2-{2-chloro-4-mesyl-3-[(tetrahydrofuran-2-ylmethoxy)methyl]benzoyl}cyclohexane-1,3-dione

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 Jul - 03 Aug 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen, Düsseldorf, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: aeration tank of the wastewater treatment plant Odenthal, Germany, treating predominantly domestic sewage
- Storage conditions: at room temperature under continuous stirring with aeration
- Storage length: 2 d, i.e. date of collection: 4 Jul 2016, start of incubation: 6 Jul 2016
- Pretreatment and preparation of inoculum for exposure: One day before start of the test the sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant. An aliquot of the wet sludge was dried in order to determine the wet weight/dry weight ratio of the sludge and to prepare a stock suspension (activated sludge) of 3 g dw/L. The calculated amount of sludge, needed to achieve 300 mL of this stock suspension, was dissolved in mineral medium and then filled up to a defined end volume. The suspension was stored again at room temperature under continuous stirring with aeration until start of the study the next day. Evaporated mineral medium was replaced.
- Concentration of inoculum: 30 mg/L suspended solids

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Initial conc.:

1.698 other: mg O2/mg

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium was prepared from 4 stock solutions of mineral components in deionised water, namely of 1) Mineral salt solution, 2) Magnesium sulphate solution, 3) Calcium chloride solution and 4) Iron (III) chloride solution
- Test temperature: 22 ± 1 °C
- pH: 7.3 - 7.9 after 28 d
- pH adjusted: no
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Test apparatus: OxiTopControl System (WTW)
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: The suspension of activated sluge was continuously aerated until study start.
- Details of trap for CO2: NaOH

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes: inoculum without test item, triplicate
- Reference: yes: inoculum wtih sodium benzoate, duplicate
- Toxicity control: yes: inoculum with test item and reference compound mixed, 1 replicate

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

4

Sampling time:

28 d

The toxicity control exhibited degradation rates > 25% within 12 d. The test substance was not toxic to bacteria at the tested concentration.

The reference compound showed 69% degradation after 14 d.

Degradation of the test substance was 4% after 7 and 14 d, 6% after 21 d and 4% after 28 d. At the end of the test, at the plateau, or the end of the 10 d window, biodegradation in parallels with test item did not differ by more than 20 percentage points.

The oxygen uptake of the inoculum blank was 48.8 mg O2/L after 28 days.

The test substance was considered to be "Not Readily Biodegradable".

Validity criteria fulfilled:

yes

Remarks:

See "Any other information on results incl. tables".

Interpretation of results:

not readily biodegradable

Description of key information

Not Readily Biodegradable (4% in 28 d, OECD 301 F)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

One GLP guideline study is available, which assessed the "Ready Biodegradability" of the test substance according to OECD guideline 301 F. Activated sludge was collected from the aeration tank of a local WWTP treating predominantly domestic sewage and was continuously aerated until test start. The test medium with a nominal concentration of 100 mg/L test substance, equivalent to 1.698 mg O2/mg ThOD was inoculated with the non-adapted activated sludge and incubated in the dark. Degradation was followed for 28 days by the continuous automated measurement of BOD. Results showed 4% degradation after 7 and 14 d, 6% after 21 d and 4% after 28 d. The toxicity control determined no toxic effects of the test substance on activated sludge organisms at the tested concentration. Therefore, the test substance is considered to be not readily biodegradable.