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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Reference
Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2nd September 2019 to 09 February 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Chemical name: p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline
IUPAC name: 4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline
CAS number: 5026-74-4
Use: Chemical
Molecular formula: C15H19NO4
Molecular weight: 277.3
Physical state: Liquid
Water solubility (20°C): 3.34 g/L

Radiolabelled test item:
Source: Covance
Batch number: NPE/HQ92FF/03
Specific activity: 3.06 GBq/mmol
Radiochemical purity: The radiochemical purity was measured prior to application and was greater than 95%
Storage: -10 to -30°C under nitrogen

Radiolabelling:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
water (not specified)
Details on source and properties of surface water:
Surface water was provided by Covance as part of this study. Water was transported in containers and, upon receipt at the testing facility and prior to use, the surface water was passed through a 0.2 mm sieve and a coarse filter paper (GF/B) or a filter paper (GF/A) only. The surface water was used on the day of collection. Characterization of the surface water was carried out, to GLP, by CEM Analytical Services Ltd., Berkshire, UK. Microbiological assays of the surface water were conducted at Covance as part of this study. Sampling details are shown in Table 1 and characterization data are shown in Table 2 and Table 3.
Duration of test (contact time):
59 d
Initial conc.:
10 µg/L
Initial conc.:
100 µg/L
Parameter followed for biodegradation estimation:
CO2 evolution
radiochem. meas.
Details on study design:
Radiolabeled p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline was applied to surface water at two nominal concentrations of 10 g/L and 100 g/L. The test vessels were attached to air flow lines incorporating volatile traps and incubated with continuous stirring in the dark at 12 ± 2C for periods of up to 59 days prior to analysis. Duplicate samples of treated surface water were taken for analysis at sampling intervals.
Additional samples were established for the determination of the microbiological activity at the start and end of the incubation period and the measurement of the pH and oxygen content of the surface water.
To confirm sufficient microbiological activity in the water, additional samples of surface water were treated with reference item [14C]-benzoic acid and were arranged in flow-through systems designed to trap volatile radiolabelled 14CO2. The systems were incubated in darkness at 12  2C for 14 days prior to analysis.
Prior to conducting the main experiment, a preliminary experiment was conducted to establish the analytical methodology and confirm the sampling schedule.
Reference substance:
other: [14C]-benzoic acid
Test performance:
The total recoveries of radioactivity in the surface water treated with the reference control [14C]-benzoic acid at a concentration of 10 g/L were 95.4 – 98.6% applied radioactivity after 14 days. Direct volatile radioactivity, all associated with 14CO2, accounted for 82.4 – 82.6% applied radioactivity after 14 days.
The test was shown to be valid as the reference control degraded within the expected time interval.

The total recoveries of radioactivity (‘mass balances’, i.e. the sum of radioactivity in the water layer and volatile radioactivity) from samples in the main experiment were between 97.3 to 110.0% applied radioactivity. Volatile radioactivity (14CO2) accounted for a maximum of 15.0% applied radioactivity.
At 10 g/L nominal concentration, the radioactivity in the surface water accounted for a mean of 100.2% applied radioactivity at time zero, then generally declined to a mean of 96.2% applied radioactivity after 59 days incubation. Volatile radioactivity (14CO2) accounted for a maximum of 15.0% applied radioactivity.
At 100 g/L nominal concentration, the radioactivity in the surface water accounted for a mean of 101.0% applied radioactivity at time zero, then generally declined to a mean of 85.6% applied radioactivity after 59 days incubation. Volatile radioactivity (14CO2) accounted for a maximum of 13.3% applied radioactivity.
The total recoveries of radioactivity in the sterile surface water (FS samples) were between 99.6 to 100.6% applied radioactivity . Volatile radioactivity (14CO2) accounted for a maximum of 2.5% applied radioactivity.
Compartment:
water
Remarks on result:
not determinable because of methodological limitations
Key result
Compartment:
water
DT50:
10.2 d
Temp.:
12 °C
Key result
Compartment:
water
DT50:
11.4 d
Temp.:
12 °C
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
Details on transformation products:
A proposed pathway for the transformation of p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline in surface water is shown in an attached document. From the results obtained the main mechanism for degradation was hydrolysis, with some biotic degradation giving rise to carbon dioxide.

Table 3

Microbiological Charaterization of the Surface Water

   Start of incubation (untreated)  End of incubation (untreated)
 Aerobic bacteria  6.06E+06  1.01E+04
 Aerobic bacterial spores  1.09E+04  3.50E+01
 Actinomycetes  <10  <10
 Fungi  <10

 <20

Results are expressed as colony forming units/g

Table 4

Recoveries of Radioactivity from Incubated Surface Water Treated with Reference Contro; [14C]-benzoic acid (10ug/L)

 Time after application

(days)

 Sample Identity  Surface Water  Volatiles  Total recovery
 14

 FC-1

FC-2

Mean

 12.8

16.2

14.5

 82.6

82.4

82.5

 95.4

98.6

97.0

Results are expressed as % applied radioactivity

Table 5

Recoveries of Radioactivity from Incubated Surface Water Treated with [14C]-p-(2,3-Epoxypropoxy)-N,N-Bis(2,3-Epoxypropyl) Aniline (10 μg/L)

 time after application (days)  Sample identity  Surface water  Volatiles  Total recovery
 0

 FTL-1

FTL-2

Mean

 99.4

100.9

100.2

 na

na

na

 99.4

100.9

100.2

 2

 FTL-3

FTL-4

Mean

 101.8

100.6

101.2

 0.2

nd

0.1

 102.0

100.6

101.3

 7

 FTL-5

FTL-6

Mean

 100.0

98.3

99.2

 0.9

2.2

1.6

 100.9

100.5

100.7

 14

 FTL-7

FTL-8

Mean

 100.0

98.3

99.2

 0.9

2.2

1.6

 100.9

100.5

100.7

 30

 FTL-9

FTL-10

Mean

 94.3

93.7

94.0

 3.8

5.0

4.4

 98.1

98.7

98.4

 45

 FTL-11

FTL-12

Mean

 90.7

92.2

91.5

 7.3

5.8

6.6

 98.0

98.0

98.0

 59

 FTL-13

FTL-14

Mean

 97.4

95.0

96.2

 2.4

15.0

8.7

 99.8

110.0

104.9

Results expressed as % applied radioactivity

na not applicable

nd not detected

Table 6

Recoveries of Radioactivity from Incubated Surface Water Treated with [14C]-p-(2,3-Epoxypropoxy)-N,N-Bis(2,3-Epoxypropyl) Aniline

(100 μg/L)

 Time after application (days)  Sample Identity  Surface Water  Volatiles  Total recovery
 0

 FTH-1

FTH-2

Mean

 100.5

101.4

101.0

 na

na

na

 100.5

101.4

101.0

 2

 FTH-3

FTH-4

Mean

 101.1

101.2

101.2

 0.1

0.1

0.1

 101.2

101.3

101.3

 7

 FTH-5

FTH-6

Mean

 100.1

99.2

99.7

 0.7

0.4

0.6

 100.8

99.6

100.2

 14

 FTH-7

FTH-8

Mean

 99.0

99.9

99.5

 1.5

0.9

1.2

 100.5

100.8

100.7

 30

 FTH-9

FTH-10

Mean

 94.6

95.2

94.9

 3.4

3.8

3.6

 98.0

99.0

98.5

 45

 FTH-11

FTH-12

Mean

 89.7

95.0

92.4

 7.8

3.5

5.7

 97.5

98.5

98.0

 59

 FTH-13

FTH-12

Mean

 87.1

84.0

85.6

 13.0

13.3

13.2

 100.1

97.3

98.7

Results expressed as % applied radioactivity

na not applicable

nd not detected

Table 7

Recoveries of Radioactivity from Incubated Sterile Surface Water Treated with [14C]-p-(2,3-Epoxypropoxy)-N,N-Bis(2,3-Epoxypropyl) Aniline

 Application Rate (ug/L)  Sample identity  Surface water  Volatiles  Total Reovery
 10

 FSL-1

FSL-2

Mean

 97.5

98.9

98.2

 2.5

1.2

1.9

 100.0

100.1

100.1

 100

 FSH-1

FSH-2

Mean

 99.9

98.2

99.1

 0.7

1.4

1.1

 100.6

99.6

100.1

Results expressed as % applied radioactivity

Validity criteria fulfilled:
yes
Conclusions:
The test item, p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline, degraded moderately rapidly in the surface water with estimated DT50 values of 10.2 days (at 10 g/L) and 11.4 days (at 100 g/L).
Degradation was observed to polar material and many unidentified components some of which accounted for maximum means of 15.0, 28.5, 7.7, 11.5, 8.4, 8.3 and 12.5% applied radioactivity. Volatile radioactivity (14CO2) accounted for a maximum of 15.0% applied radioactivity.
Tentative identification of four hydrolysis products and their oxidised forms was made. The products were 3-(4-(bis(oxiran-2-ylmethyl)amino) phenoxy)propane-1,2-diol, 3-((4-(oxiran-2-ylmethoxy)phenyl)(oxiran-2-ylmethyl) amino)propane-1,2-diol, 3-((2,3-dihydroxypropoxy)phenyl)(oxiran-2-ylmethyl)amino) propane-1,2-diol and 3,3’-((4-(oxiran-2-ylmethoxy)phenyl)azanediyl) bis(propane-1,2-diol).
Executive summary:

The biodegradation and fate ofp-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) anilinehas been studied at low concentrations in surface water under laboratory conditions. Surface water was treated with [14C]-p-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) anilineat nominal application rates of 10 µg/L and 100 µg/L. Treated surface water samples were attached to air flow lines with traps to collect carbon dioxide and incubated with continuous stirring to maintain aerobic conditions at 12 ± 2°Cin darkness for periods of up to 59 days. 

Total recoveries of radioactivity(mass balances)for samples treated at 10 µg/L and 100 µg/L were between 97.3 and 110.0% applied radioactivity. Carbon dioxide accounted for a maximum of 15.0% applied radioactivity.

Separate sterile samples were treated to provide controls (FS). Total recoveries of radioactivity (mass balances) for samples treated at 10 µg/L and 100 µg/L were 99.6% and 100.6% applied radioactivity, respectively. Carbon dioxide accounted for a maximum of 2.5% applied radioactivity. 

After 59 daysp-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline accounted for 1.0 to 3.8% applied radioactivity.

DT50, DT70 and DT 90 values were as follows:

 Concentration (ug/L ) DT50 (days)  DT70 (days)  DT90 (days)
 10  10.2    33.9
 100  11.4    37.7

Analysis of the surface water samples showed thatp-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) anilinedegraded to 8 major unidentified degradates; polar material and unknowns 1, 3, 7, 10, 13, 14 and 17, accounting for maximums of 16.8, 11.7, 31.4, 10.2, 12.3, 11.9, 9.4 and 13.1% applied radioactivity, respectively. Identification of these degradation products was attempted by mass spectrometry. Tentative identification of four hydrolysis products and their oxidised forms was made. The products were 3-(4-(bis(oxiran-2-ylmethyl)amino) phenoxy)propane-1,2-diol, 3-((4-(oxiran-2-ylmethoxy)phenyl)(oxiran-2-ylmethyl) amino)propane-1,2-diol, 3-((2,3-dihydroxypropoxy)phenyl)(oxiran-2-ylmethyl)amino) propane-1,2-diol and 3,3’-((4-(oxiran-2-ylmethoxy)phenyl)azanediyl) bis(propane-1,2-diol).All other (unidentified) degradation products were present at levels of ≤8.6% applied radioactivity

Description of key information

Data is available from an OECD 309 aerobic mineralisation study which agve DT50 and DT70 values as follows:

DT50 (10ug/L) 10.2 days

DT50 (100ug/L) 11.4 days

DT70 (10ug/L) 17.7 days

DT70 (100ug/L) 19.7 days

Analysis of the surface water samples showed degradation to 8 major unidentified degradates. Tentative identification of four hydrolysis products and their oxidised forms was made. Proposed pathways are available in the relevant end point study record in section 5.2.2.

Key value for chemical safety assessment

Half-life in freshwater:
10.8 d

Additional information