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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: A0076
- Expiration date of the lot/batch: 2021


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient, in the dark
- Stability under test conditions: Stable
- Solubility and stability of the test substance in the solvent/vehicle:
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium:

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test material was stated to be poorly soluble in water therefore a surfactant was used to emulsify the sample. To prepare the emulsion, 0.4990g of the test item was intimately mixed with 0.2516g of a non-ionic surfactant (IGEPAL CA 630). The emulsion was gradually diluted by the addition of deionised water and then made up to volume (500ml) to give a concentration of
0.9980g/l.

FORM AS APPLIED IN THE TEST (if different from that of starting material) : emulsion was prepared with non-ionic surfactant (IGEPAL CA 630)

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The inoculum was the secondary effluent from a predominantly domestic sewage treatment works, collected from Cambridge STW, Cowley Road, Cambridge on 10/05/2017.
- Laboratory culture: no
- Pretreatment: Filtered
- Concentration of sludge: 1 mL/L
- Type and size of filter used, if any: Whatman No. 54
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: The dilution water was prepared by adding secondary effluent inoculum and mineral nutrient stock solutions to deionised water, aerating it strongly for 35 minutes then letting it stand for 23
hours and 1 minute.
- Solubilising agent (type and concentration if used): The test material was stated to be poorly soluble in water therefore a surfactant was used to emulsify the sample. A non-ionic surfactant (IGEPAL CA 630) was used to emulsify the test item.
- Test temperature: 19.8-20.7oC
- Aeration of dilution water: The dilution water was aerated strongly for 35 minutes after preparation.
- Continuous darkness: yes
- Other: In order to account for any degradation of the surfactant in the test vessels, a series of surfactant control bottles were prepared by addition of the surfactant stock to inoculated mineral medium (1ml/l) to give a final concentration of 1.014g/l, representing the final concentration of the surfactant used in the test sample bottles. These were used as the blank values when calculating test material degradation.

TEST SYSTEM
- Culturing apparatus: temperature regulated incubator
- Number of culture flasks/concentration: 3
- Measuring equipment: dissolved oxygen meter
- Test performed in closed vessels due to significant volatility of test substance: no

SAMPLING
- Sampling frequency: measurements of dissolved oxygen concentration were made on bottles removed after 0, 7, 14, 21 and 28 days.


CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated mineral medium
- Toxicity control: 2.0 mg/L test item and 5.01 mg/L sodium acetate
- Functional/reference control: 5.01 mg/L sodium acetate
- Other: In order to account for any degradation of the surfactant in the test vessels, a series of surfactant control bottles were prepared by addition of the surfactant stock to inoculated mineral medium.

Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
36
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
54
Sampling time:
14 d
Details on results:
The reaction mass of amines, hydrogenated tallow alkyl and azelaic acid and lithium hydroxide failed to meet the requirements for a pass in this test (>60% degradation relative to the ThOD/ThODNO3 of the test item) a maximum of 54% (53% with nitrification) was recorded on day 14. The test item is not inhibitory to sewage treatment microorganisms at tested concentration of 2.0 mg/L.
Results with reference substance:
For the reference material, sodium acetate, 88% degradation was achieved by day 28, blank DO loss reached a maximum of 1.05 mg/l recorded on day 28.

Table 1.Degradation values for the test substance based on the ThOD (assuming no

nitrification), ThODNO3 (assuming nitrification) and for the reference material

Sample

Replication

Incubation period (days)

7

14

21

28

1

2

1

2

1

2

3

1

2

3

Reference material

Degradation (%)

74

71

71

85

73

72

71

90

87

87

Average degradation (%)

72

78

72

88

Test item

Degradation (%)

25

15

56

53

38

37

37

36

34

39

Average degradation (%)

20

54

37

36

Test item (nitrification)

Degradation (%)

25

15

54

51

37

36

36

35

33

38

Average degradation (%)

20

53

36

35

In the toxicity control, 30% degradation was observed after 7 days, and 51% after 17 days.

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test item achieved 36 % degradation after 28 days and is considered not readily biodegradable.
Executive summary:

The 28 day degradation of Reaction mass of amines, hydrogenated tallow alkyl and azelaic acid and lithium hydroxide was determined by a procedure following the OECD Guideline 301D.

The test material was poorly soluble in water therefore a surfactant was used to emulsify the sample.

Initial dissolved oxygen (DO) concentrations were measured, using a dissolved oxygen meter. The bottles were stored in a temperature regulated incubator and incubated in the dark at 19.8-20.7แต’C for the duration of the test period. Further measurements of dissolved oxygen concentration were made on bottles removed after 7, 14, 21 and 28 days.The theoretical oxygen demand (ThOD) has been calculated based on empirical formula of the test item. As the test item contains nitrogen as part of its formulation the potential effects of nitrification has been taken into account.

 

After 28 days, the biodegradation of the teste item was 36 % (35 % assuming nitrification) based on ThOD. The maximum of 54% (53% with nitrification) degradation was recorded on

day 14.

It was concluded that the reaction mass of amines, hydrogenated tallow alkyl and azelaic acid and lithium hydroxide is not readily biodegradable under the conditions of this test. The results of the study also show that the test item is not inhibitory to sewage treatment microorganisms at tested concentration of 2.0 mg/L.

The study is a GLP-complant and was conducted according to the OECD guideline, therefore is considered valid and reliable without restrictions.

Description of key information

For the test item, 36% of biodegradation was observed after 28 days in the study according to the OECD 301D guideline. Therefore it was concluded that test item is not readily biodegradable under the conditions of the test.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

A GLP-compliant study following the OECD Guideline 301D is available for the test item, Reaction mass of amines, hydrogenated tallow alkyl and azelaic acid and lithium hydroxide (Crane 2019).