Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 May - 12 Jun 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: activated sludge from municipal wastewater treatment plant Breisgauer Bucht, Freiburg Region, Germany, capacity: 600000 inhabitant equivalents, sampled on 13th May 2003
- Pretreatment: Activated sludge was washed twice by settling the sludge, decanting the supernatant and resuspending the sludge in aerated tap water.
- Concentration of sludge: 4.5 g/L dry solids
Duration of test (contact time):
28 d
Initial conc.:
8.12 mg/L
Based on:
other: organic carbon
Parameter followed for biodegradation estimation:
CO2 evolution
Remarks:
via IC measurement
Details on study design:
TEST CONDITIONS
- Composition of medium: To a mineral medium, according to OECD 301B, 10 mL activated sludge (corresponding to 30 mg dry solids/L) was added. It was stirred overnight with a magnetic stirrer in a sealed CO2 free system (aeration with 2.7 - 5.5 bubbles CO2-free air/sec). Afterwards the test substance (8.12 mg organic carbon/L) was added. The stirring was continued over the whole test period.
- Test temperature: 22.0 - 24.0 °C
- Aeration of dilution water: with CO2 free air, aeration with 2.7 - 5.5 bubbles CO2-free air/sec

TEST SYSTEM
- Culturing apparatus: CO2-free air production system (reactor connected to two 1000 mL gas wash bottles filled with dry soda lime, followed by one bottle filled with 0.1 M sodium hydroxide, followed by one gas wash bottle filled with demineralised water, followed by an empty gas wash bottle to catch any drops of condensation water.)
- Number of culture flasks/concentration: 3 containing test item, 2 containing inoculum blank, 2 containing reference substance, 1 containing toxic reference

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
Reference substance:
benzoic acid, sodium salt
Remarks:
51.3 - 52.4 mg (corresponding to 19.9 - 20.4 mg TOC/L)
Parameter:
% degradation (CO2 evolution)
Value:
95
Sampling time:
14 d
Parameter:
% degradation (CO2 evolution)
Value:
100.5
Sampling time:
28 d
Details on results:
The test substance was biodegraded by > 60%, within the 10-day time window. Thus, it can be considered as readily biodegradable.
Results with reference substance:
The reference substance degraded > 60% within the 10-day time window. Thus, the inoculum and test system can be considered valid.

Table 1: Biodegradation of test substance, reference substance and toxic control

Days after test start Biodegradation [%]
test substance (mean of 3) Reference substance (mean of 2)  Toxic reference
0 0 0 0
4 69.4 69.8 74.2
7 87.6 76 83.3
10 84.7 77.8 89.1
14 95 83.4 97.4
21 91.1 86.7 104.2
28 100.5 87.9 111.2
28 (after acidification) 90.5 86.9 110.2
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 Aug - 06 Sep 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: activated sludge from municipal wastewater treatment plant Breisgauer Bucht, Freiburg Region, Germany, capacity: 600,000 inhabitant equivalents, sampled on 30 Jun 2003
- Pretreatment: Activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in aerated tap water.
- Concentration of sludge: 3.9 g/L dry solids
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
other: organic carbon
Parameter followed for biodegradation estimation:
CO2 evolution
Remarks:
via IC measurement
Details on study design:
TEST CONDITIONS
- Composition of medium: To a mineral medium according to OECD 301B, 30 mg/L activated sludge (corresponding to 20 mg organic carbon/L) was added. It was stirred overnight with a magnetic stirrer in a sealed CO2 free system (aeration with 2.7 - 5.5 bubbles CO2-free air/sec). Afterwards the test substance (15 g/L) was added. The stirring was continued over the whole test period.
- Test temperature: 21.3 - 23.0 °C
- Aeration of dilution water: with CO2 free air, aeration with 2.7 - 5.5 bubbles CO2-free air/sec

TEST SYSTEM
- Culturing apparatus: CO2-free air production system (reactor connected to two 1000 mL gas wash bottles filled with dry soda lime, followed by one bottle filled with 0.1 M sodium hydroxide, followed by one gas wash bottle filled with demineralised water, followed by an empty gas wash bottle to catch any drops of condensation water.)
- Number of culture flasks/concentration: 3 containing test item, 2 containing inoculum blank, 3 containing reference substance, 1 containing toxic reference

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
Reference substance:
benzoic acid, sodium salt
Remarks:
20 mg organic carbon/L
Parameter:
% degradation (CO2 evolution)
Value:
89.3
Sampling time:
28 d
Details on results:
The test substance was biodegraded by >60%, within the 10-day time window. Thus, it can be considered as readily biodegradable.
Results with reference substance:
The reference substance degraded > 60% within the 10-day time window. Thus, the inoculum and test system can be considered valid.

Table 1: Biodegradation of test substance, reference substance and toxic control

Days after test start Biodegradation [%]
Test substance (mean of 3) Reference substance (mean of 3) Toxic reference
0 0 0 0
4 41.4 73.1 43
7 62.7 80.6 52.3
10 79.6 86.1 73.9
14 82.5 82.5 75.9
20 85.4 96.1 84.8
28 88.7 101.3 82.6
28 (after acidification) 89.3 101.7 87.8
Interpretation of results:
readily biodegradable

Description of key information

Readily biodegradable according to OECD criteria: 100% after 28 days based on CO2 evolution (OECD 301 B).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Since no reliable biodegradability tests are available for Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to other structurally related substances was conducted.

One GLP study assessing biodegradation of the C12-isoAS Na (CAS 94200-74-5), performed according to OECD guideline 301 B is available (Sasol, 2003). Activated, non-adapted domestic sludge was used as inoculum. The substance was tested in a concentration of 8.12 mg/L (as organic carbon) and CO2 evolution was measured. In result, 100% of biodegradation was observed after 28-day test period, passing 10-day window. It can be concluded that the substance is readily biodegradable.

A supporting GLP test was performed according to OECD guideline 301 B (Sasol, 2003) with CAS 126-92-1 (C8-isoAS Na). Activated, domestic, non-adapted sludge was used as inoculum and the initial concentration of the test substance was 20 mg/L expressed as organic carbon. CO2 evolution was measured for 28 days. Biodegradation reached 89.3% after 28 days and 79.6% after 10 days passing the 10-day window. It can be concluded that C8-isoAS Na (CAS 126-92-1) is readily biodegradable according to OECD criteria.

Due to structural and property similarities with the tested substances it can be concluded that the above results apply also to Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt. The substance can be considered as readily biodegradable according to OECD criteria.