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Revisiting Bioaccumulation Criteria
Citation:
GOBAS, F., W. DE WOLF, E. VERBRUGGEN, K. PLOTZKE, AND L. P. BURKHARD. Revisiting Bioaccumulation Criteria. Presented at SETAC Annual Meeting, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs.
Description:
The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined a B(ioaccumulative) substance as a substance which biomagnifies in the food-web, i.e. increases in normalized concentration (or fugacity) with increasing trophic position. It was concluded that the most relevant B criterion is the TMF (Trophic Magnification Factor, and that the most conclusive evidence to demonstrate that a chemical substance biomagnifies is a TMF > 1. It is crucial that in the characterization of the TMF both aquatic and terrestrial food-webs are considered. In absence of data on the TMF, the BMF (i.e. Biomagnification Factor) is an indicator of the chemical’s potential to biomagnify through the food chain. While the BCF is generally used to characterize B substances, the BCF is not a good surrogate for BMF or TMF in terrestrial food-webs. The BCF is an acceptable surrogate for the BMF or TMF in aquatic food-webs if the route of exposure (water vs. diet) does not affect biotransformation rate of the chemical in the organisms and if bioavailability issues are not introducing significant experimental artefacts. Because empirical data regarding the TMF and BMF are available for few chemicals that are considered in large scale chemical evaluation initiatives, it is important to propose surrogate criteria to identify potentially biomagnifying substances. Surrogate criteria suggested are log Kow or log Koa, potentially supplemented with whole organism in-vivo biotransformation rate constant (kM). Furthermore screening assessments of chemicals for B can benefit from the use of food-web bioaccumulation models.