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(251) A practical testing approach for assessing the bioaccumulation potential of poorly water soluble organic chemicals. Parkerton, T.1, Letkinski, D.1, Febbo, E.1, Davi, R.1, Dzamba, C.1, Connelly, M.1, Christensen, K.1, Peterson, D.1, 1 ABSTRACT- Bioaccumulation is increasingly an important consideration in the environmental risk assessment of chemicals since this process 1) provides the link between environmental exposure and mode-of-action based residue-effect relationships in ecotoxicology; 2) dictates the extent to which humans may be indirectly exposed via the foodchain. Bioaccumulation is also a critical consideration in a number of international and regional regulatory prioritization schemes for chemical assessment / management. The laboratory derived bioconcentration factor (BCF) in fish is often used as the initial benchmark for characterizing the bioaccumulation potential of substances. However, this test is quite costly and often practically difficult or impossible to conduct for biodegradable, poorly water soluble chemicals since aqueous exposure concentrations cannot be mantained at constant or detectable concentrations during the uptake phase of the test. Due to lack of reliable BCF data, Log Kow is often used as a surrogate to characterize bioaccumulation potential. However, since the mitigating role of biotransformation is not considered, this default approach often exagerates the true bioaccumulation potential. To provide relevant experimental data that can be used to overcome default assumptions and ensure priorities are not misdirected, a cost-effective dietary bioaccumulation test protocol has been applied to a variety of petrochemicals. Results from this test provide an estimate of the dietary biomagnification factor (BMF) which is defined as the ratio of the concentration in fish to that in the administered diet at steady-state. BMFs for selected hydrocarbons, alcohols and phthalate esters are compared to literature BMFs for other chemical classes known to exhibit a high bioaccumulation potential. It is suggested that a dietary bioaccumulation test provides a pragmatic alternative to the aqueous bioconcentration test for correctly characterizing the bioaccumulation potential of hydrophobic petrochemicals. Key words: Bioaccumulation, Biotransformation, Petrochemicals, Testing Methodology |
