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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:
from 1999-03-25 to 1999-04-22
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study was performed according to OECD Guideline 301D and EU Method C.4-E with GLP statement. This study is deemed reliable although no pH measurement and no detail on mineral medium preparation were reported.
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Type: mixed population of aquatic microorganisms (activated sludge)
- Origin: the end of a sewage treatment plant, which is operated with municipal wastewater (Wupperverband).
- Day of Collection: 19.03.1999
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 2.7 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The substance is dissolved in a mineral medium inoculated with a mixed population of aquatic microorganisms and 28 days under aerobic conditions were incubated in the dark at 20 ± 1 ° C. The biodegradability of the substance is determined approaches during this time by the decrease of the concentration of dissolved oxygen in the test
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 82
Sampling time:
28 d
Remarks on result:
other: meeting the 14d window
Details on results:
34 and 37% biodegradation after 7 days (2 replicates)
52 and 62% biodegradation after 14 days (2 replicates)
69 and 71% biodegradation after 21 days (2 replicates)
81 and 83% biodegradation after 28 days (2 replicates)
Results with reference substance:
67 and 69% biodegradation after 7 days (2 replicates)
80 and 81% biodegradation after 14 days (2 replicates)
81 and 82% biodegradation after 21 days (2 replicates)
86 and 89% biodegradation after 28 days (2 replicates)

None

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance reached 82% biodegradation in 28 days. The test material met the 14-day window requirement for ready biodegradability. Therefore, under the test conditions, test substance was readily biodegradable.
Executive summary:

In a ready biodegradation study performed according to OECD Guideline 301 D and GLP, the test substance was tested at concentrations of 2.7 mg/L and the inoculum was activated sewage sludge, domestic. The degradation of the test material was assessed by the determination of the oxygen consumption. The test treatments, inoculum blank, and reference (sodium benzoate) were measured in duplicates.

At 2.7 mg/L test concentration, greater than 60% biodegradation was reached on Day 15. However, the test material met the 14-day window requirement for ready biodegradability. On Day 28, the biodegradation was 82%.

 

The reference material, sodium benzoate, reached greater than 60% biodegradation on Day 7. Test substance was considered to be non-toxic to micro-organisms as inhibition of the endogenous respiration of the inoculum was not detected during the test. Hence, it met the validity criteria for reference material and toxicity control. The endogenous respiration at Day 28 was less than 1.0 mg/L and oxygen concentration during the test was greater than 0.5 mg/L.

 

Under the test conditions, test substance was readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
From 1990-07-19 to 1990-08-16
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Remarks:
This study was performed according to OECD Guideline 301C without GLP statement. As some information on method (composition of mineral medium) and results are missing, the reliability of the study cannot be evaluated.
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
yes
Remarks:
no pH data reported, Temp. of 20°C instead of 25°C, inoculum prepared from only three samples
Principles of method if other than guideline:
Not applicable
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The activated sludge was prepared by mixing three fresh samples:
1. sludge from the biological waste water treatment plant of the City of Geneva (Aïre)
2. sludge from the biological waste water treatment plant of Vernier-Ouest, Geneva
3. soil sampled on the bank of the Rhône river
- Laboratory culture: no data
- Method of cultivation: no data
- Storage conditions: no data
- Storage length: no data
- Preparation of inoculum for exposure: no data
- Pretreatment: no data
- Concentration of sludge: 30 mg/L
- Initial cell/biomass concentration: no data
- Water filtered: no data
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: no data
- Additional substrate: no data
- Solubilising agent (type and concentration if used): no data
- Test temperature: 20°C
- pH: NO DATA
- pH adjusted: no data
- CEC (meq/100 g): no data
- Aeration of dilution water: no data
- Suspended solids concentration: no data
- Continuous darkness: no data

TEST SYSTEM
- Culturing apparatus: no data
- Number of culture flasks/concentration: 2 for the test substance, 1 for the reference substance, 1 for the blank
- Method used to create aerobic conditions: no data
- Measuring equipment: VOITH SAPROMAT, Laborapparte AG, CH-9105 SCHÖNENGRUND
- Test performed in closed vessels due to significant volatility of test substance: no data
- Test performed in open system: no data
- Details of trap for CO2 and volatile organics if used: no data

SAMPLING
- Sampling frequency: daily
- Sampling method: no data
- Sample storage before analysis: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: no data
Reference substance:
aniline
Preliminary study:
None
Test performance:
During this study, the oxygen consumption of the reference substance (aniline) started late (after 6 days only) but reached 70% degradation after 28 days. However this anomaly does not impact the conclusion of this study.
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 74
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
ca. 73
Sampling time:
13 d
Parameter:
% degradation (O2 consumption)
Value:
ca. 6
Sampling time:
3 d
Details on results:
See Table 5.2.1/1 in "Any other information on results incl. tables" for oxygen consumption results.
Results with reference substance:
The degradation rate of the reference substance (aniline) started late (after 6 days only) but reached 10% after 7 days and 70% degradation after 28 days.

Table 5.2.1/1: Oxygen consumption

Bottle n° Conc. of test chemical (mg/L) Respiration mg O2/L Respiration calc. for 100 mg/L Average
1 121 225 186 192
2 86 171 199
3 114 193 169  
4   0    
Validity criteria fulfilled:
not specified
Remarks:
no measure of pH
Interpretation of results:
readily biodegradable
Conclusions:
Despite the rather abnormal behaviour of the reference substance, the test substance should be considered readily biodegradable under the conditions of this test.
Executive summary:

A study was performed to assess the ready biodegradability of the test substance in an aerobic aqueous media. The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 301 C, "Modified MITI Test (I)".

The test material was exposed to activated sludge prepared by mixing three fresh samples (1. sludge from the biological waste water treatment plant of the City of Geneva (Aïre), 2. sludge from the biological waste water treatment plant of Vernier-Ouest, Geneva, 3. soil sampled on the bank of the Rhône river) at a concentration of 100 mg/L at 20°C for 28 days. The degradation of the test material was assessed by the measurement of daily oxygen consumption. Control solutions with inoculum and the reference substance, aniline, was used for validation purposes. No abiotic control was used.

This study lacks many endpoints required for assessing its reliability, such as pH measurement or details on inoculum preparation.

The degradation rate of the reference substance (aniline) started late (after 6 days only) but reached 10% after 7 days and 70% degradation after 28 days.

Under the conditions of this test , the test substance attained 74% degradation after 28 days and therefore should be considered to be readily biodegradable, under the strict terms and conditions of OECD Guideline No 301 C, despite the slightly abnormal behaviour of the reference substance.

Description of key information

OECD Guideline 301D, GLP, key study, validity 2:

82% biodegradation after 28 days, meeting the "10 -day window" criterion.

Readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

Two studies are available to assess the biodegradation of the registered substance.

The first study, assessed as a reliable key study, was performed on the registered substance according to OECD Guideline 301 D and GLP. The substance was exposed to activated sewage sludge (domestic) at a concentration of 2.7 mg/L. The degradation of the test material was assessed by the determination of the oxygen consumption. The test treatments, inoculum blank, and reference (sodium benzoate) were measured in duplicates. At 2.7 mg/L test concentration, greater than 60% biodegradation was reached on Day 15. However, the test material met the 14-day window requirement for ready biodegradability. On Day 28, the biodegradation was 82%. The reference material, sodium benzoate, reached greater than 60% biodegradation on Day 7. Test substance was considered to be non-toxic to micro-organisms as inhibition of the endogenous respiration of the inoculum was not detected during the test. Hence, it met the validity criteria for reference material and toxicity control. The endogenous respiration at Day 28 was less than 1.0 mg/L and oxygen concentration during the test was greater than 0.5 mg/L. Under the test conditions, the test substance was readily biodegradable.

The second study, assessed as a not assignable supporting study, was performed on the registered substance in an aerobic aqueous media, according to OECD Guideline 301 C. Due to the lacks of many endpoints required such as pH measurement or details on inoculum preparation, the reliability of this study cannot be evaluated. The substance was exposed to activated sludge prepared by mixing three fresh samples at a concentration of 100 mg/L at 20°C for 28 days. The degradation of the test substance was assessed by the measurement of daily oxygen consumption. Control solutions with inoculum and the reference substance, aniline, was used for validation purposes. The degradation rate of the reference substance (aniline) started late (after 6 days only) but reached 10% after 7 days and 70% degradation after 28 days. The test substance attained 74% degradation after 28 days and therefore should be considered to be readily biodegradable.

 

In conclusion, based on data available on the registered substance, this substance is considered readily biodegradable.