Dose-response. Of, relating to, or graphing the pattern of physiological response to varied dosage (as of a drug or radiation) in which there is typically little or no effect at very low dosages and a toxic or unchanging effect at high dosages with the maximum increase in effect somewhere between the extremes.

Drift. A horizontal opening in or near an orebody and parallel to the course of the vein or the long dimension of the orebody.

Effluent. A liquid discharged as waste, such as contaminated water from a factory or the outflow from a sewage works; water discharged from a storm sewer or from land after irrigation.

Eh (redox potential). Measures the tendency of a chemical species to acquire electrons and be reduced. Reduction/oxidation potential of a compound is measured under standards conditions against a standard reference half-cell. In biological systems, the standard redox potential is defined at pH 7.0 versus the hydrogen electrode and partial pressure of hydrogen = 1 bar.

Epithelium. A membranous cellular tissue that covers a free surface or lines a tube or cavity of an animal body and serves especially to enclose and protect the other parts of the body, to produce secretions and excretions, and to function in assimilation.

Equilibrium factor. The ratio of decay products to radon.

Equivalent dose. An absorbed dose that is averaged over an organ or tissue and weighted for the radiation quality.

Erosion. The general process or the group of processes whereby the materials of the Earth’s crust are loosened, dissolved, or worn away, and simultaneously moved from one place to another, by natural agencies, which include weathering, solution, corrasion, and transportation, but usually exclude mass wasting; specifically the mechanical destruction of the land and the removal of material (such as soil) by running water (including rainfall), waves and currents, moving ice, or wind.

Exposure. The condition of being subject to some detrimental effect or harmful condition.

Exposure pathway. The route a substance takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination, an environmental medium and transport mechanism, a point of exposure, a route of exposure, and a receptor population.

Felsic. A mnemonic adjective applied to an igneous rock having abundant light-colored minerals in its mode; also, applied to those minerals (quartz, feld-spars, feldspathoids, muscovite) as a group.

Fluvial. Produced by the action of a stream or river.

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