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Environmental fate & pathways

Biodegradation in soil

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Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 2013 - February 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
GLP compliance:
yes (incl. QA statement)
Test type:
laboratory
Specific details on test material used for the study:
The radio-labeled test substance, [14C]DBDPEthane, was received from Perkin Elmer on February 23,
2010, and assigned Wildlife International identification number 9412. The test substance was supplied in
solid form, and was identified as 1,2-Bis[pentabromophenyl]ethane, [Phenyl-14C[U]];
CUSC72819000MC; lot number 3626190. Information provided by the supplier indicated the
radiochemical purity was 94.5%, the specific activity was 32.4 mCi/mmol, and the molecular weight was
972 mg/mmol. A total of 14.0 mCi was supplied, and no expiration date was provided. The test substance was stored in
a freezer set to approximately -20 C. Albemarle Corporation’s trade name for this substance is SAYTEX®
8010 Flame Retardant.
Radiolabelling:
yes
Oxygen conditions:
aerobic
Soil classification:
USDA (US Department of Agriculture)
Year:
2013
Soil no.:
#1
Soil type:
loamy sand
% Clay:
9
% Silt:
9
% Sand:
82
% Org. C:
0.9
pH:
5.2
CEC:
10.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.16
Soil no.:
#2
Soil type:
sandy clay loam
% Clay:
21
% Silt:
13
% Sand:
66
% Org. C:
1.9
pH:
6.9
CEC:
17.9 meq/100 g soil d.w.
Bulk density (g/cm³):
1.04
Soil no.:
#3
Soil type:
clay loam
% Clay:
29
% Silt:
27
% Sand:
44
% Org. C:
4
pH:
5.4
CEC:
31.4 meq/100 g soil d.w.
Bulk density (g/cm³):
0.99
Soil no.:
#4
Soil type:
sandy clay loam
% Clay:
29
% Silt:
23
% Sand:
48
% Org. C:
2.8
pH:
7.9
CEC:
68.8 meq/100 g soil d.w.
Bulk density (g/cm³):
1.01
Details on soil characteristics:
The four soils used in this study were supplied by Agvise Laboratories (Northwood, North Dakota,
USA). The soils were collected from four different sites on July 24, 2013. The soils were collected to a depth
of approximately 0-15 cm using a shovel, and sieved through a 2-mm screen. Samples were analyzed by
Agvise Labs to determine textural class, bulk density, cation exchange capacity, moisture content at 1/3 bar,
organic carbon content, pH, concentrations of selected cations, microbial biomass, and ferrous iron content.
Copies of the characterization reports are presented in Appendix III. The soils were received at Wildlife
International on August 7, 2013, and stored in a walk-in cooler set at approximately 5 degrees C.
The soils were selected to be consistent with the referenced OECD test guideline [1], and representative
of different agricultural soil types. The guideline calls for the use of a representative soil with one of four
textural classifications, a pH of 5.5 to 8.0, an organic carbon content of 0.5% to 2.5%, and a microbial
biomass of at least 1% of total organic carbon content. Soil 2 listed above (MSL-PF, sandy clay loam)
matched this description. The other soils provided a variety of organic carbon content, pH, clay content and
microbial biomass.

The water holding capacities and moisture contents of the soils were determined by Wildlife
International, prior to use in the study. The properties of all four soils are presented in Table 1.
Soil No.:
#1
Duration:
182 d
Soil No.:
#2
Duration:
182 d
Soil No.:
#3
Duration:
182 d
Soil No.:
#4
Duration:
182 d
Soil No.:
#1
Initial conc.:
1.8 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#2
Initial conc.:
1.8 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#3
Initial conc.:
1.8 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#4
Initial conc.:
1.8 mg/kg soil d.w.
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
radiochem. meas.
Soil No.:
#1
Temp.:
20 C
Humidity:
14.6% moisture content @ 1/3 bar
Microbial biomass:
211.7 ug/g
Soil No.:
#2
Temp.:
20 C
Humidity:
25.5% moisture content @ 1/3 bar
Microbial biomass:
543.2 ug/g
Soil No.:
#3
Temp.:
20 C
Humidity:
35.2% moisture content @ 1/3 bar
Microbial biomass:
531.5 ug/g
Soil No.:
#4
Temp.:
20 C
Humidity:
33.5% moisture content @ 1/3 bar
Microbial biomass:
548.3 ug/g
Soil No.:
#1
% Recovery:
94
Soil No.:
#2
% Recovery:
94
Soil No.:
#3
% Recovery:
94
Soil No.:
#4
% Recovery:
94
Key result
Soil No.:
#1
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
>= 18.3 - <= 22 °C
Key result
Soil No.:
#2
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
>= 18.3 - <= 22 °C
Key result
Soil No.:
#3
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
>= 18.3 - <= 22 °C
Key result
Soil No.:
#4
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
>= 18.3 - <= 22 °C
Transformation products:
no
Details on transformation products:
Through all test intervals, the mean maximum percentages of radioactivity recovered as other
products were 3.4%, 3.5%, 2.5% and 2.7% for soils 1, 2, 3 and 4, respectively. The amount of impurities
in the test substance applied to the soils was 5.5%, based on the certificate of analysis. The other
products observed in the soil extracts were attributed to impurities in the test substance, rather than
transformation products. There were no distinct, consistent transformation product peaks observed during
the study.
Details on results:
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.

Table 3. Mean Cumulative Radioactivity in All Transformation Vessel Gas Traps

Test

Soil

Interval

(Days)

Evolved 14CO2

(%)

Volatile 14C Gases

(%)

Total Gases

(%)

Soil 1

32

61

91

120

152

182

0.00

0.00

0.01

0.01

0.01

0.01

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.01

0.01

0.01

0.02

Soil 2

32

61

91

120

152

182

0.00

0.00

0.01

0.01

0.01

0.01

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.01

0.01

0.01

0.01

Soil 3

32

61

91

120

152

182

0.00

0.00

0.01

0.01

0.01

0.01

0.00

0.00

0.00

0.00

0.00

0.01

0.00

0.00

0.01

0.01

0.01

0.02

Soil 4

32

61

91

120

152

182

0.00

0.00

0.01

0.01

0.01

0.01

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.01

0.01

0.01

0.01

 

Table 4. Mean Cumulative Radioactivity in All Mineralization Vessel Gas Traps

Test

Soil

Interval

(Days)

Evolved 14CO2

(%)

Volatile 14C Gases

(%)

Total Gases

(%)

Soil 1

32

61

91

120

152

182

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.01

0.02

0.02

0.03

0.04

0.00

0.02

0.03

0.05

0.06

0.08

Soil 2

32

61

91

120

152

182

0.00

0.00

0.01

0.02

0.03

0.03

0.01

0.01

0.02

0.02

0.03

0.04

0.01

0.01

0.03

0.05

0.06

0.07

Soil 3

32

61

91

120

152

182

0.00

0.00

0.01

0.01

0.02

0.03

0.00

0.01

0.01

0.02

0.03

0.03

0.00

0.01

0.02

0.04

0.05

0.06

Soil 4

32

61

91

120

152

182

0.00

0.01

0.02

0.02

0.03

0.04

0.00

0.01

0.01

0.02

0.03

0.03

0.00

0.01

0.03

0.04

0.06

0.07

 

Table 5. Mean Distribution of Radioactivity from Test Vessels

Test

Soil

Interval

(Days)

MeOH

Extracts

(%)

THF

Extracts

(%)

Combusted

Soil

Solids

(%)

Total

Gases

(%)

Material

Balance

(Recovery %)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

1.3

1.0

1.0

0.9

0.8

0.9

0.8

0.8

98.5

107.8

103.0

103.9

105.9

101.9

104.6

93.9

1.6

1.8

1.6

1.3

1.3

1.0

5.4

1.6

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

101.4

110.7

105.6

106.1

108.0

103.9

110.8

96.3

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.4

0.3

0.5

0.4

0.3

0.4

0.4

0.4

93.6

108.8

95.4

96.2

95.4

99.8

98.6

92.2

2.9

3.5

3.0

3.4

4.0

2.4

3.1

3.1

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

96.8

112.6

98.8

99.9

99.7

102.6

102.1

95.8

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.2

0.2

0.1

0.2

0.2

0.2

0.1

0.1

93.5

105.4

95.5

96.3

98.3

91.5

88.6

96.5

3.7

2.9

3.6

3.7

4.7

4.1

3.4

4.2

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

97.4

108.4

99.2

100.1

103.1

95.7

92.2

100.9

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.4

0.3

0.3

0.5

0.3

0.4

0.3

0.3

83.3

96.3

88.6

85.8

90.9

83.7

87.6

103.1

3.2

3.0

3.3

2.7

3.8

3.1

3.2

4.3

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

86.9

99.6

92.3

89.0

95.1

87.2

91.1

107.8

NA - Not Applicable 

Table 6. Mean Soil Extraction Efficiencies

Test

Soil

Interval

(Days)

Mean

DPM in

Comb. Soil

Extracts

Mean

DPM in

Soil

Solids

Mean

DPM in

Soil

Sample

Proportion

In/on

Solids

(%)

Mean

Extraction

Efficiency

(%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

13357268

14786908

14036384

14084677

14471119

13880357

14224357

12810752

218362

247916

219841

180842

176536

138208

733230

212827

13575631

15034824

14256225

14265519

14647655

14018565

14957587

13023579

1.6

1.6

1.5

1.3

1.2

1.0

4.9

1.6

98.4

98.4

98.5

98.7

98.8

99.0

95.1

98.4

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

12621684

14704700

12935449

13029508

12883069

13488774

13325476

12385438

385028

467400

403618

451873

535071

329862

414394

418881

13006712

15172100

13339068

13481380

134181140

13818636

13739870

12804319

3.0

3.1

3.0

3.4

4.0

2.4

3.0

3.3

97.0

96.9

97.0

96.6

96.0

97.6

97.0

96.7

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

12677898

14133520

12911136

13085171

13344245

12421630

11966506

12958412

500235

383182

487409

501087

630778

549186

454579

562464

13178133

14516701

13398545

13586258

13975022

12970815

12421085

13220876

3.8

2.6

3.6

3.7

4.5

4.2

3.7

4.2

96.2

97.4

96.4

96.3

95.5

95.8

96.3

95.8

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

11207518

13070062

11985068

11631389

12283397

11287266

11829907

14021792

428190

404697

450585

363317

518115

422175

424803

587865

11635708

13474759

12435653

11994706

12801512

11709441

12254710

14609657

3.7

3.0

3.6

3.0

4.0

3.6

3.5

4.0

96.3

97.0

96.4

97.0

96.0

96.4

96.5

96.0

 

Table 7. Mean Chloroform Extraction Results

Test

Soil

Interval

(Days)

Mean

DPM in

Conc.

Soil Extracts

Mean

DPM in

Chloroform

Extracts

Mean

DPM in

Aqueous

Fractions

Recovery

%

% in

Aqueous

Fractions

Mean

Extraction

Efficiency

(%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

13407906

12884914

13437515

13604526

13909800

13798073

13341821

11455942

13168000

12786367

13122522

13309898

13369939

12806920

13478960

12041979

835

1755

1281

1771

6595

6892

10763

258

98.2

99.2

97.7

97.9

96.2

92.9

101.1

105.1

0.0

0.0

0.0

0.0

0.0

0.1

0.1

0.0

100.0

100.0

100.0

100.0

100.0

99.9

99.9

100.0

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

12556569

13104943

12310025

12669978

12686792

13505553

12681536

11157301

11814638

13195000

12053512

12142280

12231342

12751270

12784523

11585783

41484

1285

1629

1914

7432

5374

8514

184

94.5

100.7

98.0

95.9

96.5

94.5

100.9

103.8

0.3

0.0

0.0

0.0

0.1

0.0

0.1

0.0

99.7

100.0

100.0

100.0

99.9

100.0

99.9

100.0

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

12495944

12657898

11634233

12771115

12320132

12480917

11116512

11834851

12355050

12836638

12168738

12372940

12537585

11875160

11381349

12289458

3865

1155

828

453

4696

4402

7182

398

98.9

101.4

104.6

96.9

101.8

95.2

102.5

103.8

0.0

0.0

0.0

0.0

0.0

0.0

0.1

0.0

100.0

100.0

100.0

100.0

100.0

100.0

99.9

100.0

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

11138429

11606454

11351013

11579553

11965920

11718105

11132480

12752288

10859122

12017233

11288738

11019135

11508375

11098690

11426410

13395855

8022

1203

908

509

8327

3135

7746

1182

97.6

103.5

99.4

95.2

96.3

94.7

102.7

105.1

0.1

0.0

0.0

0.0

0.1

0.0

0.1

0.0

99.9

100.0

100.0

100.0

99.9

100.0

99.9

100.0

 

Table 8. Mean Procedural Recoveries

Test

Soil

Interval

(Days)

Mean Recovery

Combined

Soil Extract

Concentration

(%)

Mean

Recovery

Chloroform

Extraction

(%)

Mean Recovery

Chloroform

Extract

Concentration

(%)

Overall

Mean

Procedural

Recovery

(%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

107.5

92.4

99.9

100.2

100.5

102.8

97.9

95.9

98.2

99.2

97.7

97.9

96.2

92.9

101.1

105.1

108.6

102.7

103.2

106.8

112.9

109.6

121.5

98.2

114.7

94.3

100.7

104.8

109.1

104.7

120.2

99.0

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

105.8

64.0

99.2

102.6

103.4

104.5

100.2

97.3

94.5

100.7

98.0

95.9

96.5

94.5

100.9

103.8

110.3

106.8

100.5

104.9

105.0

106.1

120.7

101.8

110.3

101.2

97.6

103.1

104.7

104.6

122.0

102.8

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

105.2

94.0

94.1

101.5

97.2

104.2

98.0

99.7

98.9

101.4

104.6

96.9

101.8

95.2

102.5

103.8

113.1

105.4

102.2

101.7

106.5

104.8

108.8

106.6

117.7

100.4

100.5

100.0

105.3

103.9

109.3

110.4

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

105.8

94.1

98.7

103.8

102.6

107.2

99.5

989.9

97.6

103.5

99.4

95.2

96.3

94.7

102.7

105.1

114.1

108.4

104.2

104.9

103.3

116.0

126.0

110.2

117.7

105.6

102.1

103.6

102.2

117.9

128.7

114.4

  

  

Table 9. Mean Distribution of Parent and Other 14C Products in Soil Extracts

Test

Soil

Interval

(Days)

Aqueous

Fraction

(%)

Before

(1.0-11.3)

(%)

Parent

(11.3-12.3)

(%)

After

(12.3-16.0)

(%)

Total

% of

Sample

Total %

Other 14C

Products

 

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.0

0.0

0.0

0.0

0.1

0.1

0.1

0.0

0.7

0.5

0.0

0.8

0.4

1.6

0.5

0.9

94.9

96.8

97.8

96.1

96.7

96.2

94.3

96.5

2.7

1.0

0.6

1.9

1.7

1.2

0.2

0.9

98.3

98.3

98.5

98.7

98.8

99.0

95.1

98.3

3.4

1.5

0.6

2.7

2.1

2.8

0.8

1.9

 

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.3

0.0

0.0

0.0

0.1

0.0

0.1

0.0

0.6

0.9

0.0

0.3

1.3

0.3

0.6

0.6

93.5

94.1

95.7

95.4

94.7

95.7

95.1

94.4

2.6

1.9

1.2

1.0

0.0

1.5

1.2

1.7

97.0

96.9

96.9

96.6

96.1

97.6

97.0

96.7

3.5

2.8

1.2

1.2

1.4

1.8

1.9

2.3

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.0

0.0

0.0

0.0

0.0

0.0

0.1

0.0

1.0

0.8

0.0

0.2

0.0

1.3

0.4

0.3

93.6

94.9

95.9

95.4

94.0

94.4

95.4

92.8

1.5

1.6

0.5

0.7

1.4

0.0

0.4

2.7

96.1

97.3

96.4

96.3

95.4

95.7

96.3

95.8

2.5

2.5

0.5

0.9

1.4

1.3

1.0

3.1

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.1

0.0

0.0

0.0

0.1

0.0

0.1

0.0

0.6

0.8

0.0

0.1

0.1

1.2

0.6

1.0

93.9

95.1

95.1

96.5

94.6

93.7

94.2

94.5

1.8

1.2

1.3

0.4

1.1

1.5

1.7

0.5

96.4

97.0

96.4

97.0

96.0

96.4

96.6

96.0

2.5

1.9

1.3

0.5

1.4

2.7

2.3

1.5

 

 Total Other 14C Products = Total % of Sample - Parent

Table 10. Disappearance of DBDPEthane from Soil 1

Interval

(Days)

Soil Extracts

%

ug/kg

0

32

61

91

120

152

182

94.9

96.8

97.8

96.1

96.7

96.2

94.3

1718

1753

1771

1739

1750

1741

1706

 

Table 11. Regression Analysis of DBDPEthane in Soil 1 Extracts: Simple First-Order Model Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

96.55

0.8585

5.269E-10

94.35

87.76

K_Parent

4.993E-05

8.156E-05

0.2836

-0.0001597

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

1.388E+04

4.612E+04

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.07027

0.07027

Parent

0.07027

0.07027

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8327

K_Parent

0.8327

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

94.9

96.55

-1.652

32

96.8

96.4

0.4019

61

97.8

96.26

1.541

91

96.1

96.11

-0.07463

120

96.7

95.98

0.7244

152

96.2

95.82

0.3776

182

94.3

95.68

-1.379

 

Table 12. Disappearance of DBDPEthane from Soil 2

Interval

(Days)

Soil Extracts

%

ug/kg

0

32

61

91

120

152

182

93.5

94.1

95.7

95.4

94.7

95.7

95.1

1693

1703

1733

1726

1714

1733

1721

 

Table 13. Regression Analysis of DBDPEthane in Soil 2 Extracts: Simple First-Order Model Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

94.89

0.628

1.205E-10

93.27

96.5

K_Parent

5.77E-14

6.054E-05

0.5

00.0001556

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

1.2E+13

3.988E+13

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.418

0.418

Parent

0.418

0.418

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8337

K_Parent

0.8337

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

93.5

94.89

-1.386

32

94.1

94.89

-0.7857

61

95.7

94.89

0.8142

91

95.4

94.89

0.5142

120

94.7

94.89

-0.1858

152

95.7

94.89

0.8141

182

95.1

94.89

0.2141

 

Table 14. Disappearance of DBDPEthane from Soil 3

Interval

(Days)

Soil Extracts

%

ug/kg

0

32

61

91

120

152

182

93.6

94.9

95.9

95.4

94.0

94.4

95.4

1695

1717

1736

1727

1702

1709

1727

 

 

Table 15. Regression Analysis of DBDPEthane in Soil 3 Extracts: Simple First-Order Model Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

94.8

0.6259

1.19E-10

93.19

96.4

K_Parent

5.494E-12

6.039E-05

0.5

-0.0001552

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

1.262E+11

4.191E+11

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.05605

0.05605

Parent

0.05605

0.05605

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8337

K_Parent

0.8337

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

93.6

94.8

-1.2

32

94.9

94.8

0.09997

61

95.9

94.8

1.1

91

95.4

94.8

0.5999

120

94

94.8

-0.8001

152

94.4

94.8

-0.4001

182

95.4

94.8

0.5998

 

Table 16. Disappearance of DBDPEthane from Soil 4

Interval

(Days)

Soil Extracts

%

ug/kg

0

32

61

91

120

152

182

93.9

95.1

95.1

96.5

94.6

93.7

94.2

1699

1721

1722

1747

1713

1695

1705

 

 

Table 17. Regression Analysis of DBDPEthane in Soil 4 Extracts: Simple First-Order Model Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

94.99

0.7022

2.095E-10

93.18

96.8

K_Parent

2.973E-05

6.774E-05

0.3395

-0.0001444

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

2.332E+04

7.745E+04

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.03729

0.03729

Parent

0.03729

0.03729

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8331

K_Parent

0.8331

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

93.9

94.99

-1.085

32

95.1

94.9

0.2048

61

95.1

94.81

0.2866

91

96.5

94.73

1.771

120

94.6

94.65

-0.0473

152

93.7

94.56

-0.8573

182

94.2

94.47

-0.2731

 

Conclusions:
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.
Executive summary:

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.

Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 12, 2013 - January 23, 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
GLP compliance:
yes
Test type:
laboratory
Specific details on test material used for the study:
14C-ring-labeled DBDPEthane
Radiolabelling:
yes
Remarks:
14C- ring-labeled
Oxygen conditions:
anaerobic
Soil classification:
other:
Year:
2013
Soil no.:
#1
Soil type:
loamy sand
% Clay:
9
% Silt:
9
% Sand:
82
% Org. C:
0.94
pH:
5.2
CEC:
10.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.16
Soil no.:
#2
Soil type:
sandy clay loam
% Clay:
21
% Silt:
13
% Sand:
66
% Org. C:
1.9
pH:
6.9
CEC:
17.9 meq/100 g soil d.w.
Bulk density (g/cm³):
1.04
Soil no.:
#3
Soil type:
clay loam
% Clay:
29
% Silt:
27
% Sand:
44
% Org. C:
4
pH:
5.4
CEC:
31.4 meq/100 g soil d.w.
Bulk density (g/cm³):
0.99
Soil no.:
#4
Soil type:
sandy clay loam
% Clay:
29
% Silt:
23
% Sand:
48
% Org. C:
2.8
pH:
7.9
CEC:
68.8 meq/100 g soil d.w.
Bulk density (g/cm³):
1.01
Soil No.:
#1
Duration:
6 mo
Soil No.:
#2
Duration:
6 mo
Soil No.:
#3
Duration:
6 mo
Soil No.:
#4
Duration:
6 mo
Soil No.:
#1
Initial conc.:
1.5 mg/kg soil d.w.
Soil No.:
#2
Initial conc.:
1.5 mg/kg soil d.w.
Soil No.:
#3
Initial conc.:
1.5 mg/kg soil d.w.
Soil No.:
#4
Initial conc.:
1.5 mg/kg soil d.w.
Parameter followed for biodegradation estimation:
radiochem. meas.
Soil No.:
#1
Temp.:
20C
Microbial biomass:
211.7 ug/g
Soil No.:
#2
Temp.:
20C
Microbial biomass:
543.2 ug/g
Soil No.:
#3
Temp.:
20C
Microbial biomass:
531.5 ug/g
Soil No.:
#4
Temp.:
20C
Microbial biomass:
548.3 ug/g
Details on experimental conditions:
This study was conducted to assess the potential mineralization and transformation of DBDPEthane
in anaerobic soil systems. Four types of soil were utilized in the study. Soils were dosed with 14C-ring
labeled DBDPEthane at a nominal concentration of 1.5 mg/kg dry soil. Test systems were incubated at
approximately 20 ºC for up to 182 days. Aerobic conditions were maintained for the first 32 days 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. On day 32, the soils were
flooded, purged with nitrogen, and sealed to maintain anaerobic conditions. Duplicate test chambers of
each soil type were sacrificed on months 0, 1, 2, 3, 4, 5 and 6. The water layers, soil extracts and soil
solids were analyzed separately for total radioactivity by liquid scintillation counting (LSC).
Soil No.:
#1
% Recovery:
96.4
Soil No.:
#2
% Recovery:
95.3
Soil No.:
#3
% Recovery:
95.3
Soil No.:
#4
% Recovery:
93.5
Key result
Soil No.:
#1
% Degr.:
2.1
Parameter:
radiochem. meas.
Sampling time:
6 mo
Key result
Soil No.:
#2
% Degr.:
3.8
Parameter:
radiochem. meas.
Sampling time:
6 mo
Key result
Soil No.:
#3
% Degr.:
4.2
Parameter:
radiochem. meas.
Sampling time:
6 mo
Key result
Soil No.:
#4
% Degr.:
3.4
Parameter:
radiochem. meas.
Sampling time:
6 mo
Key result
Soil No.:
#1
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Key result
Soil No.:
#2
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Key result
Soil No.:
#3
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Key result
Soil No.:
#4
DT50:
> 6 mo
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Transformation products:
no
Remarks:
There were no distinct, consistent tramsformation product peaks observed during the study.

Material Balance Results

A summary of the distribution of 14C in the various fractions and material balance results is

presented in Table 7. The table contains the mean results from both test vessels of each soil type sacrificed at each sampling interval. The mean material balances ranged from 90.7% to 107.9% throughout the test, and were considered acceptable.

 

Transformation Results in Soils

Soils were collected and extracted on days 0, 32, 62, 92, 120, 152 and 182. The total amount of

radioactivity in each soil sample was calculated as the sum of the amounts measured in the overlying

water layers, MeOH soil extracts, THF soil extracts, plus the amounts measured in the soil solids after

extraction. Extraction efficiencies were calculated as the proportion of radioactivity in the extracts versus the total radioactivity in the soil sample. A summary of the extraction efficiencies is presented in

Table 8. The table contains the mean results from both test vessels of each soil type sacrificed at each

sampling interval. Mean extraction efficiencies ranged from 96.8% to 99.0% on day 0. Extraction

efficiencies remained relatively constant, and were ≥95% throughout the study. On day 182, mean

extraction efficiencies for transformation test vessels ranged from 95.7% to 98.0.

 

The overlying water layers contained ≤0.2% of the radioactivity at any sampling interval; therefore,

no further work was performed on the water layer samples.

 

The MeOH and THF soil extracts were combined and concentrated, prior to extraction with

chloroform. The combined, concentrated soil extracts were partitioned three times with chloroform to

remove endogenous matrix materials that might interfere with chromatographic analyses. A summary of the chloroform extraction results is presented in Table 9. The table contains the mean results from both test vessels of each soil type sacrificed at each sampling interval. Mean recoveries for the chloroform extraction procedure ranged from 92.2% to 130%. The proportion of 14C in the CHCl3 extracts was >95%, with the following three exceptions. The aqueous fraction from soil 3 on day 92 (test vessel 40) contained 17.8% of the 14C, the aqueous fraction from soil 4 on day 92 (test vessel 55) contained 8.2%, and the aqueous fraction from soil 1 on day 182 (test vessel 14) contained 7.7%. In each case, an emulsion formed causing some of the chloroform to remain suspended in the aqueous fraction. The chloroform extracts were concentrated prior to HPLC analyses. A summary of the procedural recoveries during soil extract processing is presented in Table 10. The table contains the mean results from both test vessels of each soil type sacrificed at each sampling interval. With the exception of two samples that were partially spilled, the overall procedural recoveries were >93%.

 

The concentrated chloroform extracts were analyzed using HPLC/-RAM to determine the relative

distributions of parent test substance and other 14C products. In addition, aqueous fractions that

contained >1% of the 14C were analyzed using HPLC/-RAM. The integration results from each sample were divided into three regions of interest (ROIs), as described previously in the “HPLC/β-RAM Analyses” section of this report. A summary of the HPLC results is presented in Table 11. The table contains the mean results from both test vessels of each soil type sacrificed at each sampling interval. The mean amounts of 14C remaining in the overlying water layers plus the aqueous fractions after chloroform partitioning are presented as a region named “Aqueous Sample”. Aqueous fractions that contained >1% of the 14C were analyzed by HPLC and results were included in the ROIs, rather than the “Aqueous Sample”. The mean amount of parent DBDPEthane in the soil extracts on day 0 ranged from 91.5% to 95.1%. At the end of the test, the mean amount of DBDPEthane ranged from 93.5% to 96.4%. Further discussions of the results can be found in the sections for each soil.

 

Supplemental Extractions

At the end of the test, the amount of radioactivity remaining in/on the soil solids after extractions

was ≤5% for all samples. Supplemental extractions were not conducted and no further

analytical work was performed on the soil solids.

 

Results from Soil 1

The mean material balance results from soil 1 are presented in Table 7. Material balance results from individual test vessels ranged from 96.3% to 108.5% throughout the test. On day 0, the mean percent of dosed radioactivity in the soil extracts was 103.4%, and 1.1% was bound to the soil solids. At the end of the test, the mean amount in the soil extracts was 100.5%, and 2.1% was bound to the soil solids. During the study, the mean soil extraction efficiency was 98.0% for all 16 samples. The mean cumulative amount of 14C gas production over the 6-month test period was 0.08% (Table 6).

 

The mean distributions of [14C]DBDPEthane and other products in the soil extracts are presented in

Table 11. The mean amount of parent (DBDPEthane) was 95.1% on day 0 and 96.4% on day

182. The mean amounts and concentrations of DBDPEthane are presented in Table 12. The means were

used in regression analyses in an attempt to determine disappearance rates for DBDPEthane, and did not include the 14C bound to the soil solids. The results from a simple first-order (SFO) decay curve model are presented in Table 13.. The SFO model did not fit the data well (r2 <0.70), but none of the other models were a better fit. The amount of DBDPEthane in the soil extracts never dropped below 92%, so the DT50 was >6 months. The mean total amount of other products was 3.9% on day 0, and was the maximum amount observed at any interval for Soil 1. The amount of impurities in the test substance was 5.5%. The other product peaks observed in the soil extracts were attributed to impurities, rather than transformation products. None of the individual peaks accounted for >2.0% of the dose.

No further attempts were made to identify the other products.

 

Results from Soil 2

The mean material balance results from soil 2 are presented in Table 7. Material balance results from individual test vessels ranged from 91.1% to 106.9% throughout the test. On day 0, the mean percent of dosed radioactivity in the soil extracts was 89.1%, and 2.6% was bound to the soil solids. At the end of the test, the mean amount in the soil extracts was 96.2%, and 3.8% was bound to the soil solids. During the study, the mean soil extraction efficiency was 96.3% for all 16 samples. The mean cumulative amount of 14C gas production over the 6-month test period was 0.09% (Table 6).

 

The mean distributions of [14C]DBDPEthane and other products in the soil extracts are presented in

Table 11. The mean amount of parent (DBDPEthane) was 92.0% on day 0 and 95.3% on day

182. The mean amounts and concentrations of DBDPEthane are presented in Table 14. The means were

used in regression analyses in an attempt to determine disappearance rates for DBDPEthane, and did not include the 14C bound to the soil solids. The results from a simple first-order (SFO) decay curve model are presented in Table 15. The SFO model did not fit the data well (r2 <0.70), but none of the other models were a better fit. The amount of DBDPEthane in the soil extracts never dropped below 90%, so the DT50 was >6 months. The mean total amount of other products was 5.2% on day 0, and was the maximum amount observed at any interval for soil 2. The amount of impurities in the test substance was 5.5%. The other product peaks observed in the soil extracts were attributed to impurities, rather than transformation products. None of the individual peaks accounted for >3.2% of the dose.

 No further attempts were made to identify the other products.

 

Results from Soil 3

The mean material balance results from soil 3 are presented in Table 7. Material balance results from individual test vessels ranged from 91.3% to 107.3% throughout the test. On day 0, the mean percent of dosed radioactivity in the soil extracts was 92.5%, and 2.6% was bound to the soil solids. At the end of the test, the mean amount in the soil extracts was 93.8%, and 4.2% was bound to the soil solids. During the study, the mean soil extraction efficiency was 96.1% for all 16 samples. The mean cumulative amount of 14C gas production over the 6-month test period was 0.09% (Table 6).

 

The mean distributions of [14C]DBDPEthane and other products in the soil extracts are presented in

Table 11. The mean amount of parent (DBDPEthane) was 91.5% on day 0 and 95.3% on day 182. The

mean amounts and concentrations of DBDPEthane are presented in Table 16. The means were used in

regression analyses in an attempt to determine disappearance rates for DBDPEthane, and did not include the 14C bound to the soil solids. The results from a simple first-order (SFO) decay curve model are presented in Table 17. The SFO model did not fit the data well (r2 <0.70), but none of the other models were a better fit. The amount of DBDPEthane in the soil extracts never dropped below 89%, so the DT50 was >6 months.

 

The mean total amount of other products was 5.8% on day 0, and was the maximum amount

observed at any interval for soil 3. The amount of impurities in the test substance was 5.5%. The other

product peaks observed in the soil extracts were attributed to impurities, rather than transformation

products. None of the individual peaks accounted for >2.2% of the dose. No further attempts were made to identify the other products.

 

Results from Soil 4

The mean material balance results from soil 4 are presented in Table 7. Material balance results from individual test vessels ranged from 89.7% to 101.1% throughout the test (Appendix XV). On day 0, the mean percent of dosed radioactivity in the soil extracts was 90.0%, and 2.9% was bound to the soil solids. At the end of the test, the mean amount in the soil extracts was 87.3%, and 3.4% was bound to the soil solids. During the study, the mean soil extraction efficiency was 96.5% for all 16 samples. The mean cumulative amount of 14C gas production over the 6-month test period was 0.08% (Table 6).

 

The mean distributions of [14C]DBDPEthane and other products in the soil extracts are presented in

Table 11. The mean amount of parent (DBDPEthane) was 94.6% on day 0 and 93.5% on day 182. The mean amounts and concentrations of DBDPEthane are presented in Table 18. The means were used in regression analyses in an attempt to determine disappearance rates for DBDPEthane, and did not include the 14C bound to the soil solids. The results from a simple first-order (SFO) decay curve model are presented in Table 19. The SFO model did not fit the data well (r2 <0.70), but none of the other models were a better fit. The amount of DBDPEthane in the soil extracts never dropped below 91%, so the DT50 was >6 months.

 

The mean total amount of other products was 2.2% on day 0, and reached a maximum of 3.1% on

day 92. The amount of impurities in the test substance was 5.5%. The other product peaks observed in

the soil extracts were attributed to impurities, rather than transformation products. None of the individual peaks accounted for >2.0% of the dose. No further attempts were made to identify the other products.

Table 3. Woil RedOx Potentials

Interval (Study Day)

Date

Soil 1

Soil 2

Soil 3

Soil 4

32

33

34

35

39

46

53

62

71

82

92

109

120

137

152

167

182

October 14, 2013

October 15, 2013

October 16, 2013

October 17, 2013

October 21, 2013

October 28, 2013

November 4, 2013

November 13, 2013

November 22, 2013

December 3, 2013

December 13, 2013

December 30, 2013

January 10, 2014

January 27, 2014

February 11, 2014

February 26, 2014

March 13, 2014

537

506

501

492

-11

-95

-144

-183

-178

-172

-182

-190

-185

-211

-218

-225

-215

445

307

263

1

-154

-274

-253

-262

-262

-235

-233

-239

-247

-255

-254

-252

-253

419

449

468

453

161

-79

-140

-197

-239

-233

-231

-227

-225

-212

-193

-198

-217

436

209

214

137

-197

-268

-278

-280

-278

-271

-266

-260

-258

-253

-254

-258

-258

Redox potential of soil layer (Eh)

Table 4. Viability Assessment Results

Test Start

(Study Day)

Interval

(Study Day)

Soil 1

(%)

Soil 2

(%)

Soil 3

(%)

Soil 4

(%)

62

7

14

21

28

26.7

803

--

--

23.3

41.6

52.9

--

17.5

37.6

53.3

--

18.1

44.1

52.6

--

182

7

14

21

28

51.2

67.7

--

--

23.0

38.5

46.8

56.1

25.7

47.0

55.8

--

29.7

47.0

52.4

--

Results given in cumulative % of applied 14C recovered in gas traps

Table 5. Mean Cumulative Radioactivity in All Transformation Vessel Gas Traps

Test Soil

Interval

(Days)

Volatile

14C Gases

(%)

Evolved 14CO2

(%)

 

Total

Gases

(%)

Soil 1

32

62

92

120

152

182

0.00

0.01

0.01

0.01

0.01

0.01

0.00

0.01

0.02

0.01

0.01

0.01

0.00

0.03

0.03

0.02

0.01

0.01

Soil 2

32

62

92

120

152

182

0.00

0.00

0.01

0.01

0.01

0.01

0.00

0.01

0.02

0.01

0.01

0.00

0.00

0.02

0.02

0.02

0.01

0.01

Soil 3

32

62

92

120

152

182

0.00

0.00

0.01

0.01

0.01

0.00

0.00

0.01

0.00

0.02

0.01

0.01

0.00

0.02

0.01

0.03

0.02

0.01

Soil 4

32

62

92

120

152

182

0.00

0.01

0.01

0.01

0.01

0.00

0.00

0.01

0.02

0.01

0.01

0.01

0.00

0.02

0.02

0.02

0.01

0.01

 

 

 

Table 6. Mean Cumulative Radioactivity in All Mineralization Vessel Gas Traps

Test

Soil

Interval

(Days)

Evolved 14CO2

(%)

Volatile 14C Gases

(%)

Total Gases

(%)

Soil 1

32

61

91

120

152

182

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.02

0.04

0.05

0.07

0.08

Soil 2

32

61

91

120

152

182

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.01

0.02

0.03

0.04

0.05

0.00

0.02

0.04

0.05

0.07

0.09

Soil 3

32

61

91

120

152

182

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.01

0.02

0.03

0.04

0.05

0.00

0.02

0.04

0.06

0.07

0.09

Soil 4

32

61

91

120

152

182

0.00

0.01

0.02

0.03

0.03

0.04

0.00

0.01

0.02

0.03

0.04

0.04

0.00

0.02

0.04

0.05

0.07

0.08

 

 

 

 

Table 7. Mean Distribution of Radioactivity from Test Vessels

Test

Soil

Interval

(Days)

Water

Layers

(%)

Combined

Sediment

Extracts

(%)

Combusted

Soil

Solids

(%)

Total

Gases

(%)

Material

Balance

(Recovery %)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

NA

0.1

0.0

0.0

0.0

0.0

0.0

0.0

103.4

105.8

99.3

98.6

96.3

95.1

100.5

95.8

1.1

2.0

1.6

2.0

2.4

2.6

2.1

2.2

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

104.5

107.9

100.9

100.7

98.7

97.7

102.6

98.1

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.0

89.1

102.1

94.8

89.8

96.6

93.2

96.2

92.1

2.6

3.5

3.3

3.6

4.0

4.1

3.8

3.8

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

91.6

105.6

98.1

93.4

100.6

97.4

100.1

96.0

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

NA

0.0

0.0

0.0

0.1

0.0

0.0

0.0

95.5

96.5

92.6

91.1

94.3

95.7

93.8

90.1

2.6

3.1

3.7

3.5

4.9

4.0

4.2

3.9

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

95.0

99.6

96.4

94.7

99.3

99.8

98.1

94.2

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.0

90.0

96.7

93.6

91.9

89.3

93.4

87.3

89.8

2.9

2.8

2.9

3.2

4.4

3.6

3.4

3.4

NA

0.0

0.0

0.0

0.0

0.0

0.0

0.1

92.9

99.5

96.5

95.1

93.7

97.0

90.7

93.3

NA – Not Applicable

 

Table 8. Mean Soil Extraction Efficiencies

Test

Soil

Interval

(Days)

Mean

DPM in

Comb. Soil

Extracts

Mean

DPM in

Soil

Solids

Mean

DPM in

Soil

Sample

Proportion

In/on

Solids

(%)

Mean

Extraction

Efficiency

(%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

11786796

12071011

11324398

11198084

11004845

10811351

11434600

10867271

124314

224071

187487

232648

275033

297287

234082

250257

11911110

12303936

11512417

11433067

11281371

11109089

11669706

11118931

1.0

1.8

1.6

2.0

2.4

2.7

2.0

2.3

99.0

98.1

98.4

97.9

97.5

97.3

98.0

97.7

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

10151650

11668153

10810553

10220103

10973690

10681752

10928808

10512733

291997

398488

373237

405301

452779

474774

437067

437228

10443647

12066798

11184097

10625651

11426921

11156997

11366287

10950744

2.8

3.3

3.3

3.8

4.0

4.3

3.8

4.0

97.2

96.7

96.7

96.2

96.0

95.7

96.2

96.0

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

10591991

11020261

10591810

10429650

10763792

10935012

10673887

10251547

294400

352709

426868

399692

560761

458662

480219

446977

10886391

11373066

11019301

10833878

11333084

11395004

11156101

10700515

2.7

3.1

3.9

3.7

4.9

4.0

4.3

4.2

97.3

96.9

96.1

96.3

95.0

96.0

95.7

95.8

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

10217138

11092015

10633424

10510338

10215858

10678878

9984150

10268187

344917

318824

333863

364494

499320

415058

385401

388785

10552056

11411008

10967542

10874851

10715408

11094264

10370095

10657436

3.2

2.8

3.0

3.4

4.7

3.7

3.7

3.6

96.8

97.2

97.0

96.6

95.3

96.3

96.3

96.3

 

Table 9. Mean Chloroform Extraction Results

Test

Soil

Interval

(Days)

Mean

DPM in

Conc.

Soil Extracts

Mean

DPM in

Chloroform

Extracts

Mean

DPM in

Aqueous

Fractions

Recovery

%

% in

Aqueous

Fractions

Mean

Extraction

Efficiency

(%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

11764818

10699181

10035853

10138838

9994961

10100748

9959962

10386560

11847724

10543665

10593007

10508927

10504496

10144895

9406999

10107760

4986

126115

4834

11543

5545

12121

431910

94291

100.8

99.7

105.6

103.7

105.2

100.6

99.0

98.2

0.0

1.2

0.0

0.1

0.1

0.1

4.2

0.9

100.0

98.8

100.0

99.9

99.9

99.9

95.8

99.1

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

8480418

10273270

10244022

8891377

10314738

10061562

10217082

10114832

8332737

10514367

10202407

9624253

10404598

10303730

10108471

10052771

18947

4215

2255

11442

216771

5394

1896

18049

98.2

102.5

99.7

108.5

103.4

102.4

99.0

99.6

0.3

0.0

0.0

0.1

2.0

0.1

0.0

0.2

97.7

100.0

100.0

99.9

98.0

99.9

100.0

99.8

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

10512618

9817289

9917273

9740174

10248083

9067497

9401930

9745450

9624067

9986942

10194283

8581573

10155211

9948605

9520535

9113277

73345

4726

7566

835771

163574

25039

71716

194462

92.2

101.8

102.9

96.8

100.6

110.2

102.1

95.5

0.8

0.0

0.1

8.9

1.6

0.2

0.8

2.1

99.2

100.0

99.9

91.1

98.4

99.8

99.2

97.9

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

10075209

7723379

10006780

10251688

10047018

9401960

9449130

9761775

9873335

10020570

10013533

9385400

9617600

9674928

8987129

9425953

7696

2626

25200

432080

249270

113639

236817

216560

98.1

129.9

100.4

95.7

98.2

105.0

97.6

98.8

0.1

0.0

0.3

4.3

2.5

1.3

2.6

2.2

99.9

100.0

99.7

95.7

97.5

98.7

97.4

97.8

 

Table 10. Mean Procedural Recoveries

Test

Soil

Interval

(Days)

Mean Recovery

Combined

Soil Extract

Concentration

(%)

Mean

Recovery

Chloroform

Extraction

(%)

Mean Recovery

Chloroform

Extract

Concentration

Overall

Mean

Extraction

Efficiency (%)

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

105.3

93.9

93.6

94.6

94.5

100.3

94.6

101.5

100.8

99.7

105.6

103.7

105.2

100.6

99.0

98.2

95.0

99.4

102.9

100.8

106.1

107.1

107.9

106.6

100.8

93.1

101.5

98.8

105.4

108.0

101.0

106.3

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

90.6

92.9

98.8

90.1

97.4

100.2

101.5

101.8

98.2

102.5

99.7

108.5

103.4

102.4

99.0

99.6

102.5

102.6

96.5

105.4

105.0

102.2

105.0

107.2

91.1

97.6

95.0

102.9

105.5

104.9

105.4

108.7

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

105.3

94.0

97.5

97.8

99.5

88.9

95.0

104.1

92.2

101.8

102.9

96.8

100.6

110.2

102.1

95.5

112.1

107.6

103.6

105.6

104.7

106.4

104.9

104.9

109.0

102.9

103.9

99.8

104.7

103.9

101.7

104.3

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

104.0

74.0

98.1

101.9

101.8

94.0

100.5

103.7

98.1

129.9

100.4

95.7

98.2

105.0

97.6

98.8

107.4

107.5

102.8

106.1

102.8

101.9

104.6

103.7

109.6

103.2

101.2

103.4

102.8

100.3

102.6

106.3

 

 

 

 

 

 

 

Table 11. Mean Distribution of Parent and Other 14C Products in Soil Extracts

Test

Soil

Interval

(Days)

Aqueous

Fraction

(%)

Before

(1.0-11.3)

(%)

Parent

(11.3-12.3)

(%)

After

(12.3-16.0)

(%)

Total

% of

Sample

Total %

Other 14C

Products

 

Soil 1

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.1

0.1

0.1

0.1

0.1

0.2

0.4

0.9

2.1

1.6

0.6

0.2

0.3

0.7

0.9

0.2

95.2

95.4

95.8

97.3

96.3

93.9

96.4

96.4

1.6

1.1

1.8

0.3

0.9

2.7

0.3

0.2

99.0

98.2

98.4

98.0

97.6

97.4

98.0

97.7

3.8

2.8

2.5

0.6

1.2

3.5

1.6

1.3

 

Soil 2

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.3

0.0

0.0

0.1

0.1

0.1

0.0

0.2

0.3

0.4

0.0

1.1

0.3

1.6

0.5

0.0

92.0

91.8

95.8

94.0

94.9

93.4

95.3

95.5

4.6

4.5

0.9

1.1

0.8

0.7

0.3

0.3

97.2

96.7

96.6

96.2

96.1

95.7

96.1

96.0

5.2

4.8

0.9

2.2

1.2

2.3

0.8

0.5

Soil 3

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.2

0.1

0.1

0.1

0.5

0.3

0.1

0.0

2.9

0.2

1.4

1.0

0.7

1.1

0.2

0.7

91.5

95.9

93.3

92.1

92.8

92.7

95.3

95.1

2.6

0.8

1.3

3.0

1.1

1.9

0.1

0.0

97.3

96.9

96.2

96.2

95.1

96.0

95.6

95.8

5.8

1.0

2.8

4.1

2.3

3.2

0.4

0.7

Soil 4

 

 

 

 

 

 

Mineral

0

32

61

91

120

152

182

182

0.1

0.0

0.3

0.3

0.0

0.1

0.2

0.0

0.8

0.7

0.3

1.3

0.2

0.8

0.3

1.5

94.8

94.7

95.9

93.5

93.7

95.2

93.5

93.6

1.1

1.8

0.5

1.6

1.4

0.1

2.4

1.3

96.8

97.1

97.0

96.7

95.3

96.3

96.3

96.4

2.0

2.5

1.0

3.1

1.6

1.0

2.8

2.8

 

 

 

 

Table 12. Disappearance of DBDPEthane from Soil 1

Interval

(Days)

Soil Extracts

Mean %

ug/kg

0

32

61

91

120

152

182

95.2

95.4

95.8

97.3

96.3

93.9

96.4

1.47

1.47

1.48

1.50

1.48

1.45

1.49

 

Table 13. Regression Analysis of DBDPEthane in Soil 1 Extracts: Simple First-Order Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

95.76

0.811

4.133E-10

93.67

97.84

K_Parent

1.427E-19

7.733E-05

0.5

-0.0001988

0

 

 

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

4.858E+18

1.614E+19

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.006144

9.055E-06

Parent

0.006144

9.055E-06

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8348

K_Parent

0.8348

1

 

 

  

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

95.2

95.76

-0.5571

32

95.4

95.76

-0.3572

61

95.8

95.76

0.0428

91

97.3

95.76

1.543

120

96.3

95.76

0.5427

152

93.9

95.76

-1.857

182

96.4

95.76

0.6427

 

 

Table 14. Disappearance of DBDPEthane from Soil 2

Interval

(Days)

Soil Extracts

Mean %

ug/kg

0

32

61

91

120

152

182

92.0

91.8

95.8

94.0

94.9

93.4

95.3

1.42

1.41

1.48

1.45

1.46

1.44

1.47

 

 

 

 

 

Table 15. Regression Analysis of DBDPEthane in Soil 2 Extracts: Simple First-Order Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

93.89

1.183

3.011E-09

90.84

96.93

K_Parent

2.741E-16

0.0001151

0.5

-0.0002958

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.223

5

Parent

1.223

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

2.528E+15

8.4E+15

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.3579

4.65E-05

Parent

0.3579

4.65E-05

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8348

K_Parent

0.8348

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

92

93.89

-1.8862

32

91.8

93.89

-2.086

61

95.8

93.89

1.914

91

94

93.89

0.1142

120

94.9

93.89

1.014

152

93.4

93.89

-0.4859

182

95.3

93.89

1.414

 

 

Table 16. Disappearance of DBDPEthane from Soil 3

Interval

(Days)

Soil Extracts

Mean %

ug/kg

0

32

61

91

120

152

182

91.5

95.9

93.3

92.1

92.8

92.7

95.3

1.41

1.48

1.44

1.42

1.43

1.43

1.47

 

  

Table 17. Regression Analysis of DBDPEthane in Soil 3 Extracts: Simple First-Order Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

93.37

1.229

3.73E-09

90.21

96.53

K_Parent

2.055E-12

0.0001202

0.5

-0.0003089

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.29

5

Parent

1.29

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

3.37E+11

1.121E+12

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.04802

1.63E-05

Parent

0.04802

1.63E-05

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8348

K_Parent

0.8348

1

 

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

91.5

93.37

-1.871

32

95.9

93.37

2.529

61

93.3

93.37

-0.07149

91

92.1

93.37

-1.272

120

92.8

93.37

-0.5715

152

92.7

93.37

-0.6716

182

95.3

93.37

1.928

 

Table 18. Disappearance of DBDPEthane from Soil 4

Interval

(Days)

Soil Extracts

Mean %

ug/kg

0

32

61

91

120

152

182

94.8

94.7

95.9

93.5

93.7

95.2

93.5

1.46

1.46

1.48

1.44

1.44

1.47

1.44

  

 

Table 19. Regression Analysis of DBDPEthane in Soil 3 Extracts: Simple First-Order Statistics

Estimated Values:

Parameter

Value

Sigma

Prob.>t

Lower CI

Upper CI

Parent_O

95.02

0.6385

1.3E-10

93.38

96.66

K_Parent

6.325E-05

6.158E-05

0.1757

-9.504E-05

0

 

Chi-Squared:

Parameter

Error %

Degrees of

Freedom

All data

1.005

5

Parent

1.005

5

 

Decay Times:

Compartment

DT50 (Days)

DT90 (Days)

Parent

1.096E+04

3.641E+04

 

Additional Statistics:

Parameter

r2 (Obs. v. Pred.)

Efficiency

All data

0.1743

0.1743

Parent

0.1743

0.1743

 

Parameter Correlation:

 

Parent_O

K_Parent

Parent_O

1

0.8335

K_Parent

0.8335

1

Observed v. Predicted:

Time (Days)

Value

(% of Dose)

Predicted

Value

Residual

0

94.8

95.02

-0.2186

32

94.7

94.83

-0.1265

61

95.9

94.65

1.253

91

93.5

94.47

-0.9674

120

93.7

94.3

-0.6003

152

95.2

94.11

1.09

182

93.5

93.93

-0.4313

 

 

Conclusions:
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.
Executive summary:

This study was conducted to assess the potential mineralization and transformation of DBDPEthane in anaerobic soil systems. Four types of soil were utilized in the study. Soils were dosed with 14C-ring labeled DBDPEthane at a nominal concentration of 1.5 mg/kg dry soil. Test systems were incubated at approximately 20 ºC for up to 182 days. Aerobic conditions were maintained for the first 32 days 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. On day 32, the soils were flooded, purged with nitrogen, and sealed to maintain anaerobic conditions. Duplicate test chambers of each soil type were sacrificed on months 0, 1, 2, 3, 4, 5 and 6. The water layers, soil extracts and soil solids were analyzed separately for total radioactivity by liquid scintillation counting (LSC).

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. 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. Through all test intervals, the mean maximum percentages of radioactivity recovered as other products were 3.9%, 5.2%, 5.8% and 3.1% for soils 1, 2, 3 and 4, respectively. The amount of impurities in the test substance applied to the soils was 5.5%, based on the certificate of analysis. The other products observed in the soil extracts were attributed to impurities in the test substance, rather than transformation products. There were no distinct, consistent transformation product peaks observed during the study. The mean fractions of radiolabeled residues that could not be extracted from soils 1, 2, 3 and 4 at the end of the test were 2.1%, 3.8%, 4.2% and 3.4%, respectively. The maximum cumulative amount of mineralization or ultimate biodegradation observed was <0.1% is all four soils. Mean material balances (recoveries) ranged from 90.7% to 107.9% throughout the study.

Endpoint:
biodegradation in soil, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June - October 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guidline/GLP-compliant study performed by an experienced laboratory
Qualifier:
according to guideline
Guideline:
other: OECD 302 D, Proposed, Inherent Biodegradability
Principles of method if other than guideline:
Pre-exposed soil/activated sludge were addied to mineral test media and incubated under aerobic conditions for 90 d. Hexadecane served as the positive control. Replicate chambers were analyzed at intervals during the test for inorganic carbon and 14C-parent and metabolites. Conditions were optimized in favor of biodegradation.
GLP compliance:
yes
Test type:
laboratory
Specific details on test material used for the study:
The test substance was received from Albemarle Corporation on November 28, 2007 and was
assigned Wildlife International, Ltd. identification number 8303. The following is a description of
the test substance used in this study:
Identity: Saytex® 8010
Lot Number: S17009C
Physical Description: Solid
Purity: 97.6%
Expiration Date: November 26, 2012
Storage Conditions: Room temperature in a closed container
Carbon Content: 17.30%
The test substance was administered to the treatment group test chambers by direct weight
addition. Direct weight addition is an appropriate route of administration for poorly water-soluble
materials. The amount of test substance used to dose the treatment group test chambers, was
calculated based on the carbon content. The carbon content of the test substance was determined
based on the molecular weight and chemical formula of the test substance.
The radiolabeled form of the test substance was received from Perkin Elmer on February 23,
2010 and was assigned Wildlife International, Ltd. identification number 9412. The following is a
description of the radiolabeled test substance used in this study:
Name: 1,2-Bis[pentabromophenyl]ethane, [Phenyl-14C[U]]
Lot number: 3626190
Formula weight: 972
Specific activity: 32.4 mCi/mmol, (33.3 μCi/mg)
Radiochemical purity: 94.5%
Sample form: solid
Radiolabelling:
yes
Oxygen conditions:
aerobic
Soil classification:
not specified
Year:
2010
Details on soil characteristics:
Soil was collected from Claiborne, MD and used the same day of collection. Activated sludge was collected from the Cambridge Wastewater Treatment Facility, Cambridge, MD, which treats predominantly residential wastes. The sludge was seved using a 2-mm screan and aerated until use.
Soil No.:
#1
Duration:
> 0 - < 90 d
Soil No.:
#2
Duration:
> 0 - < 90 d
Soil No.:
#1
Initial conc.:
20 other: mg C/L
Soil No.:
#2
Initial conc.:
70 other: ug/L
Parameter followed for biodegradation estimation:
radiochem. meas.
Soil No.:
#1
Temp.:
19.5 - 22.3 degrees C
Details on experimental conditions:
The aerobic inocula were pre-exposed to DBDP-Ethane prior to use. For each group, soil (1.0 g), activated sludge (2 ml) and yeast extract (50 mg) were added to test medium (1 L). The pH was adjusted to 7.4 ± 0.2, and DBDP-Ethane added at concentrations equivalent to 4, 8, and 8 mg C/L on days 0, 7 and 11, respectively. The contents were mixed with a magnetic stirrer and allowed gaseous exchange with a foam stopper for the duration of the pre-exposure. On day 14, the inoculum was screened (filter paper) and aerated overnight to reduce the organic carbon content. On the day of use, the inoculum was sparged with CO2-free air for 1 hour, and the dissolved organic (DOC) and inorganic (DIC) levels measured.
Key result
Soil No.:
#1
% Degr.:
0
Parameter:
inorg. C analysis
Sampling time:
90 d
Remarks on result:
not determinable
Key result
Soil No.:
#2
% Degr.:
0
Parameter:
radiochem. meas.
Sampling time:
90 d
Remarks on result:
not determinable
Key result
Soil No.:
#1
DT50:
> 90 d
Temp.:
20 °C
Remarks on result:
other: not calculated
Key result
Soil No.:
#2
DT50:
> 90 d
Temp.:
20 °C
Remarks on result:
other: not calculated
Transformation products:
no
Details on transformation products:
There were no transformation products.
Evaporation of parent compound:
no
Volatile metabolites:
no
Details on results:
Table 1. Inherent aerobic biodegradation results of decabromodiphenyl ethane (DBDP-Ethane) and hexadecane as the test and reference substances, respectively, expressed as inorganic carbon (IC) and percent of theoretical inorganic carbon (TIC) evolved (Mean ± Standard deviation; n=3 chambers/group D 14-73; n = 5 chambers/group D90).

Day IC (mg C/L) % TIC Evolved
Blank Hexadecane DBDP-Ethane Blank Hexadecane DBDP-Ethane
14 1.0 ± 0.1 16.3 ± 0.9 1.2 ± 0.1 NA 76.5 ± 4.4 1.2 ± 0.4
28 1.2 ± 0.4 19.2 ± 1.9 0.9 ± 0.1 NA 90.2 ± 9.6 -1.6 ± 0.5
42 1.6 ± 0.4 22.9 ± 1.9 2.4 ± 0.6 NA 106.3 ± 9.8 4.3 ± 3.1
56 1.9 ± 0.3 23.1 ± 2.0 2.3 ± 0.4 NA 106.1 ± 10.1 2.3 ± 1.9
73 2.6 ± 0.2 23.1 ± 1.8 3.2 ± 0.3 NA 103.1 ± 9.2 3.1 ± 1.4
90 2.9 ± 1.2 23.0 ± 1.9 3.4 ± 0.9 NA 100.1 ± 9.3 2.2 ± 4.5
Overall Mean* 1.9 ± 0.8 21.3 ± 2.9 2.2 ± 1.0 NA 97.0 ± 11.7 1.9 ± 2.0
NA=not applicable.
*Calculated from means.

Results with reference substance:
see results

The test met the validity criteria specified in the guideline. The mean percentage biodegradation of hexadecane was ≥60% ThIC and was reached by Day 14, indicating the inoculum was viable and performed as expected. Further, the mean amount of IC produced by the blank controls at the end of the test was ≤15% of the organic carbon added initially as DBDP-Ethane to the test bottles.  

The mean evolved IC from the hexadecane reference group was substantially greater than either the untreated control or the DBDP-Ethane treatment group on all days while the mean evolved IC in the DBDP-Ethane group was similar to that of the untreated control (Table 1). While bottles treated with hexadecane evolved a mean of 97.0 % ThIC over the study, ThIC evolved from the DBDP-Ethane bottles was similar to the blank controls. Substances are considered to lack inherent biodegradation when <= 20% ThIC is evolved.  

The entire contents of the test chamber were extracted and analyzed for14C-activity. No indication of degradation of [14C]DBDP-Ethane was observed on HPLC/β-RAM analysis. One peak containing the radiolabel was detected. That peak had a retention time consistent with the parent molecule.

Conclusions:
Not inherently biodegradable under optimized conditions over a 90 d period.
Executive summary:

Inherent biodegradation of DBDP-Ethane 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 DBDP-Ethane is unlikely to undergo aerobic biodegradation in the environment or in sewage treatment plants. 

Description of key information

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.


EBP: 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 (note this study is summarized in section 5.6. of IUCLID as it could not be included technically into 5.2.3)

 ​[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 thepredominant 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 evidence 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.    

Key value for chemical safety assessment

Additional information