Answer: It is all to do with the emitted radiation and the half-life of the source. Carbon 14 is a beta emitter with a half-life of 5570 years. Of course a small fraction of the carbon atoms in your body are carbon 14 so you are already radioactive!!

What are the negative effects of carbon-14?

At this population, Pauling calculated the effects of carbon-14 from one year worth of bomb-testing to be 55,000 children with gross physical and mental defect, 170,000 stillbirths and childhood deaths, and 425,000 embryonic and neonatal deaths.

What is the medical use of carbon-14?

The isotope also is used as a tracer in following the course of particular carbon atoms through chemical or biological transformations. In carbon-14 dating, measurements of the amount of carbon-14 present in an archaeological specimen, such as a tree, are used to estimate the specimens age.

How are C 12 C 13 and C 14 alike?

THE DIFFERENT ATOMIC WEIGHT VARIANTS OF AN ELEMENT ARE CALLED THE ISOTOPES OF THAT ELEMENT. (For example C12, C13, and C14 are all isotopes of carbon, all have 6 protons but each has a different number of neutrons).