Bioaccumulation
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Lipid (fat) soluble poisons include tetra-ethyl lead compounds (the lead in leaded petrol), and DDT. These compounds are stored in the body's fat, and when the fatty tissues are used for energy, the compounds are released and cause acute poisoning.
Strontium 90, part of the fallout from atomic bombs, is mistaken by the human body for calcium, and is laid down in the bone, where its radiation can cause damage for a long time.
Naturally produced toxins can also bioaccumulate. The marine algal blooms known as "red tides" can result in local filter feeding organisms such as mussels and oysters becoming toxic; coral fish can be responsible for the poisoning known as ciguatera when they accumulate a toxin called ciguatoxin from reef algae.
Some animal species exhibit bioaccumulation as a mode of defense; by consuming toxic plants or animal prey, a species may accumulate the toxin which then presents a deterrent to a potential predator. One example is the tobacco hornworm, which concentrates nicotine to a toxic level in its body as it consumes tobacco plants.
Other compounds that are not normally considered toxic can be accumulated to toxic levels in organisms. The classic example is of Vitamin A, which becomes concentrated in carnivore livers of e.g. polar bears: as a pure carnivore that feeds on other carnivores (seals), they accumulate extremely large amounts of Vitamin A in their livers. It was known by the native peoples of the arctic that the livers should not be eaten, but arctic explorers have suffered Hypervitaminosis A from eating the bear livers (and there has been at least one example of similar poisoning of Antarctic explorers eating husky dog livers).
See also
- List of environment topics
- Biomagnification (magification of toxins with increasing trophic level)
External links
- http://www.marietta.edu/~biol/102/2bioma95.html
- http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ec/m3/s4/ (excellent graphic)
- http://toxics.usgs.gov/definitions/biomagnification.htmlda:Biomagnifikation
de:Biomagnifikation fr:Bioaccumulation it:Bioaccumulo nl:Bioaccumulatie ja:生物濃縮sv:Bioackumulation
