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Environmental fate & pathways

Biodegradation in water: screening tests

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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.
Justification for type of information:
Hydrocarbons, C9-C10, aromatics, >1% Naphthalene are a combination of Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics. Read across data is available for Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics and the worst case scenario for each end point has been presented.
Reason / purpose for cross-reference:
read-across: supporting information
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.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This summary represents a key study because it followed an OECD standard guideline, which describes a procedure specifically designed to evaluate this endpoint, and the results were reviewed for reliability and assessed as valid.
Justification for type of information:
Hydrocarbons, C9-C10, aromatics, >1% Naphthalene are a combination of Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics. Read across data is available for Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics and the worst case scenario for each end point has been presented.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1993
Deviations:
no
GLP compliance:
no
Remarks:
Not specified
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.:
45 mg/L
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 45mg/L. Sodium benzoate (positive control) concentration was 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:
30.9
Sampling time:
2 d
Parameter:
% degradation (O2 consumption)
Value:
50.2
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
62.1
Sampling time:
10 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
78
Sampling time:
28 d
Details on results:
% Degradation on day 28: 79.5, 78.6, 76.0
Results with reference substance:
% Degradation on day 28: 88.7, 88.9
Mean % Degradation: 88.8

The biodegradation half-life was <2 weeks. By day 28, 78.0% degradation of the test material was observed. 10% biodegradation was achieved on approximately day 3, 50% biodegradation on approximately day 7.

By day 14, >60% biodegradation of positive control was observed, which meets the guideline requirement. No deviations 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.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Biodegradation was greater than 60% in 28 days, therefore the test substance is readily biodegradable.
Executive summary:

This study was done to determine the ready biodegradability of the test substance. 45 mg/l of test stubstance was added to test medium containing activated sludge. The O2 consumption of the sludge was then monitored for the next 28 days. The test substance was degraded 78% in 28 days. The reference substance, sodium benzoate, was degraded 88.8% in 28 days, so the test is considered valid. The test substance is therefore readily biodegradable.

Description of key information

Hydrocarbons, C9-C10, aromatics, >1% Naphthalene are a combination of Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics. Read across data is available for Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics and the worst case scenario for each end point has been presented.

Hydrocarbons, C9, aromatics, were inherently to readily biodegradable in an OECD 301B, 301D and OECD 301F Manometric Respirometry test. The OECD 301F test resulted in 78% biodegradation in 28 days using a predominantly domestic aerobic non-acclimated activated sewage sludge inoculum. The OECD 301B and 301D tests resulted in 56% and 21%, respectively.

 

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.

This data is used for read across to Hydrocarbons, C9-C10, aromatics, >1% Naphthalene.

Key value for chemical safety assessment

Additional information

Hydrocarbons, C9, aromatics, are inherently to readily biodegradable in aerobic freshwater systems with a biodegradation potential in the range of 56 to 78% following standard testing guidelines. These substances are not expected to persist in the environment under aerobic conditions.

 

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.

 

The above data is used for read across to Hydrocarbons, C9-C10, aromatics, >1% Naphthalene. However, Hydrocarbons, C9-C10, aromatics, >1% Naphthalene are hydrocarbon UVCBs. Standard tests for this endpoint are intended for single substances and are not appropriate for these complex substances. However, this endpoint is characterized using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model (see Product Library in PETRORISK spreadsheet attached to IUCLID Section 13 of the dossier).