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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 11 April, 2012 to 06 June, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
On Day 5 a temporary breakdown in the aeration (< 1 d) was noted. On Day 4 and 6 the system was functioning correctly. The study integrity was not adversely affected by the deviation.
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
yes
Remarks:
On Day 5 a temporary breakdown in the aeration (< 1 d) was noted. On Day 4 and 6 the system was functioning correctly. The study integrity was not adversely affected by the deviation.
Qualifier:
according to
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
Deviations:
yes
Remarks:
On Day 5 a temporary breakdown in the aeration (< 1 d) was noted. On Day 4 and 6 the system was functioning correctly. The study integrity was not adversely affected by the deviation.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Source: The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.

Treatment: The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was 3.1 g/L in the concentrated sludge (information obtained from the municipal sewage treatment plant). Before use, the sludge was allowed to settle (45 min) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 17.5 mg/L
Based on:
test mat.
Initial conc.:
12 mg/L
Based on:
other: Total organic Carbon (TOC)
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: 1 L mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B) to (D) and Milli-RO water
Stock solutions of mineral components
A) 8.50 g KH2PO4; 21.75 g K2HPO4; 67.20 g Na2HPO4.12H2O; 0.50 g NH4Cl; dissolved in Milli-Q water and made up to 1 L, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli-Q water and made up to 1 L.
C) 36.40 g CaCl2.2H2O dissolved in Milli-Q water and made up to 1 L.
D) 0.25 g FeCl3.6H2O dissolved in Milli-Q water and made up to 1 L.

- Test temperature: between 21.8 and 22.3°C.
- pH:
At t=0 d: 7.4 - 7.6
At t=28 d: 7.5 – 7.9
- pH adjusted: only before the start of the test from 7.7-7.8 to 7.4-7.6 (adjusted using 1 N HCl).
- Aeration of dilution water: Not before the test, the test is aerated continously
- Suspended solids concentration: The concentration of suspended solids was 3.1 g/L in the concentrated sludge (information obtained from the municipal sewage treatment plant). Before use, the sludge was allowed to settle (45 min) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: 2 L all-glass brown coloured bottles
- Number of culture flasks/concentration:
Test suspension: Containing test substance and inoculum (2 bottles).
Inoculum blank: Containing only inoculum (2 bottles)
Positive control: Containing reference substance and inoculum (1 bottle).
Toxicity control: Containing test substance, reference substance and inoculum (1 bottle).
- Method used to create aerobic conditions:
Synthetic air (a mixture of oxygen (ca. 20%) and nitrogen (ca. 80%)) was sparged through the solutions at a rate of approx 1-2 bubbles per sec (ca. 30-100 mL/min).
- Test performed in open system: Yes
- Details of trap for CO2 and volatile organics if used:
CO2 was trapped in barium hydroxide solution. The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 M standardized HCl (1:20 dilution from 1 M HCl (Titrisol® ampul). Titrations were made every second or third day during the first 10 d, and thereafter at least every fifth day until the 28th d, for the inoculum blank and test suspension. Titrations for the positive and toxicity control were made at least 14 d.

SAMPLING
- Sampling frequency: Titration were made on Day: 3, 6, 8, 10, 14, 17, 22, 27 and 29
- Sampling method: Titration of the whole volume of CO2-absorber

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: Yes


Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
ca. 4
Sampling time:
29 d
Remarks on result:
other: HCl added on Day 28 (last CO2 measurement on Day 29)
Key result
Parameter:
% degradation (CO2 evolution)
Value:
ca. 14
Sampling time:
29 d
Remarks on result:
other: HCl added on Day 28 (last CO2 measurement on Day 29)
Details on results:
The relative biodegradation values calculated from the measurements performed during the test period revealed 4 and 14% biodegradation of the test substance for the duplicate bottles tested. Thus, the criterion for ready biodegradability was not met. In the toxicity control more than 25% biodegradation occurred within 14 d (39%, based on ThCO2). Therefore, the test substance was assumed not to inhibit microbial activity.

Results with reference substance:
The positive control substance was biodegraded by at least 60% (81%) within 14 d.

Theoretical CO2 production: The TOC of the test substance was determined to be 69%. ThCO2 was calculated to be 2.52 mg CO2/mg. The ThCO2 of sodium acetate was calculated to be 1.07 mg CO2/mg.

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the conditions of the modified Sturm test, the test substance was not readily biodegradable.
Executive summary:

The ready biodegradability of the test substance was assessed using the CO2 evolution (modified Sturm) test according to OECD Guideline 301B, in compliance with GLP. In addition, the procedures were designed to meet the test methods of the Commission Regulation (EC) No. 440/2008 of 30 May 2008, Publication No. L142, Part C.4-C and the ISO International Standard 9439, 1999 and ISO Standard 10634, 1995. The substance was tested in duplicate at approximately 17.5 mg/L, corresponding to 12 mg total organic carbon (TOC)/L, during 28 d. Based on the TOC content, the theoretical CO2 demand (ThCO2) of the test substance was calculated to be 2.52 mg CO2/mg. The relative biodegradation values revealed 4 and 14% biodegradation of the test substance for the duplicate bottles tested. Thus, the criterion for ready biodegradability was not met. In conclusion, the test substance is not considered to be readily biodegradable in this study (Desmares-Koopmans, 2012).

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From16 July , 2014 to 15 September, 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
yes
Remarks:
minor: Ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound).
Qualifier:
according to
Guideline:
ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)
Deviations:
yes
Remarks:
minor: Ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound).
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
minor: Ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound).
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
River water was sampled from the Rhine near Heveadorp, The Netherlands (10-07-2014). The nearest plant (Arnhem-Zuid) treating domestic waste water biologically was 3 km upstream. The river water was aerated for 7 d before use to reduce the endogenous respiration. River water without particles was used as inoculum. The particles were removed by sedimentation after 1 d while moderately aerating. The inoculum was not pre-adapted to the test substance.
Duration of test (contact time):
ca. 60 d
Initial conc.:
4 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Test bottles
The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.

Nutrients, stocks and administration
The river water used in the Closed Bottle test was spiked per liter of water with 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.3 mg Na2HPO4.2H2O, 22.5 mgMgSO4.7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3.6H2O. Ammonium chloride was not added to the river water to prevent nitrification. Test substance was administered using a stock emulsion prepared in deionized water with polyalkoxylate alkylphenol both at a concentration of 1.0 g/L. Additional control bottles contained polyalkoxylate alkylphenol. Sodium acetate was added to the bottles using a stock solution of 1.0 g/L.

Test procedures
Use was made of 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance and surfactant, and 10 bottles containing river water with surfactant. The concentrations of the test substance, surfactant and sodium acetate in the bottles were 4.0, 4.0 and 6.7 mg/L, respectively. The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at Day 7, 14, 21, and 28. The Closed bottle test was prolonged by measuring the course of the oxygen decrease in the bottles of Day 28 using a special funnel and oxygen electrode.
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 25
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 46
Sampling time:
60 d
Details on results:
Theoretical oxygen demand (ThOD)
The calculated theoretical oxygen demand (ThOD) of the main component was 1.9 mg/mg. All other components present in the test substance (information of the sponsor) do have comparable ThODs. The ThOD of sodium acetate was 0.8 mg/mg.

Toxicity
Inhibition of the degradation of a well-degradable compound, sodium acetate by the test substance in the closed bottle test was not determined because possible toxicity of test substance to microorganisms degrading acetate is not relevant. Inhibition of the endogenous respiration of the inoculum by the test substance was not detected. Therefore, no inhibition of the biodegradation due to the "high" initial concentration of the test substance is expected.

Test conditions
The pH of the media was 8.0 at the start of the test. The pH of the medium at Day 28 was 7.9 (controls) and 7.8 (test). Temperatures were within the prescribed temperature range of 22 to 24°C.

Validity of the test
The validity of the test is demonstrated by an endogenous respiration of 1.5 mg/L at Day 28. Furthermore, the differences of the replicate values at Day 28 were less than 20%. The biodegradation percentage of the reference substance, sodium acetate, at Day 14 was 83. Finally, the validity of the test was shown by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Biodegradability
The test substance was biodegraded by 25% at Day 28 in the Closed Bottle test. In the prolonged Closed Bottle test this substance was biodegraded by 46% at Day 60. These results demonstrate that the test substance is inherently biodegradable.
Results with reference substance:
The biodegradation percentage of the reference substance, sodium acetate, at Day 14 was 83.

Table 1: Oxygen consumption (mg/L) and the percentages biodegradation of the test Substance (BOD/ThOD) and reference substance (BOD/ThOD) in the Closed Bottle test

Time (d)

Oxygen consumption (mg/L)

Biodegradation (%)

Test substance

Reference substance

Test substance

Reference substance

0

0.0

0.0

0

0

7

0.3

4.2

4

78

14

0.4

4.5

5

83

21

0.8

 

11

 

28

1.8

 

25

 

42

1.8

 

25

 

60

3.5

 

46

 

Validity criteria fulfilled:
yes
Interpretation of results:
other: Not readily biodegradable, but results on Day 60 indicate inherent biodegradation potential
Conclusions:
Under the conditions of the study, the test substance is not readily biodegradable, but can be considered to be inherently biodegradable.
Executive summary:

A study was conducted to determine the inherent biodegradability of the test substance according to an extended version of OECD Guideline 301D (prolonged closed bottle test) , in compliance with GLP. The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers. There were 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance and surfactant, and 10 bottles containing river water with surfactant. The concentrations of test substance, surfactant and sodium acetate in the bottles were 4.0, 4.0 and 6.7 mg/L, respectively. No reduction in the endogenous respiration was observed at Day 7. The test substance was therefore considered to be non-inhibitory to the inoculum. The test was valid, as shown by an endogenous respiration of 1.5 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 83% of its theoretical oxygen demand after 14 d. Oxygen concentrations remained >0.5 mg/L in all bottles during the test period. The test substance was biodegraded by 25% at Day 28 and by 46% at Day 60. Under the conditions of the study, the test substance can therefore be considered inherently biodegradable (Ginkel, 2014).

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction from a well-known and acknowledged tool. See below under ''attached background material section' for methodology and QPRF.
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs: Chapter R.6. QSARs and grouping of chemicals
Principles of method if other than guideline:
Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation), the ultimate half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted-average value based on mole fractions.
Specific details on test material used for the study:
Input data for the model: SMILES of the individual constituents:
1) di-TMPTTA: CCC(COCC(CC)(COC(=O)C=C)COC(=O)C=C)(COC(=O)C=C)COC(=O)C=C
2) dimer di-TMPTA + di-TMPTTA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
3) di-TMPTA: CCC(CO)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
4) di-TMPTTA + AA: CCC(COCC(CC)(COC(=O)C=C)COC(=O)C=C)(COC(=O)CCOC(=O)C=C)COC(=O)C=C
5) dimer di-TMPTA + di-TMPTA: CCC(CO)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)CCOCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
6) dimer di-TMPTA + di-TMPTTA + AA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)CCOC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
7) Trimer AA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
8) di-TMPDA: CCC(CO)(COCC(CC)(CO)COC(=O)C=C)COC(=O)C=C
9) dimer di-TMPTA + di-TMPDA: CCC(CO)(COCC(CC)(COCCC(=O)OCC(CC)(COCC(CC)(CO)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C

*All constituents present at >5% have been taken into account for QSAR modelling.
Key result
Parameter:
half-life in days (QSAR/QSPR)
Remarks:
Ultimate half-life (weighted average)
Value:
ca. 53
Remarks on result:
other: according to CATALOGIC 301C v.11.15
Details on results:
For detailed results and domain evaluation, kindly refer the attached QPRF in attached background material section of IUCLID.

Results:

Constituent (acronyms)

Boundary composition (% w/w)

Mole fraction Xi = (mi/Mi)/∑ (mi/Mi)

CATALOGIC 301C ultimate half-life

CATALOGIC 301C Ultimate half-life (in days)

CATALOGIC 301C Ultimate half-life (in days)*xi

Domain evaluation

di-TMPTTA

20-70

0.54

1m14d

44

23.58

ID

dimer di-TMPTA + di-TMPTTA

0-15

0.08

2m20d

80

6.35

ID

di-TMPTA

2-40

0.14

1m24d

54

7.61

ID

di-TMPTTA + AA

0-15

0.11

1m9d

39

4.21

ID

dimer di-TMPTA + di-TMPTA

0-12

0.04

3m3d

93

3.28

ID

dimer di-TMPTA + di-TMPTTA + AA

0-10

0.03

2m9d

69

2.11

ID

Trimer AA

0-10

0.02

3m7d

97

2.18

ID

di-TMPDA

0-14

0.03

2m14d

74

2.40

ID

dimer di-TMPTA + di-TMPDA

0-10

0.02

3m8d

98

1.48

ID

Weighted average (WA)

53

For detailed results and domain evaluation, kindly refer the attached QPRF in attached background material section of IUCLID.

Validity criteria fulfilled:
not applicable
Interpretation of results:
not readily biodegradable
Conclusions:
The predicted ultimate half-life values of the individual constituents ranged from 39 to 113 days, leading to a weighted average half-life value of 53 days for the test substance.
Executive summary:

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC 301C v.11.15. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted ultimate half-life values of the individual constituents ranged from 39 to 113 days, leading to a weighted average half-life value of 53 days for the test substance. All the QSAR predicitons were within the domain of the QSAR model (LMC, 2018). According to the ECHA Guidance Chapter R.11, June 2017, the weighted average half-life value indicates that the test substance is not very persistent (not vP).

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction from a well-known and acknowledged tool. See below under ''attached background material section' for methodology and QPRF.
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs: Chapter R.6. QSARs and grouping of chemicals
Principles of method if other than guideline:
Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation), the ultimate half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted-average value based on mole fractions.
Specific details on test material used for the study:
Input data for the model: SMILES of the individual constituents:
1) di-TMPTTA: CCC(COCC(CC)(COC(=O)C=C)COC(=O)C=C)(COC(=O)C=C)COC(=O)C=C
2) dimer di-TMPTA + di-TMPTTA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
3) di-TMPTA: CCC(CO)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
4) di-TMPTTA + AA: CCC(COCC(CC)(COC(=O)C=C)COC(=O)C=C)(COC(=O)CCOC(=O)C=C)COC(=O)C=C
5) dimer di-TMPTA + di-TMPTA: CCC(CO)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)CCOCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
6) dimer di-TMPTA + di-TMPTTA + AA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)CCOC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
7) Trimer AA: CCC(COCCC(=O)OCC(CC)(COCC(CC)(COCCC(=O)OCC(CC)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)(COCC(CC)(COC(=O)C=C)COC(=O)C=C)COC(=O)C=C
8) di-TMPDA: CCC(CO)(COCC(CC)(CO)COC(=O)C=C)COC(=O)C=C
9) dimer di-TMPTA + di-TMPDA: CCC(CO)(COCC(CC)(COCCC(=O)OCC(CC)(COCC(CC)(CO)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C)COC(=O)C=C

*All constituents present at >5% have been taken into account for QSAR modelling.
Key result
Parameter:
half-life in days (QSAR/QSPR)
Remarks:
Ultimate half-life (weighted average)
Value:
ca. 38
Remarks on result:
other: according to CATALOGIC Kinetic 301F v.13.16
Details on results:
For detailed results and domain evaluation, kindly refer the attached QPRF in attached background material section of IUCLID.

Results:

Constituent (acronyms)

Boundary composition (% w/w)

Mole fraction Xi = (mi/Mi)/∑ (mi/Mi)

CATALOGIC Kinetic 301F v.13.16 - ultimate half-life

CATALOGIC Kinetic 301F v.13.16 - ultimate half-life (in days)

CATALOGIC Kinetic 301F v.13.16 - ultimate half-life *xi

Domain evaluation

di-TMPTTA

20-70

0.54

1m9d

39

21

ID

dimer di-TMPTA + di-TMPTTA

0-15

0.08

1m7d

37

3

ID

di-TMPTA

2-40

0.14

1m7d

37

5

ID

di-TMPTTA + AA

0-15

0.11

30.14

30.14

3

ID

dimer di-TMPTA + di-TMPTA

0-12

0.04

1m10d

40

1

ID

dimer di-TMPTA + di-TMPTTA + AA

0-10

0.03

1m5d

35

1

ID

Trimer AA

0-10

0.02

1m9d

39

1

ID

di-TMPDA

0-14

0.03

1m11d

41

1

ID

dimer di-TMPTA + di-TMPDA

0-10

0.02

1m9d

39

1

ID

Weighted average (WA)

38

For detailed results and domain evaluation, kindly refer the attached QPRF in attached background material section of IUCLID.

Conclusions:
The predicted ultimate half-life values of the individual constituents ranged from 30 to 57 days, leading to a weighted average half-life value of 38 days for the test substance.
Executive summary:

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC Kinetic 301F v.13.16. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted ultimate half-life values of the individual constituents ranged from 30 to 57 days, leading to a weighted average half-life value of 38 days for the test substance. All the QSAR predicitons were within the domain of the QSAR model (LMC, 2018). According to the ECHA Guidance Chapter R.11, June 2017, the weighted average half-life value indicates that the test substance is not persistent (not P) or very persistent (not vP).

Description of key information

Based on the results of the modified Sturm test as well as closed bottle test, the test substance is not readily biodegradable. However, extension of the close bottle test up to Day 60, resulted in 46% degradation, indicating an inherent biodegradation potential of the test substance. This is further supported by the ultimate half-life QSAR predictions, which indicates that the test substance is not very persistent in the environment.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information

Experimental data:

A study was conducted to determine the ready biodegradability potential of the test substance in a CO2 evolution (modified Sturm) test, according to OECD Guideline 301B, in compliance with GLP. In addition, the procedures were designed to meet the test methods of the Commission Regulation (EC) No. 440/2008 of 30 May 2008, Publication No. L142, Part C.4-C and the ISO International Standard 9439, 1999 and ISO Standard 10634, 1995. The substance was tested in duplicate at approximately 17.5 mg/L, corresponding to 12 mg total organic carbon (TOC)/L, during 28 d. Based on the TOC content, the theoretical CO2 demand (ThCO2) of the test substance was calculated to be 2.52 mg CO2/mg. The relative biodegradation values revealed 4 and 14% biodegradation of the test substance for the duplicate bottles tested. Thus, the criterion for ready biodegradability was not met. In conclusion, the test substance is considered to be not readily biodegradable in this study (Desmares-Koopmans, 2012).

Another study was conducted to determine the ready and inherent biodegradability of the test substance in a prolonged close bottle test, according to an extended version of OECD Guideline 301D, in compliance with GLP.The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers. There were 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance and surfactant, and 10 bottles containing river water with surfactant. The concentrations of test substance, surfactant and sodium acetate in the bottles were 4.0, 4.0 and 6.7 mg/L, respectively. No reduction in the endogenous respiration was observed at Day 7. The test substance was therefore considered to be non-inhibitory to the inoculum. The test was valid, as shown by an endogenous respiration of 1.5 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 83% of its theoretical oxygen demand after 14 d. Oxygen concentrations remained >0.5 mg/L in all bottles during the test period. The test substance was biodegraded by 25% at Day 28 and by 46% at Day 60. Under the conditions of the study, the test substance is not readily biodegradable, but can be considered inherently biodegradable (Ginkel, 2014).

QSAR predictions:

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC 301C v.11.15. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted ultimate half-life values of the individual constituents ranged from 39 to 113 days, leading to a weighted average half-life value of 53 days for the test substance.All the QSAR predicitons were within the domain of the QSAR model(LMC, 2018). According to the ECHA Guidance Chapter R.11, June 2017,the weighted average half-life value indicates that the test substance is not very persistent (not vP).

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC Kinetic 301F v.13.16. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) half-life values were predicted for the individual constituents (present at >5%) followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted ultimate half-life values of the individual constituents ranged from 30 to 57 days, leading to a weighted average half-life value of 38 days for the test substance.All the QSAR predicitons were within the domain of the QSAR model(LMC, 2018). According to the ECHA Guidance Chapter R.11, June 2017, the weighted average half-life value indicates that the test substance is not persistent (not P) or very persistent (not vP).

Overall, the ultimate half-life QSAR predictions indicate that the test substance is not very persistent in the environment.