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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report date:
1995

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
4,4'-dithiobis(5-amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-1H-pyrazole-3-carbonitrile)
EC Number:
603-434-4
Cas Number:
130755-46-3
Molecular formula:
C22 H8 Cl4 F6 N8 S2
IUPAC Name:
4,4'-dithiobis(5-amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-1H-pyrazole-3-carbonitrile)
Details on test material:
- Name of test material (as cited in study report): MB46307
- Physical state: light yellow powder
- Analytical purity: 972 g/kg
- Batch No.: 95.4023
- Storage condition of test material: at room temperature in the dark

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): From a municipal sewage treatment plant: "Waterschap de Maaskant", 's-Hertogenbosch, The Netherlands
- Method of cultivation: The sludge was kept under continuous aeration untill further treatment. Before use, the sludge was allowed to settle for at least 30 minutes.
- Concentration of sludge: 4.2 g/L

Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
40.65 - 40.85 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Test temperature: 20 - 22.5 °C
- pH: 7.5 - 7.8
- pH adjusted: no
- Aeration of dilution water: aerated with CO2-free air

TEST SYSTEM
- Culturing apparatus: 2 litre all-glass brown coloured bottles
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Aeration with CO2-free air
- Measurement: The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate. The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 M standardized HCl.
- Details of trap for CO2 and volatile organics if used: Three CO2-absorbers (bottles filled with 100 ml 0.0125 M Ba(OH)2) were connected in series to the exit air line of each test bottle.

SAMPLING
- Sampling frequency: Titrations were made every second or third day during the first 10 days, thereafter every fifth day until the 28th day.
- Sampling method: Each time the CO2-absorber nearest to the test bottle was removed for titration; each of the remaining two absorbers was moved one position in the direction of the test bottle. A new CO2-absorber was placed at the far end of the series.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Positive control: 1 replicate
- Toxicity control: 1 replicate

Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
< 10
Sampling time:
28 d
Details on results:
Fulfilled validation criteria:
- The positive control substance was degraded 65% in 14 days and 69% degradation was reached at the end of the test period.
- The total CO2 release in the blank reached a total value of 29 mg CO2 per 2 litres of medium.
- The difference of duplicate values for degradation of MB46307 was always less than 20%.
- MB46307 was found to be not inhibitory.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed