PARENT SESSION

MA9 Emerging Contaminants/Receptors
Room 12A/B, Level 4
8:00 AM - 12:00 PM, Monday, 10 November 2003
Chair: Gaylor, Michael ,

(086) Bioavailability of Sewage Sludge-Associated PBDEs to Earthworms.

Gaylor, M¹, Hale, R¹, ¹ Department of Environmental and Aquatic Animal Health, VIMS, Gloucester Point, VA 23062, Gloucester Point, VA, USA

ABSTRACT- Polybrominated diphenyl ethers (PBDEs) are used widely as flame-retardant additives and have been identified as emerging contaminants of concern. The Penta-BDE mixture, consisting of 70% tetra- and penta-substituted congeners, is used predominantly in polyurethane foam. Flame-retarded foam may consist of 10-30% w/w of this mixture. The Deca-BDE mixture, used mostly in thermoplastics and on textiles, constitutes 82% of the global PBDE market. However, the Penta-BDE constituents are the most widely distributed in the environment, the most bioaccumulative and appear to pose the greatest risks. Nonetheless, mechanisms to explain their introduction into the environment remain enigmatic. We have recently detected high levels of PBDEs in sewage sludge destined for land application (e.g. biosolids). Consequently, we hypothesize that land application of sewage sludge may be a significant conduit for dissemination of PBDEs to the environment. As such, PBDE bioavailability to soil organisms is of particular concern. To assess PBDE bioavailability, a 28-day ASTM earthworm bioaccumulation assay was conducted using Class A and Class B biosolids as well as penta-spiked artificial soil. Substantial PBDE accumulation (lipid basis) was observed in earthworms from all treatments. PBDE burdens generally increased as a function of time and sludge treatment. Differences in PBDE congener accumulation patterns were observed among treatments and were not typical of those reported in the literature for biota. Significant differences in biota-to-sediment accumulation factors (BSAFs) were observed between sludge treatments and penta-spiked artificial soil. Significant differences in BSAFs were also observed among PBDE congeners differing in degree of bromine substitution. These results suggest that PBDE bioavailability to earthworms exposed to biosolids is dependent upon several factors, including matrix properties, duration of exposure and bromine substitution pattern.

Key words: Earthworms, PBDEs, Sludge, Bioavailability