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:
2002-05-08 - 2002-06-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
GLP compliance:
yes (incl. certificate)
Remarks:
2000-04-26

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Specific details on test material used for the study:
- Synonyms: ITC 908, vinylidenephosphonic acid tetrasodium salt (VDPA tetrasodium salt)
- Lot/batch No.of test material: 562CH/646
- Purity: 87.33%
- Storage condition of test material: Room temperature, in the dark

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: A mixed population of activated sewage sludge micro-organisms was obtained on 7 May 2002 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughboroug, Leicestershire, UK, which treats predominantly domestic sewage.
- Laboratory culture: The sample of activated sludge was maintained on continuous aeration upon receipt. A sample of the activated sewage sludge was washed three times by settlement and resuspension in culture medium to remove any excessive amounts of dissolved organic carbon (DOC) that may have been repsent.
- Method of cultivation: The culture medium used in this study was that recommended in the OECD guideline.
- Concentration of sludge: Determination of the suspended solids level of the activated sewage sludge was carried out by filtering a sample (100 ml) of the activated sewage sludge by suction through a piece of pre-weighed GF/A filter paper using a Buchner funnel. The piece of GF/A filter paper was then dried in an oven at approximately 110 °c for 1 hour and allowed to cool before reweighing. The suspended solids was equal to 3.3 g/L prior to use.
Duration of test (contact time):
29 d
Initial test substance concentration
Initial conc.:
5 mg/L
Based on:
DOC
Remarks:
A concentration of 10 mg C/L is equivalent to 126.3 mg/L of test material. It was considered that this amount could cause toxic effects on the micro-organisms used in this study and therefore, a reduced test concentration of 5 mg/L was employed.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: Follows the recommendation of the OECD Guideline
- Test temperature: 21 °C
- pH: 7.5 - 7.7 (pH values of the test preparations on Day 28
- Aeration of dilution water: CO2-free air bubbled through the solution at a rate of approximately 40 ml/minute and stirred continuously.
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: 5L glass culture vessels
- Number of culture flasks/concentration: 2 (except the toxicity control, only one repllicate)
- Method used to create aerobic conditions: Air bubbled

SAMPLING
- Sampling frequency:
* Samples (2 ml) were taken from the first CO2 absorber vessel on days 0, 1, 2, 3, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 27, 28 and 29. The second absorber vessel was sampledon days 0 ad 29.
* On days 0 and 28 samples (20 ml) were removed from all culture vessels and centrifuged (3500 rpm, 15 minutes) prior to DOC analsyis
- Sample storage before analysis:
* Samples from days 0, 1, 2, 3, 6, 8, 12, 14, 16, 20, 22, 27, 28 and 29 were analysed for CO2 immediately. The samples from days 10, 18 and 24 were stored deep frozen at -20 °C in case of need for additional analysis (not analyzed in this case)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

STATISTICAL ANALYSIS:
One way analysis of variance incorporating Bartlett's test for homogeneity of variance and Dunnett's multiple comparison procedure for comparing several treatments with a control was carried out on the day 28 IC values for the control and test material vessels to determine any statistically differences between the test and control groups. All statistical analyses were performed using the SAS computer software package.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
0
Sampling time:
28 d
Details on results:
There was not statistically significant difference between the control and test material day 28 IC values. The test material was therefore considered not to have had a toxic effect on the sewage sludge micro-organisms used in the study. The toxicity control attained 44% degradation after 14 days and 54% degradation after 28 days thereby confirming that the test material was not toxic to sewage treatment micro-organisms used in the study.

Sodium benzoate attained 88% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

The total CO2 evoluation in the control vessels on Day 28 was 26.07 mg/L and therefore satisfied the validation criterion given in the OECD test guidelines.
The IC/TC ratio of the test material suspension in the mineral medium at the start of the test was below 5% and hence satisfied the validation criterion given in the OECD test guidelines.
The difference between the values for CO2 production at the end of the test for the replicate vessels was < 20 % and hence satified the validation criterion given in the OECD test guidelines.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test material attained 0% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the conditions of OECD Guideline 301B.
Executive summary:

The test material attained 0% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the conditions of OECD Guideline 301B.