The radioactive decay of other naturally occurring elements produces the radioactive gases radon and thoron.
Space (cosmic radiation) (cosmic radiation).
Biologically produced radioactive minerals Internal (in your body) (in your body). Terrestrial (in the earth) (in the ground).
According to the NRC, the majority of people's main source of man-made radiation is medical imaging. However, as doses vary greatly, your circumstances will determine your yearly dose. Roughly 1.5 mrem is produced by dental X-rays and about 10 mrem by chest X-rays.
If you live in a rural location, it comes from wells, whereas if you live in an urban area, it comes from lakes and rivers where it may take up radiation from the rocks and soil.
"The 2000 CDC growth charts were developed using a reference population of infants. A pediatrician looks up one of the charts and finds that the 10th percentile for weights of baby girls at 7-1/2 months is 16.5 pounds. This means that"
