Effective half-life

For other uses, see Half-life (disambiguation).

Effective half-life denotes the halving of radioactive material in a living organism by means of radioactive decay and biological excretion. A decay constant is needed to calculate the half-life. It is the sum of the biological and physical decay constants, as in the formula:

${\lambda _{e}}\,={\lambda _{p}}\,+{\lambda _{b}}\,$

With the decay constant it is possible to calculate the effective half-life using the formula:

$t_{1/2}={\frac {\ln(2)}{\lambda _{e}}}$

The biological decay constant is often approximated as it is more difficult to accurately determine than the physical decay constant.

External links

• Biological Half-life