Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 28, 1994 - August 25, 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
other: Effluent from a strongly aerated laboratory activated sludge plant (RBM plant)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Effluent from a strongly aerated laboratory activated sludge plant (RBM plant).
- Storage conditions: The effluent was kept under aerobic conditions in the period between sampling and application.
- Preparation of inoculum for exposure: The sample was filtered through a coarse filter, the first 200 ml being discarded. The rest of the filtrate was kept aerobic until used. The inoculum was used on the day of collection.
- Initial cell/biomass concentration: Number of bacteria was determined by means of Cult-Dip plus (Merck)
- Water filtered: yes
- Type and size of filter used, if any: coarse filter.
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
Mineral medium:
Deionized water: <0.01 mg/Cu/l (EEC Directive 80/778)
Salt stock solutions:
Solution 1 (buffer solution): 8.5g KH2PO4, 28.5g K2HPO·3H2O, 33.4g Na2HPO4·2H2O and 0.5g NH4Cl were dissolved in 1 L distilled water. pH=7.4
Solution 2: 22.5 g MgSO4·7H2O/L distilled water
Solution 3: 36.4 g CaCl2·2H2O distilled water
Solution 4: 0.25 g FeCl3·6H2O distilled water
Preparation of the mineral medium: 1 ml each solutions 1 to 4 was added to 800 ml up to 1 L.
The large bottles were first filled to about one third of their volume with fully aerated mineral medium by hose. 0,5 ml of test or/and reference substance were added (0,5 ml of 1% w/v water solution) to obtain 2 mg/l concentration. Subsequently, the inoculum was added to the solution. Each prepared solution was filled into the respective group of bottles by hose from the lower quarter of the bottle to ensure adequate mixing.
- Test temperature: 20 ºC
- pH adjusted: No
- Aeration of dilution water: Yes, the inoculum was kept aerobic until used (shaking).
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Calibrated BOD bottles with glass stoppers.
- Number of culture flasks/concentration: 2 series of bottles (9 bottles): 1 (zero control), 2 (7 days), 2 (14 days), 2 (21 days), 2 (28 days).
- Method used to create aerobic conditions: The inoculum was kept aerobic until used (shaking). The inoculum was used on the day of collection.
- Measuring equipment: The concentration of dissolved oxygen was determined with the Winkler method.
- Other: water bath for keeping the bottles at constant temperature (20 ºC) excluding light.

SAMPLING
- Sampling frequency: 0, 7, 14, 21 and 28 days
- Sampling method: The bottles were removed from the water bath (20 ºC, dark) after 7, 14, 21 and 28 days and analysed for dissolver oxygen determination.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes.
- Toxicity control: Yes, inhibition test (reference substance and test control)
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Details on results:
The test article Fosfomycin PEA salt did not show biodegradability.
The test article Fosfomycin PEA salt did not show any biochemical oxygen demand during the test period.
The test article has no inhibitory effects on the bacteria inoculum at the concentration used in this study.
Key result
Parameter:
COD
Value:
1.638 mg O2/g test mat.
Results with reference substance:
The biodegradability of the reference substance (sodium acetate) on days 7, 14, 21 and 28 days was 71, 73, 83 and 92% respectively.

The test article Fosfomycin PEA salt did not show biodegradability.

The test article Fosfomycin PEA salt did not show any biochemical oxygen demand during the test period.

The test article has no inhibitory effects on the bacteria inoculum at the concentration used in this study.

Validity criteria fulfilled:
yes
Remarks:
Oxygen depletion in blank test did not exceed 1.5 mg dissolved 02/l after 28 d. Oxygen concentration in test bottle did not fall below 0,5 mg/L.
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The average COD value was 1.638 mg O2/mg.
In the conditions adopted in this study, the test article Fosfomycin PEA salt was not biodegradable and showed no inhibitory effect (toxicity) on the bacteria inoculum at the concentration used (2mg/l), although the biodegradation value in the inhibition test (about 37% of ThOD) may be considered as borderline.
Executive summary:

The ready biodegradability of the test article Fosfomycin PEA salt in an aerobic aqueous medium at the concentration of 2 mg/l was performed according to EU Method C.4 and OECD Guideline 301D by the Closed Bottle Test. Parallel groups of BOD bottles were prepared for the determination of the BOD values of the test article (2 mg/l of Fosfomycin PEA salt), reference substance (2 mg/l of sodium acetate, to check the activity of the substance) and the test plus the reference substance (inhibition test, to check inhibition effects of the substance, if any) together with the blank, with inoculum, in two simultaneous experimental series. The degradation was followed by oxygen analysis (Winkler method) over a 28 day period (7, 14, 21 and 28 days). The test article Fosfomycin PEA salt did not show any biochemical oxygen demand during the test period.

The biodegradability was calculated as BOD (mgO2/mg) / COD (mgO2/mg) x 100.

The COD test was performed in accordance with ISO 606 -1986. The average COD of the test article was 1.638 mg O2/mg.

In the condition adopted in this study the test article Fosfomycin PEA salt was not biodegradable and showed no inhibitory effect (toxicity) on the bacteria inoculum at the concentration used (2 mg/l), although the biodegradation value in the inhibition test (about 37% of ThOD) may be considered as borderline.

Description of key information

Key study: Test method according to EU Method C.4 and OECD Guideline 301D. GLP study.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Key study: Test method according to EU Method C.4 and OECD Guideline 301D. GLP study. In the conditions adopted in the study, the test article Fosfomycin PEA salt was not biodegradable at the concentration of 2 mg/l.