Bioaccumulation storage

The biochemistry of iron has just been discussed in some detail including the biochemical species involved, bioaccumulation, transport, storage, and toxicity- Space does not permit an extensive discussion of other elements of importance. However, a brief discussion will be presented here with a table summarizing what is currently known. 

A striking aspect of lead in the body is its very rapid transport to bone and storage there. Lead tends to undergo bioaccumulation in bone throughout life, and about 90% of the body burden of lead is in bone after long-term exposure. The half-life of lead in human bones is estimated to be around 20 years. Some workers exposed to lead in an industrial setting have as much as 500 mg of lead in their bones. Of the soft tissues, the liver and kidney tend to have somewhat elevated lead levels. 

Sale S (1980) Metabolism, uptake, storage and bioaccumulation. In Kimborough RD (ed) Halogenated Biphenyls, Terphenyls, Naphthalenes, Dibenzodioxins and Related Products. Elsevier/North Holland Biomedical Press, Amsterdam, p 81... 

Petroleum products are released into the environment inadvertently and intentionally at all stages of petroleum use, from exploration, production, transportation, storage, use and disposal (Figure 3). The more volatile components of oil partition preferentially into the atmosphere and hydrosphere, and to a lesser extent, the geosphere (e.g., sorption onto sediments), and biosphere (i.e., bioaccumulation), whereas the higher molecular... 

TCDD and other chlorinated dibenzo-J -di-oxins are released during the combustion of many polychlorophenols and also occur as contaminants in various chemicals such as the herbicide 2,4,5-trichlorophenoxyacetic acid. Most high-level exposure to 2,3,7,8-TCDD and other dioxins results from accidental releases or explosions in chemical plants or storage facilities for dioxin-containing chemicals. Because of the persistence of dioxin congeners in the environment and their potential for bioaccumulation, exposure may occur via the soil, air (especially when dioxins occur as combustion products), or water. When bound to components of the soil, the health hazard from 2,3,7,8-TCDD is reduced compared to ingestion of the pure compound. However, its bioavailability varies with the specific media in which it occurs. 

Bioaccumulation can be estimated by a kinetic model. In kinetic models (sometimes called physiological models or physiologically based pharmacokinetic models), consideration is given to the dynamics of ingestion, internal transport, storage, metabolic transformation, and excretion processes that occur in each type of organism for each type of chemical. In kinetic models,... 

Safe S. 1980. Metabolism, uptake, storage and bioaccumulation of halogenated aromatic pollutants. 

Xenobiotics enter in the bloodstream, following one of the described absorption routes, are distributed into the body and undertaken by different organs. It is possible that a part of the xenobiotics distributed into the body may be stored in tissues or even in the blood. A word commonly used to refer to storage of a pollutant at higher levels than those found in the environment is bioaccumulation, for example, PAHs, PCBs, dioxins and some organometallic forms of metals bioaccumulate in fat, fluoride and lead in bones etc. Sometimes biomagnification takes place, as a bioaccumulation process within the trophic chain, in indirect relationship with biota. 

Mildly toxic by ingestion the oral median lethal doses in all experimental animals were >5000 mg/kg however, produced moderate to severe effects when administered intravenously toxic properties are somewhat similar to those of DDT susceptible to storage in fat also bioaccumulative a teratogenic substance sufficient evidence of carcinogenicity in mice, but inadequate evidence in other animals cancer-causing effects in human unknown. 

Bioaccumulation is the critical process by which xenobiotics can influence the living species in the aquatic ecosystems. This process can be divided into two types one involving bioconcentration, and the other biomagnification, which is more complex. Bioconcentration refers to an increase in the concentration of a chemical in the organism over a period of time compared with the chemical s concentration in the aqueous phase and is a net result of uptake, storage and elimination. The bioconcentration factor (BCF) is defined as the ratio of the concentration of a chemical in an aquatic organism to that in the aqueous... 

Most chemical toxicants are biotransformed and eliminated from the body in urine or bile however, some xenobiotics are not amenable to these transformations—that is, the body s enzyme systems are ineffective in transforming these compounds to more polar forms. Since these compounds are often very lipid soluble and cannot be quickly eliminated, the body stores them in our fat tissues throughout the body—a process known as bioaccumulation. In order for bioaccumulation to occur, a chemical toxicant must be absorbed faster than it is eliminated. These chemical toxicants are stored in the body s fat or lipids until a dynamic state is reached where the rates of absorption and elimination become about the same. The concentrations of these xenobiotics in fat tissues can be estimated from concentrations in blood that normally carries a small amount of circulating lipid, as reported in Incident 4.3.2.I. (See also in Section 4.2.1, Chemical Connection 4.2.1.1 Solubility, Storage, and Elimination.)... 

The controlled release of these nanoparticles is important for long-term storage of foods or for imparting spedfic desirable characteristics, such as flavour, to a food system (Lagaron, 2011 Sorrentino et al 2007). However, the available literature suggests that many uncertainties remain about nanomaterials, including their potential for bioaccumulation and human health risks. More studies are therefore required to ensure that nanomaterials are not a concern to human health. 

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