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Environmental fate & pathways

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:
May 12, 1982 - June 12, 1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Qualifier:
according to
Guideline:
other: Biodegradation tests of chemicals by microorganisms (Kanhogyo No.5, Yakuhatsu No. 615, and 49 Kikyoku No. 392)
Principles of method if other than guideline:
Biodegradation tests of chemicals by microorganisms (Kanhogyo No.5, Yakuhatsu No. 615, and 49 Kikyoku No. 392)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Concentration of the activated sludge: 30ppm
Duration of test (contact time):
28 d
Initial conc.:
100 other: ppm
Based on:
test mat.
Parameter followed for biodegradation estimation:
TOC removal
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Additional substrate: No.
- Solubilising agent: Not used.
- Test temperature: 25 degree C

TEST SYSTEM
- Measuring equipment: BOD meter

SAMPLING
BOD was continuously measured by BOD analysis. Direct analysis by HPLC and TOC was conducted after 28 days.
Reference substance:
aniline
Parameter:
other: BOD
Value:
6
Sampling time:
28 d
Details on results:
Biodegradation (%)
oxygen consumption 6%
By a TOC meter ***
By LC ***
***: No calculation due to precipitates formed

Discussion regarding changes of the test compound in water and in the presence of sludge

Coloration and brown precipitates occurred both in water samples and samples with sludge during the test. By LC analysis performed at the end of the test, it was confirmed the complete disappearance of the test compound and the generation of altered compounds with molecular weight of 1000-4000 (calculated by conversion into polystyrene). The spectra of the product showed no absorption peak near 3400 m-1of amino group suggesting oxidation of the test compound in water followed by polymerization of quinone structures.
Validity criteria fulfilled:
not specified
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
p-Aminophenol is not-readily biodegradable under these test conditions.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2017-06-26 to 2017-01-23
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
Temperature range was 19.4 – 21.6 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range, this is considered as uncritical concerning the outcome of the study.
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
30. May 2008
Deviations:
yes
Remarks:
Temperature range was 19.4 – 21.6 °C instead of 20.0 – 24.0 °C. As degradation of the positive control was in the normal range, this is considered as uncritical concerning the outcome of the study.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sludge was collected from the aeration basin of the sewage treatment plant, Maxeville WWTP, 54320, France, 1 day before the start of the test.
Date of collection: 24. Aug. 2017, batch no: 20170824.
- Pretreatment: The same day of the collection, the pre-treatment of the activated sludge was performed.
The sludge was washed by threefold centrifugation for 10 minutes at 1100 x g. After centrifugation the supernatant was removed and the sludge was resuspended in mineral medium and after the third centrifugation filtrated using a stainless steel sieve (100 μm diameter). It was then aerated. The dry matter was determined as 3020 mg suspended solids/L.
- Concentration of sludge: concentration in the test 30.0 mg dry matter/L.
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
other: Content of organic carbon (calculated from TC/IC measurement)
Initial conc.:
16.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: The medium was prepared with the stock solutions. The stock solution of the positive control was prepared and its DOC was measured. The inoculum was taken from its source, washed, aerated and the dry matter was determined.
The test vessels were filled with medium and inoculum. Then, all flasks were aerated for 72 hours with purified, CO2-free, moistened air to purge the system of CO2.
Composition:
Solution a 10 mL
Solution b 1 mL
Solution c 1 mL
Solution d 1 mL
H2O demin. ad 1000 mL
Solution a:
Potassium dihydrogenephosphate (KH2PO4) 8.5 g
Di-potassium hydrogenephosphate (K2HPO4) 21.75 g
Di-sodiumhydrogenephosphate dihydrate (Na2HPO4*2H2O) 33.4 g
Ammonium chloride (NH4Cl) 0.5 g
H2O demin. ad 1000 mL
The pH was 7.4
Solution b:
Calcium chloride dihydrate (CaCl2*2H2O) 27.5 g
H2O demin. ad 1000 mL
Solution c:
Magnesium sulfate heptahydrate (MgSO4*7H2O) 22.5 g
H2O demin. ad 1000 mL
Solution d:
Iron(III) chloride hexahydrate (FeCl3*6H2O) 0.25 g
Di-sodium-ethylene diamintetraacetate dihydrate (Na2EDTA*2H2O) 0.4 g
H2O demin ad 1000 mL
The medium was freshly prepared

- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 19.4 – 21.6 °C
- pH: at day 28, pH ranged from 6.7 (abiotic control) to 7.4 (blanck control); test flask: 7.5
- pH adjusted: no
- Aeration of dilution water: all flasks were aerated for 72 hours
- Suspended solids concentration: The dry matter was determined as 3020 mg suspended solids/L.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2000 mL-SCHOTT-flasks were used as test vessels, 100 mL scrubber flasks as absorbent vessels.Test volume: 1500 mL
- Number of culture flasks/concentration:
Test flasks: 2, containing test item, mineral medium and inoculum, 2 additional replicates for COD determination (under non-GLP conditions)
- Method used to create aerobic conditions: The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
- Measuring equipment: Analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC multi N/C 2100S, Analytik Jena. Each sample was measured in duplicate or triplicate, respectively (depending on the variation between the measured values). The carbon analyser was calibrated with freshly prepared reference solutions containing potassium hydrogen phthalate (TC), sodium hydrogen carbonate and sodium carbonate (IC) every month. After every start, quality control samples were measured.
- Details of trap for CO2 and volatile organics if used: The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels.
- Other: Magnetic stirrers were used to prevent deposition of inoculum.

SAMPLING
- Sampling frequency: From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.
- Sampling method: The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2.
- Sterility check if applicable: no
- Sample storage before analysis: no as concerns sample for CO2 emission. Samples for COD determination were taken and immediately frozen. At the end of the test, the samples were sent to the laboratory EUROFINS Institut Jäger GmbH, Ernst-Simon-Straße 2 – 4, Tübingen.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 (+2 for COD determination)
- Abiotic sterile control: 1
- Toxicity control:1
- Other: positive control flasks: 2; apparatus blanck (containing mineral medium only): 2
Reference substance:
aniline
Test performance:
IC-Values: the IC values were measured in the samples of the front scrubber flasks. IC values were also measured in the samples of the back scrubber flasks. For each flask, the net IC was calculated by subtracting the mean IC value of the apparatus blanks of the corresponding sampling date from the remaining IC values. Exception: Values of day 0 do not need to be corrected.

Emitted carbon in mg/L test solution in the respective vessel at time t was calculated using the following equation:
emittC=[(IC(t)-IC(0))*VolNaOH (t)]/VolTestVessel
with:
emittC: emitted carbon in mg/L test solution
IC(t): net inorganic carbon in mg/L NaOH in the respective vessel at time t
IC(0): net inorganic carbon in mg/L NaOH in the respective vessel at the start of the test
VolNaOH (t): remaining volume NaOH in L in the scrubber at time t (Volume at t = 0 (here: 0.1 L) - Σ(all sample volumes up to time t))
VolTestVessel: test vessel volume in L (here: 1.5)
For day 29, the IC content of both scrubber flasks was taken into account.
Calculation of emitted carbon is necessary for the assessment of validity. The value obtained with this equation is multiplied with 3.667 (44/12) in order to obtain emitted CO2.
The percentage biodegradation in the test flasks was calculated from:
%deg=[emitted C (test) in mg/L - Mean emittedC (controls) in mg/L]/added C in mg/L*100%
Degradation in positive control and toxicity flasks was calculated analogously.
Abiotic degradation was calculated from:
% deg= mg/L emitted C (abiotic)/added C in mg/L * 100%
Key result
Parameter:
% degradation (CO2 evolution)
Value:
5
Sampling time:
28 d
Details on results:
Degradation behaviour of positive control was normal. Both replicates of the test item showed very good correspondence. If degradation in the toxicity flask is below 25 % after 14 days, the test item can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 20.7 % after 14 days, the test item can be stated as “toxic towards the inoculum in a concentration of 16.2 mg/L”.
Ready biodegradability is defined in the guidelines as degradation surpassing 60% within 10 days after reaching a level of 10 %. Degradation missed 60% within 28 days, though. Therefore, the test item can be considered as “not readily biodegradable”.
The COD values in the test flasks were scattering, but until the end of the test in a similar range. This was in agreement with the missing biodegradation of the test item. No observations were made which might cause doubts concerning the validity of the study outcome.
Results with reference substance:
Degradation of the positive control was 73 % after 9 days.

Emitted Carbon in mg/L:

In the following table, the calculated emitted carbon (from net IC and equation above) is presented.


Day

Blank Control 1

Blank Control 2

Positive Control 1

Positive Control 2

Test 1

Test 2

Abiotic

Control

Toxicity Control

2

1,33

1,30

1,11

1,16

0,85

0,53

0,83

1,02

4

1,75

1,83

3,04

3,74

1,92

1,37

0,94

1,62

7

2,22

2,35

7,42

8,33

2,51

2,18

0,89

2,99

9

2,27

2,35

9,07

10,11

2,76

2,51

0,89

3,76

11

2,41

2,59

10,27

10,99

2,95

2,67

0,80

6,05

14

2,61

2,90

11,36

11,55

3,25

2,89

0,85

6,92

18

2,64

2,98

12,21

11,95

3,35

3,05

0,78

7,08

23

2,93

3,48

12,36

11,80

3,38

3,18

0,58

8,23

29

3,24

3,82

13,24

12,59

4,27

3,80

0,51

9,98

 

Degradation Values (%):

In the following table, the percentage biodegradation is presented:

Day

Positive Control 1

Positive Control 2

Positive Control Mean

Test 1

Test 2

Test Mean

Abiotic

Control

Toxicity Control

2

-2.1

-1.6

-1.8

-4.7

-7.8

-6.3

8.3

-1.5

4

12.4

19.4

15.9

1.3

-4.2

-1.4

9.4

-0.8

7

51.0

60.1

55.6

2.2

-1.0

0.6

8.9

3.5

9

67.3

77.6

72.5

4.5

2.0

3.3

8.9

7.2

11

77.3

84.5

80.9

4.5

1.7

3.1

8.0

17.7

14

85.6

87.5

86.6

5.0

1.3

3.1

8.5

20.7

18

93.5

90.9

92.2

5.4

2.4

3.9

7.8

21.3

23

91.1

85.5

88.3

1.8

-0.3

0.8

5.8

25.0

29

96.6

90.1

93.3

7.4

2.7

5.0

5.1

32.2

 

 

Validity criteria fulfilled:
yes
Remarks:
IC content of test item solution in medium: 0% (should be <=5% of TC). CO2 emitted by the controls: 12.9 mg/L (should be <70 mg/L). Difference within replicates: 4.7 % (should be <=20%). Degradation of positive control > 60%: 9 days (should be <=14d).
Interpretation of results:
not readily biodegradable
Conclusions:
Test item degradation reached 5% at the end of the test (28 days). Therefore, the test item is not readily biodegradable following OECD 301B and EU C.4-C respectively.
Executive summary:

The test item was tested using a concentration of nominally 10 mg organic carbon/L (corresponding to 16.2 mg test item/L) in test medium according to OECD 301B and EU Method C.4-C, and following GLP.

Aniline was chosen as positive control. Activated sludge was used as inoculum (concentration in the test 30.0 mg dry matter/L). The test was left running for 28 days. All validity criteria were met. Degradation of the positive control was 73 % after 9 days.

The following data were determined for the test item :

10-day-window: not detected

degradation at the end of 10-day-window: none

degradation at the end of the test: 5%

pass level following guideline: 60 % at the end of 10-day-window for pure substances

Therefore, regardless of the 10-day-window, the test item is not readily biodegradable following OECD 301B and EU C.4-C respectively.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2017-06-26 to 2018-01-24
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Version / remarks:
26. Sep. 2014
Deviations:
yes
Remarks:
Temperature was 19.5 – 22.2 °C (not 20.0 ± 1.0 °C). Because degradation of the positive control was in the normal range, this is considered as uncritical concerning the outcome of the study.
Qualifier:
according to
Guideline:
EU Method C.29 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test))
Version / remarks:
14. Feb. 2017
Deviations:
yes
Remarks:
For preparation of solution b, CaCl2 was used instead of CaCl2 *2H2O and the stock solutions were stored at room temperature and not in a fridge. Because all validity criteria were met, this deviation can be stated as uncritical.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sludge was taken from the aeration basin of the sewage treatment plant at Maxeville WWTP, 54320 France.
Date of collection: 05. Jul. 2017
- Pretreatment: The same day of the collection, the pre-treatment of the activated sludge was performed. The sludge was washed by threefold centrifugation for 10 minutes at 1100 x g. After centrifugation, the supernatant was removed and the sludge was resuspended in mineral medium and after the third centrifugation filtrated using a stainless steel sieve (100 μm diameter). The sludge was continuously aerated until usage on the next day. The dry matter was determined with 3300 mg suspended solids / L.
- Concentration of sludge: 15 mg suspended solids/L in test flasks
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
TOC
Initial conc.:
15.3 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium:
Solution a: 10 mL
Solution b: 1 mL
Solution c: 1 mL
Solution d: 1 mL
H2O demin ad 1000 mL
Solution a:
Potassium dihydrogenephosphate (KH2PO4) 8.5 g
di-Potassium hydrogenephosphate (K2HPO4) 21.75 g
di-Sodium hydrogenephosphate dihydrate (Na2HPO4*2H2O) 33.4 g
Ammonia chloride (NH4Cl) 0.5 g
H2O demin ad 1000 mL
The pH was 7.4
Solution b:
Calcium chloride (CaCl2) 27.5 g
H2O demin ad 1000 mL
Solution c:
Magnesium sulphate heptahydrate (MgSO4*7H2O) 22.5 g
H2O demin ad 1000 mL
Solution d:
Iron(III) chloride hexahydrate (FeCl3*6H2O) 0.25 g
HCl conc. 1 drop
H2O demin ad 1000 mL

- Additional substrate: No
- Solubilising agent (type and concentration if used): No
- Test temperature: 19.5 – 22.2 °C
- pH: nd
- Aeration of dilution water: no
- Suspended solids concentration: 15 mg/L in test flasks
- Continuous darkness: The test was performed without direct lighting.
- Other: The test item stock solution containing 1000.2 mg/L was prepared. Its TOC (total organic carbon) was determined in order to estimate the amount to be added to the test flasks. The TOC was 653.06 mg/L, giving an organic carbon content of 65.3 %.

TEST SYSTEM
- Culturing apparatus: 250 mL-narrow-flasks were used as test vessels. These were closed with lids and silicon septa. The test was conducted with a volume of 150 mL in each test vessel.
- Number of culture flasks/concentration: 2 blank controls, 2 flasks containing aniline as positive control, 2 flasks containing test item, 1 flask containing test item and 0.05 g HgCl2/L, but no inoculum (testing for abiotic degradation) and 1 flask containing test item and aniline (testing for toxic effects) were tested at each point of measurement. Additionally, 1 blank control was analysed in order to determine IC coming from medium and/or NaOH.
- Method used to create aerobic conditions: The test was performed in sealed bottles with a headspace of air, which provides a reservoir of oxygen for aerobic biodegradation
- Measuring equipment: Analyses of the emitted CO2 were made by inorganic carbon (IC) measurement following SOP 118 009 02 „Bestimmung von Kohlenstoff in wässrigen Lösungen“ in the current edition. To each vessel to be measured, 1.5 mL of NaOH 7 M was added by syringe and needle and the vessel was shaken for 1 hour again. After settling down, a sample of 1.5 mL was pipetted into TOC-vials which were closed. They were measured at least 2 times. The carbon analyser was calibrated with freshly prepared reference solutions (containing a mixture of Na2CO3 and NaHCO3 for IC and C8H5KO4 for TC for TC)) every month. After every start, quality control samples were measured. At each sampling date, a blank containing mineral medium and NaOH 7 M was measured and the IC of the blank was subtracted from the IC of all sampled vessels.
- Test performed in open system: no, the vessels were closed with silicone septa and lids
- Details of trap for CO2 and volatile organics if used: To each vessel to be measured, 1.5 mL of NaOH 7 M was added by syringe and needle and the vessel was shaken for 1 hour again.
- Other: At last, the vessels were closed with silicone septa and lids and were put on the orbital shaker.

SAMPLING
- Sampling frequency: at days 0, 4, 7, 11, 14, 19, 22, 25 and 28
- Sampling method: 1.5 mL was pipetted into TOC-vials which were closed
- Sterility check if applicable: nd
- Other: At each sampling point, samples for COD determination from the test and blank control replicates were taken and immediately frozen. At the end of the test, the samples were sent to laboratory EUROFINS Institut Jäger GmbH, Ernst-Simon-Straße 2-4, Tübingen.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1
- Positive controls: 2
- Other: Additionally, 1 blank control was analysed in order to determine IC coming from medium and/or NaOH.
Reference substance:
aniline
Test performance:
IC values were determined at each sampling dates. At the end of the test (day 28), 6 vessels (test series blank control, positive control, test) resp. 3 vessels (test series apparatus blank, abiotic control, toxicity control) were measured.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
10
Sampling time:
28 d
Details on results:
Lag phase: 14 days
10-day-window: day 14 – 24
Degradation at the end of 10-day-window: 10 %
Degradation at the end of the test: 10 %
The test item must be considered as not readily biodegradable.
The IC content of the controls at the end of the test was higher than stated in the study plan. This was caused by the very low test item concentration corresponding to 10 mg/L organic carbon in conjunction with the very high inoculum concentration of 15 mg/L. The high IC concentration in the control can be stated as uncritical for the outcome of the study because no degradation of the test item was observed and the activity of the inoculum was very good. The pass level of 60 % degradation of the positive control was surpassed on day 7 and degradation of the toxicity control was normal.
Degradation behaviour of positive control was normal.
Abiotic degradation was not observed. Both replicates of the test item showed very good correspondence.
If degradation in the toxicity flask is below 25% at the end of the test, the test item can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 37 % at the end of the test, the test item can be stated as “not toxic towards the inoculum in a concentration of 15.3 mg/L”. However until day 7, no degradation was observed for the toxicity control. Based on the ratio of degradation of the toxicity control and positive control it may be assumed that the test item inhibited the activity of the inoculum.
Results with reference substance:
Degradation of the positive control was 75 % after 7 days.

Net IC-values in ppm

Day

Blank Control 1

Blank Control 2

Positive

Control 1

Positive

Control 2

Test 1

Test 2

Abiotic

Control

Toxicity Control

0

0.11

-0.01

-0.21

0.23

0.01

1.02

0.58

-0.40

4

0.88

0.79

3.22

2.23

0.94

1.17

0.80

0.98

7

1.68

1.77

9.30

9.22

2.34

2.85

0.82

1.97

11

1.51

2.85

9.35

9.38

2.82

2.29

1.07

9.99

14

0.73

0.71

9.02

9.04

1.60

1.79

-0.22

7.84

19

1.83

1.53

10.42

11.00

3.00

2.93

0.47

8.61

22

2.01

1.97

10.55

10.68

3.05

2.75

0.85

8.26

25

2.26

2.37

11.64

11.32

3.12

3.56

1.19

8.76

28

2.30

2.40

11.34

11.90

3.36

3.41

1.29

10.02

28

2.51

2.36

11.72

11.99

3.37

3.51

1.15

8.99

28

2.55

2.55

11.83

11.77

3.54

3.42

0.82

10.40

Note: At the end of the test (day 28), 6 vessels (test series blank control, positive control, test) resp. 3 vessels (test series apparatus blank, abiotic control, toxicity control) were measured.

 

Degradation values in %

Day

Positive

Control 1

Positive

Control 2

Positive

Control Mean

Test 1

Test 2

Test Mean

Abiotic

Control

Toxicity Control

0

-2.60

1.80

-0.40

-0.40

9.71

4.65

5.29

-2.24

4

23.86

13.96

18.91

1.05

3.35

2.20

-0.35

0.72

7

75.79

74.99

75.39

6.15

11.26

8.71

-9.04

1.22

11

71.74

72.04

71.89

6.40

1.10

3.75

-11.08

38.94

14

83.04

83.24

83.14

8.81

10.71

9.76

-9.39

35.50

19

87.44

93.25

90.35

13.21

12.51

12.86

-12.02

34.55

22

85.64

86.94

86.29

10.61

7.60

9.11

-11.38

31.26

25

93.30

90.10

91.70

8.05

12.46

10.26

-11.23

32.13

28

91.90

94.46

93.18

9.79

10.02

9.91

-13.56

36.69

Note: Values on day 28 were calculated from the means of the triplicate measurement.

 

 

Validity criteria fulfilled:
yes
Remarks:
Degradation of positive control: 75 % on day 7 (should be 60 % within 14 days); Mean IC content of controls at the end of the test: 2.44 mg/L (should be below 3 mg/L)
Interpretation of results:
not readily biodegradable
Conclusions:
After the end of the 10-day-window the degradation reached 10 %. At the end of the test, it was still 10%. Therefore, the test item can be considered as “not readily biodegradable”.
Executive summary:

The purpose of the test was the determination of the aerobic ready biodegradability of the test item in the CO2-Headspace Test according OECD 310 resp. EU C.29 and following GLP.

The test item was tested using a concentration of 15.3 mg/L corresponding a carbon concentration of 10 mg/L in test medium.

Activated sludge from a sewage treatment plant was used as inoculum (concentration 15 mg suspended solids/L). The test was left running for 28 days.

All validity criteria were met.

Aniline was chosen as positive control. Degradation of the positive control was 75 % after 7 days.

If degradation in the toxicity flask is below 25% at the end of the test, the test item can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 37 % at the end of the test, the test item can be stated as “not toxic towards the inoculum in a concentration of 15.3 mg/L”. However until day 7, no degradation was observed for the toxicity control. Based on the ratio of degradation of the toxicity control and positive control it may be assumed that the test item inhibited the activity of the inoculum.

The following data were determined for the test item :

10-day-window: day 14 - 24

degradation at the end of 10-day-window 10 %

degradation at the end of the test 10 %

Therefore, the test item is not readily biodegradable following OECD 310 and. EU C.29.

Endpoint:
biodegradation in water: screening tests
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
Activated sludge taken from a sewage plant was cultivated for the test.
Duration of test (contact time):
5 d
Initial conc.:
200 mg/L
Based on:
COD
Parameter:
% degradation (DOC removal)
Value:
87
Sampling time:
5 d
Details on results:
The rate of biodegradation based on COD removal was 16.7 mg COD/gram per hour.
Interpretation of results:
other:
Conclusions:
87% COD removal was reached in 5 days in a screening test using acclimated activated sludge.
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline available
GLP compliance:
not specified
Parameter:
% degradation (DOC removal)
Value:
92
Sampling time:
22 d
Interpretation of results:
inherently biodegradable, not fulfilling specific criteria
Conclusions:
screening study, 92 % biodegradation in 22 days with synthetic activated sludge (acclimated to 1000 ppm COD test) SCAS unit. Inherent ultimate biodegradability( > 70 %)

Description of key information

Substance is not readily biodegradable but inherently biodegradable with pre-adapted sludge (aniline).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria

Additional information

This substance was not ready biodegradable in standard screening studies (310 Headspace C02 in sealed vessels, 301B C02 Evolution and 301C MITI test). 4 -aminophenol was considered inherently biodegradable with pre-adaptation. Three studies observed significant (≥ 66%) biodegradation of the test substance when using pre-adapted sludge, and can be considered inherent, primary biodegradable ( > 20% as defined in OECD Guideline for testing of Chemicals, Revised Introduction to the OECD guidelines for testing of chemicals, section 3, 23 March 2006). Two of the screening studies support the concept that the substance is inherent, ultimate biodegradable (> 70 % as defined in OECD Guideline for testing of Chemicals, Revised Introduction to the OECD guidelines for testing of chemicals, section 3, 23 March 2006) with 92% biodegradation in 22 days with pre-adapted sludge (synthetic activated sludge acclimated to 1000 ppm COD test) using a SCAS unit and > 87 % DOC removal in 5 days. This is an indication that the substance has the potential for degradation under favorable conditions, such as STP or biological treatment plant.