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Environmental fate & pathways

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HBCDD is predicted to partition in the environment to soil and sediment (approximately 98%) where it will bind extensively to organic carbon (estimated Kocsoil 1.25 x 105) and to be essentially immobile in soil. Based on a release of 1,000 kg/hr to air, water and soil, the predicted partitioning is: air 0.0007%, water 2.1%, soil 40% and sediment (58%) (Level III Fugacity Model, EPIWIN v3.04, Syracuse Research Corporation). Aerobic and anaerobic biodegradation in soil and sediment has been demonstrated in microcosms. Half-lives of 7 to 63 days (soil) and 1 to 32 days (sediment) has been demonstrated with the shortest half-lives in anaerobic systems. HBCDD is expected to partition from water to organic matter (biomass to water partition coefficient 1 x 107) (EPIWIN v3.04 Syracuse Research Corporation). Sewage treatment plants are predicted to remove HBCDD from the influent to a high degree (94% removal) via partitioning to sludge. Aerobic biodegradation in the treatment plant is not expected. Degradation in the anaerobic digester of treatment plants is expected.