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(P271) Review of Uptake and Depuration Kinetics for Metals in Aquatic Biota and Implications for Hazard Classification.
DeForest, David*,1, Brix, Kevin2, Toll, John1, Adams, William3, 1 Parametrix, Inc., Kirkland, WA, USA2 EcoTox, Newport, OR, USA3 Kennecott Utah Copper, Magna, UT, USA
ABSTRACT- Bioaccumulation, along with toxicity and persistence, is traditionally an important property in assessing the hazard potential of a chemical in the environment. Bioaccumulation potential is typically defined using bioconcentration factors (BCFs), bioaccumulation factors (BAFs), and biota-sediment accumulation factors (BSAFs). These factors were initially used to describe the bioccumulation potential of organics, but have since been applied to metals as well. Recently, the applicability of these factors for describing the hazard potential of metals has been called into question. This is largely driven by the essentiality of many metals to aquatic biota and/or natural storage and regulatory mechanisms that many organisms have developed to internally sequester non-essential metals from exposure to background concentrations. These factors limit the use of individual BCFs, BAFs, or BSAFs for hazard identification because they often naturally exceed traditional regulatory hazard identification values and are not constant across a range of exposure concentrations (i.e., an inverse relationship exists between exposure and BCF/BAF/BSAF). Using data on uptake and depuration kinetics for essential (e.g., Cu, Zn) and non-essential (e.g., Cd, Pb) metals, the mechanistic basis for this inverse relationship is evaluated and compared to bioaccumulation kinetics for organics. Overall, the mechanistic data demonstrate that metals are bioaccumulated much differently than organics, and BCF/BAF/BSAFs for these two classes of chemicals cannot be interpreted the same with regard to their hazard potential in the environment.
Key words: metals, bioaccumulation, hazard classification
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