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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:
2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
see 'principles of method if other than guideline'
Principles of method if other than guideline:
The study plan states that the test vessels should be incubated at 22±2°C for the duration of the study. However, over the course of the experimental period the temperature ranged from 19.9 – 21.3°C. Incubation temperatures dropped to a minimum of 19.9°C on days 2, 3, and 12 of the experimental period. As these were minor deviations limited in number and duration, these temperature excursions are not considered to have had any impact on the ultimate result of this study.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Inoculum source: Cambridge STW, Cowley Road, Cambridge
Date of collection: 1st October 2019
Pre-treatment: Filtered (Whatman No. 54)
Temperature at start of test: 21.2°C
Concentration of inoculum: 1mL/L
Duration of test (contact time):
28 d
Initial conc.:
3 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
35
Sampling time:
7 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
81
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
52
Sampling time:
21 d
Parameter:
% degradation (O2 consumption)
Value:
63
Sampling time:
28 d
Details on results:
Phenol, ethoxylated achieved the requirements for a pass in this test (60% degradation relative to the ThOD value a maximum average degradation of 81% was recorded on day 14).

The OECD 301D guideline also requires that the test substance achieve a 14-day window, whereby 60% removal of the test substance is achieved within 14 days of 10% removal having been reached. As 81% removal was achieved within 14 days Phenol, ethoxylated passed this criteria.

All of the validity criteria were achieved over the course of the experimental period. Therefore, the final conclusion of this study is that Phenol, ethoxylated is readily biodegradable under the conditions of this test.
Results with reference substance:
The guideline requires that the reference material degrades by at least 60% of its ThOD, and that the blank dissolved oxygen loss does not exceed 1.5mg/l after 28 days. Both of these criteria were satisfied for this test; a maximum average degradation value of 80% degradation of the sodium acetate was achieved on day 14, and the maximum blank DO loss was 1.03mg/l recorded on day 28. The difference in degradation values at the replicate extremes should also not exceed 20%, test item degradation values differed by 5% on day 28, reference replicates did not differ on day 14.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Phenol, ethoxylated is concluded to be ready biodegradable under the conditions of the test.
Executive summary:

The biodegradation of Phenol, ethoxylated was evaluated in accordance with the OECD Testing Guideline 301D (Closed Bottle Test) and measured based on O2 consumption. The study was GLP-compliant.

The ThOD of the substance was calculated based on stuctural information. A ThOD of 2,145 mg O2 / g (corrected for concentration) was determined and used for the purpose of the study.

All of the validity criteria were achieved over the course of the experimental period. Phenol, ethoxylated achieved the requirements for a pass in this test (60% degradation relative to the ThOD value a maximum average degradation of 81% was recordedon day 14). The OECD 301D guideline also requires that the test substance achieve a 14-day window, whereby 60% removal of the test substance is achieved within 14 days of 10% removal having been reached. As 81% removal was achieved within 14 days Phenol, ethoxylated passed this criteria.

Phenol, ethoxylated is concluded to be ready biodegradable under the conditions of the test.

Description of key information

The biodegradation of Phenol, ethoxylated was evaluated in accordance with the OECD Testing Guideline 301D (Closed Bottle Test) and measured based on O2 consumption. The study was GLP-compliant.

The ThOD of the substance was calculated based on stuctural information. A ThOD of 2,145 mg O2 / g (corrected for concentration) was determined and used for the purpose of the study.

All of the validity criteria were achieved over the course of the experimental period. Therefore, the final conclusion of this study is that Phenol, ethoxylated is readily biodegradable under the conditions of this test.

Phenol, ethoxylated achieved the requirements for a pass in this test (60% degradation relative to the ThOD value a maximum average degradation of 81% was recorded on day 14). The OECD 301D guideline also requires that the test substance achieve a 14-day window, whereby 60% removal of the test substance is achieved within 14 days of 10% removal having been reached. As 81% removal was achieved within 14 days Phenol, ethoxylated passed this criteria.

Phenol, ethoxylated is concluded to be ready biodegradable under the conditions of the test.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information