Biomagnification Bioaccumulation

Most methods for experimental BCF determinations represent an assessment of the potential for accumulation. They do not account for specific environmental conditions, such as diflferences in the species exposed or the environmental bioavailability of the chemicals. The tests generally use fish as a model organism to serve as a predictor for bioconcentration in other aquatic species as well, and for bioaccumulation/biomagnification along aquatic foodwebs. Test guidelines for BCF in fish are available (e.g. OECD, 1981a), where the fish are exposed to the chemicals and from the concentrations in fish and water the BCF is obtained. The tests vary with respect to ... 

Health risks associated with PFASs are not yet well established however the assessment of potential risks is the subject of numerous studies [151—153]. Knovm or suspected risks include chronic toxicity, carcinogenic activity, endocrine effects, and bioaccumulation—biomagnification. PFASs are included in the National Health and Nutrition Examination Survey (NHANES) conducted by the Centers for Disease Control and Prevention (CDC) [154], and the National Toxicology Program has included various PFASs in their assessment of toxicity, carcinogenicity, and persistence in human blood [155]. 

Biomagnification along terrestrial food chains is principally due to bioaccumulation from food, the principal source of most pollutants (Walker 1990b). In a few instances, the major route of uptake may be from air, from contact with contaminated surfaces, or from drinking water. The bioaccumulation factor (BAF) of a chemical is given by the following equation ... 

Biomagnification along aquatic food chains may be the consequence of bioconcentration as well as bioaccumulation. Aquatic vertebrates and invertebrates can absorb pollutants from ambient water bottom feeders can take up pollutants from sediments. The bioconcentration factor (BCF) of a chemical absorbed directly from water is defined as... 

PAHs can be bioconcentrated or bioaccumulated by certain aquatic invertebrates low in the food chain that lack the capacity for effective biotransformation (Walker and Livingstone 1992). Mollusks and Daphnia spp. are examples of organisms that readily bioconcentrate PAH. On the other hand, fish and other aquatic vertebrates readily biotransform PAH so, biomagnification does not extend up the food chain as it does in the case of persistent polychlorinated compounds. As noted earlier, P450-based monooxygenases are not well represented in mollusks and many other aquatic invertebrates (see Chapter 4, Section 4.2) so, this observation is not surprising. Oxidation catalyzed by P450 is the principal (perhaps the only) effective mechanism of primary metabolism of PAH. 

Bowles KC, Apte SC, Maher WA, Kawei M, Smith R. 2001. Bioaccumulation and biomagnification of mercury in Lake Murray, Papua New Guinea. Can J Fish Aquat Sci 58 888-897. 

Mercury (Hg) can occur in a large number of physical and chemical forms with a variety of properties, thus determining complex distribution, bioavailability, and toxicity patterns [1]. The most important chemical forms are elemental Hg (Hg°), ionic Hg (Hg2+ and Hg22+), and alkylmercury compounds. Because of their capability to permeate through biological membranes and to bioaccumulate and to biomagnificate through the trophic chain, alkylmercury compounds are the most toxic mercury species found in the aquatic environment [2]. 

Wren, C.D., H.R. MacCrimmon, and B.R. Loescher. 1983. Examination of bioaccumulation and biomagnification of metals in a precambrian shield lake. Water Air Soil Pollut. 19 277-292. 

Endrin released to water will adsorb to sediments or bioaccumulate in fish and other aquatic organisms. Both bioaccumulation and biomagnification of endrin were reported to occur in an aquatic laboratory microcosm system (Metcalf et al. 1973). In terrestrial ecosystems, endrin transformation products (endrin ketone, endrin aldehyde, and endrin alcohol) have been measured in plants grown on endrin-treated soil (Beall et al. 1972 Nash and Harris 1973). 

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