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Environmental fate & pathways

Biodegradation in water: screening tests

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biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Nov. 18, 2002-Dec. 19, 2002
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Marl-Ost municipal sewage treatment plant
- Initial cell/biomass concentration: 3.94 g/l dry matter
Duration of test (contact time):
29 d
Initial conc.:
34.3 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- Test temperature: 19.7-21.9 degree C
- pH: 7.4-7.5
- Aeration of dilution water: yes, overnight
- Suspended solids concentration: 26.3 mg/L

- Culturing apparatus: 5000 ml Woullf flasks
- Number of culture flasks/concentration: 2 flasks

- Sampling frequency: 0, 2, 5, 9, 12, 14, 21, 28, and 29 days

- Inoculum blank: 2 flasks

STATISTICAL METHODS: Results were calculated using the EXCEL computer program.
Reference substance:
benzoic acid, sodium salt
Key result
% degradation (CO2 evolution)
Sampling time:
29 d
Details on results:
The test substance was 85% degraded on day 29.
Results with reference substance:
The reference substance was 89% degraded in 29 days.

% Degradation

Test Duration
Sodium Benzoate Test Vessel 1 Test Vessel 2 Test Vessel Mean
0 0 0 -1 -1
2 32 1 -5 -2
5 59 24 19 22
9 76 57 46 52
12 84 73 66 70
14 84 72 67 70
21 93 76 79 78
28 95 86 80 83
29 89 84 85 85
Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
The test substance was 85% degraded in 29 days, and is considered readily biodegradable.
Executive summary:

This study examined the biodegradability of the test substance. 34.3 mg/L of test substance was added to flasks containing activated sludge. The amount of CO2 evolved was then measured over the next 29 days. Sodium benzoate was used as a reference substance. The reference substance was 89% degraded in 29 days. Therefore the test is valid. The test substance was 85% degraded in 29 days. The test substance is readily biodegradable.

biodegradation in water: ready biodegradability
Data waiving:
other justification
Justification for data waiving:

Description of key information

Benzenesulfonic acid, 4-dodecyl-, cerium(4+) salt consists of cerium cations and benzenesulfonic acid (4-C10-13-sec-alkyl derivate) anions. Based on the solubility of Benzenesulfonic acid, 4-dodecyl-, cerium(4+) salt in water, a complete dissociation resulting in cerium and benzenesulfonic acid (4-C10-13-sec-alkyl) ions may be assumed under environmental conditions.

The concept of biodegradation is not applicable to inorganic elements, including cerium. However, sodium 4-undecylbenzenesulfonate (CAS 68411-30-3), a structural analogue of benzenesulfonic acid (4-C10-13-sec-alkyl derivate) is readily biodegradable based on a standard OECD 301B test (83% degradation in 28 days meeting the 10-d window).

Key value for chemical safety assessment

Additional information