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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:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP Guideline study with acceptable restrictions
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: Biodegradation; Repetitive Die Away Test, DGXI/400/84, Rev1; European Economic Communities, 1984
Principles of method if other than guideline:
The RDA (Repetitive Die Away) test is used, because according to De Morsier et al. (1987), this method is suitable for poorly-soluble substances.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, non-adapted
Details on inoculum:
Closed bottle test:
- Source of inoculum/activated sludge: The inoculum is an industrial activated sludge from Unichemia Chemie, Gouda.
- Pretreatment: The sludge is preconditioned during a week, to reduce high residual respiration rates. The density of the inoculum is 32 mg s.s./L.

Duration of test (contact time):
6 wk
Initial conc.:
40 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: According to guideline but without ammonia. This modification is introduced to minimize the consumption of the dilution water and analyses.
- Solubilising agent: Genapol PF-40 (Hoechst), 10% of the weight of the test material and nonylphenol+10 EO+ 5 PO, 20% of the weight of the test material (according to De Morsier et al., 1987)

TEST SYSTEM
- Number of culture flasks/concentration: 3

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
- Other: vehicle control
Parameter:
% degradation (O2 consumption)
Value:
16
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
21
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
27
Sampling time:
42 d

Since the emulsifier showed to be slightly biodegradable in the Closed Bottle test, they were also tested in the RDA-test, separately as well as combined. Again some oxygen consumption was observed in some cases, but this was not consistent in time. Moreover, the oxygen consumption of combined emulsifier reference (Gen + non) did not account tor the oxygen consumption of the separate samples (Genapol; nonyl phenol). lt is concluded that small differences cannot be detected with accuracy. Therefore, no attempt is made tor correction, although lt should be kept in mind that the following biodegradation percentages in industrial sludge may be overestimated tor week 6: 16% after 2 weeks, 21% after 4 weeks, and 27% after 6 weeks.

The slow linear increase in the percentage biodegradation may be explained by the limited bioavailability of the test substance, due to the poor water-solubility.

Biodegradability test with industrial sludge:

week

 

 

pH

oxygen concentration mg 02/L
3 replicates

 

mean

 

C-C,D
mg 02/L

 

 

1

blanc

control (NaAc) Genapol

 nonyl phenol Gen + non

oleyl palmitamide

7.4

7.3

7.3

7.4

7.4

7.3

8.43 8.49 8.56

4.67 4.81 5.00

8.45 8.43 8.47

8.47 8.52 8.51

8.28 8.39. 8.33

8.06 7.95 7.57

8.49

4.83

6.45

8.50

8.33

7.86

 

3.36

0.04

-0.01

0.16

0.63

2

blanc

control (NaAc) Genapol

 nonyl phenol Gen + non

oleyl pamitamide

7.3

7.4

7.3

7.3

7.3

7.1

8.87 8.62 9.05

8.42 8.32 8.04

8.81 8.63 8.54

8.65 8.49 8.63

8.75 8.37 8.45

8.49 8.09 7.48

8.85

8.26

8.66

8.59

8.52

8.02

 

0.59

0.19

0.26

0.33

0.83

4

blanc

control (NaAc) Genapol

 nonyl phenol Gen + non

oleyl pamitamide

7.4

7.5

7.4

7.4

7.5

7.3

8.90 8.82 8.80

8.24 8.31 8.29

8.83 8.80 8.82

8.83 8.83 8.78

9.00 8.88 8.81

8.35 8.49 8.23

8.84

8.28

8.82

8.81

8.90

8.36

 

0.56

0.02

0.03

-0.06

0.48

6

blanc

control (NaAc) Genapol

 nonyl phenol Gen + non

oleyl pamitamide

7.4

7.6

7.3

7.3

7.4

7.3

9.27 9.20 9.00

8.89 8.64 8.74

8.92 8.82 8.65

8.90 8.80 8.82

8.90 8.90 8.79

8.81 8.54 8.68

9.16

8.76

8.80

8.84

8.86

8.68

 

0.40

0.36

0.32.

0.30

0.48

The test was performed with 7.86 mg substance per bottle. Each bottle contained 0.92 mg nonyl phenol and 0.40 mg Genapol.

The reference Genapol contained 0.46 mg/bottle.

The reference nonyl phenol contained 0.94 mg/bottle.

The reference gen + non contained 0.46 mg Genapol and 0.94 mg nonyl phenol/bottle.

The control (NaAc) contained 42 mg with a ThOD of 18.33 mg 02/bottle.

 

Toxicity control for RDA Test, industrial sludge. Exposition time: 8 days.

 

pH

oxygen concentration

mg 02/L

3 replicates

mean

Ct – Cb

mg 02/L

inhibition

%

Blanc

NaAc

 

NaAC+ oleyl palmitamide

42 mg/L 

7.4

7.3

 

 

7.2

8.43 8.49 8.56

4.67 4.81 5.00

 

 

4.18 4.22 4.43

8.49

4.83 

 

 

4.28

 

3 . 66

 

 

4.21

 

 

 

 

0

 

Interpretation of results:
other: not readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP Guideline study with acceptable restrictions (only 3 measurements)
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
, modification of medium (recommendations of Block et al, 1985), only 3 measurements
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Closed bottle test:
- Source of inoculum/activated sludge: Municipal waste water treatment plant in Duiven, The Netherlands
- Pretreatment: The sludge is preconditioned: a sludge suspension of 1 g s.s./L is aerated during 3 days, to reduce high residual respiration rates.
- Concentration of sludge: 3 mg s.s./L
Duration of test (contact time):
6 wk
Initial conc.:
2.06 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline but without ammonia. This modification is introduced to minimize
- Solubilising agent: Genapol PF-40 (Hoechst), 10% of the weight of the test material and nonylphenol+10 EO+ 5 PO, 20% of the weight of the test material (according to De Morsier et al., 1987)

TEST SYSTEM
- Number of culture flasks/concentration: 3

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
- Other: vehicle control
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
14
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
27
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
30
Sampling time:
42 d

Biodegradability test with domestic sludge:

week

 

 

pH

oxygen concentration mg 02/L
3 replicates

 

mean

 

C-C,D
mg 02/L

 

biodegradation
BOD/COD
(%)

 

 

2

blanc

control (NaAc)

emulsifier

oley palmitamide

7.0
6.9
7.1
6.8

 

7.42 7.43 7.19
1.74 1.99 1.72
7.40 7.20 7.30
6.31 6.14 6.30

 

7.35
1.82
7.30
6.25

 

 

5.53
0.05
1.10

 

 

 

5.53/6.86= 81
1.05*/7.25= 14

 

4

blanc

control (NaAc)

emulsifier

oley palmitamide

7.0
6.9
7.0
6.9

 

6.73 6.70 6.99
1.12 0.98 1.22
6.70 6.85 6.40
4.74 4.60 4.72

 

6.81
1.11
6.65
4.69

 

 

5.70
0.18
2.12

 

 

 

5.70/6.85= 83
1.96*/7.25= 27

 

6

blanc

control (NaAc)

emulsifier

oley palmitamide

7.1
6.9
7.0
6.9

 

6.70 6.76 6.83
0.82 1.18 0.80
6.30 6.25 6.50
4.40 4.23 4.07

 

6.76
0.93
6.35
4.23

 

 

5.83
0.41

2.53

 

 

 

5.83/6.86= 85
2.16*/7.25= 30

 

* correction for degradation of emulsifiers

The test medium contained per liter 2.06 mg oleyl palmitamide, 0.69 mg nonyl phenol 10E05P0 and 0.33 mg Genapol PF40.

The COD was 2.06 * 3.52= 7.25 mg/l (T47 p. 45).

The emulsifier reference did show some biodegradation. Therefore, a correction was made as follows:

The emulsifier reference contained 0.76 mg nonyl phenol and 0.38 mg Genapol/L. The sample emulsion contained 0.69 mg nonyl phenol/L at the most. The oxygen consumption in the sample due to the emulsifier is 0.69/0.76= 91% of the oxygen consumed in the emulsifier reference, resulting in week 2: 0.05 * 91%= 0.05, and the corrected BOD is 1.10 — 0.05= 1.05; in week 4: 0.18 * 91% 0.16, the corrected BOD is 2.12 - 0.16= 1.96; and in week 6: 0.41 * 91%= 0.37, the corrected BOD is 2.53 - 0.37= 2.16.

Toxicity control for Closed Bottle Test, domestic sludge. Exposition time: 8 days.

 

pH

oxygen concentration

mg 02/L

3 replicates

mean

Ct – Cb

mg 02/L

inhibition

%

oleyl

palmitamide

2.1 mg/1

6.2 mg/1

 

 

 

6.8

6.7

 

 

2.32 2.32 2.30

1.17 1.56 2.08

 

 

2.31

1.60

 

 

5.72

6.43

 

 

0

0

Interpretation of results:
other: not readily biodegradable

Description of key information

Not readily biodegradable: 42% (ThO2) after 30 days (OECD 301 D) and 27% (ThO2) after 42 days (DGXI/400/84)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The ready biodegradability of (Z)-N-Octadec-9-enylhexadecan-1-amide (CAS No. 16260-09-6) was investigated in one GLP-study comprising a test according to OECD guideline 301 D and a repetitive die away test following DGXI/400/84, EEC 1984 (Balk and Hantink-de Rooij, 1989). In the OECD closed bottle test 2.06 mg/L of the substance was incubated with domestic activated sludge for 6 weeks. The substance reached 27% degradation after 27 days and 42% degradation after 30 days. In the die away test 40 mg/L of the substance was incubated with industrial non-adapted activated sludge as inoculum over 6 weeks. Degradation rates were 21% after 21 days and 27% after 42 days. Hence, the substance is considered to be not readily biodegradable.