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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:
02 Nov - 30 Nov 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
July 17, 1992
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
9-Octadecenoic acid (Z)-, ester with oxybis[propanediol] (2:3)
EC Number:
289-147-1
EC Name:
9-Octadecenoic acid (Z)-, ester with oxybis[propanediol] (2:3)
Cas Number:
86088-80-4
Molecular formula:
not applicable, the substance is UVCB
IUPAC Name:
9-Octadecenoic acid (Z)-, ester with oxybis[propanediol] (2:3)

Study design

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): Activated sludge was obtained from the aerobic reactor of a sewage treatment plant receiving predominantly domestic sewage. The plant is located at Kurume central sewage treatment center, Fukuoka, Japan. The sludge was sampled on November 1, 2017.
- Storage length and conditions: After collection, the activated sludge was aerated at test temperature until it was used for the test.
- Concentration of sludge: 30 mg suspended solids per L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 22.0 °C
- pH: The pH of the test solutions was not measured at test start since the test item did not dissolve in water at the test concentration.
- pH adjusted: yes, adjusted to 7.4
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: glass vessels with 300 mL test solution
- Number of culture flasks/concentration: 2 flasks for test item solutions
- Measuring equipment: During the incubation period, the biochemical oxygen demand (BOD) was measured continuously with a closed oxygen consumption measuring apparatus (No. CM-061). The identity of the test item was confirmed by IR spectroscopy. Since IR spectra were identical before test start and after experimental completion, it was concluded that the test item was stable throughout the entire experimental period.
- Details of trap for CO2: soda lime no. 1

SAMPLING
- Sampling frequency: days 7, 14, 21 and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 vessels
- Abiotic sterile control: no
- Toxicity control: yes, 1 vessel
- Reference control: yes, 1 vessel
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
75
Sampling time:
28 d
Details on results:
The substance did not meet the 10 day window (47% degradation at the end of the 10 day window). For substances with different chain lengths the 10-day window should not be used for the interpretation of results. It is possible that a sequential biodegradation occurred which might have resulted in a prolonged lag-Phase and therefore a slower biodegradation period, although the test substance was biodegraded in a large amount after the test duration. In this case the pass level can be applied after 28 days and therefore the test substance is considered readily biodegradable.

The toxicity control reached a degradation of 42% after 14 days (pass level 25%). The substance is therefore considered not inhibitory to microorganisms.

BOD5 / COD results

Results with reference substance:
The reference substance attained a degradation of 89% after 14 days (pass level 60%). The test system is therefore considered valid.

Any other information on results incl. tables

Table 1: Calculation table for % biodegradation by BOD

Vessel

7th day

14th day

21st day

28th day

Average after 28 days

BOD (mg)

Deg. (%)

BOD (mg)

Deg. (%)

BOD (mg)

Deg. (%)

BOD (mg)

Deg. (%)

Deg. (%)

Test item 1

28.9

53

43.0

49

53.4

61

61.7

72

75

Test item 2

31.2

35

45.9

53

57.0

66

66.4

78

Toxicity control

47.6

34

58.9

42

75.1

54

88.7

64

-

Control 1

4.6

-

6.2

-

7.0

-

7.8

-

-

Control 2

4.6

-

6.1

-

6.9

-

7.4

-

-

Reference control

45.9

82

50.9

89

52.8

92

54.5

94

-

Table 2: Validity criteria

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%.

 6%

 yes

Percentage degradation of the reference compound has reached the pass levels by day 14.

 89%

 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.

 42%

 yes

The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.

 25 mg/L

 yes

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
For further details please refer to “Any other information on results incl. tables”.
Interpretation of results:
readily biodegradable