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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
October 5, 1993 to December 13, 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum: Chemical Biotesting Center, Chemical Inspection and Testing Institute, Japan
- Concentration of sludge: 30 mg/L
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 25 ± 1°C
- Test volume: 300 mL

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Value:
3
Sampling time:
28 d
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: OECD 301B (1981)
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: EN 160068.82
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge of the sewage treatment plant of CH - 4106 Therwil on 08/05/89
- Preparation of inoculum for exposure: According to guideline
Duration of test (contact time):
28 d
Initial conc.:
10.4 mg/L
Based on:
test mat.
Initial conc.:
20.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: 1200 mL of the medium with the inoculum were aerated for 24 hours in the test vessel. In 300 mL mineral solution 0.5 mL Nonylphenol 10E05P0 (solution of 30 mg in 100 mL bidist. water) and 15.6 rsp. 30.8 mg of test substance were added and homogenized. This solution was given to the test vessel which was immediately connected to the CO2 traps.
- Solubilising agent: Nonylphenol
- Test temperature: 22 ± 2°C
- Aeration of dilution water: 25 mL/min air free of carbon dioxide.

TEST SYSTEM
- Culturing apparatus: 2 Liter flasks (dark brown glass) equipped with gas inlet and magnetic stirrer.
- Number of culture flasks/concentration: 1
- Measurements: The CO2 formed by biodégradation was absorbed with NaOH and determined on a carbon analyzer.
- Test performed in open system: No

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
2
Sampling time:
28 d
Remarks on result:
other: Test substance concentration: 20.5 mg/L
Key result
Parameter:
% degradation (CO2 evolution)
Value:
4
Sampling time:
28 d
Remarks on result:
other: Test substance concentration: 10.4 mg/L
Details on results:
Points of degradation plot (test substance):
0 % degradation after 3 d
0 % degradation after 7 d
1 % degradation after 10 d
1 % degradation after 17 d
1 % degradation after 20 d
2 % degradation after 24 d
2 % degradation after 27 d
2 % degradation after 28 d
Results with reference substance:
Points of degradation plot (reference substance):
0 % degradation after 3 d
49 % degradation after 7 d
65 % degradation after 10 d
77 % degradation after 17 d
80 % degradation after 20 d
85 % degradation after 24 d
88 % degradation after 27 d
92 % degradation after 28 d
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable

Description of key information

Not readily biodegradable


2-4% biodegradation (Co2 formation/ O2 consumption) in 28 days (OECD 301B/C)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The available studies according to OECD guidelines No. 301 B and C revealed 2 to 4 % biodegradation of the test substance after 28 days respectively (Ciba-Geigy, 1989; Ciba-Geigy 1994).

Furthermore, a disregarded study revealed a chemical oxygen demand of 1.77 g O2/g test material.

The results show, that the substance is not readily biodegradable.