values in the five states we've considered can be found at the end of this Appendix.
Many people receive additional radiation fro medical reasons.
The average dose from one chest X-ray is 0.027 rem. The estimated surface skin dose per abdominal X-ray is 0.62 rem. The possible annual dose from working 8 hours a day near a granite wall is 0.2 rem. Radiation, like many things, can be harmful. Control of exposure to radiation is based on the assumption that no exposure, no matter how small , involves some risk.