The bioaccumulation factor is the ratio of the concentration of a radionuclide in a biological organism or tissue to the concentration in water or soil.

The accumulation of radioactive substances in organs or tissues is used for diagnosis and therapy.

See also Bioaccumulation Factor and Administered Activity.

An assay is an analytic test to detect the presence, measure the concentration, and determine the biological activity of molecule, ions, or cells. Assays are based on measurable parameters that enable the evaluation of differences between samples and controls. Sensitivity, the ability to detect small amounts of a substance, and specificity, the ability to detect only the analyte, are essential features of an assay.

See also Bioassay, Biochemical, Biohazards, Biokinetic Model and Bioaccumulation Factor.