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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Guideline study (OECD 301 E) with acceptable restrictions which do not impair the overall conclusion from the data; buffer used has a higher capacity than that described in OECD Guideline, incubation at 20+/-2°C instead of 22+/-2°C, no information about light conditions; information on purity of test substance is missing,but as ths substance is readily biodegradable potential impurities don't have a negative influence on the test result.
Qualifier:
according to
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
yes
Remarks:
incuabtion at 20+/-2°C instead of 22+/-2°C, no information about light conditions
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Initial conc.:
12.2 mg/L
Based on:
test mat.
Initial conc.:
24.3 mg/L
Based on:
test mat.
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
0 d
Remarks on result:
other: 12.2 mg/l BN added
Parameter:
% degradation (DOC removal)
Value:
100
Sampling time:
14 d
Remarks on result:
other: 12.2 mg/l BN added
Key result
Parameter:
% degradation (DOC removal)
Value:
100
Sampling time:
28 d
Remarks on result:
other: 12.2 mg/l BN added
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
0 d
Remarks on result:
other: 24.3 mg/l BN added
Key result
Parameter:
% degradation (DOC removal)
Value:
100
Sampling time:
14 d
Remarks on result:
other: 24.3 mg/l BN added
Details on results:
The results show a complete degradation of sodium acetate within one week as expected of an inoculum with sufficient activity. This degradation of sodium acetate was not influenced by the presence of benzonitrile in the medium.
A complete degradation of benzonitrile took place within 7 days.
12.2 mg/l BN added 24.3 mg/l BN added
Days mg DOC/l % mg DOC/l %
0 6 0 12 0
7 0 100 1 92
14 0 100 0 100
28 1 83 1 92
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Benzonitrile is regarded as readily biodegradable.
Executive summary:

The biodegradability of the product Benzonitrile was determined by the method laid down in the OECD Guideline 301E; 'Ready Biodegaradbility: Modified OECD Screening Test'.

Benzonitrile was tested in two concentrations: 12 mg/L and 24 mg/L. A control test with sodium acetate showed that the activity of the inoculum was sufficient, and that there was no inhibition of the inoculum activity by Benzonitrile.

Significant biodegradability was found in the test bottles with Benzonitrile; this substance is regarded as readily biodegradable.

Description of key information

Benzonitriles is regarded as readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradability of the product Benzonitrile was determined by the method laid down in the OECD Guideline 301E; 'Ready Biodegaradbility: Modified OECD Screening Test'.

Benzonitrile was tested at two concentrations: 12 mg/L and 24 mg/L. A control test with sodium acetate showed that the activity of the inoculum was sufficient, and that there was no inhibition of the inoculum activity by Benzonitrile.

Significant biodegradability was found in the test bottles with Benzonitrile; this substance is regarded as readily biodegradable.