Bioaccumulation

Bioaccumulation is the gradual accumulation of substances, such as pesticides, or other chemicals in an organism.[1] Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.[2] Bioaccumulation, for example in fish, can be predicted by models.[3][4] Hypotheses for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data.[5] Biotransformation can strongly modify bioaccumulation of chemicals in an organism.[6]

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.).[1]

Examples

An example of poisoning in the workplace can be seen from the phrase "mad as a hatter" (18th and 19th century England). The process for stiffening the felt used in making hats more than a hundred years ago involved mercury, which forms organic species such as methylmercury, which is lipid-soluble, and tends to accumulate in the brain, resulting in mercury poisoning. Other lipid-soluble (fat-soluble) poisons include tetraethyllead 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. This can kill an Organism.

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 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. 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 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 of carnivores should not be eaten, but Arctic explorers have suffered Hypervitaminosis A from eating the livers of bears (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 seabirds (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 contaminant with an increase in trophic level and is due to higher concentrations of algae and bacteria to "dilute" the concentration of the pollutant.

See also

References

  1. ^ a b Alexander (1999). "Bioaccumulation, bioconcentration, biomagnification". Environmental Geology. Encyclopedia of Earth Science. pp. 43–44. doi:10.1007/1-4020-4494-1_31. ISBN 978-0-412-74050-3.
  2. ^ Bioaccumulation of Marine Pollutants [and Discussion], by G. W. Bryan, M. Waldichuk, R. J. Pentreath and Ann Darracott Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences.
  3. ^ Stadnicka, J; Schirmer, K; Ashauer, R (2012). Predicting Concentrations of Organic Chemicals in Fish by Using Toxicokinetic Models. Environ. Sci. Technol. doi:10.1021/es2043728
  4. ^ Otero-Muras, I; Franco-Uria, A; Alonso, A A; Balsa-Canto, E (2010). Dynamic multi-compartmental modelling of metal bioaccumulation in fish. Environ. Modell. Soft. DOI:10.1016/j.envsoft.2009.08.009
  5. ^ Jon Arnot et al. Molecular size cutoff criteria for screening bioaccumulation potential: Fact or fiction? DOI:10.1897/IEAM 2009-051.1.
  6. ^ Ashauer, R; Hintermeister, A; O'Connor, I; Elumelu, M, et al. (2012). Significance of Xenobiotic Metabolism for Bioaccumulation Kinetics of Organic Chemicals in Gammarus pulex. Environ. Sci. Technol. doi:10.1021/es204611h

External links

Bioconcentration

Bioconcentration is the accumulation of a chemical in or on an organism when the source of chemical is solely water. Bioconcentration is a term that was created for use in the field of aquatic toxicology. Bioconcentration can also be defined as the process by which a chemical concentration in an aquatic organism exceeds that in water as a result of exposure to a waterborne chemical.There are several ways in which to measure and assess bioaccumulation and bioconcentration. These include: octanol-water partition coefficients (KOW), bioconcentration factors (BCF), bioaccumulation factors (BAF) and biota-sediment accumulation factor (BSAF). Each of these can be calculated using either empirical data or measurements as well as from mathematical models. One of these mathematical models is a fugacity-based BCF model developed by Don Mackay.Bioconcentration factor can also be expressed as the ratio of the concentration of a chemical in an organism to the concentration of the chemical in the surrounding environment. The BCF is a measure of the extent of chemical sharing between an organism and the surrounding environment.In surface water, the BCF is the ratio of a chemical's concentration in an organism to the chemical's aqueous concentration. BCF is often expressed in units of liter per kilogram (ratio of mg of chemical per kg of organism to mg of chemical per liter of water). BCF can simply be an observed ratio, or it can be the prediction of a partitioning model. A partitioning model is based on assumptions that chemicals partition between water and aquatic organisms as well as the idea that chemical equilibrium exists between the organisms and the aquatic environment in which it is found

Biomagnification

Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a result of:

Persistence – where the substance cannot be broken down by environmental processes

Food chain energetics – where the substance's 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 work their way into lakes, rivers and the ocean, and then move up the food chain in progressively greater concentrations as they are incorporated into the diet of aquatic organisms such as zooplankton, which in turn are eaten perhaps by fish, which then may be eaten by bigger fish, large birds, animals, or humans. The substances become increasingly 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.

Biosorption

Biosorption is a physiochemical process that occurs naturally in certain biomass which allows it to passively concentrate and bind contaminants onto its cellular structure. Biosorption can be defined as the ability of biological materials to accumulate heavy

metals from wastewater through metabolically mediated or physico-chemical pathways of uptake. Though using biomass in environmental cleanup has been in practice for a while, scientists and engineers are hoping this phenomenon will provide an economical alternative for removing toxic heavy metals from industrial wastewater and aid in environmental remediation.

Ciguatoxin

Ciguatoxins are a class of toxic polycyclic polyethers found in fish that cause ciguatera.

There are several different chemicals in this class. "CTX" is often used as an abbreviation.

CID 5311333 from PubChem - Ciguatoxin 1

CID 6441260 from PubChem - Ciguatoxin 2

CID 6444399 from PubChem - Ciguatoxin 3

CID 6450530 from PubChem - Ciguatoxin 4B (Gambiertoxin 4b)

Creosote

Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood or fossil fuel. They are typically used as preservatives or antiseptics.Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties, see image). Samples may be commonly found inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke. Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived from Greek, Modern κρέας (kreas), meaning 'meat', and σωτήρ (sōtēr), meaning 'preserver'.The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood; coal-tar creosote was also formerly used as an escharotic, to burn malignant skin tissue, and in dentistry, to prevent necrosis, before its carcinogenic properties became known. The wood-tar variety has been used for meat preservation, ship treatment, and such medical purposes as an anaesthetic, antiseptic, astringent, expectorant, and laxative, though these have mostly been replaced by modern formulations.Varieties of creosote have also been made from both oil shale and petroleum, and are known as oil-tar creosote when derived from oil tar, and as water-gas-tar creosote when derived from the tar of water gas. Creosote also has been made from pre-coal formations such as lignite, yielding lignite-tar creosote, and peat, yielding peat-tar creosote.

Desulfovibrio

Desulfovibrio is a genus of Gram-negative sulfate-reducing bacteria. Desulfovibrio species are commonly found in aquatic environments with high levels of organic material, as well as in water-logged soils, and form major community members of extreme oligotrophic habitats such as deep granitic fractured rock aquifers.

Like other sulfate-reducing bacteria, Desulfovibrio was long considered to be obligately anaerobic. This is not strictly correct: while growth may be limited, these bacteria can survive in O2-rich environments. These types of bacteria are known as aerotolerant.

Some Desulfovibrio species have in recent years been shown to have bioremediation potential for toxic radionuclides such as uranium by a reductive bioaccumulation process.

Environmental toxicology

Environmental toxicology is a multidisciplinary field of science concerned with the study of the harmful effects of various chemical, biological and physical agents on living organisms. Ecotoxicology is a subdiscipline of environmental toxicology concerned with studying the harmful effects of toxicants at the population and ecosystem levels.

Rachel Carson is considered the mother of environmental toxicology, as she made it a distinct field within toxicology in 1962 with the publication of her book Silent Spring, which covered the effects of uncontrolled pesticide use. Carson's book was based extensively on a series of reports by Lucille Farrier Stickel on the ecological effects of the pesticide DDT.Organisms can be exposed to various kinds of toxicants at any life cycle stage, some of which are more sensitive than others. Toxicity can also vary with the organism's placement within its food web. Bioaccumulation occurs when an organism stores toxicants in fatty tissues, which may eventually establish a trophic cascade and the biomagnification of specific toxicants. Biodegradation releases carbon dioxide and water as by-products into the environment. This process is typically limited in areas affected by environmental toxicants.

Harmful effects of such chemical and biological agents as toxicants from pollutants, insecticides, pesticides, and fertilizers can affect an organism and its community by reducing its species diversity and abundance. Such changes in population dynamics affect the ecosystem by reducing its productivity and stability.

Although legislation implemented since the early 1970s had intended to minimize harmful effects of environmental toxicants upon all species, McCarty (2013) has warned that "longstanding limitations in the implementation of the simple conceptual model that is the basis of current aquatic toxicity testing protocols" may lead to an impending environmental toxicology "dark age".

Filter feeder

Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish (including some sharks). Some birds, such as flamingos and certain species of duck, are also filter feeders. Filter feeders can play an important role in clarifying water, and are therefore considered ecosystem engineers. They are also important in bioaccumulation and, as a result, as indicator organisms.

Ipomoea carnea

Ipomoea carnea, the pink morning glory, is a species of morning glory. This flowering plant has heart-shaped leaves that are a rich green and 6–9 inches (15–23 cm) long. It can be easily grown from seeds which are toxic and it can be hazardous to cattle; the toxicity is related to the swainsonine produced by endophytes and to bioaccumulation of selenium species in leaves but mostly in seedsThe stem of I. carnea can be used for making paper. The plant is also of medicinal value. It contains a component identical to marsilin, a sedative and anticonvulsant. A glycosidic saponin has also been purified from I. carnea with anticarcinogenic and oxytoxic properties.One selection of I. carnea, 'Inducer', has been used as a rootstock for inducing flowering of sweetpotato cultivars which otherwise prove reticent to produce flowers.Another common name is "bush morning glory", but particularly in temperate North America, that usually refers to I. leptophylla.

In Brazil, I. carnea (in addition to other common names) is known as canudo-de-pito, literally "pipe-cane", as its hollow stems were used to make tubes for tobacco pipes. It thus became the namesake of Canudos, a religious community in the sertão of Bahia, over which the War of Canudos was fought 1893–1897.

Macoma nasuta

Macoma nasuta, commonly known as the bent-nosed clam, is a species of bivalve found along the Pacific Ocean coast of North America. It is about 6 cm (2.4 in) long. It is often found buried in sands of 10–20 cm (3.9–7.9 in) in depth. This rounded clam has no radial ribs. Archaeological data supports the use of this species by Native Americans such as the Chumash peoples of central California.

Mesopelagic zone

The mesopelagic zone (Greek μέσον, middle) (also known as the middle pelagic or twilight zone) is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins at the depth where only 1% of incident light reaches and ends where there is no light; the depths of this zone are between approximately 200 to 1000 meters (~660 to 3300 feet) below the ocean surface. It hosts a diverse biological community that includes bristlemouths, blobfish, bioluminescent jellyfish, giant squid, and a myriad of other unique organisms adapted to live in a low-light environment. It has long captivated the imagination of scientist, artists and writers; deep sea creatures are prominent in popular culture, particularly as horror movie villains.

Mirex

Mirex is an organochloride that was commercialized as an insecticide and later banned because of its impact on the environment. This white crystalline odorless solid is a derivative of cyclopentadiene. It was popularized to control fire ants but by virtue of its chemical robustness and lipophilicity it was recognized as a bioaccumulative pollutant. The spread of the red imported fire ant was encouraged by the use of Mirex, which also kills native ants that are highly competitive with the fire ants. The United States Environmental Protection Agency prohibited its use in 1976. It is prohibited by the Stockholm Convention on Persistent Organic Pollutants.

Organofluorine chemistry

Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents.

Particle (ecology)

In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater. However, they eventually settle (rate determined by Stokes' law) and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei (CCN). Many organisms filter particles out of the water with unique filtration mechanisms (filter feeders). Particles are often associated with high loads of toxins which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen and can cause the water to become hypoxic.

Persistent, bioaccumulative and toxic substances

Persistent, bioaccumulative and toxic substances (PBTs) are a class of compounds that have high resistance to degradation from abiotic and biotic factors, high mobility in the environment and high toxicity. Because of these factors PBTs have been observed to have a high order of bioaccumulation and biomagnification, very long retention times in various media, and widespread distribution across the globe. Majority of PBTs in the environment are either created through industry or are unintentional byproducts.

Persistent organic pollutant

Persistent organic pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of their persistence, POPs bioaccumulate with potential adverse impacts on human health and the environment. The effect of POPs on human and environmental health was discussed, with intention to eliminate or severely restrict their production, by the international community at the Stockholm Convention on Persistent Organic Pollutants in 2001.

Many POPs are currently or were in the past used as pesticides, solvents, pharmaceuticals, and industrial chemicals. Although some POPs arise naturally, for example volcanoes and various biosynthetic pathways, most are man-made via total synthesis.

Tributyltin

Tributyltin (TBT) is an umbrella term for a class of organotin compounds which contain the (C4H9)3Sn group, with a prominent example being tributyltin oxide. For 40 years TBT was used as a biocide in anti-fouling paint, commonly known as bottom paint, applied to the hulls of ocean going vessels. Bottom paint improves ship performance and durability as it reduces the rate of biofouling (the growth of organisms on the ship's hull). The TBT slowly leaches out into the marine environment where it is highly toxic toward nontarget organisms. After it led to collapse of local populations of organisms, TBT was banned.

Triclocarban

Triclocarban is an antibacterial agent common in personal care products like soaps and lotions as well as in the medical field, for which it was originally developed. Studies on its antibacterial qualities and mechanisms are growing. Research suggests that it is similar in its mechanism to triclosan and is effective in fighting infections by targeting the growth of bacteria such as Staphylococcus aureus. Additional research seeks to understand its potential for causing antibacterial resistance and its effects on organismal and environmental health.

Triclosan

Triclosan (sometimes abbreviated as TCS) is an antibacterial and antifungal agent present in some consumer products, including toothpaste, soaps, detergents, toys, and surgical cleaning treatments. It is similar in its uses and mechanism of action to triclocarban. Its efficacy as an antimicrobial agent, the risk of antimicrobial resistance, and its possible role in disrupted hormonal development remains controversial. Additional research seeks to understand its potential effects on organisms and environmental health.

Triclosan was developed in the 1960s. In September 2016, the FDA announced that effective September 2017, it would prohibit the sale of "consumer antiseptic washes" containing triclosan or 18 other ingredients marketed as antimicrobials due to FDA findings of the lack of efficacy in these products.

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