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EC number: 247-148-4
CAS number: 25637-99-4
Davis, J. W., Gonsior, S. J. and Marty, G. T. (2003b). Evaluation of aerobic and anaerobic transformation of Hexabromocyclododecane in aquatic sediment systems.Report no.: 021081. Report date: 2003-03-05.Davis, J. W., Gonsior, S. J., Markham, D. A. and Marty, G. T. (2004). Investigation of the biodegradation of [14C]Hexabromocyclododecane in sludge, sediment and soil. Report no.: 031178. Report date: 2004-11-30.Davis, J. W., Gonsior, S., Marty, G. and Ariano, J. (2005). The transformation of hexabromocyclododecane in aerobic and anaerobic soils and aquatic sediments. Water Research (2005) Vol. 39, pp. 1075-1084.Davis, J. W., Gonsior, S. J., Markham, D. A., Friedrich, U., Hunziker, R. W. and Ariano, J. M. (2006). Biodegradation and Product Identification of [14C]Hexabromocyclododecane in Wastewater Sludge and Freshwater Aquatic Sediment. Environ. Sci. Technol. (2006) Vol. 40, pp. 5395-5401.
In studies conducted according to OECD Guidelines 307 and 308 (aerobic
and anaerobic transformation in soil and sediment respectively), HBCDD
was tested at concentrations ranging from approximately 10 to 80 ng/g
dry weight (Davis et al., 2005; 2003). Using LC-MS, HBCDD loss was
observed in all with faster rates under anaerobic conditions.
Biologically mediated transformation accelerated the rate loss of HBCDD
compared to biologically inhibited (i.e. autoclaved) soils and
sediments. Biotransformation half-lives were 63 and 6.9 days in the
aerobic and anaerobic soils, respectively, and 11 to 32 days and 1.1 to
1.5 days in aerobic and anaerobic sediments. Brominated degradation
products were not detected in any of the soils or sediments during the
study. In the 2003 study only the γ-isomer could be analytically
In a further investigation with 14C-HBCDD, the formation and
identification of degradants were assessed in activated digester sludge,
river sediment and surface soil under aerobic and anaerobic conditions.
At concentrations of 3-5 mg/kg to generate sufficient products for
identification (Davis et al., 2004; 2006 ES&T), HPLC with radiochemical
detection, HPLC-APPI-MS and GC-EI-MS was utilised. Substantial
biological transformation was observed in the anaerobic digester sludge
and in aerobic and anaerobic freshwater sediment. No degradation was
noted in aerobic soil. In sludge and sediment, degradation of each of
the three diastereomers occurred with little difference in rates.
Formation of the following three products was observed in the sludge and
sediments: tetrabromocyclododecane, dibromocyclododecandiene and
The EU Risk Assessment Report has used the Davis et al. (2004) sediment
study to calculate half-lives which is not considered to be correct as
the concentrations in this study were chosen at rates much higher than
are adequate for a determination of degradation kinetics in order to be
able to identify metabolites. The design of this study is not considered
suitable for the determination of half-lives. Much longer half-lives are
therefore likely due to the non-availability of HBCDD to the
microorganisms in this study.
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