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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:
19-Dec-2000 to 16-Jan-2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This robust summary has a reliability rating of 2 because the study followed a standard test guideline, there were no deviations from the protocol, however it was not conducted under GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
no
Remarks:
This study was done in the spirit of the GLPs.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Inoculum used as the source of the microorganisms was an aliquot of fresh activated sludge from a domestic wastewater treatment facility in New Jersey, USA.
Duration of test (contact time):
28 d
Initial conc.:
ca. 50 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Test material was tested in triplicate, controls and blanks were tested in duplicate. The amount of oxygen consumed by microorganisms from the oxidation of the test material was continuously monitored by an automated respirometer during the 28-day test period. Test material concentration was 50mg/L. Sodium benzoate (positive control) concentration was approximately 50mg/L. All test vessels were stirred constantly for 28 days using magnetic stir bars and plates.
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
2.9
St. dev.:
3.3
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
15.9
St. dev.:
9.47
Sampling time:
6 d
Parameter:
% degradation (O2 consumption)
Value:
50.69
St. dev.:
1.75
Sampling time:
17 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
57.95
St. dev.:
0.71
Sampling time:
28 d
Details on results:
Test material was inherently biodegradable. Half-life was approximately 17 days. By day 28, approximately 58.0% degradation of the test material was observed. 10% biodegradation was achieved on approximately day 6, 50% biodegradation on approximately day 16.

By day 14, >60% biodegradation of positive control was observed, which meets the guideline requirement. No excursions from the protocol were noted.

Biodegradation was based on oxygen consumption and the theoretical oxygen demand of the test material as calculated using results of an elemental analysis of the test material.
Results with reference substance:
Sodium benzoate, the positive control, achieved 94.42% with a standard deviation of 11.42% degradation after 28 days, and therefore this test may be considered valid.
  % Degradation* Mean % Degradation
Sample (day 28) (day 28)
Test Material 57.1, 58.1, 58.5  57.95
Na Benzoate 86.4, 107.5, 89.4 94.4

* replicate data

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
Hydrocarbons, C10, aromatics, >1% naphthalene, are inherently biodegradable under the conditions of the study and are not expected to persist in the environment under aerobic conditions.
Executive summary:

Hydrocarbons, C10, aromatics, >1% naphthalene, are inherently biodegradable under the conditions of the study and are not expected to persist in the environment under aerobic conditions.

Description of key information

Hydrocarbons, C10, aromatics, >1% naphthalene, biodegraded 58% after 28 days in an aerobic OECD 301F test, and under the conditions of the study was inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information