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

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline/GLP-compliant study performed by an experienced contract laboratory

Qualifier:

according to guideline

Guideline:

other: OECD 314C

GLP compliance:

yes

Radiolabelling:

yes

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Anaerobic digester sludge was collected from the Back River Wastewater Treatment Plant (Baltimore, Maryland) five days prior to start of the test, sieved through a 2 mm screen, purged with nitrogen, and held under anaerobic conditions at 35°C. The total sludge solids were determined by combustion after drying, and adjusted to 4.17% by discarding supernatant after centrifugation. The sludge inoculum was prepared by combining equal volumes of mineral salts solution and the adjusted anaerobic digester sludge. The pH (Orion pH/ISE Meter, model: 520A) and total solids concentration of the test inoculum were 7.6 and 20,820 mg/L, respectively. The test inoculum was held at 35°C under anaerobic conditions until used in the test.

Duration of test (contact time):

63 d

Initial conc.:

0.1 mg/L

Based on:

test mat.

Initial conc.:

12 other: Ci/mL

Based on:

test mat.

Test performance:

The test met the validity criteria specified in the guideline. 14C-volatiles evolved from [14C]d-Glucose positive control chambers (n=2/interval) were quantitated at weekly intervals. By the end of the study, evolved [14C]-volatiles from the [14C]d-Glucose chambers totaled 45.29% and 74.83% of the administered dose, indicating the inocula were viable. The majority of the remaining 14C-activity was detected in the solids (20.0 and 29.3%) with lesser amounts in the aqueous layer (7.8 and 8.7%).

Compartment:

other: water / sediment, material (mass) balance

Remarks on result:

other: see below

% Degr.:

0

Parameter:

CH4 evolution

Sampling time:

63 d

% Degr.:

0

Parameter:

CO2 evolution

Sampling time:

63 d

Transformation products:

no

Details on transformation products:

See below.

Evaporation of parent compound:

no

Volatile metabolites:

no

The entire contents, less three 1 mL aliquots each, of two biotic and two abiotic test chambers treated with [¹⁴C]DBDP-Ethane were analyzed on Day 0, 30 and 63 for¹⁴C-activity. Results from the biotic and abiotic chambers were similar when compared by day and fraction. On Day 0, the mean total¹⁴C-activity from the 4 test chambers (2 biotic, 2 abiotic) was 118.1 ± 15.02%. The mean totals on Days 30 and 63 were lower than on Day 0, but similar to one another, e.g. 78.63 ± 5.12% and 76.65 ± 1.14%, respectively. The majority of¹⁴C-activity on all days was associated with the sludge solids. ¹⁴C-volatiles and supplemental extraction of test chambers and solids contributed negligible amounts to the total¹⁴C-activity recovered on any day. Mineralization was not observed.

With respect to analysis for parent compound and metabolites, results from the biotic and abiotic chambers were again similar on all days. HPLC/β-RAM analysis of sludge extracts detected one peak containing the¹⁴C-radiolabel. The peak had a retention time identical to that of the parent compound. 

The mass balance in control and treatment chambers was determined using the triplicate 1 mL samples of Day 0, 30 and 63 sludge and cumulative evolved¹⁴C-volatiles. The sludge samples were centrifuged, the solids fraction combusted, and the¹⁴C-activity in the supernatant (aqueous) and combustion gases determined on Day 63. The mass balance for the[¹⁴C]d-Glucosechambers was similarly determined on Day 63, and was 73.1% and 112.8% of the Day 0 dose (Table 3). Mass balance in the treatment groups were more variable, ranging from 42.1 – 95.1% in the biotic chambers and 36.1 – 155.1% in the abiotic chambers. The greatest variability was observed in the solids fraction, with the lowest value in the biotic Day 63 samples. In contrast, Day 63 solids extraction results (Table 2) were similar in the biotic and abiotic groups and contained a higher percentage of the dose than that of the Day 63 solids measurement, e.g. approximately 76% compared to approximately 42%. The Day 63 solids mass balance in the abiotic chambers (132.8%, 76.0%) was similar to that of the Day 63 solids extraction results (approximately 76%). 

The inability to recover approximately 22% of the anaerobic dose, when using a¹⁴C-labelled test material by an experienced laboratory, illustrates the difficulties encountered in working with DBDP-Ethane.  DBDP-Ethane is highly insoluble in water and most organic solvents and has a pronounced tendency to adsorb to surfaces. These properties suggest adherence to glassware during the incubation and extraction steps contributed to lower than expected recovery. Supplemental extraction of the glassware was unable to recover significant amounts of¹⁴C-activity, and it was not possible to measure¹⁴C-activity on the glassware itself. The majority of the dose was detected in the solids as expected, which raises the possibility that the unaccounted for fraction of the dose was also in this matrix. Incomplete combustion of the sludge solids could have resulted in a lower recovery, however the solids combustion apparatus was routinely tested during the analytical phase and performed properly. Another possible explanation is loss as unrecovered¹⁴C-volatiles, however this is highly unlikely.  DBDP-Ethane is not volatile, and mineralization of a substantial fraction of the dose within the timeframe of the study would be exceptional. 

Distribution of¹⁴C-activity in anaerobic digester sludge treated with¹⁴C-Decabromodipehnyl Ethane.

               

Day	Chamber	^14C-Activity (% of Day 0 Dose)
		Sludge		Supplemental Extraction		Evolved^14C-VOC	Σ
		Extracted	Non-extracted+	Sludge	Test Chamber
0	3-Biotic	92.6	22.6	--*	--	--	115.1
	4-Biotic	101.7	38.1	--	--	--	139.8
	9-Abiotic	99.4	12.3	--	--	--	111.7
	10-Abiotic	93.6	12.1	--	--	--	105.6
	Mean ± SD	96.83 ± 4.42	21.3 ± 12.2	--	--	--	118.05 ± 15.02
30	5-Biotic	73.9	4.4	--	0.5	0.4	79.2
	6-Biotic	69.8	3.5	--	0.5	0.4	74.1
	11-Abiotic	77.8	6.7	--	0.8	0.4	85.6
	12-Abiotic	71.9	2.5	--	0.8	0.3	75.6
	Mean ± SD	73.35 ± 3.41	4.28 ± 1.79	--	0.65 ± 0.17	0.4 ± 0.1	78.63 ± 5.12
63	7-Biotic	73.5	0.9	0.2	0.0	0.8	75.4
	8-Biotic	70.6	2.0	0.6	0.2	0.9	74.2
	13-Abiotic	72.8	1.9	0.3	0.2	0.8	76.1
	14-Abiotic	72.5	2.8	0.1	0.1	1.4	76.9
	Mean ± SD	72.35 ± 1.24	1.9 ± 0.78	0.3 ± 0.22	0.13 ± 0.1	0.98 ± 0.29	75.65 ± 1.14

 ⁺Determined by combustion of sludge after extraction.

^*Not performed or not measured.

Mass balance expressed as percentage of¹⁴C-d-glucose (control) or¹⁴C-decabromodiphenyl ethane administered on Day 0. 

Test Day	Chamber	^14C-Activity (% of Day 0 Dose)
		Solids	Aqueous	Evolved Volatiles	∑
63	1- d-Glucose	20.0	7.8	45.3	73.1
63	2- d-Glucose	29.3	8.7	74.9	112.8
0	3-Biotic	48.5	1.8	--	50.3
0	4-Biotic	93.5	1.6	--	95.1
30	5-Biotic	71.9	1.5	0.4	73.8
30	6-Biotic	72.5	1.8	0.4	74.7
63	7-Biotic	36.5	5.6	0.8	42.9
63	8-Biotic	37.0	4.2	0.8	42.1
0	9-Abiotic	35.6	0.5	--	36.1
0	10-Abiotic	153.6	1.5	--	155.1
30	11-Abiotic	75.1	6.0	0.4	81.5
30	12-Abiotic	72.7	5.3	0.4	78.4
63	13-Abiotic	126.0	6.0	0.8	132.8
63	14-Abiotic	73.3	1.3	1.4	76.0

Validity criteria fulfilled:

yes

Conclusions:

Evidence for the biodegradation of DBDP-Ethane in anaerobic sewage sludge was not observed over a 63 day period.

Executive summary:

Evidence for the biodegradation of DBDP-Ethane 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.

Reference 2

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2009

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Results available as a poster only, but performed by the German UBA in cooperation with the Franunhofer Institute.

Qualifier:

no guideline available

Principles of method if other than guideline:

DBDPEthane dissolved in organic solvents sprayed over the surface of 2 indoor ponds. Concentrations measured in water and sediment at various time points.

GLP compliance:

no

Radiolabelling:

no

Oxygen conditions:

other: water:aerobic; sediment:anaerobic

Inoculum or test system:

natural water / sediment

Duration of test (contact time):

191 d

Initial conc.:

100 other: ng/L

Based on:

test mat.

% Degr.:

0

Parameter:

test mat. analysis

Sampling time:

191 d

Compartment:

water

DT50:

1 - <= 3.8 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: DT90=9-14 d

Compartment:

sediment

DT50:

> 191 d

Type:

other: analysis performed at 191 d

Transformation products:

no

See attached poster.

Validity criteria fulfilled:

not applicable

Conclusions:

After administration to the water surface of 2 indoor ponds, DBDPEthane rapidliy disappeared from water. Degradation in the ponds' anaerobic sediment was not observed 191 d after dosing.

Executive summary:

DBDP-Ethane, dissolved in tetrahydrofurna/toluene/propanol, was applied by spraying onto the water surface of 2 indoor-mesocosm ponds at a dose of 100 ng/L. The ponds' volume ranged from 22 -25 m. DBDP-Ethane's DT50-water ranged from 1 to 3.8 d depending on the kinetic estimation method used. Degradation in anaerobic sediment was not observed over 191 d. BDE 209 also showed no degradation in sediment over 191 d. No formation of lower brominated degradation products of BDE 209 was observed in water or sediment.

Reference 3

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 21, 2013 to February 3, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)

GLP compliance:

yes

Specific details on test material used for the study:

DBDPEthane was received from PerkinElmer Health Sciences 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. A copy of the
certificate of analysis provided by PerkinElmer Health Sciences is available.

Radiolabelling:

yes

Remarks:

14C-ring-labeled DBDPEthane

Oxygen conditions:

aerobic/anaerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

Collected from Brandywine Creek, Pennsylvania and Choptank River, Maryland.

Details on source and properties of sediment:

Collected from Brandywine Creek, Pennsylvania and Choptank River, Maryland.

Duration of test (contact time):

6 mo

Initial conc.:

10.4 other: uCi per test vessel

Based on:

other:

Remarks:

liquid scintillation count

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

This study was conducted to assess the potential transformation of DBDPEthane in aerobic and
anaerobic aquatic sediment systems. Both aerobic and anaerobic sediments and their associated waters
were collected from two sites; Brandywine Creek and Choptank River. Test vessels were dosed with
14C-ring labeled DBDPEthane at a nominal concentration of 10.4 μCi per test vessel or 312 μg per test
vessel. Test systems were incubated at approximately 20 ºC for up to 182 days. Aerobic conditions were
maintained by purging the headspace in each vessel with air, while anaerobic conditions were maintained
by purging with nitrogen. 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 test system
were sacrificed on months 0, 1, 2, 3, 4, 5 and 6. The overlying water layers were decanted and filtered,
and analyzed for total radioactivity by liquid scintillation counting (LSC). The filtered materials from the
water layers were combined with the sediment layers and extracted once using methanol (MeOH). The
MeOH extracts were analyzed by LSC. The remaining solids were extracted four times using
tetrahydrofuran (THF). The THF extracts were combined and analyzed by LSC. The remaining
sediment solids were analyzed separately for total radioactivity by combustion, followed by LSC.

Reference substance:

not required

Compartment:

natural water / sediment: freshwater

% Recovery:

91

Key result

Compartment:

natural water / sediment: freshwater

DT50:

> 6 mo

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Transformation products:

no

Details on results:

Results from Aerobic Brandywine Creek
The mean material balance results from aerobic Brandywine Creek test systems are presented in
Table 8. Material balance results from individual test vessels
ranged from 86.5% to 102.7% throughout the test. On day 0, the mean percent of dosed
radioactivity in the sediment extracts was 90.8%, and 3.8% was bound to the sediment solids. At the end
of the test, the mean amount in the sediment extracts was 95.2%, and 2.7% was bound to the sediment
solids. During the study, the mean sediment extraction efficiency was 94.5% for all 16 samples. The
mean cumulative amount of 14C gas production over the 6-month test period was <0.1%.
The mean distributions of [14C]DBDPEthane and other products in the sediment extracts are
presented in Table 12. The mean amount of parent
(DBDPEthane) was 93.4% on day 0 and 92.0% on day 182. The mean amounts and concentrations of
DBDPEthane are presented in Table 13. 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 sediment solids.
The results from a simple first-order (SFO) decay curve model are presented in Table 14. 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 sediment extracts never dropped below 87%, so the
DT50 was >6 months.
The mean total amount of other products was 1.3% on day 0, and reached a maximum of 5.2% on
days 62 and 182, but none of the individual other product peaks accounted for >1.5% of the dose. The
amount of impurities in the test substance was 5.5%. The other product peaks observed in the sediment
extracts were attributed to impurities, rather than transformation products.
No further attempts were made to identify the other products.

Results from Aerobic Choptank River
The mean material balance results from aerobic Choptank River test systems are presented in Table
8. Material balance results from individual test vessels ranged from
88.6% to 103.5% throughout the test). On day 0, the mean percent of dosed radioactivity
in the sediment extracts was 96.9%, and 1.1% was bound to the sediment solids. At the end of the test,
the mean amount in the sediment extracts was 98.2%, and 1.7% was bound to the sediment solids.
During the study, the mean sediment extraction efficiency was 97.7% for all 16 samples. The mean
cumulative amount of 14C gas production over the 6-month test period was <0.1%.
The mean distributions of [14C]DBDPEthane and other products in the sediment extracts are
presented in Table 12.. The mean amount of parent
(DBDPEthane) was 94.1% on day 0 and 94.1% on day 182. The mean amounts and concentrations of
DBDPEthane are presented in Table 15. 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 sediment solids.
The results from a simple first-order (SFO) decay curve model are presented in Table 16. 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 sediment extracts never dropped below 86%, so the
DT50 was >6 months.
The mean total amount of other products was 3.7% on day 0, and reached a maximum of 7.9% on
day 32, but none of the individual other product peaks accounted for >2% of the dose. The amount of
impurities in the test substance was 5.5%. The other product peaks observed in the sediment extracts
were attributed to impurities, rather than transformation products.
No further attempts were made to identify the other products.

Results from Anaerobic Brandywine Creek
The mean material balance results from anaerobic Brandywine Creek test systems are presented in
Table 8 .balance results from individual test vessels
ranged from 84.0% to 99.3% throughout the test. On day 0, the mean percent of dosed
radioactivity in the sediment extracts was 87.3%, and 3.8% was bound to the sediment solids. At the end
of the test, the mean amount in the sediment extracts was 93.2%, and 1.8% was bound to the sediment
solids. During the study, the mean sediment extraction efficiency was 94.3% for all 16 samples. The
mean cumulative amount of 14C gas production over the 6-month test period was <0.1%.
The mean distributions of [14C]DBDPEthane and other products in the sediment extracts are
presented in Table 12. The mean amount of parent
(DBDPEthane) was 93.0% on day 0 and 91.7% on day 182. The mean amounts and concentrations of
DBDPEthane are presented in Table 17. 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 sediment solids.
The results from a simple first-order (SFO) decay curve model are presented in Table 18. 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 sediment extracts never dropped below 85%, so the
DT50 was >6 months.
The mean total amount of other products was 1.1% on day 0, and reached a maximum of 6.8% on
day 32, but none of the individual other product peaks accounted for >2.5% of the dose. The amount of
impurities in the test substance was 5.5%. The other product peaks observed in the sediment extracts
were attributed to impurities, rather than transformation products.
No further attempts were made to identify the other products.

Results from Anaerobic Choptank River
The mean material balance results from anaerobic Choptank River test systems are presented in
Table 8. Material balance results from individual test vessels
ranged from 88.0% to 103.4% throughout the test.On day 0, the mean percent of dosed
radioactivity in the sediment extracts was 92.3%, and 0.3% was bound to the sediment solids. At the end
of the test, the mean amount in the sediment extracts was 101.3%, and 1.5% was bound to the sediment
solids. During the study, the mean sediment extraction efficiency was 98.5% for all 16 samples. The
mean cumulative amount of 14C gas production over the 6-month test period was <0.1%.
The mean distributions of [14C]DBDPEthane and other products in the sediment extracts are
presented in Table 12.. The mean amount of parent
(DBDPEthane) was 97.9% on day 0 and 94.2% on day 182. The mean amounts and concentrations of
DBDPEthane are presented in Table 19. 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 sediment solids.
The results from a simple first-order (SFO) decay curve model are presented in Table 20. 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 sediment extracts never dropped below 85%, so the
DT50 was >6 months.
The mean total amount of other products was 1.6% on day 0, and reached a maximum of 9.9% on
day 32, but none of the individual other product peaks accounted for >3% of the dose. The amount of
impurities in the test substance was 5.5%. The other product peaks observed in the sediment extracts
were attributed to impurities, rather than transformation products.No further attempts were made to identify the other products.

Table 1. Properties of Sediments and Waters

Parameters	Aerobic Brandywine Creek	Anaerobic Brandywine Creek	Aerobic Choptank River	Anaerobic Choptank River
Date Collected: Water Temp. (°C) Water pH Dissolved Oxygen (mg/O2/L)	Dec. 9, 2013 3.7 7.3  9.9	Dec. 9, 2013 3.5 57.3 5.5	Nov. 12, 2013 8.3 7.31 11.51	Nov. 12, 2013 8.3 7.35 11.65
USDA Textural Class % Sand % Silt % Clay % Organic Carbon % Organic Matter Bulk Density (disturbed) (g/cc) pH in 1:1 soil:water ratio Cation Exchange Capacity (meq/100g) Moisture Content at 1/3 Bar Free Iron Oxide (ppm)	Silty Clay Loam 10 57 33 7.0 12.0  0.55   5.3   9.7     78.9   22120	Silty Clay Loam 18 49 33 5.2 9.0   0.68   5.1   9.3     63.8   21420	Sand 95 3 2 1.0 1.7   1.17   6.3   4.3    6.9   19060	Sand 93 5 2 1.4 2.5   1.08   6.3   5.5    8.8   14920
Moisture Content (Pw) Bulk Density (g/cm^3) Microbial Biomass (ug/g)	118.39%   1.2729   26.4.7	120.06%   1.3888   99.8	72.38%   1.6389   729.6	34.76%   1.8626   140.6

Table 2. Water Layer Characterization Results

Sample Interval	Parameter	Aerobic Brandywine Creek	Aerobic Choptank River	Anaerobic Brandywine Creek	Anaerobic Choptank River
Start of Acclimation	pH D.O. Redox TOC	6.8 7.8 335.8 3.1	6.9 6.6 376.8 3.9	6.9 3.8 340.1 3.5	6.8 3.6 370.0 3.6
Month 0 (Start of Test)	pH D.O. Redox TOC	7.1 5.1 349.0 3.3	6.9 3.9 325.8 7.1	7.4 0.3 319.9 2.6	7.3 0.2 89.3 4.8
Month 1	pH D.O. Redox	7.0 5.0 303.8	7.7 5.2 319.2	7.3 0.2 273.5	7.9 0.3 298.6
Month 2	pH D.O. Redox	7.2 5.7 332.4	7.6 5.8 325.7	6.7 0.3 377.1	6.9 0.4 311.7
Month 3	pH D.O. Redox	6.7 5.7 272.6	7.7 6.1 278.9	6.3 0.3 293.9	7.6 0.2 265.3
Month 4	pH D.O. Redox	6.9 6.4 234.1	7.7 6.2 251.9	6.7 0.3 256.5	7.9 0.1 220.2
Month 5	pH D.O. Redox	6.9 4.7 184.6	7.3 4.6 211.6	6.1 0.4 206.7	7.2 0.4 182.9
Month 6	pH D.O. Redox TOC	6.8 5.2 243.8 5.4	7.7 5.4 239.1 13.6	7.0 0.1 235.7 2.8	7.0 0.1 261.9 6.1

D.O.=dissolved oxygen content in overlying water layer (mg O₂/L)

RedOx=redox potential of water layer (Eh)

TOC=total organic carbon content in water layer (mg C/L)

Table 3. Sediment Layer Characterization Results

Sample Interval	Parameter	Aerobic Brandywine Creek	Aerobic Choptank River	Anaerobic Brandywine Creek	Anaerobic Choptank River
Start of Acclimation	pH Redox TOC	6.2 232.4 6.1	6.8 238.3 1.3	6.4 142.8 4.3	6.7 157.6 0.6
Month 0 (Start of Test)	pH Redox TOC Biomass	7.0 214.0 5.4 44.3	7.0 205.5 1.4 263.2	6.9 -87.4 3.8 0	6.9 -84.5 0.7 83.0
Month 1	pH Redox	6.7 137.5	7.2 124.5	7.0 -122.5	7.1 -84.6
Month 2	pH Redox	6.8 141.3	6.9 186.2	6.4 -96.4	6.6 -53.5
Month 3	pH Redox	6.8 39.3	6.7 81.2	6.4 -76.8	6.9 -51.8
Month 4	pH Redox	6.7 54.6	6.9 119.1	6.8 -44.2	7.2 -23.6
Month 5	pH Redox	6.6 51.3	6.7 59.1	6.4 -78.6	6.7 -83.1
Month 6	pH Redox TOC Black Carbon Biomass	6.9 -20.1 6.2 0.53 56.9	6.9 -27.1 1.4 0.07 180.1	7.0 -152.0 4.1 0.36 6.3	6.8 -177.1 0.6 0.19 41.9

RedOx=redox potential of sediment layer (E_h)

TOC=total organic carbon content in sediment layer (5)

Black carbon-microporous black carbon in sediment layer (%)

Biomass=microbial biomass in sediment layer (ug/g)

Table 4. Sediment RedOx Potentials

Interval	Date	Aerobic Brandywine Creek	Aerobic Choptank River	Anaerobic Brandywine Creek	Anaerobic Choptank River
Day-23 Day-22 Day-17 Day-16 Day-15 Day-14 Day-13 Day-10 Day-8 Day-7 Day-6 Day-3 Day-2 Day-1 Day 0 Day 7 Day 14 Day 21 Day 32 Day 47 Day 62 Day 77 Day 92 Day 105 Day 119 Day 137 Day 152 Day 167 Day 182	November 26, 2013 November 27, 2013 December 2, 2013 December 3, 2013 December 4, 2013 December 5, 2013 December 6, 2013 Decmber 9, 2013 December 11, 2013 December 12, 2013 December 13, 2013 December 16, 2013 December 17, 2013 December 18, 2013 December 19, 2013 December 26, 2013 January 2, 2014 January 9, 2014 January 20, 2014 February 4, 2014 February 19, 2014 March 6, 2014 March 21, 2014 April 3, 2014 April 17, 2014 May 5, 2014 May 20, 2014 June 4, 2014 June 19, 2014	NA NA NA NA NA NA NA NA 131 74 -9 -140 -164 -209 -215 -235 -236 -239 -251 -254 -252 -176 -189 -199 -202 -211 -203 -183 -187	61 59 -153 -193 -253 -246 -247 -256 -235 -255 -254 -237 -258 -255 -257 -238 -247 -254 -248 -258 -255 -229 -228 -228 -225 -226 -228 -230 -230	NA NA NA NA NA NA NA NA 91 -65 -138 -215 -227 -228 -229 -228 -230 -230 -225 -234 -230 -218 -227 -235 -235 -219 -231 -236 -231	128 -133 -256 -258 -256 -257 -257 -263 -250 -251 -251 -246 -246 -244 -245 -244 -246 -240 -246 -227 -232 -247 -249 -242 -252 -258 -251 -244 -246

Redox potentials given in E_h

_{Table 5. Viability Results}

Test Start	Interval	Anaerobic Brandywine Creek	Anaerobic Choptank River
Day 0	Day 7 Day 14 Day 21 Day 28	20.1% 40.7% 54.1% --	13.4% 39.0% 51.4% --
Day 91	Day 7 Day 14 Day 21 Day 28	22.5% 42.2% 51.0% --	26.8% 44.6% 53.9% --
Day 182	Day 7 Day 14 Day 21 Day 28	7.8% 25.4% 40.4% 53.1%	15.9% 41.2% 57.8% --

Results given in cumulative % of applied¹⁴C recovered in gas traps

Table 6. Mean Cumulative Redioactivity in All Transformation Vessel Gas Traps

Test System	Interval (Days)	Volatile ^14C Gases	Evolved ^14CO2	Total Gases
Aerobic Brandywine Creek	32 62 91 119 152 182	0.00% 0.00% 0.00% 0.00% 0.00% 0.00%	0.00% 0.00% 0.01% 0.01% 0.01% 0.02%	0.00% 0.00% 0.01% 0.01% 0.01% 0.02%
Aerobic Choptank River	32 62 91 119 152 182	0.00% 0.00% 0.00% 0.00% 0.00% 0.00%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%	0.00% 0.00% 0.00% 0.01% 0.01% 0.01%
Anaerobic Brandywine Creek	32 62 91 119 152 182	0.00% 0.00% 0.00% 0.00% 0.00% 0.00%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%
Anaerobic Choptank River	32 62 91 119 152 182	0.00% 0.00% 0.00% 0.00% 0.00% 0.00%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%	0.00% 0.00% 0.01% 0.01% 0.01% 0.01%

Table 7. Mean Cumulative Radioactivity in All Mineralization Vessel Gas Traps

Test System	Interval (Days)	Evolved ^14CO2	Volatile ^14C Gases	Total Gases
Aerobic Brandywine Creek	32 62 91 119 152 182	0.01% 0.01% 0.01% 0.01% 0.02% 0.03%	0.00% 0.00% 0.00% 0.01% 0.01% 0.01%	0.01% 0.01% 0.02% 0.02% 0.03% 0.04%
Aerobic Choptank River	32 62 91 119 152 182	0.00% 0.00% 0.01% 0.01% 0.02% 0.02%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%	0.01% 0.01% 0.01% 0.01% 0.02% 0.03%
Anaerobic Brandywine Creek	32 62 91 119 152 182	0.00% 0.00% 0.01% 0.01% 0.02% 0.02%	0.00% 0.00% 0.00% 0.00% 0.01% 0.01%	0.00% 0.00% 0.01% 0.01% 0.02% 0.03%
Anaerobic Choptank River	32 62 91 119 152 182	0.00% 0.00% 0.01% 0.01% 0.01% 0.02%	0.00% 0.00% 0.00% 0.01% 0.01% 0.01%	0.00% 0.00% 0.01% 0.01% 0.02% 0.03%

Table 8. Mean Distribution of Radioactivity from Test Vessels

Test System	Interval (Days)	Water Layers (%)	MeOH Extracts (%)	THF Extracts (%)	Combusted Sediment Solids (%)	Total Gases (%)	Material Balance (Recovery) (%)
Aerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	0.0 0.5 0.0 0.3 0.1 0.0 0.0 0.1	0.0 0.3 0.2 0.3 0.3 0.2 0.4 0.7	90.8 79.8 85.0 90.8 92.5 90.7 95.2 92.1	3.8 6.0 3.1 5.3 6.0 6.7 2.7 6.0	NA 0.0 0.0 0.0 0.0 0.0 0.0 0.0	94.7 86.6 88.5 96.6 98.9 97.6 98.3 99.0
Aerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	0.4 0.5 0.0 0.0 0.0 0.0 0.1 0.1	0.0 0.4 0.3 0.2 0.3 0.2 0.3 0.3	96.9 87.9 87.8 95.3 95.6 93.6 98.2 96.5	1.1 2.9 0.7 2.5 2.2 3.0 1.7 3.3	NA 0.0 0.0 0.0 0.0 0.0 0.0 0.0	98.5 91.7 88.9 98.1 98.2 96.7 100.4 100.2
Anaerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	0.1 0.5 2.1 0.1 0.1 0.1 0.1 0.2	0.0 0.1 0.1 0.1 0.1 0.2 0.1 0.3	87.3 78.7 87.6 89.0 87.2 84.3 93.2 90.8	3.8 5.3 5.2 5.4 4.9 6.5 1.8 6.7	NA 0.0 0.0 0.0 0.0 0.0 0.0 0.0	91.2 84.5 95.1 94.6 92.4 91.2 95.3 97.9
Anaerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	0.6 0.5 0.1 0.1 0.1 0.2 0.2 0.2	0.0 0.1 0.1 0.1 0.1 0.3 0.1 0.6	92.3 86.1 93.9 96.9 93.9 97.7 101.3 85.0	0.3 1.7 0.9 1.2 1.6 1.6 1.5 2.2	NA 0.0 0.0 0.0 0.0 0.0 0.0 0.0	93.2 88.3 95.1 98.4 95.7 99.9 103.0 88.1

NA - Not Applicable

Table 9. Mean Sediment Extraction Effeciencies

Test System	Interval (Days)	Mean DPM in Combined Extracts	Mean DPM in Sediment Solids	Mean DPM in Sediment Layer	Proportion In/On Solids (%)	Mean Extraction Efficiency (%)
Aerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	13299413 18543761 19754234 21114032 21509622 21131760 22240180 21558256	885152 1401069 722328 1225059 1390706 1554446 637408 1398247	14184565 19944830 20476563 22339091 22900329 22686206 22877589 22956503	6.2 7.0 3.5 5.5 6.1 6.9 2.8 6.1	93.8 93.0 96.5 94.5 93.9 93.1 97.2 93.9
Aerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	13523627 20505739 20409701 22231525 22289688 21775167 22920625 22539568	259631 669660 170749 575529 505686 685733 400142 759269	13783258 21175399 20580450 22807055 22795373 22460900 23320766 23298837	1.9 3.2 0.8 2.5 2.2 3.1 1.7 3.3	98.1 96.8 99.2 97.5 97.8 96.9 98.3 96.7
Anaerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	12698410 18285280 20373295 20682796 20314370 19678998 21611489 21184527	883631 1219593 1211298 1249003 1144617 1520042 421070 1553291	13582040 19504872 21584593 21931979 21458987 21199040 22032559 22737818	6.5 6.3 5.6 5.7 5.3 7.2 1.9 6.8	93.5 93.7 94.4 94.3 94.7 92.8 98.1 93.2
Anaerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	13467277 19970111 21819086 22585282 21876710 22734037 23557981 19908964	69672 385845 207158 285585 376812 370921 346889 508902	13536949 20355955 22026243 22870867 22253522 23104957 23904870 20417867	0.5 1.9 0.9 1.2 1.7 1.6 1.5 2.5	99.5 98.1 99.1 98.8 98.3 98.4 98.5 97.5

Table 10. Mean Chloroform Extraction Results

Test System	Interval (Days)	Mean DPM in Conc. Sed. Ext.	Mean DPM in Chloroform Extracts	Mean DPM in Aqueous Fractions	Recovery (%)	Percent in Aqueous Fractions (%)	Mean Extraction Efficiency (%)
ABC             Mineral	0 32 62 91 119 152 182 182	19094531 17840058 17830256 18757120 18038240 17992983 19824375 20650249	17272897 17535295 17259248 18928896 168879549 18932184 19582525 19922217	327313 74751 166491 139449 705738 85874 119745 37498	93.5 98.7 97.9 101.7 97.5 105.7 99.4 96.7	1.8 0.4 1.0 0.7 4.1 0.5 0.6 0.2	96.8 99.6 99.0 99.3 95.9 99.5 99.4 99.8
ACR             Mineral	0 32 62 91 119 152 182 182	20753958 20574258 17069184 19852672 19537934 19265216 21217780 22103148	19137357 19565473 18555183 20131044 19493621 20467864 20548863 21151433	40570 119196 930 109006 58519 8017 4366 687	93.3 95.7 108.7 102.0 100.1 106.3 96.9 95.7	0.2 0.6 0.0 0.5 0.3 0.0 0.0 0.0	98.8 99.4 100.0 99.5 99.7 100.0 100.0 100.0
NBC             Mineral	0 32 62 91 119 152 182 182	20319883 17774160 18707392 18683719 17552768 17633248 20111576 20692768	17013076 16372907 18961450 16600444 14492776 18003061 19966253 19557828	833139 91107 9735 1165286 766789 45668 806 2970	89.5 92.6 101.4 95.1 86.8 102.3 99.3 94.5	4.5 0.6 0.0 6.6 5.0 0.3 0.0 0.0	93.7 99.4 100.0 93.4 95.0 99.7 100.0 100.0
NCR             Mineral	0 32 62 91 119 152 182 182	21191348 19927923 20771030 20628182 19437952 20761760 22195217 19670792	20084589 17533445 20951175 19943992 19554403 20312021 22015100 18118638	19412 163019 1540 269734 22194 578500 1351 645	95.0 88.8 100.9 98.0 100.7 100.6 99.2 92.1	0.1 0.9 0.0 1.3 0.1 2.8 0.0 0.0	99.8 99.1 100.0 98.7 99.9 97.2 100.0 100.0

Table 11. Mean Procedural Recoveries

Test System	Interval (Days)	Mean Recovery Combined Sed. Extract Concentration (%)	Mean Recovery Chloroform Extraction (%)	Mean Recovery Chloroform Extract Concentration (%)	Overall Mean Procedural Recovery (%)
ABC             Mineral	0 32 62 91 119 152 182 182	99.8 103.2 103.2 96.1 97.1 93.3 95.1 103.1	93.5 98.7 97.9 101.7 97.5 105.7 99.4 96.7	106.5 105.9 104.0 104.2 97.6 108.3 106.5 107.8	99.3 107.9 105.0 101.8 92.3 106.8 100.6 107.3
ACR             Mineral	0 32 62 91 119 152 182 182	102.1 107.5 101.0 96.1 97.1 95.3 99.6 104.1	93.3 95.7 108.7 102.0 100.1 106.3 96.9 95.7	109.8 108.0 105.3 105.6 106.2 105.4 106.3 107.4	104.6 111.1 115.6 103.4 103.3 106.7 102.6 107.0
NBC             Mineral	0 32 62 91 119 152 182 182	109.8 106.2 99.7 99.5 98.7 97.9 100.6 105.9	89.5 92.6 101.4 95.1 86.8 102.3 99.3 94.5	104.7 104.5 106.0 102.9 104.6 102.6 104.3 109.7	102.9 102.7 107.1 97.3 898.8 102.7 104.2 109.8
NCR             Mineral	0 32 62 91 119 152 182 182	108.6 105.6 100.7 97.7 98.1 98.4 100.1 106.3	95.0 88.8 100.9 98.0 100.7 100.6 99.2 92.1	105.7 107.7 109.1 111.6 102.4 104.4 108.2 112.8	109.0 101.0 110.8 107.0 101.2 103.3 107.4 110.5

Table 12. Mean Distribution of Parent and Other¹⁴C Products in Sediment Extracts

Test System	Interval (Days)	Polar Sample (%)	Before (1.0-11.3) (%)	Parent (11.3-12.3) (%)	After (12.3-16.0) (%)	Total % of Sample	Total % Other^14C Products
Aerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	0.3* 1.2 0.3* 1.3 0.4* 0.6 1.0 1.0	0.3 0.5 2.1 0.9 0.5 0.6 1.3 1.0	93.4 88.3 91.3 90.3 92.7 90.9 92.0 90.7	0.6 2.9 2.8 2.2 0.2 1.0 2.9 1.1	94.7 92.9 96.4 94.6 93.9 93.0 97.2 93.9	1.3 4.6 5.2 4.3 1.1 2.2 5.2 3.2
Aerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	0.7 1.4 0.4 0.8 0.7 0.2 0.4 0.5	0.5 2.5 0.3 0.3 0.7 0.5 0.8 0.3	94.1 88.9 97.9 94.3 95.1 95.7 94.1 94.5	2.5 4.0 0.5 2.1 1.3 0.6 3.0 1.5	97.8 96.7 99.1 97.4 97.7 96.8 98.3 96.7	3.7 7.9 1.1 3.1 2.7 1.2 4.2 2.2
Anaerobic Brandywine Creek         Mineral	0 32 62 91 119 152 182 182	0.1* 1.2 2.4 0.2* 0.3* 0.6 0.2 0.5	0.3 0.7 0.9 0.3 1.1 0.9 0.6 0.6	93.0 86.9 89.2 90.8 90.5 89.7 91.7 90.7	0.8 4.9 1.9 3.0 2.8 1.6 5.6 1.4	94.1 93.8 94.4 94.3 94.7 92.8 98.0 93.2	1.1 6.8 5.2 3.5 4.1 3.2 6.3 2.5
Anaerobic Choptank River         Mineral	0 32 62 91 119 152 182 182	0.7 1.5 0.3 0.2* 0.3 0.6* 0.2 0.9	0.9 0.7 0.0 0.4 0.4 1.0 0.4 0.1	97.9 88.1 96.3 95.6 96.8 93.3 94.2 95.3	0.0 7.8 2.5 2.5 0.8 3.6 3.7 1.1	99.5 98.1 99.0 98.7 98.3 98.4 98.5 97.4	1.6 9.9 2.7 3.1 1.5 5.1 4.3 2.1

Polar Sample = Overlying Water Layer+MeOH Extract+Aqueous Fraction (except*)

*Results from Aqueous Fraction included in HPLC regions

Parent = Parent in Chloroform Extracts+Parent in Aqueous Fractions

Total Other¹⁴C Products = Total% of Sample - Parent (DBDPEthane)

Table 13. Disappearance of DBDPEthane from Aerobic Brandywine Creek

Interval (Days)	Sediment Extracts
	%	mg/kg
0 32 62 91 119 152 182	93.4 88.3 91.3 90.3 92.7 90.9 92.0	5.84 5.52 5.70 5.64 5.80 5.68 5.75

Table 14. Regression Analysis of DBDPEthane in Aerobic Brandywine Creek

Simple First-Order Model Statistics

Estimated Values:

Parameter	Value	s	Prob.>t	Lower CI	Upper CI
Parent_O	91.27	1.265	4.838E-09	88.02	94.52
K_Parent	1.766E-12	0.0001268	0.5	-0.0003261	0

s = sigma

Chi-Squared

Parameter	Error %	Degrees of Freedom
All data	1.36	5
Parent	1.36	5

Decay Times:

Compartment	DT50 (Days)	DT90 (Days)
Parent	3.926E+11	1.304E+12

Additonal Statistics:

Parameter	r^2(Obs. V. Pred.)	Efficiency
All data	0.00961	6.907E-06
Parent	0.00961	6.907E-06

Parameter Correlation:

	Parent_O	K_Parent
Parent_O	1	0.8343
K_Parent	0.8343	1

Observed v. Predicted:

Time (Days)	Value (% of Dose)	Predicted Value	Residual
0	93.4	91.27	2.129
32	88.3	91.27	-2.971
62	91.3	91.27	0.02851
91	90.3	91.27	-0.9715
119	92.7	91.27	1.428
152	90.9	91.27	-0.3716
182	92	91.27	0.7284

Table 15. Disappearance of DBDPEthane from Aerobic Choptank River

Interval (Days)	Sediment Extracts
	%	mg/kg
0 32 62 91 119 152 182	94.1 88.9 97.9 94.3 95.1 95.7 94.1	4.03 3.80 4.19 4.04 4.07 4.09 4.03

Table 16. Regression Analysis of DBDPEthane in Aerobic Choptank River

Simple First-Order Model Statistics

Estimated Values:

Parameter	Value	s	Prob.>t	Lower CI	Upper CI
Parent_O	94.3	2.052	4.609E-08	89.02	99.58
K_Parent	9.37E-13	0.0001992	0.5	-0.0005121	0.001

 

Chi-Squared:

Parameter	Error %	Degrees of Freedom
All data	2.133	5
Parent	2.133	5

 

Decay Times:

Compartment	DT50 (Days)	DT90 (Days)
Parent	7.391E+11	2.455E+12

 

Additional Statistics:

Parameter	r^2(Obs. V. Pred.)	Efficiency
All data	0.09116	1.355E-05
Parent	0.09116	1.355E-05

 

 Parameter Correlation: 

	Parent_O	K_Parent
Parent_O	1	0.8343
K_Parent	0.8343	1

 

Observed v. Predicted:

Time (Days)	Value (% of Dose)	Predicted Value	Residual
0	94.1	94.3	-0.2
32	88.9	94.3	-5.4
62	97.9	94.3	3.6
91	94.3	94.3	-8.581E-05
119	95.1	94.3	0.7999
152	95.7	94.3	1.4
182	94.1	94.3	-0.2002

Table 17. Disappearance of DBDPEthane from Anaerobic Brandywine Creek

Interval (Days)	Sediment Extracts
	%	mg/kg
0 32 62 91 119 152 182	93.0 86.9 89.2 90.8 90.5 89.7 91.7	5.39 5.03 5.17 5.26 5.24 5.19 5.31

Table 18. Regression Analysis of DBDPEthane in Anaerobic Brandywine Creek

Simple First-Order Model Statistics

Estimated Values:

Parameter	Value	s	Prob.>t	Lower CI	Upper CI
Parent_O	90.26	1.459	1.046E-08	86.51	94
K_Parent	2.745E-13	0.000148	0.5	-0.0003805	0

 

Chi-Squared:

Parameter	Error %	Degrees of Freedom
All data	1.585	5
Parent	1.585	5

 

Decay Times:

Compartment	DT50 (Days)	DT90 (Days)
Parent	2.525E+12	8.387E+12

 

Additional Statistics:

Parameter	r^2(Obs. V. Pred.)	Efficiency
All data	0.01205	6.629E-06
Parent	0.01205	6.629E-06

 

 Parameter Correlation:

 

	Parent_O	K_Parent
Parent_O	1	0.8343
K_Parent	0.8343	1

 

Observed v. Predicted:

Time (Days)	Value (% of Dose)	Predicted Value	Residual
0	93	90.26	2.743
32	86.9	90.26	-3.357
62	89.2	90.26	-1.057
91	90.8	90.26	0.5428
119	90.5	90.26	0.2427
152	89.7	90.26	-0.5573
182	91.7	90.26	1.443

Table 19. Disappearance of DBDPEthane from Anaerobic Choptank River

Interval (Days)	Sediment Extracts
	%	mg/kg
0 32 62 91 119 152 182	97.9 88.1 96.3 95.6 96.8 93.3 94.2	2.89 2.60 2.84 2.82 2.86 2.75 2.78

Table 20. Regression Analysis of DBDPEthane in Anaerobic Choptank River

Simple First-Order Model Statistics

Estimated Values:

Parameter	Value	s	Prob.>t	Lower CI	Upper CI
Parent_O	94.67	2.448	1.089E-07	88.38	101
K_Parent	8.409E-06	0.0002368	0.4865	-0.0006003	0.001

 

Chi-Squared:

Parameter	Error %	Degrees of Freedom
All data	2.534	5
Parent	2.534	5

 

Decay Times:

Compartment	DT50 (Days)	DT90 (Days)
Parent	8.243E+04	2.738E+05

 

Additional Statistics:

Parameter	r^2(Obs. V. Pred.)	Efficiency
All data	0.0002522	0.0002522
Parent	0.0002522	0.0002522

 

Parameter Correlation:

	Parent_O	K_Parent
Parent_O	1	0.8341
K_Parent	0.8341	1

 

Observed v. Predicted:

Time (Days)	Value (% of Dose)	Predicted Value	Residual
0	97.9	94.67	3.228
32	88.1	94.65	-6.547
62	96.3	94.62	1.677
91	95.6	94.6	0.9998
119	96.8	94.58	2.222
152	93.3	94.55	-1.252
182	94.2	94.53	-0.3279

Material Balance                  Water Layers                  Sediment Layer                  

Total Gases

Validity criteria fulfilled:

yes

Conclusions:

DPDPEthane 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.

Executive summary:

This study was conducted to assess the potential transformation of DBDPEthane in aerobic and anaerobic aquatic sediment systems. Both aerobic and anaerobic sediments and their associated waters were collected from two sites; Brandywine Creek and Choptank River. Test vessels were dosed with 14C-ring labeled DBDPEthane at a nominal concentration of 10.4 μCi per test vessel or 312 μg per test vessel. Test systems were incubated at approximately 20 ºC for up to 182 days. Aerobic conditions were maintained by purging the headspace in each vessel with air, while anaerobic conditions were maintained by purging with nitrogen. 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 test system were sacrificed on months 0, 1, 2, 3, 4, 5 and 6. The overlying water layers were decanted and filtered, and analyzed for total radioactivity by liquid scintillation counting (LSC). The filtered materials from the water layers were combined with the sediment layers and extracted once using methanol (MeOH). The MeOH extracts were analyzed by LSC. The remaining solids were extracted four times using tetrahydrofuran (THF). The THF extracts were combined and analyzed by LSC. The remaining sediment solids were analyzed separately for total radioactivity by combustion, followed by LSC.

The overlying water layers and MeOH extracts contained 4.2% on day 62. No further work was done on these fractions. The THF 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 test systems. The mean percentage of radioactivity recovered as DBDPEthane at the end of the 6-month test was >91% in all sediment 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 test systems. Through all test intervals, the mean maximum percentages of radioactivity recovered as other products were 5.2%, 7.9%, 6.8% and 9.9% for the aerobic Brandywine Creek, aerobic Choptank River, anaerobic Brandywine Creek and anaerobic Choptank River test systems, respectively. The other products included the amounts of 14C in the water layers and MeOH extracts, as well as various other peaks observed during HPLC analyses. All of the individual other product peaks represented less than 5% of each sample. The amount of 14C-labeled impurities in the test substance was 5.5%. The other products observed in the sediment 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 fractions of radiolabeled residues that could not be extracted from the sediments at the end of the test were 2.7%, 1.7%, 1.8% and 1.5% for aerobic Brandywine Creek, aerobic Choptank River, anaerobic Brandywine Creek and anaerobic Choptank River test systems, respectively. The maximum cumulative amount of mineralization or ultimate biodegradation observed was less than 0.1% in all four test systems. Mean material balances (recoveries) ranged from 84.5% to 103.0% throughout the study.

Description of key information

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.

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 biodegradation (OECD, 2006), the observed results suggest EBPis unlikely to undergo aerobic biodegradation in the environment or in sewage treatment plants. 

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 EBP 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. EBP did not appear to degrade in any of the four test systems. The mean percentage of radioactivity recovered as EBP at the end of the 6-month test was >91% in all sediment 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 test systems. Through all test intervals, the mean maximum percentages of radioactivity recovered as other products were 5.2%, 7.9%, 6.8% and 9.9% for the aerobic Brandywine Creek, aerobic Choptank River, anaerobic Brandywine Creek and anaerobic Choptank River test systems, respectively. The other products included the amounts of 14C in the water layers and MeOH extracts, as well as various other peaks observed during HPLC analyses. All of the individual other product peaks represented <5% of each sample. The amount of 14C-labeled impurities in the test substance was 5.5%. The other products observed in the sediment 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 fractions of radiolabeled residues that could not be extracted from the sediments at the end of the test were 2.7%, 1.7%, 1.8% and 1.5% for aerobic Brandywine Creek, aerobic Choptank River, anaerobic Brandywine Creek and anaerobic Choptank River test systems, respectively. The maximum cumulative amount of mineralization or ultimate biodegradation observed was <0.1% in all four testsystems. Mean material balances (recoveries) ranged from 84.5% to 103.0% throughout the study.