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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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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

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
2001
Reference Type:
publication
Title:
Unnamed
Year:
2002
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

Reference
Name:
Unnamed
Type:
Constituent
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 concentrationopen allclose all
Initial conc.:
5 other: mg/kg sediment dw
Based on:
test mat.
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
% Degradationopen allclose all
% Degr.:
0
Parameter:
CH4 evolution
Sampling time:
32 wk
% Degr.:
0
Parameter:
CO2 evolution
Sampling time:
32 wk
% Degr.:
0
Parameter:
radiochem. meas.
Sampling time:
32 wk
% 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 (%)

Total14C-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 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.