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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:
06 Jun - 13 Jul 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Sächsisches Ministerium für Umwelt und Landwirtschaft, Germany
Oxygen conditions:
aerobic
Inoculum or test system:
other: secondary effluent of a wastewater treatment plant
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sample was taken on 01.06.2012 at the wastewater treatment plant “Parthe” (Am Klärwerk 49, 04451 Borsdorf, Saxony, Germany)
- Preparation of inoculum for exposure: pre-conditioned by aerating for 5 days (from 01.- 06.06.2012) under test conditions
- Initial cell/biomass concentration: 22.37 mg suspended solids/L in the test solutions
Duration of test (contact time):
28 d
Initial conc.:
40 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: The mineral medium was prepared in accordance with OECD guideline 301 A (1992).
- Test temperature: 23.1 - 23.9 °C in a controlled-environment test room
- pH: 7.4
- Suspended solids concentration: 22.37 mg suspended solids/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2 L conical glass flask
- Number of culture flasks/concentration: 2
- Measuring equipment: DOC analyser
- Test performed in open system: The openings of the flasks were covered with aluminium foil in such a way as to allow free exchange of air between the flask and the atmosphere.

SAMPLING
- Sampling frequency: 0, 1, 2, 10, 22, 27 and 28 days after test start
- Sampling method: Before sampling water loss was compensated if necessary by adding deionised water.
- Sample storage before analysis: If possible the analysis was performed immediately after sampling. Otherwise the samples were stored at 2-4 °C for a maximum of 48 hours or below -18 °C.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 bottles
- Abiotic sterile control: no
- Toxicity control: yes, 1 bottle
- Reference item: yes, 1 bottle
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
-33.7
Sampling time:
28 d
Details on results:
- No biodegradation of the test item was observed during the study.
- The biodegradation rate of the toxicity control was 50.9 % at the end of the test period (day 28).
Results with reference substance:
23.4% biodegradation after 1 days
89.2% biodegradation after 2 days
89.0% biodegradation after 10 days
79.5% biodegradation after 22 days
79.9% biodegradation after 27 days
81.8% biodegradation after 28 days
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed

Description of key information

No biodegradation observed after 28 days (OECD 301 A; secondary effluent)

Key value for chemical safety assessment

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

Additional information

One ready biodegradability study is available for Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid. It was conducted according to OECD Guideline 301 A and GLP (Schulz, 2012). Secondary effluent of a wastewater treatment plant, used as inoculum, was exposed to the test substance during 28 days. No significant biodegradation was observed during the test period. Thus, the substance is not readily biodegradable according to the OECD criteria. The soil metabolite 3,4-dimethylpyrazole (DMP) is considered to be readily biodegradable based on reliable QSAR estimations.