Radiation doses are measured in rem, which is based on the amount of ionizing radiation received by the human body. Radiation occurs naturally in the body and can be received from external sources. A millirem is one thousandth of a rem.
The average American receives about 360 millirem of radiation per year. About 300 comes from natural sources and 60 from manmade sources. Here is a comparison of the risk of receiving 100 millirem every year of your life with other risks:
| Smoking (a pack a day) | 400 times more risky |
| Being 15 percent overweight | 100 times more risky |
| Driving a car (12,000 miles per year) | 40 times more risky |
| Comparing Radiation Sources | Annual Dose |
| Naturally inside your body (air – radon) | 200 millirem |
| Natural radiation inside food/water you eat | 40 millirem |
| Medical X-Ray | 20 millirem |
| Living in a brick or stone house | 7 millirem |
| Watching TV | 1-2 millirem |
| Computer terminal | 0.1 millirem |
| Luminous wrist watch | 0.06 millirem |
| Smoke detector | 0.008 millirem |
For More Information:
EPA - Radiation Protection
U.S. Department of Energy - Safety and Health
U.S. Nuclear Regulatory Commission - Fact Sheet on Biological Effects of Radiation
TN Department of Environment & Conservation - Division of Radiological Health