Natural Radioactive Decay Rate of a Human

This constant represents the amount of radioactive decay that occurs naturally in a human body.

The typical human body contains roughly 14 mg of naturally occurring potassium-40, contributing approximately 0.1 `mu`Ci of radioactivity and also contains approximately 16 kg of carbon (see Composition of the human body) having about 24 nanograms of carbon-14, which also contributes approximately 0.1 `mu`Ci of radioactivity. Therefore the naturally occurring radioactivity in an average human is approximately 2×0.1 μCi or 7400 decays (mostly from beta decay and rarely from gamma decay) per second inside the person's body.¹

1. ^ http://en.wikipedia.org/wiki/Curie