Bioaccumulation
Encyclopedia
Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance
at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life
of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.
Bioconcentration is a related but more specific term, referring to uptake and accumulation of a substance from water alone. By contrast, bioaccumulation refers to uptake from all sources combined (e.g. water, food, air, etc.)
, which forms organic species such as methylmercury
, which is lipid soluble, and tends to accumulate in the brain resulting in mercury poisoning
.
Other 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 chemically similar enough to calcium that it is utilized in osteogenesis, where its radiation can cause damage for a long time.
Naturally produced toxins can also bioaccumulate. The marine algal bloom
s known as "red tide
s" can result in local filter feeding organisms such as mussel
s and oyster
s 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.
Poisoning of small consumers can be passed along the food chain to affect the consumers later on.
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
liver
s of e.g. polar bear
s: 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). One notable example of this is the expedition of Sir Douglas Mawson, where his exploration companion died from eating the liver of one of their dogs.
Coastal fish
(such as the smooth toadfish
) and seabird
s (such as the Atlantic Puffin
) are often monitored for heavy metal bioaccumulation.
In some eutrophic aquatic systems, biodilution
can occur. This trend is a decrease in a comtaminant with in increase in trophic level and is due to higher concentrations of algae and bacteria to "dilute" the concentration of the pollutant.
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life
Biological half-life
The biological half-life or elimination half-life of a substance is the time it takes for a substance to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition...
of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.
Bioconcentration is a related but more specific term, referring to uptake and accumulation of a substance from water alone. By contrast, bioaccumulation refers to uptake from all sources combined (e.g. water, food, air, etc.)
Examples
An example of poisoning in the workplace can be seen from the phrase "as mad as a hatter". The process for stiffening the felt used in making hats involved mercuryMercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, which forms organic species such as methylmercury
Methylmercury
Methylmercury is an organometallic cation with the formula . It is a bioaccumulative environmental toxicant.-Structure:...
, which is lipid soluble, and tends to accumulate in the brain resulting in mercury poisoning
Mercury poisoning
Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses...
.
Other lipid (fat) soluble poisons include tetra-ethyl lead
Tetra-ethyl lead
Tetraethyllead , abbreviated TEL, is an organolead compound with the formula 4Pb. An inexpensive additive, its addition to gasoline from the 1920's allowed octane ratings and thus engine compression to be boosted significantly, increasing power and fuel economy...
compounds (the lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
in leaded petrol), and DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
. These compounds are stored in the body's fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
, and when the fatty tissues
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
are used for energy, the compounds are released and cause acute poisoning.
Strontium-90
Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
, part of the fallout
Nuclear fallout
Fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
from atomic bombs, is chemically similar enough to calcium that it is utilized in osteogenesis, where its radiation can cause damage for a long time.
Naturally produced toxins can also bioaccumulate. The marine algal bloom
Algal bloom
An algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
s known as "red tide
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...
s" can result in local filter feeding organisms such as mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s and oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s becoming toxic; coral fish can be responsible for the poisoning known as ciguatera
Ciguatera
Ciguatera is a foodborne illness caused by eating certain reef fishes whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are...
when they accumulate a toxin called ciguatoxin
Ciguatoxin
thumb|300px|right|Chemical structure of the ciguatoxin CTX1BThe ciguatoxins are a class of poisonous organic compounds found in some fish that causes ciguatera....
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
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...
to a toxic level in its body as it consumes tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
plants.
Poisoning of small consumers can be passed along the food chain to affect the consumers later on.
Other compounds that are not normally considered toxic can be accumulated to toxic levels in organisms. The classic example is of Vitamin A
Vitamin A
Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...
, which becomes concentrated in carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
s of e.g. polar bear
Polar Bear
The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...
s: 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
Hypervitaminosis A
Hypervitaminosis A refers to the effects of excessive vitamin A intake.-Presentation:Effects include* Birth defects* Liver problems* Reduced bone mineral density that may result in osteoporosis* Coarse bone growths...
from eating the bear livers (and there has been at least one example of similar poisoning of Antarctic explorers
Xavier Mertz
Xavier Mertz was a Swiss explorer, mountaineer and skier, from Basel. He took part in the Far Eastern Party, a 1912–13 component of the Australasian Antarctic Expedition, which claimed his life...
eating husky
Husky
Husky is a general name for a type of dog originally used to pull sleds in northern regions, differentiated from other sled dog types by their fast hard pulling style...
dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
livers). One notable example of this is the expedition of Sir Douglas Mawson, where his exploration companion died from eating the liver of one of their dogs.
Coastal fish
Coastal fish
Coastal fish, also called offshore fish or neritic fish, are fish that inhabit the sea between the shoreline and the edge of the continental shelf. Since the continental shelf is usually less than 200 metres deep, it follows that pelagic coastal fish are generally epipelagic fish, inhabiting the...
(such as the smooth toadfish
Smooth toadfish
The smooth toadfish or smooth toado is a species of fish in the Tetraodontidae family of order Tetraodontiformes, found along Australia's eastern and southeast coast, from northern Queensland to South Australia and Tasmania...
) and seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s (such as the Atlantic Puffin
Atlantic Puffin
The Atlantic Puffin is a seabird species in the auk family. It is a pelagic bird that feeds primarily by diving for fish, but also eats other sea creatures, such as squid and crustaceans. Its most obvious characteristic during the breeding season is its brightly coloured bill...
) are often monitored for heavy metal bioaccumulation.
In some eutrophic aquatic systems, biodilution
Biodilution
Biodilution is the decrease in concentration of an element or pollutant with an increase in trophic level. This effect is primarily caused by the observed trend that an increase in algal biomass will reduce the overall concentration of a pollutant per cell, which ultimately contributes to a lower...
can occur. This trend is a decrease in a comtaminant with in increase in trophic level and is due to higher concentrations of algae and bacteria to "dilute" the concentration of the pollutant.
See also
- Bioconcentration factorBioconcentration factorBioconcentration factor is the concentration of a particular chemical in a biological tissue per concentration of that chemical in water surrounding that tissue...
- BiomagnificationBiomagnificationBiomagnification, also known as bioamplification or biological magnification, is the increase in concentration of a substance that occurs in a food chain as a consequence of:* Persistence...
(magnification of toxins with increasing trophic levelTrophic levelThe trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism...
) - Chelation therapyChelation therapyChelation therapy is the administration of chelating agents to remove heavy metals from the body. For the most common forms of heavy metal intoxication—those involving lead, arsenic or mercury—the standard of care in the United States dictates the use of dimercaptosuccinic acid...
- International POPs Elimination NetworkInternational POPs Elimination NetworkThe International POPs Elimination Network is a global network of NGOs dedicated to the common aim of eliminating persistent organic pollutants....
- List of environment topics
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.html
- http://www.pbtprofiler.net/criteria.asp