DDT
Dichlorodiphenyltrichloroethane (colourless chemical used as an insecticide).

Decay (Radioactive)
The process of spontaneous transformation of a radionuclide. The decrease in activity of radioactive substance.

Decibel (dB)
This is not an absolute unit of measurement. It is a ratio between a measured quantity and an agreed reference level, expressed on a logarithmic scale.

Deviation
Where a process or procedure does not work as intended.

Disinfection
The reduction, by means of chemical agents and/or physical methods, of the number of micro-organisms in the environment, to a level that does not compromise food safety or suitability.

Disposal
In relation to radioactive waste, dispersal or emplacement in any medium without the intention of retrieval.

DNA
Deoxyribonucleic acid. The compound that controls the structure and function of cells and is the material of inheritance.

Dose
A general form denoting the quantity of energy imparted by ionizing radiation to unit mass of matter such as tissue. Unit gray, symbol Gy. 1 Gy = 1 joule per kilogram (J/kg). For special purposes dose must be appropriately qualified. If unqualified, it refers to absorbed dose.

Dosemeter
Instrument to detect and measure ionising radiation. For example, a pencil-size ionisation chamber with a self reading electrometer, used for personnel monitoring.

Dosimetry
Determination of cumulative radiation dose with photographic film and density measurement

DSE
Display Screen Equipment

Duty Of Care
A policy which requires all persons who have responsibility for waste to ensure that it is managed properly and recovered or disposed of safely.

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