Bis(pentabromophenyl) ether

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jan 2000 - July 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to GLPs using a protocol approved by the UK under DecaBDE's EU risk assessment.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2001

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

2002

Reference 3

Reference Type:

publication

Title:

A batch test for assessing the mineralization of 14C-radiolabelled comounds under realistic anaerobic conditions.

Author:

Nuck and Federle

Year:

1996

Bibliographic source:

Environ Sci Technol 30(12):3597-3603

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Test method based on that of Nuck and Federle.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bis(pentabromophenyl) ether

EC Number:

214-604-9

EC Name:

Bis(pentabromophenyl) ether

Cas Number:

1163-19-5

Molecular formula:

C12Br10O

IUPAC Name:

bis(pentabromophenyl) ether

Details on test material:

14C-uniformly ring labeled DecaBDE obtained from Nycomed Amersham, specific activity 19 mCi/mmol, molecular wt 959.8, radiochemical purity of 96.8%.
Composite of equal proportions of the DecaBDE commercial products of Albemarle Corp, Bromine Compounds Ltd, Great Lakes Chemical Corporation; contained BDE 209 97.4%, NonaBDEs 2.5%, OctaBDEs0.04%.

Radiolabelling:

yes

Study design

Oxygen conditions:

anaerobic

Inoculum or test system:

natural sediment

Details on source and properties of surface water:

Collected with sediment

Details on source and properties of sediment:

Freshwater sediment collected from Schuykill River, Valley Forge, PA, USA. Redox potential -284 mV.
Sediment: % sand: 50; %silt: 29; %clay:21; USDA textural class: loam. 1.00 gm/cc bulk density. 8.6 cation exchange capacity meq/100 g; 1.4% organic matter. pH in 1:1 sediment:water ratio: 6.3.
Surface Water: pH 7.6; total phosphorus 0.6 ppm; sulfte-sulfur 44 ppm; nitrate-nitrogen 2.7 ppm

Details on inoculum:

Those naturally occurring in the freshwater sediment/surface water.

Duration of test (contact time):

32 wk

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

5 other: mg/kg sediment dw

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

500 other: mg/kg sediment dw

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: CH4, CO2 evolution; [test article]; [14C-Activity]

Details on study design:

see below

Reference substance

Reference substance:

other: Glucose

Results and discussion

Test performance:

see below

% Degradation

% Degradation 1

% Degr.:

0

Parameter:

CH4 evolution

Sampling time:

32 wk

% Degradation 2

% Degr.:

0

Parameter:

CO2 evolution

Sampling time:

32 wk

% Degradation 3

% Degr.:

0

Parameter:

radiochem. meas.

Sampling time:

32 wk

% Degradation 4

% Degr.:

0

Parameter:

test mat. analysis

Sampling time:

32 wk

Half-life of parent compound / 50% disappearance time (DT50)

Remarks on result:

other: No degradation was detected over the course of th study. A half-life was not estimated.

Transformation products:

no

Evaporation of parent compound:

no

Volatile metabolites:

no

Residues:

yes

Details on results:

Mineraliztion and Mass Balance.: An average of 95% of the 14C-activity added as 14C-glucose was recovered from reference group sediment. Of this, 85% was 14CO2 and 14CH4 (mineralization of 14C-glucose) and 10% was associated with the sediment. In the DecaBDE treated groups, mineralization of the test article was not observed. Less than 1% of the total activity added as 14C-DecaBDE was recovered as 14CO2 and 14CH3.

Biotransformation: HPLC-UV: 7 replicates of each test sediment were analyzed. Mean [DecaBDE]mg/kg in the 5 mg/kg group at Day 0 and Wk 32 were 6.64 +-0.70 mg/kg adn 6.51 +- 2.15 mg/kg, respectively. Mean [DecaBDE] mg/kg in the 500 mg/kg group at Day 0 and Wk 32 were 543 +- 77 mg/kg and 612 +-158 mg/kg, repectively. The mean measured concentrations in each dose level were not statistically different at Wk32 from that at Day 0 (ANOVA; p=0.65555).

Varying amounts of gravel and stones in the sediment cores caused measured DecaBDE concentrations and 14C-activity to vary. Those sediments with greater gravel/stone content had proportionately less sediment and higher variability in DecaBDE concentration between replicates within and among the test sediments on both HPLC UV and radiometric detection. Measured DecaBDE concentrations were converted to DecaBDE mass based on the actual dry weight of the sediment and compared to the mass of DecaBDE added at test initiaion. At 5 mg/kg sediment dw, the difference between measured and added mass were 0.123 mg (D 0) and 0.127 mg (Wk 32), respectively. Similarly, the differences at 500 mg/kg sediment dw were 65.0 mg (D 0) and 0.96 mg (Wk32). No statistical difference was detected (paired t-test).

In one-third of the 32 -wk samples (9 of 21 32 -Wk samples), 1 to 3 14C-containing peaks eluting before that of 14C-DecaBDE were detected in 5 mg/kg sediments. HPLC analysis of the stock solution indicated similar peaks.

Based on these results, DecaBDE was neither biotransformed nor mineralized under anaerobic conditions in a flooded sediment over a 32 week period.

Any other information on results incl. tables

Mineraliztion and Mass Balance. An average of 95% of the 14C-activity added as 14C-glucose was recovered from reference group sediment. Of this, 85% was 14CO2 and 14CH4 (mineralization of 14C-glucose) and 10% was associated with the sediment. In the DecaBDE treated groups, mineralization of the test article was not observed. Less than 1% of the total activity added as 14C-DecaBDE was recovered as 14CO2 and 14CH3.

¹⁴C-Mineralization and Mass Balance; Mean ± S.D.

Substance	Nominal Conc. (mg/kg)	^14C-Activity as Gas (%)			^14C-Remaining with Solids (%)	Total^14C-Recovered (%)
		^14CO2	^14CH4	Total
Glucose	5	67.2±2.1	18.1±1.1	85.4±3.1	9.5±4.9	94.9±1.8
DecaBDE	5	0.4±0.04	0.4±0.04	0.86±0.06	129.9±24.1	130.8±24.1
DecaBDE	500	0.4±0.03	0.4±0.06	0.80±0.05	122.5±7.9	123.3±7.9

Biotransformation. HPLC-UV: 7 replicates of each test sediment were analyzed. Mean [DecaBDE]mg/kg in the 5 mg/kg group at Day 0 and Wk 32 were 6.64 +-0.70 mg/kg adn 6.51 +- 2.15 mg/kg, respectively. Mean [DecaBDE] mg/kg in the 500 mg/kg group at Day 0 and Wk 32 were 543 +- 77 mg/kg and 612 +-158 mg/kg, repectively. The mean measured concentrations in each dose level were not statistically different at Wk32 from that at Day 0 (ANOVA; p=0.65555).

Measured DecaBDE Sediment Concentrations

Nominal Test Concentration (mg/kg)	Sample	[DecaBDE]mg/kg dry wt sediment, replicates							Mean	S.D.	Group Mean
		1	2	3	4	5	6	7
5.00	Day 0	6.17 +	5.88	6.08	6.15	6.08	5.57	6.07	6.00	0.21	6.64
5.00	Day 0	7.53+	7.30	7.40	6.75	7.04	7.51	7.37	7.27	0.28
500	Day 0	540+	385	538	502	537	499	397	485	68	543
500	Day 0	608+	599	616	588	567	602	625	601	19
0.0	Wk 32	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	NA	<LOQ
0.0	Wk 32	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	<LOQ	NA
5.00	Wk 32	9.24+	9.26	9.17	9.24	9.15	9.04	9.28	9.20	0.08	6.51
5.00	Wk 32	5.90+	6.68	6.25	6.10	5.89	5.92	6.67	6.20	0.35
5.00	Wk 32	4.15+	4.08	4.60	3.83	4.73	3.78	3.73	4.13	0.40
500	Wk 32	840+	809	673	720	725	776	776	758	57	612
500	Wk 32	703+	693	569	724	637	694	694	666	54
500	Wk 32	444+	337	454	440	363	447	447	413	46

+Average of duplicate analyses.

NA Not applicable.

Varying amounts of gravel and stones in the sediment cores caused measured DecaBDE concentrations and 14C-activity to vary. Those sediments with greater gravel/stone content had proportionately less sediment and higher variability in DecaBDE concentration between replicates within and among the test sediments on both HPLC UV and radiometric detection. Measured DecaBDE concentrations were converted to DecaBDE mass based on the actual dry weight of the sediment and compared to the mass of DecaBDE added at test initiaion. At 5 mg/kg sediment dw, the difference between measured and added mass were 0.123 mg (D 0) and 0.127 mg (Wk 32), respectively. Similarly, the differences at 500 mg/kg sediment dw were 65.0 mg (D 0) and 0.96 mg (Wk32). No statistical difference was detected (paired t-test).

Recovery of DecaBDE and Total¹⁴C-Activity Based on Mass Conversion

Nominal Test Concentration (mg/kg)	Sample	Mean Recovery (%)
		DecaBDE*	^14C-Activity+
5	Day 0	94.1	94.1
5	Day 0	101	98.9
500	Day 0	65.6	95.4
500	Day 0	84.5	101
5	Wk 32	107	103
5	Wk 32	103	146
5	Wk 32	74.5	144
500	Wk 32	105	124
500	Wk 32	95.4	115
500	Wk 32	70.7	131

*((Measured DecaBDE-mg/kg x dry weight sediment-kg)/DecaBDE added-mg)) x 100

+ ((dpm added – dpm evolved) x dry weight sediment-kg/14C-activity added)) x 100

In one-third of the 32 -wk samples (9 of 21 32 -Wk samples), 1 to 3 14C-containing peaks eluting before that of 14C-DecaBDE were detected in 5 mg/kg sediments. HPLC analysis of the 14C-stock solution indicated similar peaks.

Based on these results, DecaBDE was neither biotransformed nor mineralized under anaerobic conditions in a flooded sediment over a 32 week period.

Applicant's summary and conclusion

Validity criteria

Validity criteria fulfilled:

yes

Conclusions:

In this study, DecaBDE was neither mineralized nor biotransformed under anaerobic conditions in a flooded sediment over a 32-wk period.

Executive summary:

An anaerobic biodegradation test was performed to determine the rate and extent of biotransformation and minerlization of the commercial DecaBDE product and 14C-labelled DecaBDE under anaerobic conditions in a flooded sediment over a 32 wk period. The mineralization portion consisted of 3 freshwater sediment groups: a refrence group treated with unlabelled and 14C-labelled d-glucose, and DecaBDE treatment groups at 5 and 500 mg/kg. Production of 14CO2 and 14CH4 were monitored. The biotransformation potential of the study evaluated degradation of DecaBDE in sediments treated with 5 or 500 mg/kg. DecaBDE was neither mineralized nor biotransformed under anaerobic conditions in a flooded sediment over a 32-wk period.