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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:
29 AUG 1996 - 14 OCT 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The test was perfomed in compliance with GLP and the method applied follows principles descibed in the OECD Guidelines for Testing of Chemicals Ready Biodegradability - CO2 Evolution Test 301 B; Paris 1993.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): 30 mg/L dry substance from laboratory waste water treatment plants with municipal and synthetic sewage.
- Laboratory culture: The inoculum was pre-aerated two days before the start of the test.
Duration of test (contact time):
28 d
Initial conc.:
31.7 mg/L
Based on:
test mat.
Initial conc.:
32.1 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: inorganic medium
- Test temperature: room temperature

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Inoculum was pre-aerated two days before the start of the test
- Measuring equipment: DOC analyser (Shimadzu TOC 5000)

SAMPLING
- Sampling frequency: Day 0, 1, 3, 5, 7, 10, 14, 17, 21, 24, 27, 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes
Reference substance:
aniline
Preliminary study:
Theoretical organic carbon (THOC) mg/g: 636
Theoretical CO2 production (ThCO2) mg/g: 2334
Test performance:
Start of the test : 30.08.1996
Test duration (days) : 28 + 1
Duration of adaptation phase (days)
Duration of degradation phase (days) : --

Validity criteria:
Maximal deviation of the degradation degree in parallel vessels: < 20%
Reference substance: ANILINE
Degradation of the reference substance (% CO2/ThCO2): 90-100 AFTER 14 DAYS
Degradation of the reference substance >60% after 14 days: YES
DIC in the blank control at 20 mg/L TOC test concentration: < 1 mg/L
CO2 production in the blank control: 30-40 mg/L
Degradation in the inhibition control (% CO2/ThCO2): 40-50
Degradation in the inhibition control after 14 days: > 25 %
Inhibition of the inoculum at the test concentration: NO
Test is valid: YES

Proof of biodegradation:
10-day-window met: NO
No pre-adapted inoculum used: YES
Test substance readily biodegradable according to OECD criteria : NO
Parameter:
% degradation (CO2 evolution)
Value:
> 0 - < 10
Sampling time:
28 d
Details on results:
sampling on days: 0, 1, 3, 5, 7, 10, 14, 17, 21, 24, 27, 28
Results with reference substance:
Degradation of the reference substance (% CO2/ThCO2): 90-100 after 14 d
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The percentage biodegradation did not exceed 60 % within the 10-day window or after 28 days of incubation. The test item can therefore be considered not to be readily biodegradable.
Executive summary:

The registered substance was tested for ready biodegradation in a CO2-evolution test according to OECD Guideline 301B following GLP.

Purpose
The purpose of this assay was to provide information on the biodegradability of the test item in aqueous environment and thus serve as a rational basis for risk assessment for environmental fate in aqueous compartments.

Study Design
The test item was investigated for its ready biodegradability in a dioxide evolution test (former Sturm test) over a period of 28 days. The biodegradation was followed measuring the production of carbon dioxide (CO2) which is a clear indication of biodegradation. The measured amount of carbon dioxide at the end of the test is compared with the calculated maximal theoretical production (ThCO2) and indicated as biodegradation degree in per cent. As the microorganisms oxidize only a part of the test substance and incorporate the rest into biomass, a degradation level >60 % is considered as sufficient biodegradation.

Result
Biodegradation
Under the test conditions the percentage biodegradation amounts to 3 % (mean value) after 28 days of incubation.
The test item can therefore be considered not to be readily biodegradable.

Biodegradation of Aniline
The reference item Aniline was sufficiently degraded to 95 % after 14 days and 96 % after 28 days of incubation thus confirming the suitability of the used activated sludge inoculum.

Biodegradation in the Toxicity Control
In the toxicity control containing both, the test item and the reference item Aniline, 42 % biodegradation was noted within 14 days and 49 % biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge micro organisms.

Conclusion
The percentage biodegradation did not exceed 60 % within the 10-day window or after 28 days of incubation. The test item can therefore be considered not to be readily biodegradable.

Description of key information

Key, CO2-evolution test, OECD 301B, GLP: not ready biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

CO2-evolution test, OECD 301B

The registered substance was tested for ready biodegradation in a CO2-evolution test according to OECD Guideline 301B following GLP.

Purpose
The purpose of this assay was to provide information on the biodegradability of the test item in aqueous environment and thus serve as a rational basis for risk assessment for environmental fate in aqueous compartments.

Study Design
The test item was investigated for its ready biodegradability in a dioxide evolution test (former Sturm test) over a period of 28 days. The biodegradation was followed measuring the production of carbon dioxide (CO2) which is a clear indication of biodegradation. The measured amount of carbon dioxide at the end of the test is compared with the calculated maximal theoretical production (ThCO2) and indicated as biodegradation degree in per cent. As the microorganisms oxidize only a part of the test substance and incorporate the rest into biomass, a degradation level >60 % is considered as sufficient biodegradation.

Result
Biodegradation
Under the test conditions the percentage biodegradation amounts to 3 % (mean value) after 28 days of incubation.
The test item can therefore be considered not to be readily biodegradable.

Biodegradation of Aniline
The reference item Aniline was sufficiently degraded to 95 % after 14 days and 96 % after 28 days of incubation thus confirming the suitability of the used activated sludge inoculum.

Biodegradation in the Toxicity Control
In the toxicity control containing both, the test item and the reference item Aniline, 42 % biodegradation was noted within 14 days and 49 % biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge micro organisms.

Conclusion
The percentage biodegradation did not exceed 60 % within the 10-day window or after 28 days of incubation. The test item can therefore be considered not to be readily biodegradable.