Hexabromocyclododecane

Short-term toxicity to fish

Description of key information

The following information is available for the short-term toxicity to fish endpoint:
Graves, W. C. and Swigert, J. P. (1997). Hexabromocyclododecane (HBCD): A 96-hour flow-through acute toxicity test with the Rainbow Trout (Oncorhynchus mykiss). Report no.: 439A-101.Report date: 1997-06-03.
Anon (1978). The acute toxicity of HBCD to the Bluegill Sunfish, Lepomis macrochirus Rafinesque. Report no.: Proj. No. 11506-03-77. Report date: 1978-10-03.
Ronisz, D., Farmen Finne, E., Karlsson, H. and Förlin, L. (2004). Effects of the brominated flame retardants hexabromocyclododecane (HBCDD), and tetrabromobisphenol A (TBBPA), on hepatic enzymes and other biomarkers in juvenile rainbow trout and feral eelpout. Aquatic Toxicology (2004), Vol. 69, pp.229-245.
Graves (1997) was selected as the key study for the endpoint based upon the reliability score of according to the criteria of Klimisch et al., 1997). Anon (1978) and Ronsiz et al. (2004) were allocated a reliability score of 3 and 4 respectively according to the same criteria.

Additional information

An early dongle study reported the 96 hour LC₅₀ of HBCDD in bluegill sunfish as >100 mg/L, the highest dose tested.

In a guideline/GLP-compliant study, HBCDD was not acutely toxic to rainbow trout at the limit of the gamma stereoisomer’s solubility. HBCDD’s 96 hour LC₅₀, no mortality concentration and NOEC were all greater than the gamma stereoisomer’s water solubility. The highest nominal dose tested was twice that water solubility. Nominal test concentrations were 0, 1.5, 2.2, 3.2, 4.6 and 6.8 µg/L and corresponded to mean measured concentrations (HPLC with UV/VIS detector) of 0, 0.75, 1.5, 2.3, 2.3 and 2.5 µg/L, respectively (Graves et al., 1997). A composite of three manufacturers' commercial products was used as test substance in this study. The dose levels in the study were based on the water solubility of HBCD (approximately 3.4 µg/L), and determined via quantiation on the gamma diastereomer. The alpha and beta diastereomers were not quantifiable at HBCDD test levels based on the water solubility of the gamma diasteromer. Thus, the HBCDD commercial product was not acutely toxic to rainbow trout at nominal concentrations of 6.8 µg/L. Correcting for content of the gamma diasteromer, the 96 hour LC₅₀ in rainbow trout was >8.5 µg/L. The lack of toxicity is consistent with results from the early non GLP study in sunfish.

Single or two intraperitoneal injections of 50 or 500 mg HBCDD/kg to juvenile rainbow apparently did not induce mortality over a 28 day period. A single IP injection of 50 or 500 mg/kg did not alter the liver to body weight ratio when tested at 5 days post-injection. Induction of hepatic glutathione reductase, catalase, EROD or GST was not observed at 5 days. Similarly no effects were seen in eelpout (a marine species) at either dose when examined at 5 days post-injection. The test substance was a commercial HBCDD product. The lack of toxicity in this study at doses of 50 and 500 mg/kg injected IP further supports that HBCDD is not toxic via administration in water at concentrations approximating the water solubility of the gamma diasteromer or when substantially higher concentrations (up to 100 mg/L) are added to water.

Thus HBCDD was not acutely toxic when tested in freshwater and marine fish species.