Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
20. Jul - 15 Sep. 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
prolonged testing period (56 days)
GLP compliance:
yes (incl. certificate)
Remarks:
Date of certificate: 17.08.2016 (The Department of Health of the Government of the United Kingdom)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural water: freshwater
Details on inoculum:
- Source of inoculum/activated sludge: Surface water was collected from Malmesbury Pond, Sandymoor, UK on 14th July 2018.
- Pretreatment: filtered and aerated at 22 ± 2°C prior to use
- Initial cell/biomass concentration: 100 ml/L test media
Duration of test (contact time):
28 - 56 d
Initial test substance concentration
Initial conc.:
15.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: 3 L test medium, the test material was added directly to the test vessels.
- Test temperature: 22 ± 2°C
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 3 Litre volumes of test media were stirred constantly in round, flat bottomed flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Carbon dioxide free air was passed through the test solutions at an estimated rate of 30 to 100 ml per minute.
- Measuring equipment: Titres were taken for the barium hydroxide at the start and end of each time period.
- Details of trap for CO2 and volatile organics if used: barium hydroxide

SAMPLING
- Sampling frequency: days 1, 3, 7, 10, 14, 17, 21 , 28, 35, 42, 49, 56 and 57.

CONTROL AND BLANK SYSTEM
- Inoculum blank: no
- Abiotic sterile control: no
- Inoculum control: 2 control vessels (containing inoculum but no test or reference material)
- Reference control: 1 vessel (containing 102.9 mg (20 mg C l-1) of the reference material, sodium benzoate in 3 litres of test media)
- Toxicity control: 1 Inhibition Control (contained sodium benzoate at 34.3 mg/L and test material at 15.5 mg/L in 3 litres of test media)


Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
47.95
Sampling time:
28 d
Remarks on result:
other: mean of two replicates
Parameter:
% degradation (CO2 evolution)
Value:
59.05
Sampling time:
56 d
Remarks on result:
other: mean of two replicates
Details on results:
A degradation figure of 35.8% after 14 days (based on total combined DOC) was obtained for the inhibition control. The Inhibition Control contained sodium benzoate at 34. 3 mg/L and test material at 15.5 mg/L in 3 litres of test media.

BOD5 / COD results

Results with reference substance:
Sodium Benzoate: 64.4% after 28 d based on CO2 evolution

Any other information on results incl. tables

Table 1: Degradation rates based on CO2 evolution of test substance, reference substance and inhibition control

Cumulative degradation (%)

Day of Titration

Sodium Benzoate

(34.3 mg l-1)

BUTYL DECANOATE

(15.5 mg l-1A)

BUTYL DECANOATE

(15.5 mg l-1B)

Inhibition Control

1

1.2

*

*

6.4

3

28.5

*

*

17.7

7

47.2

7.9

6.3

33.6

10

58.6

13.6

18.4

37.6

14

64.5

30.3

36.1

35.8

17

62.7

34.3

27.7

39.7

21

63.7

38.9

47.6

54.5

28

64.4

45.7

50.2

69.1

35

62.8

44.5

57.5

68.5

42

54.3

42.5

56.7

81.6

49

53.4

45.5

62.3

90.4

56

54.7

55.5

64.6

96.0

57

55.1

55.1

63.0

99.3

*Indicates negative degradation

Table 2: Validity criteria for OECD 301.

Criterion from the guideline

Outcome

Validity criterion fulfilled

Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.

9% (day 28)

12.7% (day 56)

yes

Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).

64.5%

yes

The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.

35.8%

yes

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
see Table 2 at "Any other information on results incl. tables"
Interpretation of results:
not readily biodegradable