Hexabromocyclododecane

Bioaccumulation: aquatic / sediment

Description of key information

The following information is available for the bioaccumulation/bioconcentration endpoint:
Drottar, K. R. and Krueger, H. O. (2000). Hexabromocyclododecane (HBCD): A flow-through bioconcetration test with rainbow trout (Oncorhynchus mykiss). Report no.: WIL 439A-111. Report date: 2000-08-10.
Veith, G.D., deFoe, D.L. and Bergstedt, B.V. (1979) Measuring and estimating the bioconcentration factor of chemicals in fish. J. Fish. Res. Board Can. 36: 1040-1048.
Zeger, B. N., Mets, A., van Bommel, R., Minkenberg, C., Hamers, T., Kamstra, J. H., Learmont, J. A., Vasquez, B. S., Pierce, G., Ried, B., Patterson, T., Rogan, E., Murphy, S., Addink, M., Hartmann, M. G., Smeenk, C., Dabin, W., Ridoux, V., González, A. F., López, A., Jauniaux, T. and Boon, J. P. (2004). Stereo-isomer specific bioaccumulation of hexabromocyclododecane (HBCD) in marine mammals. Third International Workshop on Brominated Flameretardants (BFR) (2004) pp.411-414.
Drottar and Krueger (2000) was selected as the key study based upon reliability and depth of reporting. The study was conducted according to EPA OPPTS 850.1730 and OECD Guideline 305, no deviations from these guidelines are reported in the study report. The study was conducted according to GLP standards and with full reporting of methodologies and results. Drottar and Krueger (2000) was therefore allocated the reliability score of 1 according to the criteria of Klimisch et al. (1997).
Veith et al (1979) was performed in line with sound scientific principles but not in line with GLP. The study was therefore allocated a reliability score of 2 according to the criteria of Klimisch (1997).
Zeger et al. (2004) was conducted as a field study and no test guideline was available. No details of GLP conditions were given for analysis of samples and insufficient information was provided on methodologies. The study was therefore allocated a reliability score of 4 according to the criteria of Klimisch (1997).

Key value for chemical safety assessment

BCF (aquatic species):

8 974 dimensionless

Additional information

Drottar (2000) was conducted on Oncorhynchus mykiss (rainbow trout) at test concentrations of 0.34 and 3.4 µg/l (nominal) (0.18 and 1.8 µg/l measured) according to recognised testing guidelines. The exposure period was 35 days, test solutions were prepared by continuous-flow diluter and the study was conducted as a flow-through test. A depuration period of 35 days followed the exposure period.

The following BCF values were calculated for the study:

Conc. in environment / dose	Type	Value	Basis	Time of plateau	Calculation basis
0.18 µg/l	BCF	14039	edible fraction	35-d	kinetic
0.18 µg/l	BCF	30242	non-edible fraction	35-d	kinetic
0.18 µg/l	BCF	21940	whole body d. w.	35-d	kinetic
1.8 µg/l	BCF	4650	edible fraction	35-d	steady state
1.8 µg/l	BCF	12866	non-edible fraction	35-d	steady state
1.8 µg/l	BCF	8974	whole body d. w.	35-d	steady state

Depuration times were calculated as follows:

Elimination	Endpoint	Depuration time (DT)
yes	other: DT50 edible tissues	19 d
yes	other: DT50 non edible tissues	20 d
yes	other: DT50 whole fish	19 d

The whole body (dry weight) BCF value was chosen as the key value for this endpoint as it most adequately describes the likely bioconcentration of the substance into fish, and provides an indication of the possible exposure to higher predators through prey animals. As the 1.8 µg/l group attained a steady-state within the study period it was considered to be more reliable than the 0.18 µg/l group which did not attain a steady-state.

Veith et al. (1979) determined the BCF of HBCDD in fathead minnow following exposure of the animals to 6.2 µg HBCDD/L for 32 days at 25 ± 0.5ºC. Out of a exposed population of 30 fish, five were removed for analysis after 2, 4, 8, 16 and 32 days exposure. The steady-state BCF was determined to be 18100 (log BCF 4.26).

Zeger et al. (2004) was conducted as a field study on beached Phocena phocena (Harbour porpoises) and Common dolphins (Delphinus delphis). Beached animals were sampled for concentrations of HBCDD in individual tissues. The substance was found to be metabolised in marine mammals and may accumulate to "a certain degree" in lipid-rich tissues. These findings support the results of the key study.