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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:
1997-01-15 - 1997-02-13
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
4-bromobenzonitrile
EC Number:
210-764-9
EC Name:
4-bromobenzonitrile
Cas Number:
623-00-7
Molecular formula:
C7H4BrN
IUPAC Name:
4-bromobenzonitrile
impurity 1
Chemical structure
Reference substance name:
2-bromobenzonitrile
EC Number:
218-045-1
EC Name:
2-bromobenzonitrile
Cas Number:
2042-37-7
Molecular formula:
C7H4BrN
IUPAC Name:
2-bromobenzonitrile
impurity 2
Chemical structure
Reference substance name:
3-bromobenzonitrile
EC Number:
230-127-9
EC Name:
3-bromobenzonitrile
Cas Number:
6952-59-6
Molecular formula:
C7H4BrN
IUPAC Name:
3-bromobenzonitrile
impurity 3
Chemical structure
Reference substance name:
Benzonitrile
EC Number:
202-855-7
EC Name:
Benzonitrile
Cas Number:
100-47-0
Molecular formula:
C7H5N
IUPAC Name:
benzonitrile
impurity 4
Chemical structure
Reference substance name:
Water
EC Number:
231-791-2
EC Name:
Water
Cas Number:
7732-18-5
Molecular formula:
H2O
IUPAC Name:
Water
Test material form:
solid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
The source of the test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Watershap de Maaskant', s-Hertogenbosch, the Netherlands.
The sludge was kept under continuous eration until further treatment. The concentration of suspended solids was 4.3 g/L in the concentrated sludge. Before use, the sludge was allowed to setle for at least 30 min and the liquid was decanted for use as inoculum at the amount of 10 mL/L of mineral medium.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
ca. 26 mg/L
Based on:
test mat.
Initial conc.:
ca. 12 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock solutions:
a) 08.50 g KH2PO4
21.75 g K2HPO4
67.20 g Na2HPO4 * 12 H2O
00.50 g NH4Cl
dissolved in 1 L purified deionized water, pH 7.4 +/- 0.2
b) 22.50 g MgSO4 * 7 H2O in 1 L purified deionized water
c) 36.40 g CaCl2 * 2 H2O in 1 L purified deionized water
d) 00.25 g FeCl3 * 6 H2O in 1 L purified deionized water

Mineral medium:
a) 10 mL
b) - d) 1 mL
filled up to 1 L with purified deionized water

- Additional substrate: Sodium acetate
- Solubilising agent (type and concentration if used):
- Test temperature: 20 - 23 °C
- pH: 7.3 - 7.5
- pH adjusted: yes, mineral medium
- CEC (meq/100 g):
- Aeration of dilution water: yes, CO2 free air
- Suspended solids concentration: 4.3 g/L in concentrated sludge
- Continuous darkness: yes, brown colored glass bottles
- Other:

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Mixture of O2 (21 %) and N2 (79 %), led through a solution of Ba(OH)2 (0.0125 M) to trap small amounts of CO2.
- Method used to create anaerobic conditions: %
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: yes
- Details of trap for CO2 and volatile organics if used: 3 CO2 absorbers (bottles filled with 100 ml 0.0125 M Ba(OH)2) in series
- Other:

SAMPLING
- Sampling frequency: every 2nd or 3rd day in the first 10 days, at least every 5th day until 28th day
- Sampling method: CO2 absorber nearest to test bottle was removed for titration, a new absorber was placed at the end of the series.
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes, Sodium acetate + test item
- Other:

STATISTICAL METHODS:
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
< 10
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
the percentage degradation of the reference substance reached the level for ready biodegradability (60 %) by 14 days.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
4-Brombenzonitrile is not ready biodegradable under the conditions of the modified Sturm test presently performed.
Executive summary:

4 -Brombenzonitrile was tested for its biodegradability in the carbon dioxide (CO2) evolution test (modified Sturm test) at ca. 52 mg per 2 L, corresponding to ca. 12 mg TOC / L.

The study procedure was based on ECC Directive 92769, C.4 -C, December 1992 and OECD guideline No. 301 B July 17, 1992.

The Theoretical CO2 production (ThCO2) of 4 -Bromobenzonitrile was calculated to be 1.692 CO2/mg.

The relative degradation values calculated from the measurementes perfomed during the test period revealed no significant degradation of 4 -Bromobenzinitrile (significant: >10 %).

In the toxicity control 4 -Bromobenzonitrile was found to be not inhibitory.

Since all acceptability criteria prescribed in by the protocol were met, this study was considered to be valid.

In conclusion. 4 -Bromobenzonitrile was not ready biodegradable under the conditions of the modified Sturm test presently performed.