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Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

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

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the analogue justification attached to chapter 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (DOC removal)

Value:

-33.7

Sampling time:

28 d

Remarks on result:

other: Source, RA-A, Schulz, 2012, DOC Die-Away test 28 d

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Principles of method if other than guideline:

Calculation based on BIOWIN v4.10, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

Details on results:

For detailed description on the model and its applicability, see "Any other information on materials and methods incl. tables".

Table: Ready biodegradability prediction using BIOWIN v4.1

Biowin1 (Linear Model Prediction)	0.8111	biodegrades fast
Biowin2 (Non-Linear Model Prediction):	0.9426	biodegrades fast
Biowin3 (Ultimate Biodegradation Timeframe):	2.837	weeks
Biowin4 (Primary Biodegradation Timeframe):	3.572	days-weeks
Biowin5 (MITI Linear Model Prediction) :	0.5173	biodegrades fast
Biowin6 (MITI Non-Linear Model Prediction):	0.6189	biodegrades fast
Biowin7 (Anaerobic Model Prediction):	-0.0029	does not biodegrade fast
Ready Biodegradability Prediction:		yes

 

Interpretation of results:

readily biodegradable

Description of key information

The substance is not readily biodegradable in water according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Experimental data on the ready biodegradability of Reaction mass of dipotassium 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinate and dipotassium 2-(4,5-dimethy-1H-pyrazol-1-yl) succinate are not available.The assessment was therefore based on a study conducted with the conjugate acid Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid (CAS 2241455-89-8). The read across approach is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Please refer to the analogue justification attached to IUCLID section 13 for a detailed justification.

One ready biodegradability study is available for the source substance 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. 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.

Based on the results for the source substance the target Reaction mass of dipotassium 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinate and dipotassium 2-(4,5-dimethy-1H-pyrazol-1-yl) succinate is considered to be not readily biodegradable in water according to OECD criteria.

A supporting QSAR calculation with the soil metabolite 3,4-dimethylpyrazole (DMP) of the source substance predicted ready biodegradability for the metabolite.