1,1'-(ethane-1,2-diyl)bis[pentabromobenzene]

Endpoint summary

Description of key information

EBP is not biodegradable, as demonstrated by the following six studies:

Ready Biodegradation (Kurume Labs, 1991), OECD 301C

EBP was not readily biodegradable by activated sewage sludge over a 28-day period when tested under Japanese MITI/OECD Ready Biodegradability 301C Modified MITI guidelines.  IR spectra indicated the test substance was unchanged.

Anaerobic Digester Sludge (Wildlife, 2011), OECD 314C

Evidence for the biodegradation of EBP by anaerobic digester sludge was not observed over a 63-d period. Results of the biotic and abiotic chambers were comparable.14C-DBDP-Ethane was used to definitively identify the parent molecule and any degradants.  Only one peak containing the14C-label and having a retention time of DBDP-Ethane was detected in any of the extracts.

EBP: AEROBIC AND ANAEROBIC TRANSFORMATION IN AQUATIC SEDIMENT SYSTEMS (Wildlife, 2015), OECD 308

EBP did not appear to degrade in any of the 2 aerobic and 2 anaerobic test systems. The mean percentage of radioactivity recovered as DBDPEthane at the end of the 6-month test was 91% in all sediment extracts. The DT50 values were >6 months for all four test systems.

Saytex 8010: An evaluation of inherent biodegradability using the CONCAWE test (Wildlife, 2010), OECD 302D

Inherent biodegradation of EBP by a mixture of pre-exposed sludge and soil bacteria over a 90-day period was not observed. Two methods were used to investigate biodegradation: ThIC and14C-analysis for the parent molecule and metabolites. Because inherent biodegradation tests are designed to assess whether a chemical has any potential for biodegradaton (OECD, 2006), the observed results suggest EBPis unlikely to undergo aerobic biodegradation in the environment or in sewage treatment plants. 

EBP: AEROBIC TRANSFORMATION IN SOIL (Wildlife, 2015), OECD 307

This study was conducted to assess the potential mineralization and transformation of DBDPEthane in aerobic soil systems. Four types of soil were utilized in the study. Soils were dosed with 14C-ring labeled DBDPEthane at a nominal concentration of 1.8 mg/kg dry soil. Test systems were incubated at approximately 20 ºC for up to 182 days, and maintained under aerobic conditions by purging the headspace in each vessel with air. Effluent gases were passed through ethylene glycol to trap organic volatiles, followed by alkali solutions to trap evolved carbon dioxide. Duplicate test chambers of each soil type were sacrificed on days 0, 32, 61, 91, 120, 152 and 182. Soil extracts and soil solids were analyzed separately for total radioactivity by liquid scintillation counting (LSC). Soil extracts were analyzed by HPLC for parent test substance and other radio-labeled products. DBDPEthane did not appear to degrade in any of the four soils. The mean percentage of radioactivity recovered as DBDPEthane at the end of the 6-month test was >94% in all soil extracts. There was no clear pattern of decline, and the half-lives were extrapolated well beyond the 6-month test period. The DT50 values were >6 months for all four soils.

DBDPEthane: Anaerobic transformation in soil (Wildlife, 2015), OECD 307

DBDPEthane did not appear to degrade in any of the four anaerobic soils. The mean percentage of radioactivity recovered as DBDPEthane at the end of the 6-month test was >93% in all soil extracts. The DT50 values were >6 months for all four soils.

EBP degradation in a soil-plant system

​[14C] EBP was dosed to the soil test pots via inactivated sludge carrier and incubated for up to

60-61 days with or without growing plants in a greenhouse. The study consists of 3 experiments

including 4 types of soils and 6 plant species staggered in 3 separate experiments. Day 1 and Day

60-61 sacrificial soil and plant samples were sequentially extracted with toluene and further cleaned-up

and concentrated. The sample processing procedures were able to quantitatively recover 14C from soil

and plant samples. 14C radioactivity analysis by LSC indicates that dosed [14C] EBP and Br9 as an

impurity moved to the roots of rye grass plants, and to a much less extent to the roots of other plants

species (e.g., radish, alfalfa, zucchini, corn, and pumpkin plants). No root to shoot movement of 14C was

observed for all 6 plant species. HPLC/β-RAM analysis demonstrated that [14C] EBP was the

predominant analyte in soil and root samples. LC/MS targeted analysis of soil samples observed

[14C] EBP, Br9 and Br9-II but no Br6-Br8 were detected. The levels of Br9 and Br9-II observed in all

soil samples from three experiments were either lower or statistically the same as those observed in

corresponding dose stock solution or dose mixture used for the test, indicating that [14C] EBP was not

biodegraded. LC/MS targeted analysis of root samples observed [14C] EBP in all 6 plant species but

only detected Br9 above LOQ level (10 μg/L) in ryegrass and corn plants. No Br6-Br8 and Br-9 II were

detected in root samples of all 6 plant species. This suggests that Br9 and [14C] EBP may not be further

unique isotope cluster patterns of Br6-Br10 ([14C] EBP) confirmed that [14C] EBP) was not biodegraded

to form novel metabolites with structures related to Br6-Br10 ([14C] EBP).

The experimental evidences from this study via targeted and non-targeted LC/MS analyses

indicates that no [14C] EBP biodegradation occurred in soil and plant samples during 60-61 days of

incubation.

 

Studies on degradation during the life-cycle

Several studies indicated that during normal high temperature polymer processing even under typical worst case and recycling conditions, as well as under conditions of incineration EBP did not form any degradation products of concern.