Bioaccumulation, definition

US Geological Survey. 2013. Bioaccumulation - Definitions. Web page last updated... 

To indicate the transfer of chemicals in a biogeochemical food web, both bioaccumulation factors (BAFs) and bioconcentration factors (BCFs) are used. The following definitions can be applied (de Vries and Bakker, 1998a, 1998b) ... 

Definitions and Units of Model Parameters Used in the Benthic Bioaccumulation Model of Thomann (1991, 1992). 

The definition of bioconcentration has to be distinguished from the terms of indirect contamination such as biomagnification, bioaccumulation, and ecological magnification [12,19]. 

A9.2.3.4 The precise definitions of acute toxicity of an appropriate species, lack of rapid degradation and potential to bioaccumulate are detailed in Sections A9.3, A9.4 and A9.5 respectively. 

Multiple exposure studies may include obtaining information on possible enzymatic inhibition or induction effects as well as the possibility of bioaccumulation. In such studies, animals are dosed by gavage (or other appropriate route) for 14 days with one dose, usually the highest anticipated dose sufficient animals are used so that three data points are available at each blood sampling time. Blood samples are taken at multiple time points after dosing and analyzed for test chemical or metabolite. These results are compared to the results of the single- exposure definitive study to determine possible enzymatic inhibition or induction effects and bioaccumulation of the test chemical. 

Bioconcentration and bioaccumulation (in its more restricted definition) can operate together, and determining their precise contributions can be extremely difficult. For example, tributyl tin (TBT) is relatively soluble in water, so the dog whelk absorbs it across its gills and mantle tissue, but it can also absorb a significant proportion from its food (Section 7.5.1 Bryan et al. 1989 Langston 1996). Throughout this book bioaccumulation is used in its most general sense. 

The term bioaccumulation factor (BAF) is a coefficient used to quantify the net body burden of chemicals (given uptake, distribution, metabolism, and excretion rates) and is expressed as the ratio of the concentration of a compound in the organism (or normalized to the lipid weight of the organism) to the concentration in its food or, for benthic or soil invertebrates, in the sediment or soil [9] (also see Chapter 6). Although by definition, BAF is measured at steady state, due to the complex nature of multiplepathway exposure, steady-state measures of BAF are often difficult to obtain. 

Bioaccumulation in aquatic species is essentially bioconcentration plus uptake by any other process such as ingestion of food, and usually applies to field observations where the routes of exposure are not known. The quantitative definition again is the ratio of the concentrations of the chemical in the... 

It is well known that farmers use different types of insecticides to protect crops from insects. The more widely used insecticides are organophosphates, carbamates and organochlorides. Of these, organophosphates and carbamates are less persistent in the environment compared to the organochlorides (for example aldrin, dieldrin and DDT). Though the latter are definitely effective but they tend to bioaccumulate in many plant and animal species and incorporate into the food chain. Some of the insecticides are also responsible for the population decline" of beneficial insects and animals, such as honeybees, lacewings, mites, bald eagles etc. 

By virtue of their inertness and permanence in their desired applications, high performance pigments must definitely be considered persistenf. The idea of a non-persistent HPP is, in fact, unthinkable However, in recent years, the term Persistenf , together with the related terms, Bioaccumulative , and Toxic (or PBT), has... 

Chemicals, which are persistent, toxic and liable to bioaccumulation, are called PTBs. They have primarily local effects. Persistence is the evidence that the substances half-life is greater than two months in water and greater than sue months in soil or sediment. Toxicity is the potential to adversely affect human health and/or the environment. Bioaccumulation is the evidence that the Bio-Accumulation Factor (BAF) is greater than 5000. Up to 1995, there was no clear definition of which products belong to this class [394]. Heavy metals, such as mercury and POPs fall into this category. 

Fig. 16. Bioaccumulation factor (normalized to organism lipid and sediment organic carbon) as a function number of aromatic rings in PAHs. Mean and standard error of the mean BAFi c for PAHs consists of 2-6 aromatic rings. Each mean represents several PAHs and sediments (sites = 7 for amphipod = 5 for polychaete). [See Table 1 for PAHs and ring categories.] Polychaete (Armandia brevis) and amphipod (Rhepoxynius abronius) individuals were exposed to Raritan-Hudson estuary (New York) sediments for 10 d. See Appendix for BAFioc definition. (Data from Meador et al. 1995.)...

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