Becquerel (Bq).

A quantity of radioactivity equivalent to 1 decay per second. The Becquerel is a SI unit named on behalf of the French scientist Henri Becquerel.


The fourth in a series of National Research Council reports called the Biological Effects of ionizing Radiation. The 1988 report is titled: Health Risks of Radon and Other Internally Deposited Alpha-Emitters.


The sixth in a series of National Research Council reports called the Biological Effects of Ionizing Radiation. The 1999 report is titled: Health Risks of Exposure to Radon.

Best available technology (BAT).

The most efficient treatment method for removal of a given contaminant.

Beta particle (β).

A particle emitted during the decay of certain radioactive elements. It is identical to an electron.


The difference between the average value obtained from a measurement (estimate) of a specific quantity and the true value of that quantity. Bias is the complement of accuracy.



A malignant tumor of potentially unlimited growth, capable of invading surrounding tissue or spreading to other parts of the body by metastasis.


An agent that can cause cancer.


A family of proteolytic enzymes that are normally found complexed with peptide inhibitors which are released by caspase activity itself. This results in an autocatalytic increase in pretense activity (cascade) that degrades specific protein substrates especially those involved in structural components of the cell.


The combination of DNA and proteins which together make up the main structural units of the nucleus and the chromosomes. The first order of structure consists of DNA wrapped around specific histone proteins packed together to form nucleosomes.

Countercurrent flow.

The hydraulic regime in a treatment unit where the flow of the fluid being cleaned is in the opposite direction to that of the fluid to which the contaminant is transferred.


Pits formed by depressions in the surface of the stomach or intestinal lining cells within the crypts divide and secrete digestive enzymes.

Curie (Ci).

A quantity of radioactivity equivalent to 3.7 × 10l0 (37 billion) decays per second. The curie is a traditional unit named on behalf of the French scientist Marie Curie.


The branch of genetics devoted to the study of chromosomes.


Extracellular molecules that transmit signals to control gene expression in target cells, often through interaction with specific receptors on the cell surface.



The normal state of the genome of cells in most body tissues172.16.50.51 in which each cell has two copies of each chromosome, one copy originating from each parent.

Disinfection by-products (DBPs).

Compounds formed when organic matter in raw water is oxidized by disinfectants. For example, chloroform is formed when natural organic matter is oxidized by chlorine.

DNA homologs.

Two DNA sequences or chromosomal regions which have sufficiently similar nucleotide sequence to represent the same genes or intervening sequences.


Effective dose (HE).

The product of the equivalent dose, HT, in a tissue, T, multiplied by the tissue weighting factor wT. The purpose of this is to take into consideration the difference in sensitivity of various tissues or organs to radiation induced cancer.

Electron volt (eV).

A unit of energy equal to the kinetic energy gained by a particle having one electronic charge when it passes in a vacuum through a potential difference of 1 volt. 1 eV = 1.602 × 1019 joules, 1 MeV = 1,000,000 eV. 1 kev = 1,000 eV.

Empty bed contact time (EBCT).

The average interval of time that a fluid containing a contaminant remains in contact with a bed of granular activated carbon. EBCT is the volume of the reactor (not containing GAC) divided by the flow rate of water being treated.


A term describing sources of reactive molecules that originate from within the cell.


A small circular DNA molecule that can be maintained for varying periods of time within the nucleus but is not a functional part of the DNA for the host cell.

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