Bioaccumulation

Bioaccumulation is the accumulation of a substance in an organism due to uptake from the surrounding medium or via the food (see food chain). The term bioaccumulation is used both for the operation of the accumulating and for the identification of the instantaneous or reached equilibrium.

Bioaccumulation as a physiological process

Bioaccumulation can refer to a chemical compound (such as DDT), a chemical element ( as lead ) or an isotope (eg 90Sr, the radioactive strontium -90). Bioakkumulationen occur predominantly in substances which have a long biological half-life, which are neither surprising biochemically from or rebuilt yet rapidly excreted. If the concentration in the external medium (water, soil, food) back again, reduces the Bioakkumulationshöhe in the organism often gradually, with the reduction but with a time delay, and often is incomplete.

The phenomenon of bioaccumulation is not limited to pollutants, but also comes in essential biochemical compounds (eg vitamins ) and chemical elements (such as minerals ) before. An example of this is the bioaccumulation of vitamin A in the liver of predators, such as polar bears, which feed themselves from other predators (seals ).

Bioaccumulation

The relative amount of substance concentration in an organism compared to about the surrounding soil, the surrounding water or the food ingested is called bioaccumulation. This is a dimensionless quantity which represents the ratio of the concentrations in the two comparison compartments.

Specifically, the bioaccumulation is the ratio between the concentration in the body and a reference medium, such as the surrounding soil, the surrounding water or the food ingested. If a specific bioaccumulation factor specified, must also always the physical reference in the two compared compartments with be specified, because the concentrations should refer to the two compared compartments as possible in the same measure, such as on fresh weight, dry weight or volume. A volume- related bioaccumulation factor of 1000 with respect to water is then called about that the concentration in the organism is a thousand times greater than in the surrounding water when both comparison values ​​are relative to the respective volumes. Bio-accumulation can also be specified for individual organs as compared to a Referenzkompartiment. So show fat organs (such as liver ) are often higher concentrations and thus higher bio-accumulation of lipophilic environmental pollutants on a low-fat organs (eg muscles). Heavy metals often accumulate at specific binding sites in the body, such as lead (as Pb 2 ) by displacement of calcium (as Ca2 ) in the bone.

Biomagnify and bioconcentrate

In many cases, the bioaccumulation is conceptually divided into the bioconcentration, the pure absorption from the environment via body surfaces representing ( absorption through the gills is important for many aquatic organisms ) and in the biomagnification, which is the dietary intake. The different meanings of these two entry paths is sometimes difficult to determine in practice, since the routes of exposure often run in parallel is (eg in aquatic organisms) and the particular level of bioaccumulation in the organism in balance with the reduction or elimination of the substance from the body.

PBT

PBT (persistent, bioaccumulative and toxic contaminants ) can be defined as organic, persistent, bioaccumulative substances with toxic properties which express adverse effects on humans and the environment. PBT information can be specified in safety data sheets.