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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:
20 October 2017 - 21 November 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

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 D (Ready Biodegradability: Closed Bottle Test)
Version / remarks:
17 July 1992
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Physical appearance: colourless to pale yellow liquid
Storage conditions: at room temperature protected from light, container flushed with nitrogen.
Specific details on test material used for the study:
The test item is insoluble in water.

Study design

Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of activated sludge: secondary effluent, freshly obtained from a municipal sewage treatment plant ('Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands)
- Pretreatment: Secondary effluent was filtered through a coarse filter paper; the first 200 mL were discarded.
- Storage conditions: aerated
- Concentration of sludge: not indicated, 4 mL filtrate of secondary effluent per litre of final volume was used
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
1 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 OECD guideline 301
- Test temperature: 22-23°C
- pH: 7.5 (at the start of the test)
- pH adjusted: no
- Continuous darkness: yes
- Other: Oxygen concentration in the test solutions was between 9.31 and 9.41 mg/L at the start of the test and between 7.45 and 7.84 mg/L at the end of the test. The O2 depletion during the test in the inoculum blank was 1.42 mg/L.

TEST SYSTEM
- Culturing apparatus: 250-300 mL BOD bottles with glass stoppers
- Number of culture flasks/concentration: 2
- Measuring equipment: oxygen meter

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, containing only inoculum
- Abiotic sterile control: no
- Toxicity control: yes, containing reference ite, test item (1 mg/L) and inoculum
- Other: procedure control, containing only reference item and inoculum

STATISTICAL METHODS: no statistical analysis was applied, a figure of more than 10% biodegradation was considered biologically relevant.
Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
Purity: 99.5%

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
5
Sampling time:
28 d
Remarks on result:
other: 1 mg test item/L
Key result
Parameter:
% degradation (O2 consumption)
Value:
6
Sampling time:
28 d
Remarks on result:
other: 3 mg test item/L
Details on results:
- No biologically relevant biodegradation was observed during the 28-day test period. Biodegradation in individual bottles was 4 and 5% for the test solution at 1 mg test item/L and 6% in both test solutions at 3 mg test item/L.
- In the toxicity control more than 25% biodegradation occurred within 14 days (29%, based on ThOD), showing that the test item did not inhibit microbial activity.

BOD5 / COD results

Results with reference substance:
The reference item biodegraded for 74% after 14 days.

Any other information on results incl. tables

Table 1 Mean Values of Oxygen Depletion at Different Points in Time

Test medium

Concentration

Oxygen depletion (mg O2/L) after X daysa)

(mg/L)

7

14

21

28

Procedure control A

2

1.08

1.06

Procedure control B

2

1.06

1.24

Test item low A

1

0.14

-0.01

-0.04

0.10

Test item low B

1

-0.08

0.00

0.09

0.13

Test item high A

3

-0.04

0.24

0.57

0.52

Test item high B

3

0.07

0.33

0.41

0.47

Toxicity control A

2 / 1b)

1.09

1.31

Toxicity control B

2 / 1b)

1.16

1.17

 

 

a): Corrected for oxygen depletion in the blank control (mean value).

b): Toxicity control contains sodium acetate andFLORANTONE T.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Se 'overall remarks' section
Interpretation of results:
not readily biodegradable
Conclusions:
In the closed bottle test, performed according to OECD 301D and GLP, Florantone T was not readily biodegradable (5 and 6% in test solutions at 1 mg test item/L and 3 mg test item/L, respectively).