Environmental Fate
A summary of selected measured and predicted physical and chemical properties for HBCD is presented in Table 2.
Releases of HBCD to the Canadian environment due to the substance’s use as a flame retardant are expected to be diffuse and primarily to wastewater. Release to the soil could also occur through the application of sewage sludge as biosolids to agricultural and pasture lands. Releases may occur in both indoor and outdoor environments. Dust, food, serum and indoor air concentrations are presented in Tables 12-14.
Low water solubility (3.4 × 10-3 mg/L at 25°C; see Table 2), low vapour pressure (6.27 × 10-5 Pa at 21°C) and high partition coefficients (log Kow of 5.625 - 5.81, estimated log Koc of 5.097) suggest that HBCD released into the environment will be unlikely to partition into air and water, moving instead into the sediment and soil compartments. The high partition coefficients indicate that HBCD that is released into water is expected to adsorb to the organic fraction of suspended solids and sediments. If released to soil, HBCD is expected to be minimally mobile based on its estimated log Koc. Based on its low vapour pressure, the substance is not expected to volatilize from dry soil surfaces. The results of Level III fugacity modelling support the expectation that HBCD predominantly resides in soil or sediment, depending on the compartment of release. EPIWIN Suite III fugacity modelling predicted the following partitioning to air, water, soil and sediment: air 0.0007%, water 2.1%, soil 40%, and sediment 58% (EPIsuite 2007).