如標題可以參考下列原文
A third factor for some substances is bioaccumlation, in which some
molecules are absorbed and stored in specific organs or tissues at higher than
normal levels. As a consequence, a chemical found at a fairly low
concentration
in the environment can build up to a harmful level in certain organs and
tissues.
A related factor is biomagnification, in which levels of some potential
toxins in the environment become magnified as they pass through food chains
and webs. Organisms at low trophic levels might ingest only small amounts of
a toxin, but each animal on the next trophic level up that eats many of those
organisms will take in increasingly larger amounts of that toxin. Examples of
chemicals that can be biomagnified include long-lived, fat-soluble organic
compounds such as DDT, PCBs (oily chemicals used in electrical transformers),
and some radioactive isotopes (such as strontium-90)
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