2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol

Long-term toxicity to aquatic invertebrates

Description of key information

21 d Daphnia study
70 d Saltwater mussel study
5 d Acartia tonsa study

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.38 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

17 µg/L

Additional information

The cladoceran Daphnia magna was exposed in a flow-through system for 21 days to concentrations of 14C-TBBPA ranging from 0.056 to 0.98 mg/L, according to procedures consistent with the requirements published in the US EPA Tetrabromobisphenol A Final Test Rule (1987). Measured endpoints included survival, reproduction, immobilization, and growth. After 21 days exposure, daphnid survival in all concentrations ranged from 95 to 100%, statistically comparable to the survival of pooled control organisms. Reproduction in the highest test concentration (0.98 mg/L TBBPA) was significantly less than the reproduction of control organisms (21 offspring per female in the highest test concentration compared to 60 offspring/female in the pooled control organisms). Based on the mean MATC value reported (0.54 mg/L for reproductive endpoints), the NOEC for daphnids exposed to TBBPA was estimated to be 0.38 mg/L (e. g. the MATC divided by the square root of 2).

A flow-through toxicity study has also been carried out with the common mussel (Mytilus edulis) using an ultrasonicated solution of TBBPA in seawater with dimethylformamide as solvent. The total duration of the test was 70 days, and measured endpoints included growth and mortality. The 70-day NOEC for growth (based on shell length and dry tissue weight) was 17 µg/L TBBPA, and the corresponding 70-day LOEC was 32 µg/L. There was no reported mortality over the duration of the exposure.

A larval development test was carried out with Acartia tonsa in a study which was not according to any recognised guideline. The effect of the test material on larval development was assessed in a semi-static test, covering the period of development from egg until approximately 50 % of the larvae in the control had reached the copepodite stage. A. tonsa were exposed to the test material for 5 days at nominal concentrations of 2, 5, 13, 32, 80 and 200 µg/L. the test was carried out in a synthetic saltwater medium prepared from M7 and a synthetic seawater concentrate. The salinity was 18 ‰.

The test material inhibited larval development of A. tonsa in a concentration-dependent manner. Egg hatching was not affected by exposure to the test material. Larval survival after 5 days of exposure was higher than 80 % in unaffected treatments.

Under the conditions of this study statistically significant effects on larval growth rate were only observed at the highest dose. The 5 day EC50 of the test material to Acartia tonsa was 125 µg/L (95 % CL 65.1 - 238 µg/L) and the EC10 of the test material was 12.7 µg/L (95 % CL 2.5 - 63.6 µg/L). A NOEC is not quoted in the paper but would be 80 µg/L. No analytical verification of the dose was performed in the study and as statistically significant effects were only observed at the highest dose it is uncertain how statistically robust the EC10 and EC50 are. Also acetone was used as a solvent in the study at a concentration of 1/2 the NOEC when the OECD 23 guideline for difficult substances advises that the concentration should be an order of magnitude below the NOEC. It is therefore concluded that the results of this study cannot be relied upon and were not used for risk assessment purposes.