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Biomagnification, also known as bioamplification or biological magnification,
occurs when the concentration of a substance, such as DDT or mercury,
in an organism exceeds the background concentration of the substance in its diet.
[1] This increase can occur as a result of:
Persistence � where the substance can't be broken down by environmental processes
Food chain energetics � where the substance concentration increases progressively as it moves up a food chain
Low or non-existent rate of internal degradation or excretion of the substance � often due to water-insolubility
Biological magnification often refers to the process whereby certain substances such as pesticides or
heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms
such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated
in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in
concentration in living organisms as they take in contaminated air, water, or food because the substances
are very slowly metabolized or excreted.