Languages:

Half life

Definition:

The term which is used for the time required for the amount of a particular substance to be reduced to one half of its value when the rate of decay is exponential.

Radioactive half-life refers to the decay of radioactive substances. Iodine-131, for instance, has a half-life of 8 days whereas that of Plutonium-239 is more than 23 000 years.

Biological half-life refers to decay by biological processes. Substances with a long biological half-life will tend to accumulate in the body and are, therefore, particularly to be avoided. Substances with a short biological half-life may accumulate if some becomes tightly bound, even if most is cleared from the body rapidly. There is also the possibility of cumulative effects of chemicals which have a short residence time in the body.

Source: GreenFacts

More:
Graphic representation of half-life Graphic representation of half-life

Source: GreenFacts

Related words:

Bioaccumulation

Translation(s):

Français: Demi-vie biologique

Related publications:
FacebookTwitterEmail
  • ABC - DEF - GHI - JKL - MNO - PQRS - TUV - WXYZ
  • Themes covered
    Publications A-Z
    Leaflets

    Video