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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Test phase 2013-6-12 to 2013-8-21. Report complete 2013-09-17.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Report on substance meets the criteria for classification as reliable without restriction according to Klimisch et al (1997).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate
EC Number:
700-787-7
Cas Number:
769953-18-6
Molecular formula:
C11H9N2O3S2Li
IUPAC Name:
lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate
Test material form:
solid: particulate/powder

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of activated sludge: Totnes Sewage Treatment Works, Totnes, Devon, UK
- Storage conditions: Aerated at room temperature and pH maintained at 7.0 +/-1.0
- Preparation of inoculum for exposure: Seven days prior to the exposure start the activated sludge was centrifuged, washed and resuspended in the mineral medium and the solids concentration determined. This sluge was then diluted in medium, added to test bottles and stirred until required for use. The seeded mineral medium was pre-conditioned for seven days to reduce the blank oxygen uptake readings in the test.
- Concentration of sludge: 30 mg/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:The mineral medium was made up according to the OECD guidelines and contained the following nutrients per litre of RO water: 85mg of KH2PO4, 217.5mg K2HPO4, 334mg Na2HPO4.2H20, 5MG NH4CL, 22.5MG MgSO4.7H20, 36.4mg CaCl2.2H2O, 0.25mg FeCl3.6H2O.
- Test temperature:22 +/-1 C
- pH:7.4 +/-0.2
- Continuous darkness: yes


TEST SYSTEM
- Number of culture flasks/concentration: 3
- Measuring equipment: Oxitop respirometer (Wissenschaftlich-Technische Werkstatten, GmbH, Germany)
- Details of trap for CO2: KOH placed in a seal cup in the neck of each test bottle.

SAMPLING
- Sampling frequency: Oxygen uptake was recorded every 112min during the 28 day experimental period.
- Sampling method: The Oxitop controller collected pressure values from the measuring tops.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Seeded mineral medium with no test or reference substance

Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
100mg/l

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
< 5.1
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
< 7.3
Sampling time:
10 d
Parameter:
% degradation (O2 consumption)
Value:
< 7.1
Sampling time:
15 d
Parameter:
% degradation (O2 consumption)
Value:
< 7.1
Sampling time:
20 d
Parameter:
% degradation (O2 consumption)
Value:
< 6.9
Sampling time:
28 d
Details on results:
The test substance acheived a maximum mean level of biodegradation (based on BOD:ThOD ratio) of <7.3%.
The difference of extreme of replicates biodegradation values were less than 20% for both the sodium benzoate and the test substance after the 10 day window, at plateau, and on day 28, as required in the OECD guideline

BOD5 / COD results

Results with reference substance:
The reference substance attained a maximum mean level of biodegradation of 73% and the results showed good replication. More than 60% degradation was acheived within the 10 day window as expected for a biodegradable substance thus confirming that the activated sludge contained viable organisms.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
At the end of this study there had been no measurable biodegradation of the test substance after 28 days. therefore the test substance failed to meet the criteria for ready biodegradability.
Executive summary:

Introduction

This study was undertaken to determine the ready biodegradability of the test substance by measurement of biochemical oxygen demand (BOD) in a manometric respirometry test. The method used was designed to be compatible with the following guidelines:

- OECD Guideline for the Testing of Chemicals. Test Guideline 301F, Ready Biodegradability: Manometric Respirometry. Adopted 17 July 1992.

Results & Conclusions

At the end of the study the test substance had attained a maximum mean level of biodegradation of <7.3%. Therefore the test material failed to meet the criteria for ready biodegradability.

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